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 Alias|Wavefront / Assistant Online / Maya / How Tos




                                                How-to's are step-by-step tutorials that are designed to help you
                                                learn more about Maya. While some lessons let you start from
                                                scratch, other lessons may provide a start file for you to begin with.
                                                Note - These files may not perform as expected. Always back up
                                                your work before using any files downloaded from this website.
                                                These how-to's have been updated to work in Maya 2.5. However,
                                                unless otherwise noted, they will also work in Maya 2.0.
                                                Maya how-to's are available in the following categories:
                                                 Animation
                                                How to Model a Flexo                            Maya 2.5 Complete
                                                How to Build and Animate an Iris                Maya 2.5 Complete
                                                How to Pick Up an Object                        Maya 2.5 Complete
                                                How to Animate an Accurate Clock                Maya 2.5 Complete
                                                How to Animate an Extrusion                     Maya 2.5 Complete
                                                How to Animate the Aiming of a Spotlight        Maya 2.5 Complete
                                                How to Animate a Rolling Cube                   Maya 2.5 Complete
                                                How to Animate with Flow (Object)               Maya 2.5 Complete
                                                How to Animate with Flow (Curve)                Maya 2.5 Complete
                                                 Character
                                                How to Create SoftBodies in Character
                                                                                                      Maya 1.5 FX
                                                Animation
                                                How to Blend Facial Poses                       Maya 2.5 Complete
                                                 Compositing
                                                How to Composite Hardware and Software
                                                                                                        Maya Fusion Lite
                                                Rendered Images NEW!
                                                How to Composite using zDepth Maps                        Composer 5.0
                                                How to change the default event colors                    Composer 5.0
                                                How to create a Composer undo                             Composer 5.0
                                                How to Extract Images from a Movie                      Maya Fusion Lite
                                                How to fake 3D shadows                                    Composer 5.0
                                                How to Glow Highlights                                    Composer 5.0
                                                How to layer an unpre-multiplied image                    Composer 5.0
                                                How to Manage your macros                                 Composer 5.0
                                                How to set up Maya renders for Compositing                Composer 5.0
                                                 Dynamics - Particle

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Assistant Online - Maya/How Tos

                                             How to Create a Ring of Fire                Maya 2.5 Complete
                                             How to use Particles to Drive Rigid Bodies  Maya 2.5 Complete
                                             How to Create an Exploding Fireball         Maya 2.5 Complete
                                              Dynamics - Rigid Body
                                             How to Animate a Chain Link                 Maya 2.5 Complete
                                             How to Create a Newton's Pendulum           Maya 2.5 Complete
                                              Dynamics - Soft Body
                                             How to Animate a Melting Object             Maya 2.5 Complete
                                             How to Create an Inflating Balloon          Maya 2.5 Complete
                                             How to animate a Gelatin cube               Maya 2.5 Complete
                                             How to Create a Waving Flag                 Maya 2.5 Complete
                                             How to Create Footprints                    Maya 2.5 Complete
                                              Games - NEW!
                                             How to Prelight a Scene                       Maya 2.5 Builder
                                              Maya Fur
                                             How to Comb Fur                             Maya 2.5 Unlimited
                                              MEL
                                             How to use attrCollection.mel Script        Maya 2.5 Unlimited
                                             How to use an "relocateTexturesWin"          Maya 2 Complete
                                             How to use an Assistant Online MEL
                                                                                         Maya 2.5 Complete
                                             Script
                                             Hot to use QTVR.mel Script                  Maya 2.5 Complete
                                              Miscellaneous
                                             Learning Maya 2.5 Addendum (PDF 128k)       Maya 2.5 Complete
                                              Modeling
                                             How to Build a Spiral Staircase             Maya 2.5 Complete
                                             How to Build a Polygonal Gear               Maya 2.5 Complete
                                             How to Use bevelCaps.mel Script             Maya 2.5 Complete
                                             How to Use NURBS Booleans                   Maya 2.5 Unlimited
                                             How to Create Square Surfaces               Maya 2.5 Unlimited
                                              Paint Effects - NEW!
                                             How to Create a Tree using PaintFX NEW!     Maya 2.5 Complete
                                              Rendering
                                             How to Make Natural Clouds                  Maya 2.5 Complete
                                             How to Animate Texture Files                Maya 2.5 Complete
                                             How to Create a Ball Env Reflection Map     Maya 2.5 Complete
                                             How to Create Camera Cuts                   Maya 2.5 Complete
                                             How to Create a Double-sided shader         Maya 2.5 Complete
                                             How to Create a Ghost Shader                Maya 2.5 Complete
                                             How to Create a Light GOBO with Barn Doors Maya 2.5 Complete
                                             How to Create a Realistic Sky with EnvSky   Maya 2.5 Complete
                                             How to Create Realistic Shadows with EnvSky Maya 2.5 Complete
                                             How to Create Realistic Glass               Maya 2.5 Complete
                                             How to Create a Soft Spotlight              Maya 2.5 Complete
                                             How to Combine Bump and Displacement
                                                                                         Maya 2.5 Complete
                                             Maps
                                             How to Make a Cartoon Shader                Maya 2.5 Complete


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                                             How to Make Water Ripple                                   Maya 2.5 Complete
                                             Technical Overview on Aliasing
                                                                                                           Maya 1.5 Base
                                             Artifacts
                                             Technical Overview of Maya Software
                                                                                                           Maya 1.5 Base
                                             Rendering
                                             How to Set up Reflections and Refractions                  Maya 2.5 Complete
                                             How to Share Texture Nodes                                 Maya 2.5 Complete
                                             How-to Set Up Depth of Field                               Maya 2.5 Complete




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Assistant Online - Maya/How Tos/Animation/Flexo




 Alias|Wavefront / Assistant Online / Maya / How Tos / Animation / Flexo




                                                  HOW TO MODEL A FLEXO WITH                               namtar@scsinet.es
                                                 MAYA

                                                                                         by Lluís Llobera Trias - Quod/IDEP
                                                                                                                      Spain


                                                 Maya Complete
                                                 Animation
                                                 This is a tutorial to
                                                 create and make fully
                                                 operative, with Maya,
                                                 a flexo-type arm like
                                                 those used to hold
                                                 lights. You will work
                                                 with expressions,
                                                 driven keys, pivot
                                                 position, and
                                                 constraints. You will               Click to view larger version
                                                 also learn to add attributes and work with the Graph Editor.
                                                 The point of this exercise is to create a series of arms that
                                                 rotate properly together when the main arm of the flexo does.
                                                 Note: throughout the tutorial, you are told how to create a 5-arm flexo;
                                                 however, all the pictures contained in this document show a 10-arm
                                                 flexo. In fact, there's no arm limit as long as you follow the method
                                                 correctly.


                                                    STEP ONE

                                                 In "extensible" arms
                                                 such as these, you get
                                                 the same element
                                                 repeated a number of
                                                 times. Therefore it is
                                                 very important that the
                                                 first arm created has
                                                 some kind of a solid
                                                 structure. You are
                                                 going to create a cylinder grouped twice with itself, positioning
                                                 the pivot for every node in a proper position.


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Assistant Online - Maya/How Tos/Animation/Flexo

                                                  q     Create a NURBS cylinder and name it "c_i", for "inferior
                                                        constraint". Go to the Channel Box and set its Y scale
                                                        to 10, and its Z scale to 0.4.
                                                  q     Enter "Insert" to edit the Pivot Point position, then go to
                                                        the Numerical Input Line, which is a white space just
                                                        above the Channel Box. Enter the values 0 -10 0.
                                              You should see that the pivot has moved at the bottom of the
                                              cylinder. Enter "Insert" again to go back to object editing
                                              mode.
                                              Group the cylinder with itself, and name the new group "c_s",
                                              for "superior constraint". Now follow the previous steps to
                                              position its pivot point at the top of the cylinder (that's 0 10 0).
                                              Group the node c_s with itself, and name the new group
                                              "SUP_01". Now you can rotate the node SUP_01 45 degrees
                                              in the Z axis. You have successfully created the first arm of
                                              the flexo.


                                                STEP TWO

                                              Enter
                                              Edit->Duplicate->
                                              Options and reset the
                                              values.
                                              Duplicate the node
                                              SUP_01 and name its
                                              copy INF_01. In the
                                              Channel Box, set its Z
                                              translation to 1.
                                              Now you are going to create an expression to make this new
                                              node rotate every time that the superior arm does. Check that
                                              INF_01 is still selected, and go to Window->Expression
                                              Editor. Name the new expression "inf_rotate", and enter in the
                                              expressions area
                                              INF_01.rz = 180 - SUP_01.rz ;
                                              Click on "Create". From now on, every time that the SUP_01
                                              rotates in the Z axis, the INF_01 will rotate also. Check it if
                                              you want. After you have, set the Z rotation for the SUP_01 to
                                              45 again -- the whole exercise will assume this as its value.
                                              Since the arms of the flexo are alternated, you will now have
                                              to move the pivot points of the c_i and c_s nodes of the
                                              SUP_01 and INF_01 arms in an absolute Z translation of 0.5.
                                              To achieve this, the easiest procedure is to select each of the
                                              sub-nodes, click "Insert" and, in the Numeric Input Line,
                                              enter
                                              . . 0.5



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Assistant Online - Maya/How Tos/Animation/Flexo

                                              You will have to repeat this operation for each of the
                                              sub-nodes.


                                                STEP THREE

                                              Select SUP_01 and
                                              INF_01 and then select
                                              Edit-> Duplicate->
                                              Options. Set the
                                              number of copies to 4
                                              and click on the
                                              "Duplicate Input
                                              Connections" box.
                                              When you click on
                                              "Duplicate", Maya will create four new superior cylinders,
                                              called SUP_02 to SUP_05, and four inferior cylinders which
                                              are named INF_02 to INF_05. Select in the Outliner the nodes
                                              SUP_02 and INF_02, and set them to an X translate of 14
                                              units. Pick the next two nodes, move them to 28, and so on.
                                              Now look what happens when you rotate the SUP_01 : only
                                              the inferior arms rotate with it. This is because only INF_01
                                              had the expression applied, and therefore the superior arms
                                              aren't aware of what is going on.


                                                STEP FOUR

                                              Select the nodes
                                              SUP_02 to SUP_05
                                              and (in the
                                              Animation menu)
                                              select
                                              Animate-> Set
                                              Driven
                                              Key-> Set-> Options.
                                              The Set Driven Key
                                              window will pop up (from now on, we will call it SDK). In the
                                              "Driven" frame you'll see the four nodes you have just
                                              selected.
                                              In any orthographic window select the SUP_01 and, returning
                                              to the SDK, click on "Load Driver" to place it in the "Driver"
                                              frame.
                                              Click on the "Rotate Z" next to the Driver frame (it'll get dark),
                                              and select the four nodes in the Driver. Click on their "Rotate
                                              Z". Now click on "Key" to set the first connection.
                                              Select the SUP_01 node and set its Z rotation to 60 degrees.
                                              After that, select the SUP_02 to SUP_05 nodes and rotate
                                              them to 60 in Z as well. In the SDK window, set the second
                                              connection by clicking on "Key". Close the SDK.


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Assistant Online - Maya/How Tos/Animation/Flexo

                                              Look what you have now: the superior arms only seem to
                                              work properly when the Z rotation of SUP_01 is between 45
                                              and 60 degrees. Let us fix this.
                                              Select the nodes SUP_02 to SUP_05 and go to Window->
                                              Animation Editors-> Graph Editor. Press the "f" key to
                                              execute a "frame all"; a blue curve will appear in the right
                                              window. Select it (all of it, including its beginning and end) and
                                              enter :
                                              Curves -> Pre Infinity -> Cycle with Offset
                                              Curves -> Post Infinity -> Cycle with Offset
                                              Close the Graph Editor. Now all the arms rotate correctly.


                                              STEP FIVE

                                              Using the Outliner or
                                              the Hypergraph, add
                                              constraints from
                                              certain nodes to the
                                              other ones. This is the
                                              formula to do it:
                                                 q Select the node
                                                    c_i from
                                                    SUP_0x, then
                                                    the node c_s
                                                    from INF_0(x+1).
                                                 q Select
                                                    Constraints->
                                                    Point. You also
                                                    have to do it the
                                                    other way
                                                    around, i.e.:
                                                    select the node
                                                    c_i from INF_0x,
                                                    then the node
                                                    c_s from
                                                    SUP_0(x+1) and
                                                    select
                                                    Constraints->
                                                    Point.
                                              For example, the first step is to select c_i from SUP_01 and
                                              c_s from INF_02 and constraint them. Then, pick the c_i from
                                              INF_01 and the c_s from SUP_02 and constraint them too.
                                              Continue until you have no arms left.




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Assistant Online - Maya/How Tos/Animation/Flexo

                                                STEP SIX

                                              You should now have
                                              the flexo working
                                              correctly. But having to
                                              depend on the Z
                                              rotation for SUP_01 is
                                              time consuming, and
                                              inefficient.
                                              Now we will create a
                                              new node with an attribute to get it to work.
                                                 q Select all the nodes (Right Click and "select all" is the
                                                   easiest way) and group them.
                                                 q Name the group "FLEXO".

                                                 q Enter "Insert" to edit its pivot point position.

                                                 q Go to the Numeric Input Line and enter:

                                                                                      . 15 .
                                              Select Display-> Objects Components-> Selection
                                              Handles. From now on, you'll be able to select the whole
                                              object by clicking on this handle.
                                              Now select Modify-> Add Attribute. Name the new attribute
                                              "Length", enter 0 for its minimum value, 100 for the
                                              maximum, and 50 as default value.
                                              Select the node SUP_01, and select Animate -> Set Driven
                                              Key -> Set -> Options. Load the node FLEXO as the driver.
                                              Select the attribute "Length" next to the Driver frame, and the
                                              Z rotation from the Driven frame. Press Enter.
                                              Set the "Length" Value to 0, and the Z rotation for SUP_01 to
                                              0. Click on "Key". Now set "Length" to 100 and the Z rotation
                                              for the SUP_01 to 90. "Key" it again.


                                              CONCLUSION

                                              Well then you have
                                              just finished building
                                              the flexo!
                                              Now it's up to you to
                                              add details, such as
                                              the joints (which
                                              should be constrained
                                              to the nodes c_i from
                                              the arms), etc.
                                                                                Click to view larger version
                                              Here's the final file for
                                              you to download. You can open it with any version of Maya.
                                              flexo.ma (~270k)


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                                              Use of this file confirms your agreement to the Terms and Conditions
                                              set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Animation/Iris




 Alias|Wavefront / Assistant Online / Maya / How Tos / Animation / Iris




                                                    HOW TO BUILD AN IRIS                                               By Alan Harris
                                                  Maya Complete
                                                  Animation
                                                  In this lesson, you will learn
                                                  how to build an iris and use
                                                  Set Driven Key to animate it
                                                  opening and closing.
                                                  To achieve this, you will
                                                  create a locator and add an
                                                  attribute called Shutter. This
                                                  attribute will range from 0 to                 Play Movie [321 k]
                                                  10. 10 equals the iris in closed the position.


                                                     STEP ONE

                                                  Set the Grid Options to
                                                  default settings.
                                                  Create two Nurbs circles at
                                                  the origin -- one 10 units and
                                                  the other 5 units. Template
                                                  them to use as guides.
                                                     q Create a closed CV
                                                        Curve as shown.
                                                     q Duplicate the curve
                                                        and translate in Y to
                                                        -0.2
                                                     q Select the top curve
                                                        and select Surfaces >
                                                        Planar.
                                                     q Select the top curve
                                                        and the bottom curve
                                                        and select Surfaces >
                                                        Loft.
                                                     q Delete the curves or
                                                        delete history on the
                                                        surfaces.



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Assistant Online - Maya/How Tos/Animation/Iris

                                                 STEP TWO

                                              You will need to group these
                                              surfaces twice to get two different
                                              pivot points. One for creating the
                                              subsequent shutters and the other
                                              for the local rotation.
                                                  q Select the two surfaces.

                                                  q Select Edit > Group and
                                                     rename this node localPivot.
                                                  q Select the node localPivot,
                                                     then select Edit > Group
                                                     again and rename this node
                                                     centerPivot. This node should
                                                     be at the origin.
                                              You will now change the location of
                                              the localPivot.
                                                 q Select the localPivot node.

                                                 q Press Insert on the keyboard
                                                    to modify the pivot point.
                                                 q In the top view, Move the pivot
                                                    to the corner of the shutter
                                                    piece as shown.
                                                 q Press Insert again when
                                                    finished.


                                                 STEP THREE

                                              You will now be duplicating
                                              surfaces to create the other
                                              pieces.
                                                 q Select the centerPivot
                                                    node.
                                                 q Select Edit >
                                                    Duplicate - Options
                                                    and set the following:
                                                    Rotate Y to 30;
                                                    Translate Y to 0.1;
                                                    Number of Copies to
                                                    11
                                                 q Press Duplicate.




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Assistant Online - Maya/How Tos/Animation/Iris

                                                 STEP FOUR

                                              You will be creating a Locator with an attribute called shutter to
                                              control the opening and closing of the iris.
                                                 q Select Create > Locator.

                                                 q Select Modify > Add Attribute... and set the following:

                                                    Attribute name to shutter;
                                                    Minimum to 0;
                                                    Maximum to 10
                                                 q Press OK.



                                                 STEP FIVE

                                              The Locator now needs a connection to the rotation attribute of
                                              the local pivot. To achieve this connection, you will use Set
                                              Driven Key .
                                                 q Select all twelve of the localPivot nodes.

                                                 q Select Animate > Set Driven Key > Set - Options.

                                                 q With the localPivots selected, press Load Driven.

                                                 q Highlight all the localPivots in the left column.

                                                 q In the right column of the Driven section, highlight rotate
                                                    Y.
                                              You will now load the Locator as the Driver.
                                                q Select the Locator.

                                                q Press Load Driver.

                                                q Highlight the locator in the left column.

                                                q In the right column of the Driver section, highlight shutter

                                              In this next step you will be setting the keys.
                                                  q Press Key.
                                                     This will set a key for the shutter value of 0 when the iris
                                                     is fully open.
                                                  q In the Channel Box, set the shutter value to 10.

                                                  q Select all the localPivot nodes.

                                                  q Highlight the Rotate Y attribute name in the Channel Box.

                                                  q Use the virtual slider with the MMB in the workspace by
                                                     click- dragging to the left until the iris is closed.
                                                  q Press Key.

                                              Test the Set Driven Key by selecting the Locator and entering
                                              different values or by using the virtual slider.




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Assistant Online - Maya/How Tos/Animation/Iris

                                                 CONCLUSION

                                              You should now have the
                                              shutter attribute controlling
                                              the animation of the iris.
                                              Experiment with different
                                              curve shapes and amount
                                              of shutters. You can also
                                              experiment with different
                                              translate offsets when
                                              duplicating the shutters.                                        Play Movie [321 k]

                                              Your use of this file confirms your agreement to the
                                              Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Animation/Pick Up Object




 Alias|Wavefront / Assistant Online / Maya / How Tos / Animation / Pick Up Object




                                                  HOW TO PICK UP AN OBJECT                                by Robert Magee
                                                 Maya Complete
                                                 Animation
                                                 In this lesson, you will
                                                 learn how to make an
                                                 Inverse Kinematic arm
                                                 pick up an object and
                                                 place it on a table. This
                                                 will involve constraining
                                                 the IK handle to two
                                                 Locators then animating
                                                                                                             Play Movie [224 k]
                                                 the constraint weights to
                                                 switch the hand between locators.
                                                 The key to this lesson is that you will animate the object first
                                                 then constrain the arm to match that movement. This ensures
                                                 that the object's movement is exactly what you want before you
                                                 even have to consider the character picking it up.


                                                  STEP ONE

                                                 Create a polygonal
                                                 cube. Scale it to create
                                                 a tabletop. In the front
                                                 view, place it on the
                                                 ground along the X axis.
                                                 Rename the cube's
                                                 transform node to table.
                                                 Create a NURBS
                                                 cylinder. Scale it so that
                                                 it is a little taller. Place it on the ground near the origin. This will
                                                 be the object that will get lifted up onto the table. Rename the
                                                 cylinder's transform node to glass.




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Assistant Online - Maya/How Tos/Animation/Pick Up Object

                                              STEP TWO

                                             In the front view, place
                                             three Joints to create a
                                             simple arm that will pick
                                             up the glass and place it
                                             on the table.
                                             Add an IK handle that
                                             runs from the root joint
                                             to the end joint of the
                                             skeleton.


                                              STEP THREE

                                             Create two Locators.
                                             Place one to the left of
                                             the glass and name it
                                             glassLocator. This
                                             locator will drive the arm
                                             when it is picking up the
                                             glass.
                                             Place the second
                                             locator up above the
                                             glass and name it freeLocator. This locator will drive the arm
                                             when it is not picking up anything.


                                              STEP FOUR

                                             In the Hypergraph
                                             window, parent the
                                             glass node to the
                                             glassLocator node. Now
                                             any animation you apply
                                             to the locator will also
                                             affect the cylinder.


                                              STEP FIVE

                                             Select the two locators
                                             and then the IK handle.
                                             Make sure that the IK
                                             handle is selected last.
                                             Select Constrain ->
                                             Point to constrain the
                                             handle to both locators
                                             at once. It will constrain
                                             to a point half way
                                             between the two locators.



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Assistant Online - Maya/How Tos/Animation/Pick Up Object

                                             If you Select and Move the freeLocator, you will see that the IK
                                             handle updates so that it always places itself halfway between
                                             the two locators. Both locators have been constrained using the
                                             same weighting, so the IK handle is trying to point at both
                                             constraints equally, The result is that the IK Handle is
                                             positioned at an equal distance between the two locators.


                                              STEP SIX

                                             Select the IK handle. In
                                             the shapes section of
                                             the Channel box, you
                                             will find the
                                             ikHandle1_pointConstraint1
                                             shape node. It contains
                                             two key attributes:
                                                 q glassLocatorW0
                                                     which is the
                                                     weighting of the
                                                     glass locator; and
                                                 q freeLocatorW1
                                                     which is the
                                                     weighting of the
                                                     other locator.
                                             Set the glassLocatorW0 attribute to 0. Now the IK handle will
                                             move to the freeLocator since it has the strongest weighting. If
                                             you Select and Move the freeLocator, you will see that the IK
                                             handle now follows this locator entirely, because you have told
                                             it not to point at the glassLocator at all.


                                              STEP SEVEN

                                             You will now animate the
                                             glass so that it is
                                             positioned exactly where
                                             you need it.
                                             Create a CV curve from
                                             the glassLocator upward
                                             to the top of the table.
                                             This will be used as a
                                             motion path for animating the movement of the glass. You
                                             could also simply set keys on the glass, but using a motion path
                                             offers another way to animate it.




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Assistant Online - Maya/How Tos/Animation/Pick Up Object

                                              STEP EIGHT

                                             Select the glassLocator
                                             and then the new curve.
                                             Select Animate ->
                                             Paths -> Attach to
                                             Path - options.
                                             Set the Time Range to
                                             Start/End then set the
                                             Start Time to 20 and
                                             the End Time to 50.
                                             Make sure that Follow is turned Off. Click Attach.
                                             Now the glass will animate along the path between frames 20
                                             and 50. If you don't like how the path is working or if the glass is
                                             not sitting on the table properly at frame 50, you can edit the
                                             shape of the curve using its CVs.


                                              STEP NINE

                                             Now you can animate
                                             the freeLocator. Use the
                                             following positions to
                                             key this node:
                                             Go to frame 1.
                                             Place the freeLocator to
                                             the left of the glass.
                                             Press Shift w to set
                                             keys for the translation attributes.


                                              STEP TEN

                                             Go to frame 20.
                                             Place the freeLocator at
                                             the start point of the
                                             motion path curve.
                                             Again, press Shift w to
                                             set keys for the
                                             translation attributes.




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Assistant Online - Maya/How Tos/Animation/Pick Up Object

                                              STEP ELEVEN

                                             Go to frame 50.
                                             Place the freeLocator at
                                             the end point of the
                                             glass motion path.
                                             Set keys for the
                                             translation attributes.




                                              STEP TWELVE

                                             Go to frame 80.
                                             Place the freeLocator at
                                             the left of the table in
                                             open space.
                                             Set keys for the
                                             translation attributes.
                                             Now if you playback the
                                             animation, you will see
                                             that the hand moves up                        Play Movie [254 k]
                                             to the table and back but it does not work properly with the
                                             glass between frames 20 and 50.


                                              STEP THIRTEEN

                                             Go to frame 1.
                                             Open the Animation
                                             Preferences Window.
                                             Change the Default
                                             Out Tangent to
                                             Stepped. This will
                                             ensure that the next few
                                             keys set on these
                                             attributes will jump to a
                                             new value at each                           Play Movie [254 k]
                                             keyframe, rather than
                                             make a gradual transition between values from one keyframe to
                                             the next.
                                             Select the IK handle. Highlight the glassLocatorW0 and
                                             freeLocatorW1 attributes on the Constraint shape node. With
                                             your right mouse button select Key Selected.
                                             Go to frame 20. Set glassLocatorW0 to 1 and freeLocatorW1
                                             to 0. Highlight the glassLocatorW0 and freeLocatorW1
                                             attributes on the Constraint shape node. With your right mouse
                                             button select Key Selected. This switches the weighting of the


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                                             constraints so that the arm is focused on the glassLocator
                                             during this time.
                                             Go to frame 50. Set glassLocatorW0 to 0 and freeLocatorW1
                                             to 1. Again Key Selected for the two attributes. This will ensure
                                             that the hand "lets go" of the glass after frame 50.
                                             When you playback the scene this time, you will see that the
                                             arm follows the glass between frames 20 and 50.


                                                CONCLUSION

                                             This animation is the result of constraining the arm to different
                                             Locators, then using the constraint weight to switch between
                                             them. You could add more objects if you wanted, then animate
                                             their weights in a similar manner.
                                             In the completed animation shown at the start of this lesson,
                                             another related technique was used. An extra joint was added
                                             to the skeleton and then the second last joint was
                                             orient-constrained to the two locators, so that if the glass to
                                             rotated then so would the hand. The weighting of the second
                                             constraint was then connected to the weighting of the first
                                             constraint so that the animation of the weights could be shared.
                                             To see the final scene, download the pickup_final.ma file and
                                             load it into Maya.

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Animation/Accurate Clock




 Alias|Wavefront / Assistant Online / Maya / How Tos / Animation / Accurate Clock




                                                 HOW TO ANIMATE AN
                                                                                                          By Robert Magee
                                                 ACCURATE CLOCK
                                                 Maya Complete
                                                 Animation
                                                 In this lesson, you will
                                                 learn how to animate the
                                                 hands of a clock using a
                                                 series of expressions
                                                 which reference Maya's
                                                 internal time variable.
                                                 You will also use attributes
                                                 that allow you to set the
                                                 start time in hours,                      Play Movie [~576kb]
                                                 minutes and seconds for the animation. This clock can then be
                                                 added to any scene and the hands will animate automatically
                                                 based on the chosen time units.


                                                   STEP ONE

                                                 Select Create > NURBS
                                                 Primitives > Circle.
                                                 Rotate and Scale the circle
                                                 to the size that you need
                                                 and place it on the ground
                                                 .
                                                 Select the circle then
                                                 select Surfaces -> Planar
                                                 to create a planar trimmed surface for the face of the clock.
                                                 Delete History on the surface and the original circle curve.
                                                 Rename the surface as face.




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                                                STEP TWO

                                             Select Create -> Polygon
                                             Primitives -> Plane.
                                             Scale and Move the plane
                                             to create a marker for the
                                             hours. Place it along the Z
                                             axis near the top. Move it
                                             up a little along the Y axis
                                             to raise it from the face of
                                             the clock.
                                             Delete History on the polygon shape.


                                                STEP THREE

                                             Select the polygon shape
                                             and choose the Rotate
                                             tool.
                                             Press the Insert key then
                                             use grid snap to snap the
                                             pivot point back to the
                                             origin.
                                             Select Edit -> Duplicate -
                                             options. Set the Y Rotation to 30 and Number of Copies to
                                             11. Press Duplicate.
                                             You now have 12 markers for the hours of the clock. You can
                                             increase the size of the markers at three, six, nine and twelve
                                             o'clock or you can delete the markers at these points and add
                                             numbers.


                                                STEP FOUR

                                             Select Create -> Polygon
                                             Primitives -> Cube.
                                             Rename the cube as
                                             hourHand.
                                             Press F8 to go into
                                             component mode then
                                             reshape the vertices to get
                                             the look that you desire.
                                             Make sure that the shape
                                             is pointing up along the Z axis.
                                             Note: By reshaping the hand at the component level, you
                                             ensure that the shape's transform pivot remains at the origin.
                                             Delete History on the polygon shape.



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                                                STEP FIVE

                                             Select Edit -> Duplicate -
                                             options. Press the reset
                                             button then press
                                             Duplicate.
                                             Move the shape up along
                                             the Y axis then reshape it
                                             using component mode to
                                             make this hand longer.
                                             Rename the new cube as minuteHand.
                                             Repeat these steps to create a third, thinner cube and name it
                                             secondHand.


                                                STEP SIX

                                             Select all of the pieces of your clock then select Edit -> Group.
                                             Rename the group node to clock.
                                             With the clock node selected, select Modify -> Add Attribute...
                                             then add the following three attributes to the clock node:
                                             Attribute name: startHour
                                             Data Type: Integer
                                             Minimum: 0
                                             Maximum: 12
                                             Default: 0
                                             Attribute name: startMinute
                                             Data Type: Integer
                                             Minimum: 0
                                             Maximum: 60
                                             Default: 0
                                             Attribute name: startSecond
                                             Data Type: Integer
                                             Minimum: 0
                                             Maximum: 60
                                             Default: 0
                                             These attributes will be used later in the expressions to set up
                                             the time at the start of your animation.




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                                                STEP SEVEN

                                             Select the secondHand polyCube. In the Channel box, click on
                                             its rotateY attribute. With your right mouse button select
                                             Expressions. This will bring up the Expression editor.
                                             Enter the following expression:
                                             $direction = -1;
                                             $degreePer = 6;
                                             $start = clock.startSecond;

                                             secondHand.rotateY = $direction * $degreePer * ($start + time);

                                             The $direction variable sets the rotation direction to clockwise.
                                             The $degreePer variable sets how many degrees your want the
                                             hand to rotate per second. (360 degrees / 60 seconds = 6).
                                             The $start variable adds the clock.startSecond attribute to time.
                                             The time portion of the expression represents the actual time,
                                             measured in seconds.
                                             Note: Later you will learn that by measuring time in seconds
                                             instead of frames, you can change time units and the clock will
                                             still work accurately in your animation.


                                                STEP EIGHT

                                             Add the following expression to the minuteHand polyCube:
                                             $direction = -1;
                                             $degreePer = 6;
                                             $start = clock.startMinute;
                                             $adjust = clock.startSecond;
                                             $convert = 60;

                                             minuteHand.rotateY = $direction * $degreePer
                                             * ($start + (time + $adjust)/$convert);

                                             The $direction variable again sets the rotation direction to
                                             clockwise.
                                             The $degreePer variable sets how many degrees your want the
                                             hand to rotate per minute. (360 degrees / 60 minutes = 6).
                                             The $start variable adds the clock.startMinute attribute to time.
                                             The time portion of the expression represents the actual time,
                                             measured in seconds.
                                             In this expression time is advanced using clock.secondStart
                                             since the start position of the second hand has an affect on
                                             where the minute hand will start. Since time and
                                             clock.secondStart are measured in seconds, they must be
                                             converted to minutes using the $convert variable which is set to
                                             60.




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                                                STEP NINE

                                             Add the following expression to the hourHand polyCube:
                                             $direction = -1;
                                             $degreePer = 30;
                                             $start = clock.startHour;
                                             $adjust = clock.startMinute;
                                             $convert1 = 60;
                                             $convert2 = 3600;

                                             hourHand.rotateY = $direction * $degreePer
                                             * ($start + $adjust/$convert1 + time/$convert2);

                                             The $degreePer variable sets how many degrees your want the
                                             hand to rotate over a twelve hour period. (360 degrees / 12
                                             hours = 30).
                                             The $start variable adds the clock.hourStart attribute to time.
                                             The time portion of the expression represents the actual time,
                                             measured in seconds.
                                             In this expression time is advanced using clock.startMinute
                                             since the start position of the minute hand has an affect on
                                             where the hour hand will start. Since time is measured in
                                             seconds, it is converted to hours using a value of 60, and since
                                             clock.startMinute is measured in minutes, it is converted to
                                             hours using a value of 3600.


                                                STEP TEN

                                             To view time moving accurately, set your time slider range to a
                                             value of about 480. Since Maya's default time unit is set to Film
                                             which is 24 frames per second, 480 frames should make the
                                             second hand on the clock move for 20 seconds. Because this is
                                             such a short time, you will barely see the minute and hour
                                             hands moving.
                                             If you set the frame range much higher than you can scroll to
                                             see the minute and hour hand moving.
                                             Don't forget that you can select the clock node and set the
                                             starting positions for the three hands using the secondStart,
                                             minuteStart and hourStart attributes. This way your clock
                                             animation could start at any time such as 4:15 and 35 seconds
                                             instead of always at midnight.
                                             Note: If you open up the General Preferences, you can click
                                             on the Animation tab then under Animation Controls you can
                                             turn Timecode to On under Options. This will show you time
                                             as well as frames.




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                                                CONCLUSION

                                             You now have a time
                                             piece that will work
                                             accurately in any
                                             animation. Even if you
                                             change your time units
                                             [In General
                                             Preferences -> Units]
                                             to another value such
                                             as NTSC (30fps), the
                                             use of time in the                                        Play Movie [~576kb]
                                             expression ensures that
                                             your clock will adjust itself accordingly.
                                             Shift-click to download a completed scene file:
                                             clock_final.ma

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Animation/Extrusion




 Alias|Wavefront / Assistant Online / Maya / How Tos / Animation / Extrusion




                                                  HOW TO ANIMATE
                                                                                                          by Robert Magee
                                                  AN EXTRUSION
                                                 Maya Complete
                                                 Animation

                                                 In this lesson, you
                                                 will learn how to
                                                 animate a profile
                                                 extruding along a
                                                 curve. This will
                                                 involve the Extrude
                                                 tool's partial curve
                                                 option to generate
                                                 extra history nodes
                                                 called subCurve                              Play Movie [256 k]
                                                 nodes. These nodes will allow you to then animate the history
                                                 of the extrusion along the path.


                                                    STEP ONE

                                                 Create a primitive circle at
                                                 the origin. Rotate by 90
                                                 degrees around the Z
                                                 axis. This will act as the
                                                 profile of the extrusion.
                                                 Create a NURBS curve
                                                 that starts at the origin.
                                                 This will be used as the
                                                 path of the extrusion. Make sure that the first two CVs lie
                                                 directly on the X axis. This ensures that this curve is normal to
                                                 the circle, making the extrusion easier to control.
                                                 Continue the curve as desired. You may also want to edit some
                                                 of the CVs to reshape the curve in 3D. Be sure not to edit the
                                                 first two CVs.




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                                                STEP TWO

                                             Select the circle first and
                                             then the path curve. Select
                                             Surfaces -> Extrude -
                                             options. In this window,
                                             set the Curve Range to
                                             Partial. Click Extrude.
                                             This will generate the
                                             surface with two extra
                                             history nodes. You can see the two nodes in the input section
                                             of the channel box.
                                             The two subCurve input nodes allow you to only use part of the
                                             original profile and path curves in the creation of the surface.
                                             One of the subCurves [subCurve1] controls how much of the
                                             profile curve is extruded along the path. The other subCurve
                                             [subCurve2] controls the length of the extrusion.


                                                STEP THREE

                                             Click on subCurve2 in the
                                             channel box. You can now
                                             edit the Max Value
                                             attribute in the channel
                                             box or you can use the
                                             Show Manipulator tool.
                                             If you use the Show
                                             Manipulator tool, you get
                                             two markers for the Min and Max value attributes for the node.
                                             By dragging on the Max value manipulator, you can change the
                                             position of the extrusion along the path.
                                             Note: In the case of this extrusion, the Min value attribute
                                             creates unpredictable results. It is recommended that you use
                                             the Max value for animating. For other types of surfaces that
                                             use subcurve nodes, the Min Value attribute can give more
                                             predictable results.


                                                STEP FOUR

                                             To animate the extrusion,
                                             you can now set keys on
                                             the Max value attribute.
                                             Set the Max value to 0 at
                                             frame 1 then set it to 1.0
                                             at frame 50.
                                             Playback the scene. You
                                             will watch the extrusion
                                             animate along the path.                                         Play Movie [176 k]


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                                                CONCLUSION

                                             The extra history nodes
                                             generated by the Partial
                                             Curve option make it easy
                                             to animate the extrusion of
                                             the circle along the path.
                                             The manipulation of the
                                             subCurve node attributes
                                             lets you edit and animate
                                             the history of the
                                             shape.The Partial Curve                     Play Movie [176 k]
                                             option can be used to add subCurve history nodes to several
                                             modeling tools such as loft and revolve.
                                             Shown here is a revolved surface animated along its profile
                                             curve.

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Animation/Aim Spotlight




 Alias|Wavefront / Assistant Online / Maya / How Tos / Animation / Aim Spotlight




                                                   HOW TO ANIMATE
                                                                                                              by Robert Magee
                                                   THE AIMING OF A SPOTLIGHT
                                                 Maya Complete
                                                 Animation
                                                 In this lesson, you will
                                                 learn how to animate
                                                 what a spotlight "looks
                                                 at" while it animates.
                                                 When you use the
                                                 Show Manipulator tool
                                                 with a selected spotlight,
                                                 it appears as if you
                                                 could select and set                             Play Movie [~544kb]
                                                 keys on the "look at"
                                                 point of the light. In fact, this point is not represented by a node
                                                 and therefore you cannot key it. Instead you will need to apply
                                                 an Aim Constraint to the light so that it always points at
                                                 another objects such as a locator.


                                                    STEP ONE

                                                 Create a spotlight. Use
                                                 the Show Manipulator
                                                 tool to place the eye point
                                                 of the manipulator in the
                                                 back corner of the
                                                 working grid and the look
                                                 at point near the origin.




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                                                STEP TWO

                                             Create a Locator. Move
                                             the locator to the front of
                                             the working grid.
                                             This locator will be used
                                             as the target for the
                                             spotlight




                                                STEP THREE

                                             Select the Locator and
                                             then the Spotlight. Make
                                             sure the light is the last
                                             object selected since it will
                                             be the aiming object.
                                             From the Animation menu
                                             set, select Constrain ->
                                             Aim - options. Set the aim
                                             vector values to 0, 0, -1 then press the Add/Remove button.
                                             Since spotlights are created with their local X axis pointing out
                                             the back of the light, you needed a value of -1 to aim the light
                                             properly.
                                             Now the light is aiming at the Locator. You can now use the
                                             Locator to animate and control the aiming of the light.


                                                STEP FOUR

                                             You can now animate
                                             the Locator in one of
                                             many ways including the
                                             following:
                                                 q Set keys on the
                                                   Locator
                                                 q Assign the Locator
                                                   to a motion path
                                                 q Parent or point
                                                   constrain the
                                                   Locator to an
                                                   existing character
                                                   or object


                                                CONCLUSION

                                             You can now easily control the aiming of your spotlight using
                                             the Locator as a target. You could also leave the target
                                             stationary and animate the light itself.

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                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Animation/Rollling Cube




 Alias|Wavefront / Assistant Online / Maya / How Tos / Animation / Rolling Cube




                                                 HOW TO ANIMATE A
                                                                                                              By Alan Harris
                                                 ROLLING CUBE
                                                 Maya Complete
                                                 Animation
                                                 One of the many powerful
                                                 features of Maya is the
                                                 ability to animate the
                                                 location and properties of
                                                 an object’s pivot point. In
                                                 this lesson, you will use
                                                 the animatable properties
                                                 of a primitive cube’s pivot
                                                 point to animate it rolling                    Play Movie [~480kb]
                                                 on its edges. This
                                                 process will involve the use of the Channel Control window to
                                                 make certain attributes keyable. Once they are keyable, they
                                                 will be available in the Channel Box for you to set keys and edit
                                                 their value. In this lesson, you will also use the Graph Editor to
                                                 refine the animation curves to get exactly the kind of motion
                                                 that you need.


                                                    STEP ONE

                                                 Place a primitive poly
                                                 cube into the scene and
                                                 scale it to 2, 2 and 2.
                                                 Select the Move tool.
                                                 Place the front of the
                                                 cube at 0 along the Z
                                                 axis. Press the Insert key
                                                 to go into edit mode then move the pivot point to the middle of
                                                 the cube’s front edge. You may want to use grid snapping to
                                                 help you position the pivot.




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                                                STEP TWO

                                             Now press the Insert key
                                             to return to the Move tool
                                             then move the cube to the
                                             origin. Select Display ->
                                             Object Components ->
                                             Local Rotation Axes and
                                             Rotate Pivots. These
                                             icons will help you visualize these components as you begin
                                             animating the pivot.


                                                STEP THREE

                                             Select Window ->
                                             General Editors ->
                                             Channel Control and
                                             select the following
                                             non-keyable attributes:
                                             Rotate Pivot Translate X
                                             Rotate Pivot Translate Y
                                             Rotate Pivot X                                      Click to view larger version
                                             Rotate Pivot Y
                                             Use the Move button to make them keyable attributes. They will
                                             now appear in the Channel Box.


                                                STEP FOUR

                                             With the cube selected,
                                             set a linear key for Z
                                             rotation at frame 1. Go to
                                             frame 10 then Rotate the
                                             cube by
                                             -90 in Z and set another
                                             key.


                                                STEP FIVE

                                             Return to frame 1. Select the Rotate Pivot
                                             Translate X, Rotate Pivot Translate Y, Rotate
                                             Pivot X, and Rotate Pivot Y in the Channel Box
                                             then use your RMB to choose Key Selected.


                                                                          Click to view larger version




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                                                STEP SIX

                                             Go to frame 10. Open the
                                             Attribute editor and open
                                             up the Pivots -> World
                                             Space section. Set World
                                             Rotate X Pivot to 2. You
                                             should notice that the
                                             pivot moves to the front of
                                             the cube. Now you can continue rotating the cube.
                                             In the Channel Box, set a key for the Rotate Pivot Translate X,
                                             Rotate Pivot Translate Y, Rotate Pivot X, and Rotate Pivot Y
                                             channels.
                                             Editing the World Rotate Pivot in the Attribute Editor affects
                                             these four attributes therefore they must all be keyed.


                                                STEP SEVEN

                                             Go to frame 20. Set
                                             another linear key frame
                                             for a Z rotation of -180.
                                             Set the World Rotate
                                             Pivot to 4 then set keys
                                             for the four pivot channels
                                             in the Attribute editor.
                                             If desired, keep rotating the cube and moving the pivot using
                                             the steps outlined above. If you playback the animation at this
                                             point, the roll of the cube will not seem correct. You need to
                                             change the animation curve tangents for the pivot attributes.


                                                STEP EIGHT

                                             The incorrect motion is
                                             because the pivot point
                                             needs to stay in one
                                             location for 10 frames
                                             then jump to its new
                                             location. Open the Graph
                                             Editor. Select the four
                                             pivot action curves and              Click to view larger version
                                             then select Tangents ->
                                             Stepped. This will create the desired results.
                                             Playback the scene.




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                                                CONCLUSION

                                             Learning how to animate the pivot location on an object
                                             demonstrates how there are hidden attributes on your Maya
                                             objects that can be used to create interesting results. Since
                                             all attributes in Maya can be turned into keyable attributes,
                                             the possibilities can enhance how you animate your scenes.
                                             If you would like to see this cube animate like gelatin, you
                                             may want to complete the How to animate a Gelatin cube
                                             lesson.

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Dynamics/Gelatin Cube




 Alias|Wavefront / Assistant Online / Maya / How Tos / Dynamics / Gelatin Cube




                                                 HOW TO ANIMATE A GELATIN CUBE                                       by Alan Harris
                                                MAYA
                                                Soft Body Dynamics
                                                The Soft Body dynamics in
                                                Maya allow you to give
                                                surfaces a more organic
                                                quality as they animate.
                                                Using the cube from the
                                                How to Animate a Rolling
                                                cube lesson, you can use
                                                Soft Body dynamics to
                                                create the rolling Gelatin                                 Play Movie [~480kb]
                                                cube.
                                                This process will start with the creation of a Soft Body cube that
                                                uses the original cube as a goal. The soft body will therefore
                                                follow the first cube while colliding with the ground and jiggling
                                                along with a turbulence field that you will add to the scene.
                                                Once all the pieces have been connected, you will have your
                                                animated dessert.


                                                   STEP ONE

                                                Select the polycube from
                                                the How to Animate a
                                                Rolling cube lesson. Click
                                                on the polyCube Input
                                                node in the Channel box
                                                then increase the
                                                Subdivisions along X, Y
                                                and Z to 6.
                                                When you create a soft body object for the cube, every vertex
                                                on the cube will be matched by a particle on the soft body. If
                                                you want more jiggle then you may want to set this value higher
                                                than 6.




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                                                STEP TWO

                                             Go to the Dynamics menu set and select Bodies -> Create
                                             Soft Body - options, and set the following:
                                                q Create Options to Duplicate, Make Copy Soft;

                                                q Hide Non-Soft Object to On;

                                                q Make Non-Soft a Goal Weight to 0.66.

                                             Press Create. Rename copyOfCube1 to Geletan. Rename
                                             pCube1 to GeletanGoal.
                                             These settings will create a soft body object that uses the
                                             original cube as a goal. Each particle will try to match the
                                             position of the vertices on the cube with a 0.66 rate of accuracy.
                                             This less than perfect accuracy will help create the follow
                                             through in the gelatin.


                                                STEP THREE

                                             Click on the Play button to
                                             see the soft body rotate
                                             across the screen.
                                             Because the soft body has
                                             nothing to collide with it
                                             seems to float. Now you
                                             will create a rigid body
                                             floor surface for the soft body to collide with.


                                                STEP FOUR

                                             Create a poly plane and
                                             scale it out. Increase the
                                             Uand V patches. Set its
                                             Translate Y value to -0.1.
                                             This makes sure that the
                                             gelatin and the floor are
                                             not touching initially.
                                             Go to Dynamics -> Bodies -> Create Passive Rigid Body -
                                             options. Set Particle Collision to On. Click Create.
                                             If you playback the scene right now, you won’t see any
                                             collisions. This is because the collision of the particles and the
                                             floor have not yet been connected.




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Assistant Online - Maya/How Tos/Dynamics/Gelatin Cube

                                                STEP FIVE

                                             Select Window ->
                                             Animation Editors ->
                                             Dynamic
                                             Relationlships... In this
                                             window, click on the
                                             Gelatin surface then set
                                             the Modes to Collisions.
                                             Click on pPlane1 to connect the collisions of the particles to the
                                             soft body particles.
                                             When working with particle collisions, you will find that you
                                             often have to manually connect the rigid bodies and the
                                             particles in this manner.


                                                STEP SIX

                                             Playback the scene to view
                                             the collision of the soft body
                                             with the ground. The
                                             particles are being pushed
                                             back as they collide with the
                                             plane. Now you want to add
                                             some more motion to the
                                             Gelatin surface.


                                                STEP SEVEN

                                             Select the Gelatin soft
                                             body object. Select Fields
                                             -> Create Turbulence. In
                                             the Channel box, change
                                             the Magnitude to 60. This
                                             will make the Gelatin jiggle
                                             a little more as it moves.
                                             Again select the Gelatin
                                             soft body. Select Bodies -> Create Springs -> options. Set
                                             Creation Methods, to Min/Max, then set the Max Distance to
                                             1.0. Click Create.
                                             The springs will help preserve the volume of the soft body as it
                                             animates. Springs also provide a sort of internal structure to a
                                             soft body as it animates.




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                                                STEP EIGHT

                                             Playback the scene. The
                                             Gelatin surface now
                                             bounces and jiggles in a
                                             recognizable manner. You
                                             may want to create a
                                             Shading group to give the
                                             soft body a
                                             semi-transparent
                                             Gelatin-like surface then
                                             render the scene.


                                                CONCLUSION

                                             To animate all the jiggling of the resulting Soft Body cube
                                             using traditional deformation techniques would have been
                                             very difficult. The advantages of using Soft Body dynamics
                                             become clear as you see the subtle movement in the
                                             surface.

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Animation/Flow Object




 Alias|Wavefront / Assistant Online / Maya / How Tos / Animation / Flow Object




                                                 HOW TO ANIMATE WITH
                                                                                                                   by Alan Opler
                                                 FLOW (OBJECT)
                                                 MAYA Complete
                                                 Animation
                                                 To animate an object
                                                 along a path you would
                                                 use Attach to path. To
                                                 deform the object to the
                                                 shape of the path curve,
                                                 you would need to use
                                                 Flow.
                                                 In this lesson, you will
                                                 learn how to assign an                      Play Movie [~576kb]
                                                 object to a path using the Flow's Object option.
                                                 The Object option applies a Lattice to your object that animates
                                                 along the path with the object. As the Lattice deforms to the
                                                 path, so does your object.


                                                    STEP ONE

                                                 In a Y-up environment,
                                                 create an object (this
                                                 lesson uses a fish) so
                                                 that it’s profile runs along
                                                 the Y-axis. After building
                                                 the object, group it to
                                                 itself twice and name the
                                                 top node of the hierarchy
                                                 Fish, and the second
                                                 node, rotateFish.
                                                 Next, build a curve that will be used as the path curve.




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                                                STEP TWO

                                             Select the top node of
                                             the fish. Select Display
                                             -> Object Components
                                             -> Local Rotation Axes.
                                             This will display the local
                                             axes of the fish. This will
                                             help you determine the
                                             follow attributes for the
                                             fish in the next step.


                                                STEP THREE

                                             With the fish's top node
                                             already selected, press
                                             the shift key, then pick
                                             the curve.
                                             Note: The curve must be
                                             chosen last for Attach to
                                             Path to work properly.
                                             Select Animate -> Paths
                                             -> Attach to Path - options. Set Time Range to Start/End. Set
                                             the Start and End frames to 1 and 120 (respectively).
                                             Set Follow to On. This reveals axis options for the Front and
                                             Up axes for the fish. You now need to determine which of the
                                             object’s local axes you want to use as the front of the object as
                                             it moves down the path.
                                             The fish’s head is what will travel down the path first. Since the
                                             fish is pointing up along its local Y axis, this will be its Front
                                             Axis. You will want the fin on the fish’s back to be on the top. It
                                             runs along the local Z Axis. Therefore the Z-Axis will be the
                                             Up-Axis for the path.
                                             Click on the Attach button.
                                             Playback the animation. The fish moves along the path based
                                             on the location of its pivot point.




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                                                STEP FOUR

                                             Now the Flow option will
                                             be added to allow the
                                             object to deform to the
                                             shape of the curve as it
                                             moves along the path.
                                             Move the Time Slider
                                             back to frame 1.
                                             Select the top node of
                                             the fish. Select Animate -> Paths -> Flow Path Object ->
                                             options. Set Lattice Around to Object. Use Divisions of 5, 2,
                                             2. Click on the Flow button.
                                             A Lattice is added to the fish. Play back the animation once
                                             again.
                                             Note - One situation to be aware of, when assigning the Lattice
                                             to the object: the Lattice Base may not be an exact fit. This can
                                             produce some undesirable effects. If this is the case with your
                                             object, simply open the Hypergraph, select the Lattice Base
                                             node and scale it up. This permits every part of the fish to fit
                                             within the Base when it moving along the path, allowing it to
                                             deform properly.


                                                STEP FIVE

                                             You may find that the
                                             deformation is not precise
                                             enough. Since the fish is a
                                             long narrow object, the
                                             number of Divisions can be
                                             increased to create
                                             smoother deformations
                                             along the path curve during
                                             the animation.
                                             Select the Lattice. In the Channel Box, under the
                                             ffd1LatticeShape node, increase the T Divisions value to 10-15.


                                                CONCLUSION

                                             You now know how to animate an object along a path using
                                             Flow to create deformations.
                                             Secondary animation can be added to the object even after the
                                             Flow option has been applied. At the beginning of this lesson
                                             you grouped the fish to itself twice and applied the Motion to the
                                             top node. Now, you can select the second node in the
                                             hierarchy. You can have the fish rotate as it moves along the
                                             path by animating the X rotation channel in the Channel Box.
                                             To see how to animate using Flow's Curve option, complete the


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                                             How to animate with Flow (Curve) lesson.

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Animation/Flow Curve




 Alias|Wavefront / Assistant Online / Maya / How Tos / Animation / Flow Curve




                                                 HOW TO ANIMATE
                                                                                                                  by Alan Opler
                                                 WITH FLOW (CURVE)
                                                MAYA Complete
                                                Animation
                                                To animate an object
                                                along a path you would
                                                use Attach to path. To
                                                deform the object to the
                                                shape of the path curve,
                                                you would need to use
                                                Flow.
                                                In this lesson, you will
                                                learn how to assign an                      Play Movie [~576kb]
                                                object to a path using the Flow's Curve option.
                                                The curve option applies a Lattice along the complete length of
                                                the curve that is deforming. At one point along the curve, you
                                                will pinch the lattice points to make the object squeeze through
                                                a tight spot.


                                                   STEP ONE

                                                In a Y-up environment,
                                                create an object (a fish)
                                                so that its profile runs
                                                along the Y-axis. After
                                                building the object, group
                                                it to itself twice and
                                                name the top node of the
                                                hierarchy Fish, and the
                                                second node, rotateFish.
                                                Next, build a curve that will be used as the path curve.




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                                                STEP TWO

                                             Select the top node of
                                             the fish. Select Display
                                             -> Object Components
                                             -> Local Rotation Axes.
                                             This will display the local
                                             axes of the fish. This will
                                             help you determine the
                                             follow attributes for the
                                             fish in the next step.


                                                STEP THREE

                                             With the fish's top node
                                             already selected, press
                                             the shift key, then pick
                                             the curve.
                                             Note: The curve must be
                                             chosen last for Attach to
                                             Path to work properly.
                                             Select Paths -> Attach
                                             to Path - options. Set Time Range to Start/End. Set the Start
                                             and End frames to 1 and 120 (respectively).
                                             Set Follow to On. This reveals axis options for the Front and
                                             Up axes for the fish. You now need to determine which of the
                                             objects local axes you want to use as the front of the object as
                                             it moves down the path.
                                             The fish’s head is what will travel down the path first. Since the
                                             fish is pointing up along its local Y axis, this will be its Front
                                             Axis. You will want the fin on the fish’s back to be on the top. It
                                             runs along the local Z Axis. Therefore the Z-Axis will be the
                                             Up-Axis for the path.
                                             Click on the Attach button.
                                             Playback the animation. The fish moves along the path based
                                             on the location of its pivot point.




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                                                STEP FOUR

                                             Now the Flow option will
                                             be added to allow the
                                             object to deform to the
                                             shape of the curve as it
                                             moves along the path.
                                             Move the Time Slider
                                             back to frame 1.
                                             Select the top node of the
                                             fish. Select Animate -> Paths -> Flow Path Object -> options.
                                             Set Lattice Around to Curve. Use Divisions of 10, 2, 2. Click
                                             on the Flow button.
                                             A Lattice is added to the fish that extends for the length of the
                                             curve. Play back the animation once again.
                                             Note - One situation to be aware of, when assigning the Lattice
                                             to the object: the Lattice Base may not be an exact fit. This can
                                             produce some undesirable effects. If this is the case with your
                                             object, simply open the Hypergraph, select the Lattice Base
                                             node and scale it up. This permits every part of the fish to fit
                                             within the Base when it moving along the path, allowing it to
                                             deform properly.


                                                STEP FIVE

                                             You may find that the
                                             deformation is not
                                             precise enough. Since
                                             the fish is a long
                                             narrow object, the
                                             number of Divisions
                                             can be increased to
                                             create smoother
                                             deformations along the
                                             path curve during the animation.
                                             Select the Lattice. In the Channel Box, under the
                                             ffd1LatticeShape node, increase the T Divisions value to 40.




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                                                STEP SIX

                                             By using the Curve
                                             option, you can create
                                             a keyhole effect by
                                             scaling down the
                                             Lattice points.
                                             Press F8 to go into
                                             component mode.
                                             Select a group of
                                             Lattice Points along the path. Scale them down in all axes.
                                             When the fish passes through these points, it will shrink in size
                                             to fit through the scaled down section of the Lattice.
                                             Note - If you are not getting the proper deformation as your
                                             object passes through the scaled down lattice, you may need
                                             to increase the number of spans on your object.


                                                CONCLUSION

                                             You now know how to animate an object along a path using
                                             Flow to create deformations.
                                             Secondary animation can be added to the object even after
                                             the Flow option has been applied. At the beginning of this
                                             lesson you grouped the fish to itself twice and applied the
                                             Motion to the top node. Now, you can select the second node
                                             in the hierarchy. You can have the fish rotate as it moves
                                             along the path by animating the X rotation channel in the
                                             Channel Box.
                                             To see how to animate using Flow's Object option, complete
                                             the How to animate with Flow (Object) lesson.

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Character/Soft Bodies




 Alias|Wavefront / Assistant Online / Maya / How Tos / Character / Soft Bodies




                                                 CREATING SOFTBODIES IN
                                                                                                                        by Tom Kluyskens
                                                 CHARACTER ANIMATION
                                                 MAYA Complete
                                                 Character
                                                 This lesson will demonstrate
                                                 how to use softbodies for
                                                 character animation purposes.
                                                 You will also learn to use a lot of
                                                 other tools and Maya features,
                                                 too.
                                                 The purpose of this project is to
                                                 explore Maya's possibilities to
                                                 automate subtle secondary skin
                                                 and body motion on animated                                     Click to view larger image
                                                 characters. We'll also see how to
                                                 control this motion.                                                   Play Movie (2.3Mb)
                                                 The three parts of the lesson include:
                                                    q SoftBody IK Splines

                                                               SoftBodies and their goal weight
                                                               q

                                                            q Spline IK

                                                            q SoftBody Spline

                                                      q   How to control the SoftBody Spline
                                                               Clusters
                                                               q

                                                             q BlendShapes

                                                             q Collisions and forces

                                                      q   SoftBody Skin
                                                               q   How to convert
                                                               q   The lag problem

                                                 Use of this file confirms your agreement to the Terms and Conditions
                                                 set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Character/Soft Bodies




 Alias|Wavefront / Assistant Online / Maya / How Tos / Character / Soft Bodies




                                                  PART ONE: SoftBody IK Splines                             by Tom Kluyskens
                                                 MAYA Complete
                                                 Character
                                                 The challenge with SoftBodies, and
                                                 Dynamics in general, is to keep a
                                                 high level of control over them. Often
                                                 the Dynamic elements in the scene
                                                 are totally at mercy of the forces that
                                                 act on that scene.
                                                 Particles have a life of their own,
                                                 which is partly what we want, because they create natural
                                                 looking motion. The question now is how to keep the SoftBody
                                                 Particles under control, while keeping their natural motion
                                                 intact.


                                                    STEP ONE
                                                      q   Click on softanimTut.zip (NT),
                                                          or softanimTut.tar (IRIX) to get
                                                          the scenes for the whole
                                                          tutorial.
                                                                            or
                                                 Click on AWIC1.mb to get the scene
                                                 for this part only
                                                                                            Play Movie (188k)
                                                 Select GLK's body, and select
                                                 Bodies -> Create Soft Body (option box). Press Reset, enable
                                                 Goal Weight (0.5), disable Hide Original Geometry and press
                                                 Create.
                                                 This function creates a duplicate geometry, and converts that
                                                 duplicate to a SoftBody, which is attracted to the original
                                                 geometry.
                                                 A SoftBody is a piece of geometry in which the CVs are
                                                 replaced by Particles, which are dynamic objects influenced by
                                                 forces like gravity, wind and inertia.
                                                 The original geometry and its CVs are the Target Geometry of
                                                 the SoftBody and its particles. Each particle is attracted to the

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                                             corresponding CV of the original object. You can easily check
                                             this by transforming (moving, deforming,...) the original
                                             geometry, and hitting play. Try also to animate the original
                                             geometry.
                                             Modify the goal weight and conserve attributes of the SoftBody
                                             to see the effect those parameters have. Conserve is the
                                             degree to which the SoftBody Particles keep their speed (their
                                             inertia). You will notice that a goal weight of 1 makes the
                                             SoftBody follow the original without lag, while a goal weight of 0
                                             makes the particles really lazy...


                                              STEP TWO

                                             How to make the head softer than
                                             the rest of the body :
                                             Set the goal weight to 1.
                                             Hide the original geometry.
                                             Select the particles of the head. You
                                             can select particles by pressing F8,
                                             and setting the selection mask to                                Play Movie (640k)
                                             particles only.
                                             Open the Attribute editor, then do goalPP (with RMB) ->
                                             Component Editor.
                                             Set Component Value on .5, and Set Attribute.
                                             Hit play. Now the head lags behind, while the body sticks to the
                                             original object.


                                              STEP THREE

                                             Download AWIC1end.mb to get the
                                             finalized scene for this part.
                                             Now set the goal weight on .5 and
                                             hit play.
                                             Now the head and the body lag
                                             again, but the head more than the
                                             body.
                                                                                                              Play Movie (620k)
                                             Note: The softBody goal weight is actually
                                             a multiplication factor to the individual particle goal weights. In the above
                                             example, the resulting goal weight of the body is 1 * .5, and that of the
                                             head .5 * .5 = .25 .




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                                              STEP FOUR

                                             Download AWIC2.mb to get the
                                             scene for this part
                                             This GLK model is already entirely
                                             skinned, and has handles on the
                                             hands and elbows. The handles are
                                             grouped to a neck bone, so the arms
                                             follow the deformations of the spine.
                                             The eye is parented to a head bone.
                                                 q Select Shading -> Shade Options -> X-Ray mode.

                                                 q Select Skeletons -> IK Spline Handle Tool.

                                                 q Press Reset Tool, disable Auto Simplify Curve and
                                                   Auto Parent Curve. Click on the root joint, then on a
                                                   neck joint.
                                             The Spline curve is created through all the bones. Simplifying
                                             the curve with the Auto Simplify option reduces the amount of
                                             CVs to the number indicated, but may move your joints at
                                             creation.
                                             Moving the curve, will now move all the joints connected to it.
                                             Because (in this example) the curve also controls the root joint,
                                             moving the curve will move the whole body with it. That's also
                                             the reason why we did not use the Auto Parent Curve.
                                             Deforming the curve will now deform the spine. Try moving
                                             some CVs of the curve. We will see more ways to deform and
                                             control the spine curve later on.
                                             Select the Spline IK Handle, and try out some parameters, like
                                             Offset Roll and Twist. All these parameters can have their use
                                             in an animation, but especially Twist is a 'natural' deformation of
                                             the spine, and very useful in animation. You can set the type of
                                             twist in the Attribute Editor.
                                             Watch how arms and eye rotate with the body. Also watch how
                                             the head follows the motion of the neck joint at the end of the
                                             spine curve.


                                              STEP FIVE

                                             Download AWIC3.mb to get the
                                             scene for this part .
                                             The translation of the spline curve
                                             has been animated in this scene.
                                             This also animates the global body
                                             movement, because the root joint is
                                             controlled by the spline curve.
                                             Now, we want to combine both tools explained above : Spline
                                             IK and SoftBodies:


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                                             Using the same SoftBody options as above, convert the spline
                                             curve to a SoftBody. The joints are now controlled by the
                                             SoftBody curve ('SoftBody Spline'), which is in turn attracted to
                                             (and thus controlled by) the original, still animated spline curve.
                                             Play and watch how the whole body lags behind the original
                                             spline curve, and 'wobbles' around it.
                                             It is now possible to set the individual particle goal weights to
                                             make some parts of the spine 'looser' than others. Typically,
                                             leave the base particles on weight 1, so they follow the root
                                             joint perfectly, and lower the upper goal weights : the closer to
                                             the head, the lower the goal weight (to a minimum of .4 or so).
                                             Download AWIC3end.mb to get the finalized scene for this part

                                             To learn how to control the SoftBody spline, continue to Part 2

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Character/Soft Bodies




 Alias|Wavefront / Assistant Online / Maya / How Tos / Character / Soft Bodies




                                                  PART TWO: How to Control the
                                                                                                            by Tom Kluyskens
                                                 SoftBody Spline
                                                 MAYA Complete
                                                 Character
                                                 Goal Weight is a first level control
                                                 over these particles, which we
                                                 discussed earlier.
                                                 Three second-level techniques will
                                                 be discussed here
                                                    q Clusters

                                                    q Blend Shapes

                                                    q Forces and Collisions

                                                 The latter technique acts directly on the particles, while the two
                                                 first methods act on the SoftBody's original target geometry.


                                                    STEP ONE

                                                 Download AWIC4.mb to get the
                                                 scene for this part
                                                 Toggle Show -> Joints and
                                                 Surfaces OFF, so that you can
                                                 concentrate on the spline. The curve
                                                 you see is the original curve, not the
                                                 SoftBody curve.
                                                 Go into Component Mode (F8), and select a CV of the spline
                                                 curve. Then select Deformations ->Cluster. A cluster is
                                                 created on the CV of the curve. Do the same on all CVs. You
                                                 can take groups of CVs, if you don't want as much control
                                                 clusters as there are CVs.
                                                 Move one or more clusters, hit play, and watch the body
                                                 update as the SoftBody and skeleton take the form of the
                                                 deformed spline curve. The clusters can be animated, and offer
                                                 a much easier control than through the CVs themselves.
                                                 Download AWIC4end.mb to get the finalized scene for this part.



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                                              STEP TWO

                                             Select the spline curve, then select
                                             Edit -> Duplicate -> Reset and
                                             Duplicate. Move the duplicated
                                             curve away from the body.
                                             Select the duplicated curve and the
                                             spline curve, and select
                                             Deformations -> Blend Shape ->
                                             Reset and Create. This duplicated curve is now a target to the
                                             spline curve (which is in turn a target to the SoftBody Spline).
                                             This technique makes sense only if you deform the duplicated
                                             curve. If you select Window -> Animation Editors -> Blend
                                             Shapes, you will see a slider controlling the degree to which
                                             the spline blends into the duplicated curve. You can also control
                                             this attribute in the Channel Box when the spline curve is
                                             selected. Animate this blend value to convey the deformation to
                                             the actual spine and body of GLK.


                                              STEP THREE

                                             Download AWIC4endB.mb

                                             You can 'cascade' these blenders to
                                             have a whole database of spine
                                             positions, like can be seen in this
                                             finalized file.
                                             In this file, select the black cross
                                             behind GLK. This will pop up the custom controls in the
                                             Channel Box
                                                 q Main Body Blend

                                                 q F, B, L, R Bow

                                                 q Custom Spine.

                                             On the far left of GLK you can see the five first-level target
                                             curves for GLK's spine : F, B, L and R, and a fifth custom' curve
                                             which you can freely deform to put the spine in positions that
                                             cannot be achieved using a combination of F, B, L or R. These
                                             five curves serve as targets for the one curve right to them.
                                             In its turn, this curve is a target to the actual spine of GLK. It's a
                                             visual aid, because the actual spine curve is hidden in GLK's
                                             body. The Main Body Blend controls the blend factor between
                                             these two curves.




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                                              STEP FOUR

                                             Download AWIC5.mb to get the
                                             scene for this part
                                             This scene contains a further
                                             developed GLK, with SoftBody
                                             Splines in his 'legs', too. It also
                                             contains objects (floor, ball) which
                                             will control GLK's body through
                                             collision with the SoftBody Particles on the splines. Hit play to
                                             get an idea of the motion.
                                             Hide the skeleton, by selecting Show -> Joints, and go into
                                             X-Ray mode. You should now see some blown-up square
                                             particles (of the SoftBody Splines) along the 'legs' and spine.
                                             We want to make those particles collide with objects of GLK's
                                             environment.
                                             First, make the plane a collision object. Select it, and then
                                             select Particles -> Add Collisions, with Resilience on 0 and
                                             Friction .5. Resilience is the normal velocity change of a particle
                                             bouncing on the surface, Friction is the velocity reduction factor
                                             tangent to the surface.
                                                 q In the Outliner, select RMB -> Show Shapes, and open
                                                    up the sphere geometry. You will find a cube parented to
                                                    it.
                                                 q Select Particles -> Add Collisions, with Resilience on 0
                                                    and Friction .5 . We will use that cube (which is slightly
                                                    bigger than the sphere) as actual collision object for the
                                                    sphere, so that at collision with the neck particles, the ball
                                                    doesn't penetrate the neck geometry.


                                              STEP FIVE

                                             Download AWIC5end.mb to get the finalized scene for this part

                                             Now we still have to tell Maya which particles are going to
                                             collide with which objects. That's exactly the functionality of the
                                             Window -> Animation Editors -> Dynamic Relationships
                                             panel.
                                             In the panel's left side, open the all_SoftSplines transform, and
                                             select the body_Spline. Check Collisions on at the right side.
                                             You should see the planet and the cube geometry. Click on the
                                             cube only to enable collision, as we won't collide the spine with
                                             the planet floor. Do the same for the Foot and tail splines, but
                                             this time connect them to the planet, not to the sphere. The
                                             message is to avoid enabling unneeded collisions, because
                                             they will slow down the scene playback and rendering.
                                             Playback, and see how the collisions affect GLK's body
                                             geometry in a natural way.


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                                              STEP SIX

                                             Download AWIC5endB.mb to get
                                             the finalized scene for this part
                                             Play this file until frame 60 or so,
                                             delete the ball, select
                                             all_HardSplines in the Outliner,
                                             and remove the animation on it.
                                             Select the Rotate channels in the
                                             Channel Box, and then
                                                q select RMB -> Break
                                                  Connections.
                                                q And then Settings -> Initial
                                                  State -> Set for all
                                                  Dynamic.
                                             This will freeze the particles in
                                             their current position. You can
                                             now rewind.
                                             Select the little black cross behind
                                             GLK. Custom added attributes will appear in the Channel Box.
                                                q The Stiffness attributes control the Goal Weights of the
                                                  spine and 'feet' of the SoftBody Splines
                                                q The Twist controls the spine's twisting motion

                                                q The Gravity Pull is connected to the Magnitude of a
                                                  previously created Gravity Field.



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                                             This gravity force is connected to the 'feet' of GLK. Set the
                                             Gravity Pull to 200, and play. See how the lifted feet come
                                             down a little, because of the gravity pulling on them. The
                                             resulting position is an equilibrium between two forces: gravity,
                                             and goal weight. Lower the Feet Stiffness (the goal weight of
                                             the feet particles), and the feet will come down even more.
                                             Try connecting the gravity to the spine particles too, to see the
                                             effect.
                                             To learn about the SoftBody Skin, continue to Part 3

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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 Alias|Wavefront / Assistant Online / Maya / How Tos / Character / Soft Bodies




                                                  PART THREE: SoftBody Skin                                by Tom Kluyskens
                                                 MAYA Complete
                                                 Character
                                                 The above techniques never
                                                 converted actual skin to SoftBody,
                                                 but rather were a SoftBody
                                                 conversion of underlying curves,
                                                 with relatively very few CVs or
                                                 vertices. This makes the dynamic
                                                 SoftBody simulation and playback
                                                 relatively faster. In some situations however, effects can only
                                                 be achieved by converting the skin itself, or a part of it, to a
                                                 SoftBody.


                                                    STEP ONE

                                                 Download AWIC6.mb to get the
                                                 scene for this part.
                                                 In this scene, the eye is a particle
                                                 collision object. Play to see the
                                                 animation.
                                                     q Select GLK's skin, and make it
                                                        a SoftBody with goal weight .5,
                                                        hiding the original target
                                                        geometry.
                                                     q In the Dynamic Relationship
                                                        panel, connect the SoftBody
                                                        particles to the eye collision
                                                        object. Play it to see the effect
                                                        (it may be slow).
                                                 Animate the spine curve to see the effect of the whole SoftBody
                                                 on GLK's body motion. Again, you can edit the individual
                                                 particle goal weights (manually or with Artisan) to stiffen or
                                                 loosen parts of the body skin. Adding Springs to the SoftBody
                                                 may make the effect even more realistic and interesting (but
                                                 slower).
                                                 Download AWIC6end.mb to get the finalized scene for this part
                                                 .

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                                              STEP TWO

                                             Download AWIC7.mb to get the scene for this part.

                                             This file contains GLK with a combination of both above
                                             techniques : a SoftBody Spline, and a SoftBody skin.
                                             Look how the skin 'lags' one frame behind, even when both
                                             goal weights are 1. That is because the SoftBody skin is
                                             controlled by a SoftBody spline. The dynamics solver calculates
                                             only one layer of SoftBody animation per frame.
                                             You will notice the same problem in the final file, too, where a
                                             layered SoftBody Spline was used for the head. In some
                                             situations (where the animation is too fast, for example),
                                             layered softbodies will become unusable. A workaround is to
                                             bake the first layer of Softbodies with the bakeSoft.mel script.
                                             This seems to be solved in Maya 2.0


                                              CONCLUSION

                                             Download AWICfinal.mb to get
                                             the
                                             finalized scene with animation
                                             and
                                             shading.
                                             Click here for the final animation.
                                             (shift-click to save it on disk)




                                                                                                           Play Movie (2.3 Mb)

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Dynamics/Balloon




 Alias|Wavefront / Assistant Online / Maya / How Tos / Dynamics / Balloon




                                                 HOW TO CREATE AN
                                                                                                               by Bob Gundu
                                                 INFLATING BALLOON
                                                MAYA Complete
                                                Particle Dynamics
                                                In this lesson, you will
                                                learn how to use particle
                                                dynamics and lattice
                                                deformers to animate a
                                                balloon being inflated.
                                                This will be
                                                accomplished by
                                                converting a lattice into a
                                                soft body and emitting it                                Play Movie [~189kb]
                                                from a particle emitter.


                                                   STEP ONE

                                                Create a profile curve for
                                                the balloon off the Y-axis.
                                                Revolve the curve to
                                                create the surface.




                                                   STEP TWO

                                                With the balloon selected,
                                                select Deform -> Create
                                                Lattice -> Options. Set
                                                the Divisions to the
                                                following:
                                                S = 3,
                                                T = 3,
                                                U=3
                                                Set Grouping to on. Press Create.


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                                                STEP THREE

                                             You will now make the
                                             lattice a soft body.
                                                  q Select ffd1Lattice.

                                                  q Select Bodies ->
                                                    Create Soft Body
                                                    -Options, and set
                                                    the following:
                                                    Hide Non-Soft Object to On
                                                    Make Non-Soft a Goal to On
                                                    Weight to .6
                                                  q Press Create.

                                                  q Open the Attribute Editor for ffd1LatticeParticleShape and
                                                    expand the Soft Body Attributes section.
                                                             Set Enforce Count from History to Off.


                                                STEP FOUR

                                             The particles are emitted
                                             in a systematic order
                                             corresponding to the
                                             numbering of the lattice
                                             points or CV's. The
                                             current orientation of the
                                             lattice will result in the
                                             balloon being inflated
                                             from left to right. You
                                             would rather have it inflate from the bottom to top. It is for this
                                             reason you will rotate the lattice 90° around the X-axis.
                                                  q Select ffd1Base, copyOfffd1Lattice, ffd1Base1, and
                                                    fd1Lattice.
                                                  q Rotate X to 90 degrees.

                                             Ensure the balloon is fully enclosed within the lattice. Scale the
                                             selected nodes if needed.




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                                                STEP FIVE

                                             You are now going to
                                             create an emitter and
                                             connect it to the soft
                                             body.
                                                q Select Particles ->
                                                   Create Emitter.
                                                q Move the emitter to
                                                   the base of the
                                                   balloon.
                                                q In the Outliner
                                                   delete the particle
                                                   shape node that is
                                                   created by default
                                                   with the emitter.
                                                q Open the Dynamic
                                                   Relationships
                                                   editor and set
                                                   Modes to Emitters.
                                                q Select
                                                   ffd1LatticeParticle
                                                   and connect it to
                                                   emitter1.


                                                STEP SIX
                                                  q   Select the
                                                      ffd1LatticeParticle.
                                                  q   In the Attribute
                                                      Editor, add a Per
                                                      Object Lifespan
                                                      attribute.
                                                  q   Select the emitter
                                                      and set the Rate
                                                      to 0.
                                                  q   Set the Playback
                                                      Range to 70 and
                                                      play the animation
                                                      until the balloon
                                                      disappears.
                                                  q   Select Solvers ->
                                                      Initial State ->
                                                      Set For All
                                                      Dynamic.




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                                                STEP SEVEN
                                                  q   Set the emitter Rate
                                                      to 100 and the
                                                      ffd1LatticeParticle
                                                      Lifespan to 5.
                                                  q   Go back to frame 1
                                                      and playback the
                                                      animation.




                                                CONCLUSION

                                             You now have a balloon being inflated from a point. The main
                                             concept here is that when an object is converted to a soft
                                             body, the CV's or lattice points are converted to particles, and
                                             therefore are able to be emitted from a particle emitter.
                                             Tips:
                                                  q   Increasing the density of the lattice requires a higher
                                                      emitter rate.
                                                  q   Decreasing the Goal Weight will require a smaller emitter
                                                      rate
                                                  q   You can emit the same object from more than one
                                                      emitter.
                                                  q   You can attach several deformers to the same object.
                                             Quick Clips:
                                             Two Lattices [~158k]
                                             An example of using two lattices on the same object. Simply
                                             select half the CV's on the balloon and apply the lattice. Do the
                                             same for the other half and rotate direction of lattice.
                                             Two Emitters [~158k]
                                             This example uses two emitters to emit geometry. One is
                                             placed at the bottom and the other in the center of the balloon.
                                             Experiment with having different emitter rates for each emitter.
                                             Emitting Geometry [~158k]
                                             This example is shows geometry instead of a lattice being
                                             emitted. Experiment with changing the surface direction of the
                                             object for different effects.
                                             Default Lattice [~158k]
                                             This is to demonstrate the order of emission of the lattice
                                             points when using default position of the lattice. For clarity, the
                                             lattice is much denser than in the tutorial. In the tutorial the
                                             lattice was rotated 90 degrees to emit from the bottom up.
                                             balloon.ma [~68k]
                                             This is the final project file you may download for comparison.


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                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Dynamics/Chain Link




 Alias|Wavefront / Assistant Online / Maya / How Tos / Dynamics / Chain Link




                                                   HOW TO ANIMATE A CHAIN LINK                            By Robert Magee
                                                MAYA Complete
                                                Rigid Body Dynamics
                                                In this lesson, you will
                                                learn how to use Rigid
                                                Dynamics to animate a
                                                chain of links. To
                                                animate the chain link,
                                                you will use a nail
                                                constrain and a gravity
                                                field.
                                                                                                      Play Movie [~704 Kb]


                                                   STEP ONE

                                                Create a polygonal
                                                Torus primitive. Edit the
                                                polyTorus input node in
                                                the channel box. Be
                                                sure to set the
                                                Subdivisions so that the
                                                Subdivisions in the X
                                                direction are about 40
                                                and in the Y direction
                                                15. Scale XYZ to 2, and
                                                the Section Radius to
                                                0.1.


                                                   STEP TWO

                                                Make five duplicates of
                                                the link. Move and
                                                Rotate the links to form
                                                a chain. Move all of the
                                                links so that the edge of
                                                the first link is at the
                                                origin.




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                                                STEP THREE

                                             Select all of the chains
                                             then select Fields ->
                                             Create Gravity. This
                                             turns all the links into
                                             rigid bodies and
                                             connects them to a
                                             gravity field. Next select
                                             the first link then select
                                             Bodies -> Create
                                             Constraint. This places
                                             a nail dynamics
                                             constraint at the origin.


                                                STEP FOUR

                                             Set your playback
                                             range to 300 frames
                                             then play back the
                                             simulation.




                                                                                                          Play Movie [~704 Kb]


                                                CONCLUSION

                                             This was a very simple example of how to use rigid body
                                             dynamics. If the objects had been more complex, these high
                                             resolution links could be parented to new low resolutions
                                             links. These low resolution models would be used in the
                                             dynamic simulation to increase interactive performance.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Dynamics/Ring of Fire




 Alias|Wavefront / Assistant Online / Maya / How Tos / Dynamics / Ring of Fire




                                                   HOW TO CREATE A RING OF FIRE                                 by Paul Anand
                                                 MAYA Complete
                                                 Particles
                                                 This lesson teaches
                                                 you how to create a
                                                 ring of fire using a
                                                 particle runtime
                                                 expression. This
                                                 expression, combined
                                                 with some keyframes,
                                                 will help define the
                                                 emission of the
                                                 particles into a ring                                    Play movie [~483kb]
                                                 shape.
                                                 At the end of the lesson, you will apply a particle cloud shading
                                                 group to define the look of the ring.


                                                    STEP ONE

                                                 Select Particles ->
                                                 Create Emitter. In either
                                                 the Attribute editor or the
                                                 Channel box, change
                                                 the Emitter Type to
                                                 Omni.
                                                 Playback the simulation
                                                 then stop after a few
                                                 frames. Select the particles.
                                                 Select Window -> Attribute Editor. In the Per Particle (Array)
                                                 Attributes section, click on the velocity field with your right
                                                 mouse button. Choose RunTime Expression from the pop-up
                                                 menu.
                                                 Enter the following in the expression box:
                                                          /* Put Velocity before manipulation in $getVel */
                                                          vector $getVel = velocity;

                                                          /* Zero out the Y velocity and put the resulting Vector in $newVel */
                                                          vector $newVel = <<$getVel.x,0,$getVel.z>>;


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                                                     /* Get the magnitude of the original velocity */
                                                     float $initMag = mag($getVel);

                                                     /* Get the magnitude of the new velocity */
                                                     float $aftMag = mag($newVel);

                                                     /* Set the new velocity to have same magnitude as original */
                                                     $newVel = ($newVel / $aftMag) * $initMag;

                                                     /* Apply our new velocity to the particles */
                                                     velocity = $newVel;

                                             Click Create.
                                             Playback to see the results. The particles are emitted along the
                                             X and Z axes but not along Y.


                                                STEP TWO

                                             You will now set keys on
                                             the rate of emission to
                                             form the inner and outer
                                             surface of the ring.
                                             Go to frame 1.
                                             Select the Emitter. In the
                                             Channel box, set the
                                             Speed to 2 and the Rate
                                             to 1000. Now select the Rate attribute then click with your right
                                             mouse button and select Key Selected.
                                             Go to frame 30. Set the Rate to 100. Set another key.
                                             Go to frame 31. Set the Rate to 0. Set another key.
                                             Playback the results. Now the emission is defined by the keys
                                             and the particles form a ring.


                                                STEP THREE

                                             Now that you have the
                                             motion, you can set the
                                             render type. You will use
                                             a pre-built particle cloud
                                             shading network to
                                             create the effect.
                                             Shift-click to download
                                             FireCloud.ma into your
                                             current project's
                                             Textures directory, or use the 'Show Me' button on the
                                             FireCloud shader page.

                                             Select the particles. In the Attribute editor, go to the Render
                                             Attributes section and change the Render Type to Cloud.
                                             Select File -> Import and load the file called FireCloud.ma.


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                                             Open the Hypershade.
                                             With the particles selected, select FireCloud.ma in the
                                             Hypershade with the Right Mouse Button select Assign
                                             Material to Selection.


                                                STEP FOUR

                                             Add a light to the scene
                                             to illuminate the
                                             particles. You can now
                                             add other objects to the
                                             scene such as the water
                                             surface shown here.
                                             Use the batch render to
                                             render the scene with
                                             Animation set to On.
                                                                                                           Play movie [~483kb]


                                                CONCLUSION

                                             Particle runtime expressions let you control various particle
                                             attributes to help you control their emission.

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Dynamics/Fireball




 Alias|Wavefront / Assistant Online / Maya / How Tos / Dynamics / Fireball




                                                  HOW TO CREATE AN EXPLODING FIREBALL by Chris Ford
                                                 MAYA Complete
                                                 Particles
                                                 This lesson teaches you
                                                 how to create the fireball
                                                 from an explosion. The
                                                 lesson also talks about
                                                 techniques for the
                                                 Hardware and Software
                                                 rendering of fire effects.
                                                 You will start by
                                                 generating all the                Play Hardware movie [~240kb]
                                                 particles used in the              Play Software movie [~240kb]
                                                 explosion in the first 30
                                                 frames of the animation. These particles will be exploded at
                                                 high speed into the surrounding atmosphere, which you will
                                                 simulate using a Drag field. A Turbulence field is used to
                                                 create eddies and swirls in the expanding fireball, and a
                                                 reversed Gravity field is used to give the explosion particles
                                                 buoyancy.
                                                 To complete this lesson, you should be familiar with the
                                                 Hardware Render buffer, and basic Software particle rendering.


                                                  STEP ONE

                                                 Select Particles ->
                                                 Create Emitter. In either
                                                 the Attribute editor or the
                                                 Channel box, change the
                                                 Emitter Type to Omni
                                                 and the Speed to 25.
                                                 Playback the simulation
                                                 then stop after a few
                                                 frames. Select the particles. In the Attribute editor, change the
                                                 Render Type to MultiStreak.
                                                 Again playback the scene. You now have a few particles
                                                 emitting at a constant rate. You want the particles to explode


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Assistant Online - Maya/How Tos/Dynamics/Fireball

                                              then fade. You will need to animate the emitter's Rate attribute.


                                               STEP TWO

                                              Make your playback
                                              range go from frame 1 to
                                              frame 50
                                              Select the emiitter. Go to
                                              frame 1. Set the Rate to
                                              0 and select Key
                                              selected from the
                                              Channel box menu. Go
                                              to frame 30 and set a second key.
                                              Go to frame 3. Set the Rate to a high value such as 10000 and
                                              select Key selected from the Channel box menu.
                                              Playback the scene. The particles are now exploding but they
                                              are not reacting in a natural manner. You now need to add
                                              some fields to give the explosion a more complex motion.


                                                STEP THREE

                                              Select the particles then
                                              select Fields -> Create
                                              Turbulence. This will
                                              shake up the particles as
                                              they emit.
                                              Set the field's
                                              Magnitude to 100,
                                              Frequency to 100, and
                                              Attenuation to 0.
                                              Again, select the particles then select Fields -> Create Drag.
                                              Set the drag's Magnitude to 5 and Use Max Distance to Off.
                                              The drag will be used to simulate the reaction of the explosion
                                              to the atmosphere.
                                              Again, select the particles then select Fields -> Create Gravity.
                                              Set the Magnitude to 20 and the Direction to 0,1,0. This field
                                              is aiming away from the ground so that it will pull the particles
                                              up in a gaseous manner.
                                              Playback the scene. The motion of the particles is more
                                              interesting but they need some color. Over the next few steps,
                                              you will apply lifespan, opacity, and color attributes to the
                                              explosion particles, and take a look at them animating with
                                              Hardware shading turned on.
                                              Tip: By making sure that the particles are selected when you create a
                                              field, they will be automatically connected to the field.

                                              Tip: When creating Fields, always assume that the Attenuation attribute
                                              should be 0.


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                                                STEP FOUR

                                              Select particles and
                                              open the Attribute Editor.
                                              Go to the Add Dynamic
                                              Attributes tab, and click
                                              on Lifespan, Opacity
                                              and Color.
                                              Choose Add PerParticle
                                              attributes for all of the
                                              options.
                                              Click with your RMB on the lifespanPP field, and select
                                              Runtime Expression.... This will open the expression editor
                                              where you will the following expression:
                                                                       particleShape1.lifespanPP = rand(.5,4);

                                              This expression makes the particles disappear or "die" at
                                              different rates by randomly assigning each particle a lifespan
                                              somewhere between .5 (min. value) and 4 (max. value).
                                              Playback the simulation. If the particles die too soon, click with
                                              your RMB on the lifespanPP field and select Runtime
                                              Expression.... Adjust the expression's min. and max. values to
                                              set the desired range for how long the particles will "live" before
                                              they "die". Click the Edit button, then click the Close button and
                                              playback the results.


                                                STEP FIVE

                                              Click with your RMB on
                                              the rgbPP field, and
                                              select Create Ramp.
                                              Edit Ramp with three
                                              colors: a flame yellow,
                                              flame Red, and Black.
                                              Click with your RMB on
                                              the OpacityPP field, and
                                              select Create Ramp.
                                              Press 6 on the keyboard to hardware shade the particles, and
                                              Playback. Now you see the particles start out yellow then turn
                                              red and black. You can edit the parts of the ramp to control
                                              when the different colors kick in.
                                              If you are happy with the motion and the look of the particles,
                                              you can now choose to complete the rendering as a hardware
                                              rendering or use software rendering. Both options are outlined
                                              below:



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                                               Hardware render

                                              The hardware render
                                              buffer can be used to
                                              render out your explosion
                                              using the following steps:
                                                 q In the Attribute
                                                    Editor, in the
                                                    Render Attributes
                                                    section, set the
                                                    Depth Sort to On.
                                                 q Click on Add                              Play Hardware movie [~240kb]
                                                    Attributes for:
                                                    Current Render
                                                    Type. This adds
                                                    new attributes to
                                                    the particle.
                                                 q Increase the Line
                                                    Width to 2, Multi
                                                    Count to 25, and
                                                    Multi Radius to
                                                    0.75.
                                              Select Window -> Rendering Editors -> Hardware Render
                                              Buffer to test a sequence. Use a Multi Pass Rendering setting
                                              of 5 to get a softer effect.
                                              Use the Hardware render Buffer flipbooks to preview the
                                              dynamics of the scene. You can now composite the explosion
                                              into other scenes using a compositing package like Maya
                                              Composer or Maya Fusion.
                                              Tip: Do not use any Color Accumulation, since this attribute tends to
                                              burn out the center of an explosion effect.


                                               Software render

                                              You can generate very
                                              realistic rendered
                                              fireballs with software
                                              particle rendering using
                                              the Particle Cloud
                                              Shader. The following
                                              items tell you how to
                                              create an explosion
                                              shader.
                                                  q Select the                                Play Software movie [~240kb]
                                                     explosion particles
                                                     and, in the Attribute
                                                     Editor, change
                                                     Render Type to
                                                     Cloud (s/w). Turn
                                                     Depth Sort to On.

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                                                   q   Go to the Add
                                                       Dynamic
                                                       Attributes section,
                                                       and click the
                                                       General Tab.
                                                       Open the Particle
                                                       tab and select and
                                                       add radiusPP from
                                                       the list of Particle
                                                       attributes.
                                                   q   Click with your
                                                       RMB on radiusPP
                                                       and create this
                                                       Creation
                                                       Expression:
                                                        radiusPP = rand(0.1,
                                                               0.75);

                                              This will randomise within the specified random number limits,
                                              the radius of each particle cloud shader on a per-particle basis.
                                              If you do not do this, then the fireball will render in a very
                                              regular manner.
                                              Select Window -> Hypershade. Select Create -> Create
                                              Render Node..., and under Volumetric Materials, choose a
                                              Particle Cloud material. You will notice that the Color ramps
                                              you made for rgbPP are already in the Hypershade.
                                              Double-click on the new Particle Cloud material node. Drag
                                              and drop the rgb color ramp onto the Map... button opposite
                                              Life Color .
                                              Connected to the ramp in the Hypershade Utilities section, is
                                              the Particle Age Mapper. You can increase this to speed up
                                              the rate with which the particles change color as they age.
                                              Map a 3D texture SolidFractal into the transparency of the
                                              Particle Cloud shader. Select the explosion particles in the
                                              modeling view and assign the particle shader.
                                              Add a light to illuminate the fireball.
                                              Select Render -> Render into New Window.


                                                CONCLUSION

                                              You now have two particle effects to help you explore the
                                              differences between hardware and software rendered
                                              particles.

                                              Use of this file confirms your agreement to the Terms and Conditions
                                              set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Dynamics/Flag




 Alias|Wavefront / Assistant Online / Maya / How Tos / Dynamics / Flag




                                                 HOW TO CREATE A FLAG USING SOFT
                                                                                                               by Steve Christov
                                                 BODIES
                                                Maya Complete
                                                Soft Body particles
                                                In this lesson you will learn
                                                how to create a flag by
                                                turning a NURBS plane into
                                                a soft body.
                                                You will then use the Artisan
                                                tools to paint Goal weights to
                                                on the soft body particles to
                                                allow the cloth to react to                                 Play Movie[~480kb]
                                                forces such as wind and turbulence.


                                                   STEP ONE

                                                Create a simple sphere and
                                                a cylinder and scale these
                                                out to become your flagpole.
                                                In the menu bar select
                                                Create-NURBS Primitives >
                                                Plane-Options. Change the
                                                U and V patches to 12.
                                                Scale the plane to get a shape of a rectangle. Set Rotate X to
                                                90 and Move it to resemble a flag hanging off a flag pole.
                                                Press F8 to go into Component Mode. In your top view select
                                                every other CV and move them up slightly. Now select the other
                                                CVs and move them down slightly to create a ripple surface.
                                                Press F8 to return to Object Mode.




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                                                STEP TWO

                                             You will now convert your
                                             Plane to a soft body.
                                             Select the surface and in
                                             your dynamics menu click on                    Click here to view larger image
                                             Bodies > Create Soft
                                             Body-Options.
                                             In the option box set the following:
                                                 q Creation Options to Duplicate,

                                                 q Make Copy Soft to On

                                                 q Hide Non-Soft Object to On

                                                 q Make Non-Soft a Goal to On.

                                                 q Goal weight to 1.0.




                                                STEP THREE

                                             With nothing selected, select
                                             Dynamics > Fields >
                                             Gravity , Turbulence and
                                             Air
                                             Select and Move the Air
                                             Field to an area behind the
                                             flag.
                                                                              Click here to view larger image
                                             Select and Move the
                                             Turbulence Field up to the middle of the flag.
                                             Select Window > Relationship Editor > Dynamic
                                             Relationships. Scroll down to select copyOfnurbsPlane,
                                             highlight the fields in the right hand window.
                                             With the copyOfnurbsPlane still selected, Click on the Bodies >
                                             Create Springs > Options.
                                             Set the Max distance to 1.0, and set the Wire Walk Length to
                                             3. Click on Create.
                                             Playback your scene. While these forces are connected and
                                             acting on the softbody, you are not getting any results. This is
                                             because of the fact that when you created the soft body you
                                             assigned a goal weight of 1, which results in the soft body
                                             always achieving its goal of maintaining it's original shape. You
                                             will need to adjust goal weights of the individual particles so
                                             that the soft body will not always achieve its goal. For this you
                                             will use the Artisan brushes to tweak the goal weights of the
                                             soft body to get a realistic flag.




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                                                STEP FOUR

                                             With your mouse over the
                                             surface of the flag click with
                                             your right mouse button, and
                                             scroll down to Paint >
                                             copyOfnurbsPlaneParticle
                                             Shape > goalPP. Your
                                             surface should turn white
                                                                                            Click here to view larger image
                                             and your cursor should
                                             become an Artisan brush.
                                             Note: Make sure you have shading turned on by pressing 5 on
                                             the keyboard.


                                                STEP FIVE

                                             Select the tool settings for
                                             the brush, by double
                                             clicking on its icon in the
                                             tool bar shelf.
                                             Click on the Display tab
                                             and click to disable lighting.
                                             Click on the Attr. Paint tab to bring up the brush attributes. Set
                                             the value to 0.1.
                                             Paint over all of the CVs except for the area near the pole. The
                                             surface should give feedback on the changes you are making
                                             to the goalweights by turning darker.


                                                STEP SIX

                                             Select the Air Field and show
                                             the manipulator by pressing
                                             the t key on your keyboard .
                                             Using the blue circle beside
                                             the icon, scale out the one
                                             marked Magnitude to about
                                             60.
                                             Press on the blue circle and
                                             change the direction of the       Click here to view larger image
                                             air flow towards the flag. In
                                             your channel box set Max Distance to Off, and Set
                                             Attenuation to 0. This will ensure that the force does not
                                             diminish with an increase in distance from the actual position of
                                             the field.
                                             Select the Turbulence field, and set the following.
                                                q Magnitude to around 100

                                                q Attenuation to 0.



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                                             Playback the animation.


                                                STEP SEVEN

                                             If you playback the animation
                                             at this point you will see that
                                             the "shape" of the turbulence
                                             seems to cycle over and
                                             over and as a result you
                                             don't quite get random
                                             ripples. You can fix this by
                                             animating the Phase
                                             attribute over time.
                                             Select the Phase attribute
                                             and with your right mouse
                                             button select expressions
                                             from the pop-up menu.
                                                                                               Click here to view larger image
                                             In the expression editor enter:
                                             phase = frame * 10.

                                             When you playback the animation at this point you will see that
                                             the flag is now fluttering in the wind. Go to a frame where the
                                             forces have evened out and in the menu go to Solvers > Initial
                                             State > Set for all dynamic. You now avoid the first couple
                                             frames where the forces need to start up.


                                                CONCLUSION

                                             This animation is the result of converting a simple plane into
                                             a soft body which is then animated using forces such as wind
                                             and turbulence. By adjusting the goal weights and tweaking
                                             the dynamic forces you are able to create a realistic looking
                                             flag. In the final animation the wind direction and magnitude
                                             have been animated.
                                             Download a finished scene file:
                                             flag.ma[~144kb]


                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Dynamics/Footprints




 Alias|Wavefront / Assistant Online / Maya / How Tos / Dynamics / Footprints




                                                 HOW TO CREATE FOOTPRINTS                                         Alias|Wavefront
                                                 MAYA Complete
                                                 Particle Dynamics
                                                 In this lesson, you will
                                                 learn how to make
                                                 footprints in a wet mud
                                                 surface. It is a good
                                                 example of the
                                                 integration of character
                                                 animation and
                                                 dynamics working
                                                 together. There are at
                                                 least two ways to
                                                 approach this problem.
                                                 One method is to make
                                                                                              Play Movie [~521K]
                                                 the boots rigid bodies,
                                                 and use rigid body/particle collision to make impressions in the
                                                 mud. The problem with this method is that rigid bodies cannot
                                                 bend as the sole of a boot does when walking. The second
                                                 method involves using fields attached to the boots to displace
                                                 mud made out of a softbody mesh. This lesson will use the
                                                 later method.


                                                    STEP ONE

                                                 Open the scene file footprints.ma.
                                                 This scene file contains a pair of animated boots walking on a
                                                 flat mud surface. If you playback the scene, the mud is not
                                                 interacting with the boots. You will begin by turning the mud
                                                 surface into a soft body. Before beginning, set your view to
                                                 persp/outliner.
                                                      q Select the mud surface.

                                                      q Select Bodies -> Create Soft Body - Option, and set
                                                        the following:
                                                           r Creation Options to Make Soft

                                                     r Press Create.

                                                     r Select mudParticles in the Outliner.

                                                     r In the Channel Box, set the Conserve to 0.



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                                                STEP TWO

                                              There still is no deformation in the mud because there are no
                                              fields effecting it. You will be adding air fields to the sole and
                                              the heel of each boot to achieve this effect.
                                                  q In the Outliner, for the left boot, select bootLsole, and
                                                     heelL.
                                                  q Select Fields -> Add Air - Options, and set the following:

                                                         s Magnitude to 100

                                                         s Attenuation to .5

                                                         s Max Distance to 0.2

                                                         s Direction to 0,-1,0

                                                  s Press Add.

                                                  s Repeat this process for the right boot.

                                              In the outliner you will notice that the boot pieces have air fields
                                              parented to them.


                                                STEP THREE

                                              You will now use the
                                              Dynamics Relationship
                                              Editor to connect the mud
                                              to the fields.
                                                  q Select Window ->
                                                    Relationship
                                                    Editors -> Dynamic
                                                    Relationships...
                                                  q In the left column
                                                    select mud.
                                                  q In the right column
                                                    select all of the
                                                    fields.
                                              The fields are now connected. Playback the scene to see the
                                              effect.
                                              Note: Must you have the animation Playback Speed
                                              preference set to Free.




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                                                  STEP FOUR

                                              The movement of the mud
                                              can look more realistic by
                                              having the mud bulge
                                              upward in front of the
                                              boots.
                                              This can be achieved by
                                              parenting another field to
                                              the boot that is pointing in
                                              the upward direction. You
                                              will also be creating an
                                              expression on the
                                              Magnitude attribute of the field to control for when the field is
                                              active. In other words, the expression will limit the magnitude of
                                              the field to operate only when the boot is at ground level and
                                              have no influence when the boot rises above the ground.
                                                  q Go back to frame 1.

                                                  q Select Fields -> Create Air - Options, press Reset, and
                                                     set the following:
                                                         r Air Name to pushUpAirL

                                                         r Attenuation to 0.5

                                                         r Direction to 0,1,0

                                                         r Speed to 1.0

                                                         r Max Distance to 1.0

                                                  q Press Create.

                                                  q Position pushUpAirL just under the left toe of the boot.

                                                  q In the Outliner, MMB-drag pushUpAirL on top of bootL.

                                              The airField pushUpAirL is now parented to bootL.
                                                 q Repeat the steps for the right boot and name the new
                                                   airField pushUpAirR.
                                                 q Open the Dynamic Relationships... editor and connect
                                                   both the pushUpAir fields to the mud surface.


                                                  STEP FIVE

                                              You will now be adding the expression to the Magnitude
                                              attribute of the pushUpAir airFields.
                                                  q Select pushUpAirL.

                                                  q In the Channel Box, highlight the Magnitude attribute.

                                                  q With the RMB over the Magnitude field, select
                                                     Expressions... from the pop-up menu.
                                                  q Enter the following expression:
                                              if (bootL.translateY > -3.0) {
                                              pushUpAirL.magnitude = 0;
                                              }



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                                              else {
                                              pushUpAirL.magnitude = 50;
                                              }
                                                  q    Press Create.
                                                  q    Repeat these steps for pushUpAirR.
                                                  q    Playback the scene.
                                              Depending on your placements of pushUpAir fields, the
                                              bootL.translateY value in the expression may have to be adjusted
                                              accordingly.


                                              CONCLUSION

                                              You now have
                                              footprints that are
                                              created using
                                              softbodies and fields.
                                              There are a couple of
                                              things to note about this
                                              workflow.
                                              You may have noticed
                                              that when you turned
                                              the mud into a softbody,                        Play Movie [~521K]
                                              you did not create a goal for it. This is because the mud is not
                                              returning to its original shape. It is also important to note that
                                              the sole and the heel surfaces were rebuilt with even
                                              parameterization to get an even distribution of the air field.

                                              Your use of this file confirms your agreement to the
                                              Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Dynamics/Melting Object




 Alias|Wavefront / Assistant Online / Maya / How Tos / Dynamics / Melting Object




                                                 HOW TO ANIMATE A
                                                                                                            by Bob Gundu
                                                 MELTING OBJECT
                                                Updated! [09.28.99]
                                                MAYA Complete
                                                Particle Dynamics
                                                In this lesson, you will
                                                learn how to use particle
                                                dynamics and lattice
                                                deformers to animate a
                                                melting vase.
                                                This will be accomplished
                                                by converting a lattice                      Play Movie [~284kb]
                                                into a soft body and
                                                adding collisions to the table surface. Other attributes will be
                                                added to lattice for further control.



                                                   STEP ONE

                                                Create a profile curve for
                                                the vase off the Y-axis.
                                                Revolve the curve to
                                                create the surface.




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                                                STEP TWO

                                             With the vase selected,
                                             select Deform -> Create
                                             Lattice -> Options. Set
                                             the Divisions to the
                                             following:
                                             S = 6,
                                             T = 6,
                                             U=6
                                             Press Create.


                                                STEP THREE

                                             You will now make the lattice a soft body.
                                             Select ffd1Lattice. Select Bodies -> Create Soft Body
                                             -options.
                                             Reset all the settings.
                                             Press Create.


                                                STEP FOUR

                                             Create a NURBS plane
                                             underneath the vase.
                                             Scale up the plane and
                                             increase the subdivisions
                                             to U 10, V 10.
                                             Move the plane slightly
                                             below the lattice soft body.
                                             This is to make sure the
                                             lattice deformer is not
                                             penetrating through the plane surface before simulation.


                                                STEP FIVE

                                             You are now going to add a gravity field to the soft object and
                                             particle collisions to the plane surface.
                                             Select ffd1Lattice. Select Fields > Create Gravity. To add
                                             collisions, select ffd1Lattice then the plane surface. Select
                                             Particles -> Make Collide.




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                                                STEP SIX

                                             You will notice an obvious problem
                                             when you playback the animation
                                             [inProgress.mpg]. The vase is
                                             bouncing up and down and not
                                             spreading outward. This can be
                                             corrected with a simple expression
                                             controlled by adding two attributes to
                                             the ffd1LatticeParticleShape node.
                                             In the Outliner, have Display >
                                             Shape turned on. Select
                                             ffd1LatticeParticleShape. Select
                                             Modify -> Add Attribute... and set
                                             the following:
                                                 q Attribute Name to spread;

                                                 q Data Type to Float;

                                                 q Attribute Type to Scalar

                                             Press Add and repeat with another attribute:
                                                     Attribute Name to thickness
                                             Press OK.


                                                STEP SEVEN

                                             With the new attributes on
                                             the soft body, you will
                                             now create an expression
                                             to spread out the bottom
                                             of the vase as it melts.
                                             Select
                                             ffd1LatticeParticleShape.
                                             Open Window ->
                                             Expression Editor.
                                             Enter the following in the expression box:
                                                     vector $melt = ffd1LatticeParticleShape.worldPosition;
                                                     float $spread = ffd1LatticeParticleShape.spread;
                                                     float $thickness = ffd1LatticeParticleShape.thickness;

                                                     if ($melt.y < $thickness) ffd1LatticeParticleShape.velocity = unit
                                                     (ffd1LatticeParticleShape.worldPosition - <<0,0,0>>) * $spread;

                                             Press Create.




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                                                STEP EIGHT

                                             It is now easy to control
                                             the quality of the melt
                                             with the spread and
                                             thickness attribute.
                                             Select the
                                             ffd1LatticeParticle. In the
                                             channel box, change the
                                             spread to .4, and the
                                             thickness to 1.                                                   Play Movie [~284kb]
                                             Playback the animation.


                                                CONCLUSION

                                             You now have a vase melting on a surface. Keep in mind
                                             that you have several parameters that can be animated to
                                             add more life:
                                                q to slow down the melting, decrease the gravity
                                                   magnitude;
                                                q try experimenting with the spread and thickness
                                                   attributes;
                                             or even add a turbulence field to add more randomness to
                                             the effect.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Dynamics/Particle Gears




 Alias|Wavefront / Assistant Online / Maya / How Tos / Dynamics / Particle Gears




                                                 HOW TO USE PARTICLES
                                                                                                             by Nancy Hosken
                                                 TO DRIVE RIGID BODIES
                                                 MAYA Complete
                                                 Particle Dynamics
                                                 In this lesson, you will
                                                 learn how to use particle
                                                 dynamics to animate the
                                                 motion of a gear that in
                                                 turn animates a second
                                                 gear. Both gears use rigid
                                                 body dynamics and a
                                                 hinge dynamic constraint.
                                                                                                         Play Movie [~576kb]
                                                 To animate the gears,
                                                 you will create two polygonal gears. By creating a hinge
                                                 constraint on the gears, they will rotate when acted on by a
                                                 force.
                                                 You will then add an emitter and make the first gear a collision
                                                 object so that it is influenced by the force of the falling
                                                 particles.


                                                   STEP ONE

                                                 Create a polygonal gear
                                                 using the steps outlined
                                                 in the How to build a
                                                 polygonal gear lesson.

                                                 Rotate the gear by 90
                                                 degrees around the X
                                                 axis so that it is sitting
                                                 upright.




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Assistant Online - Maya/How Tos/Dynamics/Particle Gears

                                                STEP TWO

                                             Duplicate the gear.
                                             Place the second gear so
                                             that the cogs are linked
                                             together. Make sure that
                                             the surfaces are not
                                             touching.




                                                STEP THREE

                                             You are now going to
                                             create hinge constraints.
                                             Select the first gear.
                                             In the Dynamics menu
                                             set, select Bodies >
                                             Create Constraint -
                                             options. Change the
                                             Constraint type to
                                             Hinge. Press Create.
                                             Place this hinge at the center of the corresponding gear.
                                             Select the second gear and again select Bodies > Create
                                             constraint. Place this hinge at the center of the corresponding
                                             gear.
                                             Note that the gears automatically become rigid bodies when
                                             you add a hinge to them. This will help you use them in the
                                             particle simulation.


                                                STEP FOUR

                                             Select Particles > Create
                                             Emitter, and place the
                                             emitter above the gears.
                                             In the Channel Box, hold
                                             down your left mouse
                                             button over the Emitter
                                             Type attribute field and
                                             select Directional. Make
                                             sure that Direction X is set to 1 and increase the Spread to
                                             0.5. This will point the emission towards the gears in a
                                             spray-like form.
                                             Play the simulation for a few frames. You can see the particles
                                             but they are not falling to the ground. You need to add gravity.




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Assistant Online - Maya/How Tos/Dynamics/Particle Gears

                                                STEP FIVE

                                             Select the particles.
                                             Select Fields > Create
                                             Gravity. This creates a
                                             gravity field and connects
                                             it to the particles.
                                             Play the simulation. Now
                                             the particles are falling
                                             but they may not be
                                             hitting the gears. Reselect the emitter and adjust the Speed
                                             attribute until the particles are landing on the gear as shown.
                                             As the particles reach the gears, you will notice that they are
                                             not animating. You need to make the first gear a particle
                                             collision object.


                                                STEP SIX

                                             Select the first gear, excluding its
                                             hinge. In the Channel Box, set the
                                             Particle Collision attribute field to
                                             on. A new collision node is created.
                                             If you were to playback the
                                             simulation you would see that the
                                             particles are still not colliding with the
                                             gear. This is because the particles
                                             need to be connected by hand to the first gear. Setting Particle
                                             Collision to On made collisions possible but didn't connect the
                                             particles.


                                                STEP SEVEN

                                             Select the particles, then the first gear. Select Particles->Make
                                             collide.
                                             The particles will now collide with the gear.




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                                                STEP EIGHT

                                             Playback the simulation
                                             and watch the gears turn.
                                             To tweak the results, you
                                             can make adjustments
                                             such as decreasing the
                                             Resilience or increasing
                                             the Friction of the gears.
                                             These attributes are
                                             found in the
                                             ParticleShape input nodes.
                                             You can adjust the emitter by increasing or decreasing the rate
                                             of emission. You can also change the mass and bounciness
                                             attributes of the gear.


                                                CONCLUSION

                                             You now have particles that are driving a gear using
                                             dynamics. That gear is in turn driving a second gear. The
                                             hinge constraints on the two gears make sure that the gears
                                             are rotating during the simulation. Now you can add shaders
                                             to the various parts to put together a complete scene.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Dynamics/Pendulum




 Alias|Wavefront / Assistant Online / Maya / How Tos / Dynamics / Pendulum




                                                HOW TO CREATE A
                                                                                                            by Steve Christov
                                                NEWTON'S PENDULUM
                                               MAYA: Complete
                                               Rigid Bodies
                                               In this lesson, you will
                                               learn how to set up rigid
                                               bodies to create a
                                               Newton's Pendulum.
                                               You will use nail
                                               constraints on a series
                                               of spheres and apply
                                               gravity fields to the
                                               constraints.
                                                                                                        Play Movie [~789kb]


                                                  STEP ONE

                                               Create a simple base
                                               for the frame of the
                                               pendulum.
                                               To get the same results
                                               as this how-to make the
                                               base 10 units high and
                                               14 units long.
                                               Or if you like download
                                               the file base.ma.[~85kb]




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Assistant Online - Maya/How Tos/Dynamics/Pendulum

                                               STEP TWO

                                            Create a sphere.
                                            Move the sphere 3
                                            units in the Y axis.
                                            Select Create -> CV
                                            Curve Tool -> options.
                                            Set the curve to be a 1
                                            degree linear curve.
                                            In the side view, while
                                            holding down the x key, place a CV in the center of the sphere
                                            and another CV at the top corner of the crossbar. Press Enter
                                            to create the curve.
                                            Press y to reinvoke the CV Curve tool. Create another curve
                                            from the center of the sphere to the opposite crossbar.
                                            Select Create -> NURBS Primitives -> Circle. Scale it down to
                                            0.1. Using the x key, snap it to the center of the sphere.
                                            Select the circle and while holding down the Ctrl key, select
                                            one of the curves. Select Surfaces -> Extrude -> options. In
                                            the option box, set Result Position to At Path.
                                            Press Extrude. Using the same circle, repeat for the other
                                            curve.
                                            In the Hypergraph window, delete the NURBS circle, and the
                                            two curves.


                                               STEP THREE

                                            Select the Sphere
                                            and Group it to itself.
                                            Select and Group the
                                            two extrudes.
                                            Rename the group for
                                            the extrudes to
                                            threads and the group
                                            for the sphere ball.
                                            Select the two groups and set the Translate X to -4.




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                                               STEP FOUR

                                            Select the threads
                                            and ball group nodes
                                            and select Edit ->
                                            Duplicate ->
                                            options.
                                            Change Translate X
                                            to 2. Set the Number
                                            of Copies to 4.
                                            Press Duplicate and close the duplicate window.


                                               STEP FIVE

                                            You are now ready to
                                            add nail constraints to
                                            the spheres.
                                            Select one of the
                                            spheres.
                                            Select Bodies ->
                                            Create Constraint ->
                                            options.
                                            In the dialogue box select nail as the constraint type. This will
                                            create a nail in the center of the sphere. With the nail still active
                                            switch to the side view.
                                            Select the Move tool and while pressing the x key, Move the
                                            nail so that it is positioned directly on the crossbar to the left of
                                            the sphere. Keep in mind that the nail constraints should follow
                                            the same path as the extrudes.
                                            Create a Second Nail constraint for the same sphere and
                                            move it so that it is positioned on the crossbar to the right of the
                                            sphere.
                                            Repeat the same procedure for the remaining spheres making
                                            sure that there are two nail constraints for each sphere.




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                                               STEP SIX

                                            You will now parent the
                                            threads to each ball.
                                            In the Hypergraph
                                            window, Click and
                                            Drag with the middle
                                            mouse button the node
                                            threads on to the
                                            nurbsSphere1 icon.
                                            Repeat for each thread
                                            node to parent the groups to the appropriate spheres.


                                               STEP SEVEN

                                            Select the ball group
                                            node.
                                            Select the Rotate tool
                                            and press Insert to
                                            relocate the pivot
                                            point. While pressing x
                                            move the pivot point
                                            up to the level of the
                                            crossbar. Press Insert to return to the rotate tool.
                                            Rotate along the Z axis to bring the sphere up and away from
                                            the others.


                                               STEP EIGHT

                                            You are now ready to
                                            add gravity to the
                                            spheres.
                                            Select each sphere,
                                            making sure that the
                                            nail constraints are not
                                            picked. With all five
                                            spheres selected,
                                            Click on Fields -> Create Gravity.
                                            NOTE: To increase the speed of the pendulum, increase the
                                            magnitude of gravity.




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                                               STEP NINE

                                            With the spheres still
                                            selected, set the following
                                            values in the channel box.
                                               q Mass = 10

                                               q Bounciness = 1.0

                                               q Static Friction = 0.1

                                               q Dynamic Friction =
                                                  1
                                            Set your time slider to 200
                                            and press play.


                                               CONCLUSION

                                            You have used some basic dynamic features to re-create
                                            Newton's pendulum. By creating nail constraints on each
                                            sphere you automatically turn them into rigid bodies - you can
                                            then add gravity to create Newton's Toy!
                                            Download the completed pendulum.ma.[~157kb]

                                            Use of this file confirms your agreement to the Terms and Conditions
                                            set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Fur/Comb Fur




 Alias|Wavefront / Assistant Online / Maya / How Tos / Fur / Comb Fur




                                                 HOW TO COMB FUR                                                     by Robert Magee
                                                Maya Unlimited
                                                Fur, Artisan
                                                In this lesson you will
                                                learn how to comb fur
                                                using the Artisan
                                                brushes.
                                                You will paint several fur
                                                attributes such as length
                                                and baldness to add
                                                some hair to the bouncing ball from Learning Maya. You will
                                                also use the brush to set the direction of the hair. With Artisan
                                                this will work just like combing your own hair.


                                                   STEP ONE

                                                Create a NURBS primitive
                                                Sphere and Scale it to
                                                look like a bouncing ball.
                                                Create and apply the
                                                face.iff texture from project
                                                one of Learning Maya.
                                                Select the sphere and
                                                select Fur > Attach Fur Description > New. Now you can see
                                                fur indicators all over the sphere.




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Assistant Online - Maya/How Tos/Fur/Comb Fur

                                                STEP TWO

                                             Select the fur. In the
                                             Channel box, select the
                                             nurbSphere_Feedback
                                             Shape node and set the
                                             following:
                                                 q U and V samples to
                                                   50
                                                 q Fur Accuracy to 1

                                                 q Color Feedback
                                                   enabled to On.
                                             Now the display is denser and will give more visual feedback.
                                             With larger models these settings might be too high and
                                             interactive feedback would be compromised but for the ball it is
                                             fine.


                                                STEP THREE

                                             Reselect the sphere.
                                             Select Fur > Paint Fur
                                             Attributes Tool - options.
                                             This opens two windows.
                                             From the Paint Fur Tool
                                             Settings window, set Fur
                                             Attribute to Baldness.
                                             In the Tool Settings window, set the stamp profile's Value to 0
                                             and its Opacity to 1. Click on the Flood button next to Value.
                                             Now the sphere is totally bald.
                                             Set the stamp profile's Value to 1 and its Opacity to 0.5. Create
                                             a Radius [u] for your brush that suits the top of the sphere then
                                             paint the hair back onto the sphere. You are reversing the
                                             baldness where you want the hair to be visible.


                                                STEP FOUR

                                             To comb the hair, you will
                                             paint the Direction.
                                             From the Paint Fur Tool
                                             Settings window, set Fur
                                             Attribute to Direction.
                                             Zoom in and brush the
                                             hair.
                                             Oops! Nothing is happening. This is because the hair is
                                             standing straight up. Therefore any changes to its direction are
                                             not noticeable. You need to set the Fur's inclination so that the

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Assistant Online - Maya/How Tos/Fur/Comb Fur

                                             hair is not standing up straight.
                                             From the Paint Fur Tool Settings window, set Fur Attribute to
                                             Inclination.
                                             In the Tool Settings window, set the stamp profile's Value to .25
                                             and its Opacity to 1. Click on the Flood button next to Value.
                                             Now the fur is tilted down. You can even see some changes in
                                             direction based on your original direction brushing.


                                                STEP FIVE

                                             From the Paint Fur Tool
                                             Settings window, set Fur
                                             Attribute to Direction.
                                             In the Tool Settings
                                             window, set the stamp
                                             profile's Value to 1 and its
                                             Opacity to 0.5.
                                             Zoom in and brush the
                                             hair.


                                                STEP SIX

                                             You will notice that it is
                                             easy to brush the hair on
                                             the sides but the top of the
                                             head is difficult. This is
                                             because the isoparm lines
                                             meet at the top and the
                                             direction is more sensitive.
                                             Tip: It might be better if the isoparm "poles" were not at the top
                                             of the head. To fix this you could create a second sphere that
                                             sits just inside the first one that holds the hair. This surface
                                             would put the isoparm poles at the ear so that the top of the
                                             head is easier to control.
                                             You can now set other fur values such as length, using either
                                             the Attribute editor or the Artisan brush. You can also set up
                                             color for the base and tip of the hair.


                                                CONCLUSION

                                             This lesson introduces you to the use of Artisan tools for
                                             combing and editing fur in Maya. You can get more in-depth
                                             information about using fur from the Using Maya Fur manual.




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                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Modeling/bevelCaps.mel




 Alias|Wavefront / Assistant Online / Maya / How Tos / Modeling / bevelCaps.mel




                                                 HOW TO USE THE "bevelCaps"
                                                                                                                 by Bob Gundu
                                                 MEL SCRIPT
                                                Maya Complete
                                                In this lesson you will
                                                learn how to use the
                                                bevelCaps.mel script.

                                                This script will add planar
                                                surfaces to the top and
                                                bottom of the selected
                                                bevelled surfaces. It will
                                                also set the planar
                                                surfaces to a high quality of tessellation to get good quality
                                                results when rendered.


                                                  INSTALLATION

                                                Copy the bevelCaps.mel into your scripts directory (typically
                                                $Maya/scripts). For general instructions on installing mel
                                                scripts, see How to Use an Assistant Online mel Script .


                                                   STEP ONE

                                                Select Create > Text
                                                -Options, and set the
                                                following:
                                                      Text to Maya
                                                      Font to
                                                      Helvetica-Bold
                                                      Type to Curves
                                                Press Create.
                                                Scale X,Y,Z to 4.




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Assistant Online - Maya/How Tos/Modeling/bevelCaps.mel

                                               STEP TWO

                                             With the type active,
                                             select Surfaces > Bevel
                                             - Options, and press
                                             Reset, then Bevel.




                                               STEP THREE

                                             You will now execute
                                             the bevelCaps script.
                                             Type bevelCaps into the
                                             command line and
                                             press Enter.
                                             There should be
                                             surfaces on the front
                                             and back of the bevelled surfaces.


                                              CONCLUSION

                                             You should have a
                                             good understanding of
                                             how to use the
                                             bevelCaps script. You
                                             should note that
                                             construction history on
                                             the bevels will not
                                             update the planar
                                             surfaces. You will
                                             need to reapply the script. Also, the script creates one planar
                                             surface for the front and one for the back. The workaround for
                                             creating a seperate face for each letter is to apply the script to
                                             each letter seperately.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Modeling/Gear




 Alias|Wavefront / Assistant Online / Maya / How Tos / Modeling / Gear




                                                 HOW TO BUILD A
                                                                                                            by Robert Magee
                                                 POLYGONAL GEAR
                                                MAYA Complete
                                                Polygon Modeling
                                                In this lesson, you will
                                                learn how to build a gear
                                                by starting with a
                                                polygonal cylinder then
                                                pulling vertices to create
                                                the final shape. You will
                                                also learn how to
                                                constrain grid snap
                                                along one axis to refine
                                                some of the points.                    Play Instructional movie [~8.6 MB]


                                                   STEP ONE

                                                Create a primitive
                                                POLYGON cylinder.
                                                Scale the cylinder along
                                                the Y axis to flatten the
                                                cylinder.
                                                Click on the cylinder's
                                                polyCylinder input node.
                                                Change the number of
                                                subdivisions to 32.
                                                This will give us enough vertices to create 8 spokes for the
                                                gear.
                                                Select the cylinder and then choose Edit > Delete by Type >
                                                History. This is very important for later when you want to
                                                harden the edges of the polyset.




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                                                STEP TWO

                                             Press F8 to go into
                                             component mode and
                                             make sure that the select
                                             by Points pick mask has
                                             been picked.
                                             In a top view, select two
                                             CVs then skip two CVs.
                                             Repeat this all round the
                                             edge of the cylinder.


                                                STEP THREE

                                             Select the Scale tool
                                             then click drag on the
                                             middle of the scale
                                             manipulator to scale in all
                                             directions.
                                             Scale the vertices out
                                             until you get the look that
                                             you want.


                                                STEP FOUR

                                             Since you scaled in all
                                             directions, the vertices at
                                             the top and bottom of
                                             your gear are no longer
                                             aligned.
                                             In a side view, select all
                                             the vertices belonging to
                                             the top of the gear.


                                               STEP FIVE

                                             Press the X key to
                                             temporarily turn on Grid
                                             snapping then click on
                                             the Y axis manipulator
                                             handle and drag the
                                             points up. They will be all
                                             snapped to the nearest
                                             grid line.
                                             Now without grid
                                             snapping, drag the points down using the Y axis manipulator
                                             handle to bring the points back down closer to the origin.



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Assistant Online - Maya/How Tos/Modeling/Gear

                                               STEP SIX

                                             Repeat the steps
                                             outlined above to flatten
                                             the vertices on the
                                             bottom of the gear.




                                               STEP SEVEN

                                             You now want to harden
                                             the edges of the
                                             polymesh. Turn the
                                             Select by Points mask
                                             button off and turn the
                                             Select by Lines button
                                             on.
                                             Click drag over the whole
                                             gear to select all of the
                                             poly edges. To harden the edges, select the Edit Polygons >
                                             Normals > Soften/Harden options. Click on the All Hard
                                             button then click on the Soft/Hard button. Now the edges will
                                             be hard when rendered later.


                                                CONCLUSION

                                             You now have a poygonal gear. You have learned how to
                                             edit vertice positions by scaling and by grid snapping while
                                             constrained along one axis.
                                             If you have Maya FX, you can now use this gear as part of a
                                             particle simulation involving particle collisions and dynamic
                                             constraints in the How to use particles to drive rigid bodies
                                             lesson.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Modeling/Nurbs Booleans




 Alias|Wavefront / Assistant Online / Maya / How Tos / Modeling / Nurbs Booleans




                                                 HOW TO WORK WITH NURBS BOOLEANS                                by Robert Magee
                                                Maya Unlimited
                                                Advanced Modeling
                                                In this lesson you will
                                                learn how to create
                                                shapes using NURBS
                                                booleans.
                                                A NURBS boolean
                                                operation treats two or
                                                more surfaces like solids
                                                then performs an
                                                intersection and trim on the participating surfaces.
                                                When working with booleans, the three main operations are
                                                Subtract which removes one surface volume from another,
                                                Intersect that creates a new shape where the two volumes
                                                share the same space and Union which adds the two shapes
                                                into a larger volume.
                                                Booleans have history and can be switched from Subtract to
                                                Intersect to Union. You can also update history by repositioning
                                                the original surfaces used to generate the boolean.
                                                To effectively use booleans, you will also explore how the
                                                surface's normals affects the results of the boolean.


                                                   STEP ONE

                                                Create a NURBS Sphere
                                                and a NURBS Cylinder.
                                                Place the two shapes so
                                                that they are intersecting.




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                                               STEP TWO

                                             Select Edit Surfaces >
                                             Booleans > Subtract
                                             Tool.
                                             Click on the sphere then
                                             press the Enter key to
                                             select it as the first
                                             object.
                                             Click on the cylinder
                                             then press the Enter key to select it as the second object. The
                                             shapes are subtracted and the sphere now has the cylinder
                                             removed from its surface.
                                             Note: If you added color in Step One to the two parts, you will
                                             notice that the color disappears. In fact the boolean operation
                                             has produced two new surfaces that will need to have shaders
                                             reapplied. In some cases more than two new surfaces may be
                                             produced.


                                               STEP THREE

                                             The boolean does use
                                             history which can be
                                             updated. The first
                                             method for updating
                                             history is to choose
                                             another boolean
                                             operation from the
                                             Channel box.
                                             Click on the boolean input node in the Channel box. Set
                                             Operation to Intersect.
                                             Now the resulting shape shows the volume that is shared by
                                             the cylinder and the sphere.


                                               STEP FOUR

                                             Select one of the boolean surfaces then click on the boolean
                                             input node in the Channel Box.
                                             In the Hypergraph, select the hidden nurbs sphere node. Move
                                             the sphere to update the history on the shape. You can even
                                             animate these hidden shape nodes although they will slow
                                             down interactive feedback when you playback the scene.




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Assistant Online - Maya/How Tos/Modeling/Nurbs Booleans

                                               STEP FIVE

                                             Another issue that
                                             affects how booleans
                                             operate is the surface's
                                             normals. By using a
                                             plane, you can see how
                                             Maya treats any surface
                                             as if it is a volume when
                                             performing booleans.
                                             Start a new scene.
                                             Create a NURBS Primitive plane. Go into component mode
                                             and pull the middle two rows of CVs up to add curvature to the
                                             surface.


                                               STEP SIX

                                             Create a NURBS
                                             sphere that intersects
                                             the plane.
                                             Duplicate both the
                                             sphere and the plane
                                             and move them to the
                                             side.



                                               STEP SEVEN

                                             Select both of the plane
                                             surfaces and select
                                             Display > NURBS
                                             Components >
                                             Normals. Be sure that
                                             you are in shaded mode.
                                             Lines protrude out from
                                             the surface to indicate
                                             the surface's normal
                                             direction.
                                             Select one of the surfaces and select Edit Surfaces > Reverse
                                             Surface Direction. Now this surface's normals are going in the
                                             opposite direction.




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Assistant Online - Maya/How Tos/Modeling/Nurbs Booleans

                                               STEP EIGHT

                                             Select Edit Surfaces >
                                             Booleans > Subtract
                                             Tool.
                                             Click on one of the
                                             spheres then press the
                                             Enter key to select it as
                                             the first object.
                                             Click on the corresponding plane then press the Enter key to
                                             select it as the second object. The shapes are subtracted and
                                             the sphere now has the cylinder removed from its surface.
                                             Repeat these steps for the other sphere/plane combination.
                                             You will notice that in the results are the opposite. This is
                                             because the side of the surface that shows the normals is seen
                                             as the "outside" of the surface volume while the opposite side is
                                             the "inside". Therefore the "inside" of the surface volume is
                                             subtracted from the sphere in both cases.


                                               CONCLUSION

                                             Booleans are a great tool for quickly bringing together NURBS
                                             shapes into a series of trimmed surfaces. Make sure that trims
                                             are what you need for your model since they can break apart if
                                             the surfaces are deformed.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Modeling/Spiral Staircase




 Alias|Wavefront / Assistant Online / Maya / How Tos / Modeling / Spiral Staircase




                                                  HOW TO BUILD A SPIRAL STAIRCASE                              by Robert Magee
                                                 Maya Complete
                                                 Modeling
                                                 In this lesson, you will learn
                                                 how to build a spiral
                                                 staircase using polygon
                                                 booleans and a bend
                                                 deformer.
                                                 This lesson highlights how
                                                 deformers can be used to
                                                 enhance the modeling                                       Play Movie [~132kb]
                                                 process.


                                                    STEP ONE

                                                 Select Create > Polygons
                                                 Primitives > Cube.
                                                 In the Channel box, set the
                                                 cube's width to 5 and its
                                                 subdivisionsZ to 10.
                                                 Move the cube so that it is
                                                 sitting on the ground plane.
                                                 This cube will act as the first tread of the staircase. The
                                                 subdivisions will help ensure a smooth bending later.




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Assistant Online - Maya/How Tos/Modeling/Spiral Staircase

                                                 STEP TWO

                                              Select Edit > Duplicate >
                                              options.
                                              Set Smart Transform to
                                              On. This option will allow
                                              you easily create multiple
                                              duplications. Click the
                                              Duplicate button.
                                              In the side view, Move the duplicated cube up and to the right.
                                              This will be the second tread.
                                              Note: Do not de-select the cube. If you do, Smart Transform
                                              will lose the offset information it needs to produce the
                                              duplicates created in the next step.


                                                 STEP THREE

                                              Press Ctrl - d. This will
                                              create another duplicate
                                              that is offset by the same
                                              amount as the second
                                              tread.
                                              Press Ctrl - d eight more
                                              times to create the treads
                                              of the stair.
                                              You now have several cubes that are all separate shapes. You
                                              will need to use polygonal booleans to create a single surface
                                              for the stair.


                                                 STEP FOUR

                                              Select the first two treads.
                                              Select Polygons >
                                              Booleans > Union. They
                                              are now one shape.
                                              Note: you can only join two
                                              polysets at a time. Now
                                              you have to add the other
                                              treads.
                                              Press the shift key then add the third tread to the selection.
                                              Press the g key to repeat the boolean union. Repeat these
                                              steps until all the treads are combined into a single polyset.
                                              The various booleans have added history to the staircase that
                                              is not needed. Select the polyset then select Edit > Delete by
                                              Type > History to remove the extra input nodes.



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Assistant Online - Maya/How Tos/Modeling/Spiral Staircase



                                                 STEP FIVE

                                              Select Create > EP Curve
                                              Tool. In the side view,
                                              draw a single span curve
                                              where you would want to
                                              place a handrail.
                                              Select Edit Curves >
                                              Rebuild Curves -
                                              options. Set Number of Spans to 20. Click Rebuild. This will
                                              add enough CVs to ensure a good bending when you add the
                                              deformer later.
                                              In the top view, place one curve at one side of the stair and
                                              then duplicate the curve to create a second handrail at the
                                              other side of the stair.
                                              Note: You have built a curve for the handrail so that you can
                                              extrude a profile after the bending. Building the handrail as a
                                              surface would add too much distortion after bending.


                                                 STEP SIX

                                              Select the curves and the
                                              stair polyset.
                                              Select Deform > Create
                                              Nonlinear > Bend -
                                              options. Set Curvature to
                                              4 then click on the Create
                                              button. This gives you a
                                              sideways bend that doesn't look like a staircase.


                                                 STEP SEVEN

                                              In the Channel box, set the
                                              bendHandle's rotateX to
                                              90. This reorients the
                                              deformer to create more of
                                              a stair shape.
                                              With the Move tool, move
                                              the bendHandle along the
                                              X axis to widen the bend. Now the handrail curves and the
                                              treads are bending nicely into a spiral stair.




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Assistant Online - Maya/How Tos/Modeling/Spiral Staircase

                                                 STEP EIGHT

                                              In the Channel box, click
                                              on the bend Input node.
                                              Now select the Show
                                              Manipulator tool. You can
                                              drag on the curvature
                                              handle to adjust the
                                              amount of curve in the
                                              bend.
                                                                                           Play Movie [~160kb]
                                              Note: You can also
                                              animate the bending of the stair by setting keys on the
                                              curvature attribute.


                                                 STEP NINE

                                              To create the handrail
                                              surfaces, create a
                                              primitive circle and scale it
                                              to a reasonable radius.
                                              Select the circle and then
                                              one of the handrail curves.
                                              The path curve for an
                                              Extrusion must be picked last.
                                              Select Surfaces > Extrude - options. Set Result Position to
                                              At Path and Pivot to Component. Click Extrude and the
                                              handrail will be placed on the handrail curve. Repeat for the
                                              other handrail.
                                              Tip: If history is maintained as you extrude then you can later
                                              select the circle and scale it. The two handrail surfaces will
                                              update to show the new profile radius. This lets you evaluate
                                              the profile size after extruding to see it in context.


                                                 CONCLUSION

                                              The bend deformer has made it easy to build a spiral staircase
                                              with handrails. You can now delete history or choose to keep it
                                              around in case you want to update some part of the model.
                                              Download a finished scene file:
                                              Staircase.ma[~188kb]


                                              Your use of this file confirms your agreement to the
                                              Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Modeling/Square Surfaces




 Alias|Wavefront / Assistant Online / Maya / How Tos / Modeling /Square Surfaces




                                                 HOW TO WORK WITH SQUARE
                                                                                                             by Robert Magee
                                                 SURFACES
                                                Maya Unlimited
                                                Advanced Modeling
                                                In this lesson, you will
                                                build two surfaces using
                                                the Square tool. You will
                                                learn how to create a
                                                square surface using four
                                                boundary curves, and a
                                                square surface that
                                                maintains continuity with a
                                                neighboring surface.


                                                   STEP ONE

                                                Select Create > EP (Edit
                                                Point) Curve Tool. Draw
                                                a single span curve along
                                                the Z axis.
                                                Duplicate the curve and
                                                Move it forward along the
                                                X axis.



                                                   STEP TWO

                                                Select Create > EP (Edit
                                                Point) Curve Tool. Press
                                                the c key to use curve
                                                snapping and click drag on
                                                the first curve until you
                                                place a point at the end of
                                                the curve. Use this
                                                snapping to place a
                                                second point at the end of
                                                the other curve.



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                                             Press the Enter key.
                                             Repeat to add a single span curve to the other end of the initial
                                             curves. Be sure to use curve snapping to place all the points
                                             since the Square tool requires intersecting curves to work
                                             properly.


                                               STEP THREE

                                             Select the front curve and
                                             the two side curves. Press
                                             F8 to go into component
                                             mode.
                                             Select all the CVs on the
                                             front curve and the two
                                             end CVs of the side
                                             curves.
                                             Move the CVs down along the Y axis. This will add some
                                             curvature to the shape you are creating.
                                             By moving the end CVs of the side curves, you make sure that
                                             they are still intersecting the front curve.


                                               STEP FOUR

                                             Press F8 to go back to
                                             object mode. Click in
                                             space to deselect the
                                             curves.
                                             Select the four curves in
                                             either a clockwise or
                                             counterclockwise
                                             direction. They must be
                                             selected in some order for the Square tool to work properly.
                                             Select Surfaces > Square. Press the 3 key to increase the
                                             surface's display smoothness.
                                             The surface is created so that it touches all the boundary
                                             curves. You are now going to build a second square surface
                                             that uses the first surface for one of its edges.




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Assistant Online - Maya/How Tos/Modeling/Square Surfaces

                                               STEP FIVE

                                             Duplicate the front curve
                                             that was used to build the
                                             surface. Move it forward
                                             and down in front of the
                                             first surface.
                                             Create two more single
                                             span edit point curves to
                                             create a boundary for a
                                             new surface. Use curve snapping to help you.


                                               STEP SIX

                                             Click on the first surface
                                             with your right mouse
                                             button and select Isoparm
                                             from the marking menu.
                                             Click on the edge isoparm
                                             that makes up the top
                                             edge of the new boundary.
                                             It will highlight in yellow
                                             when it is selected.
                                             Press the shift key and select the other three curves in
                                             clockwise or counter clockwise order.
                                             Select Surfaces > Square. Press the 3 key to increase the
                                             surface's display smoothness.
                                             You can now see a surface but the surface is not created with a
                                             clean topology. You will try and find out why this is happening.


                                               STEP SEVEN

                                             With the new surface
                                             selected and its squareSrf
                                             input node highlighted in
                                             the Channel box, select
                                             the Show Manipulator
                                             tool.
                                             Manipulators appear that
                                             show the continuity
                                             condition at the edges which are numbered in the order you
                                             picked them.
                                             Fixed means that the surface is meant to match the
                                             neighboring curve or surface based on the edge position.
                                             Tangent means that the surface will match the neighboring
                                             surface based on its tangency. This will make the surfaces
                                             appear to flow together.


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                                             The original single span curves should produce single span
                                             surfaces but the new surface has extra isoparm spans. If you
                                             zoom in closer, the surface is also not conforming to the two
                                             side curves. This is because the side curves were not tangent
                                             to the first surface. Therefore the new surface had to add
                                             isoparm spans and break away from the side curves in order to
                                             meet the tangency requirement at Edge 1.


                                               STEP EIGHT

                                             Select the first surface
                                             and one of the side
                                             curves.
                                             Select Edit Curves >
                                             Project Tangent. Now the
                                             curve should be tangent to
                                             the surface. Construction
                                             history on the second
                                             square surface will update it's topology as the curve is fixed.
                                             Note: You may have to change the projectTangent node's
                                             Tangent Direction in the Channel box from U to V depending
                                             on the order in which you chose the curves to build the first
                                             surface.
                                             Repeat for the other side curve. Now if you select the second
                                             square surface, you will see that it is a single span in both
                                             directions. Also it is not breaking away from the side curves
                                             since they now all follow the same rules of tangency.


                                               CONCLUSION

                                             By using the edge of one or more surfaces to help build another
                                             surface, the Square tool's tangent continuity capabilities can
                                             come into play. By building clean curves as boundary curves
                                             then making sure that those curves also maintain tangency with
                                             related surfaces, you can build up a patchwork of surfaces that
                                             all appear to work as a single surface.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Paint Effects/Tree




 Alias|Wavefront / Assistant Online / Maya / How Tos / Paint Effects / Tree




                                                   HOW TO CREATE A TREE
                                                                                                                 By Steve Christov
                                                   IN PAINT FX
                                                  Maya 2.5 Complete
                                                  Paint Effects
                                                  In this lesson you will
                                                  create a tree in Paint
                                                  Effects starting from a
                                                  simple black brush
                                                  stroke.
                                                  While this approach is
                                                  somewhat drastic it will
                                                  help you form a good
                                                  understanding of the                                       Play Movie [~800k]
                                                  attributes that make up
                                                  Paint Effects.
                                                  This article assumes you have Paint Effects loaded into Maya.
                                                  Please see the Maya help menu on how to install Paint Effects
                                                  if you have not already done so.
                                                  This lesson is the third of a three part lesson. You may want to
                                                  complete parts one "How to create a realistic sky using EnvSky"
                                                  and two "How to create realistic shadows using EnvSky" before
                                                  you start this lesson.


                                                    STEP ONE

                                                  Download and open the
                                                  scene
                                                  Env_sky_shadow. If you
                                                  have completed the
                                                  previous lessons, you
                                                  can use your last saved
                                                  scene file.
                                                  Delete the sphere.
                                                  Select the lights, 3D env_sky icon, and the 3D texture icon for
                                                  the cloud.
                                                  Select Display > Hide > Hide Selection. This will unclutter the


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Assistant Online - Maya/How Tos/Paint Effects/Tree

                                             scene so we can concentrate on the Paint Effects stroke.


                                               STEP TWO

                                             Switch to the Persp
                                             window. Select the
                                             plane and select the
                                             Paint Effects > Make
                                             Paintable.
                                             Open the Visor by
                                             selecting Windows >
                                             Visor. Scroll to the
                                             bottom and open the section marked Brushes. This will give
                                             you access to the Paint Effects preset brushes.
                                             Open the Pens and select the simpleLine brush.
                                             In your perspective window, Paint a small stroke near the
                                             origin.


                                               STEP THREE

                                             With the stroke still
                                             selected, open the
                                             Attribute Editor. Open
                                             the tab simpleLine1.
                                             Your first step is to add
                                             tubes to the brush.
                                             Open the tubes section
                                             and Click beside
                                             Tubes and then Tube Completion.
                                             Open the Tubes > Creation section. Change the Tubes Per
                                             Step to 0.1 and the Tube Rand attribute to 0. Also change the
                                             Length Min to 0.8, and the Length Max to 0.9.
                                             You will also see some attributes called Tube Width1 and 2.
                                             These set the width for the base of the tube and the tip of the
                                             tube respectively. Change the Tube Width1 to 0.12 and Tube
                                             Width2 to 0.09. There are settings for randomness and bias
                                             for multiple tubes across the same stroke but because we are
                                             only creating one tube, we can ignore these settings.
                                             Change the number of Segments to 40. This will increase the
                                             number of segments that are used to create the tube.
                                             The Elevation attribute dictates the lean on the tube. Where 0
                                             is the tube lying flat against the curve and 1 standing straight
                                             up. Since you want the tree to stand straight up, set the
                                             Elevation Min and Max to 1.0.
                                             NOTE: You may notice that your tube is still lying flat against
                                             the curve despite changing the elevation attribute. You can fix


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Assistant Online - Maya/How Tos/Paint Effects/Tree

                                             this in the attribute editor. Open Behavior > Forces. Change
                                             the Path Follow to 0.0.


                                               STEP FOUR

                                             Now that you have the
                                             basic shape of the
                                             trunk you are now
                                             ready to shade it.
                                             Open the Shading
                                             section in the Attribute
                                             Editor. Click on the
                                             color swatch next to
                                             Color1. In the color chooser change the RGB values to 0.64,
                                             0.52, 0.41.
                                             Open the Tube Shading section. Click on the color swatch
                                             next to Color2. Set the RGB values to 1.0, 0.85, 0.83.
                                             You have now set the colors for the trunk of your tree. If you
                                             render now you will see that it will render out in one uniform
                                             color. By adding a simple ramp texture to the tube you can
                                             simulate bark.
                                             Open the Texturing section. Click on the icon next to Map
                                             Color. We are going to map a V Ramp to the trunk of the
                                             color to give the appearance of bark.
                                             From the drop down menu beside Texture Type, Select V
                                             Ramp. Set the following attributes:
                                                q Texture2 Color to RGB 0.54, 0.49, 0.44

                                                q Repeat U to 6.0

                                                q Repeat V to 2.2

                                                q Blur Mult to .26

                                                q Smear to 0.203

                                                q Smear V to 0.61

                                             You can preview the progress this far by pressing the hotkey
                                             "8" while in the persp window to switch to the paint effects
                                             preview render window. In the menu select Stroke Refresh >
                                             Rendered. However it will take longer to refresh with each
                                             change.
                                             NOTE: When you render, depending on the length of your
                                             original stroke, you may have more than one tube attached to
                                             your stroke. One way to solve this is to lower the Tubes per
                                             Step attribute in the Tubes > Creation section.




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Assistant Online - Maya/How Tos/Paint Effects/Tree

                                               STEP FIVE

                                             In Paint Effects you
                                             have the option to
                                             Illuminate the tree with
                                             simulated or real lights.
                                             Open the Illumination
                                             section, Check the box
                                             next to Illuminated. This
                                             will use real lights from
                                             your scene on your paint effects tree.
                                             We are also going to add some specular qualities to the tree to
                                             give it some highlights. Set Specular to 0.15.


                                               STEP SIX

                                             Now that we have the
                                             trunk, we are ready to
                                             add some branches.
                                             Open the Tubes Growth
                                             section and click next
                                             to Branches to add
                                             them to the trunk.
                                             Open the Branches section. Increase the Split Max Depth to
                                             7. This increases the number of times the branch will split up.
                                             Increase the Branch Dropout to 0.02.
                                             The next set of values control different attributes for the split on
                                             the branch including Randomness, Angle of split, Twist. Feel
                                             free to experiment with these values and come up with your
                                             own style of tree or you can set the following values:
                                                 q Split Rand to .017

                                                 q Split Angle to 26.3

                                                 q Split Twist to 0.32

                                                 q Split Size Decay to 0.67

                                                 q Split Bias to 0.19




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Assistant Online - Maya/How Tos/Paint Effects/Tree

                                               STEP SEVEN

                                             Click on the box next to
                                             Twigs to turn them on.
                                             Open the twigs section.
                                             Set the Num Twig
                                             Clusters to 8.0 and set
                                             the Twig Dropout to
                                             0.439.
                                             Then next attribute set length, width,angle and twist. Again feel
                                             free to experiment with the settings to get your own tree or set
                                             the following attributes:
                                                 q Twig Length to 0.08

                                                 q Twig Base Width to 0.7

                                                 q Twig Tip Width to 0.15

                                                 q Twig Angle1 to 52.5

                                                 q Twig Angle2 to 54.0

                                                 q Twig Twist to 0.512

                                             Keep in mind that your
                                             twigs will decide the
                                             placement of leaves. So
                                             these settings can have a
                                             pretty dramatic effect
                                             down the line. For
                                             example increasing the
                                             number of Twig Clusters
                                             will result in more leaves on your final tree.


                                               STEP EIGHT

                                             You will now add some
                                             leaves to the tree to
                                             complete the look.
                                             Click the box next to
                                             Leaves. Set the
                                             following attributes:
                                                 q Leaves in
                                                   Cluster to 5.0
                                                 q Num Leaf
                                                   Clusters to 4.0
                                                 q Leaf Dropout to
                                                   0.154
                                                 q Leaf Length to
                                                   0.04
                                                 q Leaf Base Width
                                                   to 0.035
                                                 q Leaf Tip Width




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                                                      to 0.01
                                                  q   Leaf Start to 0.9




                                                  q
                                                      Leaf
                                                      Twist
                                                      to
                                                      0.5
                                                  q   Leaf
                                                      Translucence to
                                                      0.561
                                                  q   Leaf Sat Rand to
                                                      0.033
                                                  q   Leaf Val Rand to
                                                      0.114
                                             Check the box next to Terminal Leaf. This will place a leaf at
                                             the end of each twig.


                                               STEP NINE

                                             If you render your
                                             image at this point
                                             you should have a
                                             basic looking tree.
                                             You are now ready to
                                             add various other
                                             attributes to further
                                             enhance your tree.
                                             In the Attribute Editor open the Behavior Forces section. Set
                                             the Gravity slider to 0.05. You will notice that the branches
                                             and leaves out as if the weight of the leaves was pulling the
                                             branches down.




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                                               STEP TEN

                                             You are now ready to
                                             add some animation to
                                             the tree to simulate it
                                             swaying in the wind.
                                             Open the Behaviour
                                             then the Turbulence section. Set the Turbulence Type to
                                             Grass Wind. Set Turbulence Interpolation to Smooth over
                                             Time and Space.
                                             Because we are going to use this tree with a time lapse sunset,
                                             you will want the tree to behave with tight motion in the tree
                                             trunk and branches but you do want the the leaves to give the
                                             impression of some quick fluttering in the wind. Set the
                                             following values:
                                                 q Turbulence to 0.02

                                                 q Turbulence Frequency to 0.005

                                                 q Turbulence Speed to 1.0

                                             Set the Time Slider to 100. Press Play. Switch to the
                                             Perspective window. The wireframe will give you an indication
                                             of the general motion of the tree.


                                                 STEP ELEVEN

                                             You will now save your
                                             brush to the visor so
                                             you can access it in the
                                             future. With the tree
                                             selected, go to Paint
                                             Effects > Get Settings
                                             from Selected Stroke.
                                             This will apply your tree
                                             to the template brush.
                                             Now Select > Paint
                                             Effects >Save Brush
                                             Preset.
                                             Set the Label and Overlay Label to Mytree.
                                             Save it To Visor and set the Visor Directory to Trees.
                                             Click on Grab Icon and drag around your tree in the render
                                             view to make an icon for you brush.
                                             Click Save Brush Preset.




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                                               STEP TWELVE

                                             Select Panels >
                                             Perspective > Camera
                                             1.
                                             Position your tree in the
                                             frame by selecting the
                                             stroke and moving it
                                             with the manipulator.
                                             Add a texture to the
                                             ground plane.
                                             Do some test renders at different frames to make sure you are
                                             happy with the framing and lighting. When you are satisfied
                                             with the results, set the render globals to render the animation
                                             for 100 frames from Camera1.


                                               CONCLUSION

                                             You have now
                                             assembled a complete
                                             scene similar to the one
                                             above. By this point you
                                             have learned how to
                                             create and use an
                                             environment sky, add a
                                             light to it to simulate
                                             realistic shadows based
                                             on the sun position, and
                                                                                                                    Play Movie[~800k]
                                             made your own tree in
                                             paint effects.
                                             Enhance your scene by sculpting the floor surface with Artisan
                                             to make some nice rolling hills and adding some grass strokes
                                             to it.
                                             Download the completed scene file. [~100k]

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Animate Textures




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Animate Textures




                                                 HOW TO ANIMATE TEXTURE FILES                                      by Bob Gundu
                                                MAYA: Base
                                                Rendering
                                                This lesson will
                                                demonstrate how to use
                                                a numbered sequence of
                                                images as a texture map.
                                                There are basically two
                                                methods to achieve this
                                                effect; expressions, and
                                                keyframing. Both will be
                                                covered in this lesson.                                    Play Movie [~314kb]
                                                Note: Before beginning this how-to, you need to have ready a
                                                sequence of frames with a numbered extension such as
                                                filename.rgb.001, im.001, or filename.sgi.01. These frames will
                                                be used as the animated texture map.
                                                Tip: Check the images directory in your favorite Maya project
                                                for rendered frames that you can use with this how-to.


                                                   STEP ONE

                                                In the Multilister, create a File texture node and open the
                                                Attribute Editor for the File node. In the Attribute Editor set the
                                                following:
                                                    q In the File Attributes section, use the Browse button or
                                                      enter in the field the location and name of the sequence
                                                      of images. Be sure not to include the extension. For
                                                      example, if the first frame is named "myRender.sgi.001",
                                                      you should only enter "myRender.sgi".

                                                     q   Change Use Frame Extension to On.




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                                             METHOD 1:
                                             KEYFRAMING
                                             This method requires a
                                             keyframe for the
                                             beginning and the end of
                                             the sequenced images.
                                                q Go to frame 1 (or
                                                   to the frame where
                                                   you want the
                                                   texture to begin
                                                   animating).

                                                  q   With the file1
                                                      texture selected,
                                                      open the Attribute
                                                      Editor (or go to the
                                                      Channel Box) and,
                                                      in the Frame
                                                      Extension field,
                                                      enter the extension
                                                      number of the
                                                      frame where you
                                                      want the texture to
                                                      begin animating.
                                                      (e.g. if your images
                                                      are named
                                                      sequentially
                                                      filename.rgb.8
                                                      through
                                                      filename.rgb.35,
                                                      enter "8")

                                                  q   With the RMB over
                                                      the Frame
                                                      Extension
                                                      attribute, select Set
                                                      Key if using the
                                                      Attirbute Editor (or
                                                      Key Selected if
                                                      using the Channel
                                                      Box) from the
                                                      pop-up window.


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                                                  q   In the Timeline, go
                                                      to the last frame for
                                                      the texture file
                                                      animation.

                                                  q   Enter the the last
                                                      extension number
                                                      from your
                                                      sequence of
                                                      images in the
                                                      Frame Extension
                                                      field. (e.g. if your
                                                      images named
                                                      filename.rgb.8
                                                      through
                                                      filename.rgb.35,
                                                      enter 35)

                                                  q   Set another key
                                                      with the RMB over
                                                      the Frame
                                                      Extension field.

                                                  q   Connect the
                                                      texture file to a
                                                      shading group and
                                                      assign it to a
                                                      surface.
                                             If you scroll through or playback your animation, you will notice
                                             that the file textures are updating.
                                             Tip: Ensure that your animation curve tangents are set to linear
                                             for each keyframe, and that your animation preference for
                                             playback is set to Free.

                                             METHOD 2:
                                             EXPRESSIONS
                                             You can also animate
                                             texture files using an
                                             expression, achieving
                                             the same result as in
                                             Method 1 but without
                                             using key frames.
                                             If you have already
                                             completed Method 1,
                                             you can with the RMB
                                             over the Frame
                                             Extension field, select
                                             Break Connection and

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                                             continue with this
                                             method.
                                             With the RMB over the
                                             Frame Extension field,
                                             select Create New
                                             Expression... from the
                                             pop-up menu to display
                                             the Expression Editor.
                                             In the Expression Editor,
                                             complete the following
                                             steps:
                                                 q In the Attributes
                                                   column select
                                                   FrameExtension.

                                                  q   In the Expression
                                                      field enter the
                                                      following:
                                                              file1.frameExtension
                                                              = frame;
                                                  q   Press Create.
                                             The above expression assumes your file textures sequence
                                             begins with the extension ".1" (e.g. myRender.rgb.1). If your
                                             source images sequence starts with anything other than ".1",
                                             you'll need to edit the expression as follows:
                                                              file1.frameExtension = frame + 7;

                                             This means that, similar to the example given in our keyframing
                                             method where the images are numbered filename.rgb.07
                                             through filename.rgb.35, the system will read "frame" as
                                             "myRender.rgb.1", then add 6 more frames and start animating
                                             the file texture at "myRender.rgb.8".
                                             Note: If you had already created other file nodes, your file
                                             texture name may be something other than file1. If this is the
                                             case, use the name that appears in your session.
                                                 q Connect the texture file to a shading group and assign it
                                                   to a surface
                                             If you scroll through or playback your animation, you will notice
                                             that the file textures are updating.




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                                                CONCLUSION

                                             The example of the
                                             television is only one
                                             way of using an
                                             animated texture map.
                                             Another possibility is
                                             using it for animating
                                             fast moving objects like
                                             rotating tires and
                                             helicopter blades which
                                             have extreme motion                      Play Movie [~314kb]
                                             blur. The animated
                                             texture maps could already include a blurred look to
                                             decrease rendering time.
                                             The keyframing method is a flexible and straight forward
                                             approach to animating a texture map. With this method,
                                             cycling the texture map can be achieved in the Graph Editor.
                                             To do the same with method 2 requires a slightly more
                                             advanced expression.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Combine Map




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Combine Maps




                                               HOW TO COMBINE BUMP
                                                                                                        by Lorna Saunders
                                               & DISPLACEMENT MAPS
                                               Maya Complete
                                               Rendering
                                               In this lesson, you will
                                               learn how to combine a
                                               displacement map and
                                               bump map to create a
                                               brick texture. You will also
                                               learn how to use the
                                               Connection Editor to
                                               connect hidden attributes as you build a textured brick wall.
                                               To achieve both a displaced and bumped surface, you will start
                                               by displacement mapping the shading group with a file texture.
                                               You will notice that this process also maps the bump channel
                                               automatically with the same file texture. Later, a fractal will
                                               serve as a new bump map "chained" to this first bump in the
                                               dependency graph. This approach gives you the combined look
                                               of both the displacement and the bump map qualities on the
                                               shading group.


                                                 STEP ONE

                                               Open the Hypershade and
                                               create a Lambert material
                                               node with a shading group.
                                               Click the show Up and
                                               Downstream Connections
                                               icon in the Hypershade to
                                               display the shading group
                                               node. Name this shading
                                               group WallSG.
                                               Open up the Attribute
                                               editor and click on the
                                               WallSG tab. Map the displacement channel on this shading
                                               group with a grayscale brick file texture like the one shown
                                               here.




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                                              STEP TWO

                                            Assign the shading group
                                            to a plane and rotate it 90
                                            degrees around the X axis.
                                            Add a spotlight to
                                            illuminate the wall.
                                            Render the scene to see
                                            the displaced effect.


                                              STEP THREE

                                            In the Hypershade, create two new
                                            nodes using Create -> Create
                                            Render Node.
                                            Under the texture tab of the Create Render Node window,
                                            create a 2D Fractal texture. Under the Utilities tab, create a
                                            Bump 2D node.
                                            You will be layering these with the displacement map to give
                                            the brick a rougher look.


                                              STEP FOUR

                                            In the Hypershade clear the
                                            view in the work area. With
                                            your MMB, drag the WallSG,
                                            the 2Dbump, and the fractal
                                            nodes from the Visor into the
                                            Hypershade view.
                                            You will be building the rest
                                                                                               Click to view larger version
                                            of this shading network in the
                                            Hypershade.


                                              STEP FIVE

                                            In the Hypershade, drag the fractal node onto the new bump2d
                                            node. The default connection (outAlpha to bumpValue) is made
                                            automatically in this case.




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                                              STEP SIX

                                            Drag the bump2d node onto
                                            the bump2d node that is
                                            already part of the WallSG
                                            shading group. The
                                            Connection Editor opens.
                                            On the left side click on Out
                                            Normal. Go to the Right
                                            Side Filters menu and turn                         Click to view larger version
                                            on Show Hidden. Click on
                                            Normal Camera.
                                            This creates a connection between the two bump nodes. Be
                                            sure that you have Auto-connect turned on under the options
                                            menu in the Connection Editor to make connections this way.


                                              STEP SEVEN

                                            Select the second bump2d
                                            node that you just
                                            connected into the shading
                                            group. Open the Attribute
                                            editor and change the
                                            Bump Depth to about 0.2.
                                            Render your scene again
                                            to see the effect of this
                                            new bump added to the WallSG.


                                              STEP EIGHT

                                            Map an image like the
                                            one shown here to the
                                            color channel of the
                                            material on the WallSG to
                                            complete the look of the
                                            brick wall.




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                                              STEP NINE

                                            Render your scene again
                                            to see the completed
                                            brick wall.




                                              CONCLUSION

                                            You have learned how to create a shading group that has
                                            both a displacement map and a bump map by chaining two
                                            bump nodes together.

                                            Use of this file confirms your agreement to the Terms and Conditions
                                            set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Camera Cuts




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Camera Cuts




                                                HOW TO ANIMATE CAMERA CUTS                                   by Robert Magee
                                                Maya Complete
                                                Rendering
                                                When animating, you
                                                may want to be able to
                                                cut between several
                                                cameras that look at
                                                your scene from different
                                                points of view. In this
                                                lesson, you will learn
                                                how to use the
                                                cameraMain.mb camera
                                                                                                         Play Movie [~407kb]
                                                to cut between other
                                                cameras in the scene.
                                                The camera cut file is included inside cameraMain.ma.

                                                The cameraMain camera is a pre-made camera that has an
                                                expression which lets it mimic the qualities of the other
                                                cameras in the scene, based on a cameraNumber attribute
                                                that you can animate. Note: This expression has been updated
                                                for Maya 2.0.
                                                This lesson uses a scene of a robot in a tunnel to show you
                                                how the camera cuts can be animated using this camera.


                                                  STEP ONE

                                                Create several cameras
                                                in your scene. Make
                                                sure that they are named
                                                camera1, camera2 etc.
                                                The naming is important
                                                to ensure they work with
                                                the camera cut
                                                expression later.
                                                You can now position
                                                and animate these                                         Play Movie [~502kb]
                                                cameras to view your scene.
                                                For the Gunbot scene, camera1 was set up to use an


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                                             expression so that it moved along the z axis as the robot walks,
                                             camera2 is animated to move slowly down the tunnel while
                                             viewing the robot from a distance, and camera3 is waiting
                                             around the corner. This camera is also animated to react when
                                             the robot shoots at it. Each of these cameras represents a
                                             different point of view of the scene.


                                                STEP TWO

                                             Import cameraMain.mb. This
                                             file contains a new camera that
                                             uses the camera cut
                                             expression. If you want to build your own camera cut camera,
                                             or if you want to understand how the cameraMain camera
                                             works, review the How to create a camera cut camera lesson.

                                             Note: If you look through cameraMain and cameraNumber is
                                             referencing a camera that hasn't been created, then
                                             cameraMain will go to a default position at the origin. This
                                             behavior is built into the cameraMain expression.
                                             In a view panel, select Panels -> Perspective -> cameraMain.
                                             Now select View -> Select Camera. Now you have this
                                             camera's attributes in the channel box. The one attribute that is
                                             keyable is the cameraNumber attribute.
                                             By changing cameraNumber you change what camera
                                             cameraMain will look through. If cameraNumber is 2, then
                                             cameraMain will look through camera2.
                                             Note: When you first change the cameraNumber, cameraMain
                                             will not look through the chosen camera. You must playback
                                             the scene, or change your current frame for cameraMain to pop
                                             to its new position.


                                                STEP THREE

                                             You now want to set keys
                                             on cameraNumber so that
                                             you can animate the
                                             cutting of the camera.
                                             From the Animation
                                             preferences Under the
                                             Keys section, set the
                                                                                Click to view a larger version
                                             Default Out Tangent to
                                             Stepped. This will make sure that you jump from camera to
                                             camera at each key.
                                             To set keys on cameraNumber, select the cameraNumber
                                             attribute in the channel box then select Channels -> Key
                                             selected. The robot scene starts with camera3, switches to
                                             camera1, back to camera3 then finally to camera2.
                                             Once the keys are set, you can preview the cuts by playing

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                                             back the scene using cameraMain. To control the timing of
                                             when the cuts occur, you can now easily change the timing of
                                             the keys using the graph editor.


                                                CONCLUSION

                                             When you are happy with the results, you can render out the
                                             scene by making cameraMain as the renderable camera. Don't
                                             forget to turn off the renderable attribute for the perspective
                                             camera.
                                             Note: If you are using motion blur, rendering out the cuts using
                                             cameraMain will create an exaggerated blur at the first frame
                                             of every cut. For instance, as the camera cuts from camera1 to
                                             camera2, there will be a lot of motion blur as the camera leaps
                                             to the new position.
                                             If you want to use motion blur, you can either delete these
                                             incorrect frames, or you can use the cameraMain to find out
                                             where the cuts should occur then use the actual cameras
                                             (camera1, camera2 etc.) to render. To make sure that each
                                             camera renders out with the same name, use a File Name
                                             Prefix in the Render Globals Window.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Create Camera




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Create Camera




                                                HOW TO CREATE A CAMERA CUT
                                                                                                             by Robert Magee
                                                CAMERA
                                                Maya Complete
                                                Rendering
                                                This lesson teaches how to create the cameraMain.ma
                                                camera. In this lesson, you will learn how to set up a camera
                                                that will use an expression to cut between other cameras in the
                                                scene. This expression uses a new attribute called
                                                cameraNumber to decide which other camera in the scene to
                                                "mimic." Basically cameraMain takes on all the key attributes of
                                                the chosen camera.
                                                This camera is designed to be used in the How to animate
                                                camera cuts lesson.


                                                  STEP ONE

                                                Select Create -> Camera.
                                                Rename this camera cameraMain. This is very important
                                                since the expression you will be writing refers to this camera
                                                name.


                                                  STEP TWO

                                                With the Camera selected, select Modify -> Add Attribute...
                                                Set the following:
                                                   q Attribute name to cameraNumber.

                                                   q Data Type to Integer

                                                Click OK.
                                                This new Attribute will be used to determine which camera,
                                                cameraMain will be mimicking. Its name is very important
                                                since the expression uses this attribute name.




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                                               STEP THREE

                                            With the Camera selected, select Window -> Expression
                                            Editor.
                                            Create this expression. To understand how the expression
                                            works, read the script's comments.


                                               CONCLUSION

                                            When using this camera, it is important that your other
                                            cameras are named camera1, camera2 etc. To switch
                                            between them, you can now set keys on the cameraNumber
                                            attribute.
                                            For more details on how to use this camera, complete the
                                            How to animate camera cuts lesson.

                                            Use of this file confirms your agreement to the Terms and Conditions
                                            set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Clouds




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Clouds




                                                 HOW TO MAKE
                                                                                                               by Tom Kluyskens
                                                 NATURAL CLOUDS
                                                Maya Complete
                                                Rendering
                                                In this lesson you
                                                will learn how to
                                                create fly-through,
                                                shadowable clouds.
                                                To achieve this
                                                result, you will
                                                create a shading
                                                network using the
                                                sampler info node, a                                           Play Movie (472k)
                                                reverse utility node
                                                and a ramp texture.


                                                   STEP ONE

                                                Create a sphere.
                                                Use the E_copy script to randomize some copies of the sphere.
                                                Use the settings as shown below.
                                                If you are unfamiliar with the use of mel scripts, please see How
                                                to use an Assistant_Online Script




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                                              STEP TWO

                                             Delete the original sphere.
                                             The result should look like
                                             this.
                                             Select all spheres and
                                             disable their double sided
                                             option in the Window ->
                                             Rendering Editors ->
                                             Rendering Flags. This will make them more transparent,
                                             especially at the borders.
                                             Important : The spheres must have a high degree of overlap or
                                             the spheres will be visible. They must NOT be scaled too much
                                             along one axis or you will see artifacts.
                                             Also note that too many spheres will slow down the render time.
                                             Use a maximum of 10.




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                                                STEP THREE

                                             Create a Lambert shading group, a ramp texture (without
                                             texture placement), a cloud texture, a sampler info utility and a
                                             reverse utility.
                                             Assign the Lambert shading group to the spheres. Rename the
                                             LambertSG to CloudSG, and the Lambert material to CloudM.
                                             Drag the MMB with the cloud texture onto the ambient color of
                                             the CloudM material node.
                                             Scale the Cloud place3Dtexture to 4,4,4.




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                                              STEP FOUR

                                             Connect as follows,
                                             using the Hypershade.
                                                q Connect the
                                                   outColor of the
                                                   ramp to the input
                                                   of the reverse
                                                   node.

                                                  q   Connect the
                                                      reverse output to
                                                      the transparency
                                                      of the CloudM
                                                      node. We reverse
                                                      the cloud color,
                                                      because we want
                                                      the clouds
                                                      transparent where
                                                      they are colored
                                                      black.

                                                  q   Connect the
                                                      sampler info
                                                      facing ratio to the
                                                      U Coord of the
                                                      ramp

                                                  q   Set the type of the
                                                      ramp to URamp
                                                      and change the
                                                      interpolation to
                                                      exponential up.
                                                      Map the Cloud to
                                                      the top tab and
                                                      configure as
                                                      indicated. (bottom
                                                      tab just black).

                                                  q   The Ramp, using
                                                      the sampler info
                                                      facing ratio as an
                                                      Input, will modify
                                                      the Cloud so that
                                                      the borders of the
                                                      spheres will be
                                                      transparent (black
                                                      becomes white
                                                      through the
                                                      reverse utility
                                                      node, thus totally


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                                                      transparent). If the
                                                      U Coord
                                                      (connected to the
                                                      Facing Ratio in
                                                      this example) of a
                                                      U Type Ramp is 0,
                                                      the output color
                                                      will be the bottom
                                                      color of the ramp,
                                                      if it's 1, the top of
                                                      the ramp is the
                                                      output color.




                                                                        Click to view larger version
                                             Note: The Facing Ratio is the degree to which a point on a surface is
                                             facing towards the camera. If the point is located on a part of the surface
                                             that is facing 90 degrees away from the camera (typically the border of a
                                             sphere), the Facing Ratio is 0. If the angle between the surface normal
                                             and the camera ray is 0, the Facing Ratio is 1.


                                                STEP FIVE

                                             Put some lights in the scene :
                                                q 1 directional for the sunlight

                                                q 1 ambient (with a bit of ambient shade) for the scattered
                                                   light
                                                q Some colored Point lights with decay, placed inside the
                                                   clouds to give the clouds some local color (if you want or
                                                   need them).




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                                             CONCLUSION

                                             You have now
                                             created a shading
                                             network that
                                             produces some
                                             interesting
                                             transparent cloud
                                             effects.
                                             With this shader,
                                             you can also try
                                             scaling or animating                         Play Movie (472k)
                                             the 3D placement texture node, or adjusting attributes on the
                                             CloudM material node for different effects.
                                             Here is the completed cloud scene, cloud.ma (106k)

                                                                                E_copy script was written by Gyedo

                                             Jeon

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Depth of Field




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Depth of Field




                                                  HOW TO USE DEPTH OF FIELD                                 by Steve Christov
                                                 Maya Complete
                                                 Rendering
                                                 This tutorial will teach you
                                                 how to use Depth of Field in
                                                 Maya to help add some
                                                 realism of your renderings
                                                 and animations.
                                                 You will be using the
                                                 measure tool to determine
                                                 the distance from the camera to your object and then adjusting
                                                 depth of field attributes such as F-stop and Focus Scale.


                                                    STEP ONE

                                                 Open your completed Jack in the box tutorial from Learning
                                                 Maya.
                                                 Create a new camera. With the camera selected open the
                                                 Attribute Editor, click on the cameraShape tab.
                                                 Open the Depth of Field section. Set Depth of Field to On.




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                                                STEP TWO

                                              To establish what your depth
                                              of field is going to focus on,
                                              you will need to measure the
                                              distance from your camera to
                                              the object or area you
                                              focusing on.
                                              Go to Modify > Measure > Distance Tool, and use the four
                                              view panels to measure the distance from camera1 to the Jack.
                                              Reselect the new camera. In the Depth of Field section, set
                                              Focus Distance to the value determined by the measure
                                              distance tool.
                                              Render your scene in the render view window.


                                                STEP THREE

                                              You will notice that the
                                              desired effect of a focused
                                              Jack and unfocused
                                              foreground and background
                                              elements is minimal in this
                                              rendering. This is because
                                              the present units in the
                                              scene are measured in
                                              centimeters which makes the model too small to make use of
                                              any normal F-stop setting.
                                              Try to imagine photographing the toys on your desk with a
                                              camera standing only a foot away. You would not see the effect
                                              of depth of field because the objects are too small. Fortunately
                                              you have the option to scale the camera down to achieve a
                                              realistic result in these units.
                                              In the camera attribute change the Focus Region Scale to
                                              around 0.15. This is an approximate conversion from
                                              centimeters to feet. Now the camera's F-stop will acts as if Jack
                                              is a little further away.
                                              Re-render your scene. You should now see the Jack in the box
                                              in focus while the objects around it are slightly blurred.




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                                                STEP FOUR

                                              To change the range of distances in which the objects appear
                                              in sharp focus you can use the F-stop. Increase the F-stop to
                                              around 7.00 to create a longer depth of field. Aim for a result
                                              that has the entire Jack in the Box in focus while the objects
                                              around it are blurred.




                                                CONCLUSION

                                              Using Depth of Field, you can add a little realism to your
                                              renderings. As you animate your cameras, this effect will be
                                              even more visible.
                                              TIP: To make the camera automatically focus on its center of
                                              interest (similar to a real-world camera's auto-focus function),
                                              connect the output of the camera group node's Distance
                                              Between attribute to the input of the camera shape node's
                                              Focus Distance attribute. This is only possible with two-node
                                              and three-node cameras because one-node cameras do not
                                              have a camera group node.
                                              Download a finished scene file:
                                              Jack_Depth.ma[~372kb]


                                              Your use of this file confirms your agreement to the
                                              Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Double Sided Shader




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Double Sided Shader




                                                HOW TO CREATE A DOUBLE-SIDED
                                                                                                                by Robert Magee
                                                SHADER
                                                Maya Complete
                                                Rendering
                                                In this lesson, you will learn
                                                how to create a two-sided
                                                shading group where you
                                                have one material node on
                                                one side and a different
                                                material node on the other.
                                                This workflow is similar to
                                                the instructions found in the                Play Movie [~150kb]
                                                What's new in Maya 2.0
                                                guide except that rather than using different textures which
                                                share a material node, this example uses different material
                                                nodes that share a shading group node. This allows you to
                                                easily add various texture maps to the two materials, enhancing
                                                the look of both sides of the surface.


                                                   STEP ONE

                                                Select Create > NURBS
                                                Primitives > Sphere.
                                                Hit 3 on the keyboard to
                                                increase the sphere
                                                smoothness.
                                                Click on the sphere with
                                                your right mouse button
                                                and select Isoparm from
                                                the marking menu. Select an isoparm near the top of the
                                                sphere. It will highlight in yellow.




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                                                STEP TWO

                                             Select Edit Surfaces >
                                             Detach Surfaces. This
                                             breaks the sphere along
                                             the selected isoparm.
                                             Select the top surface and
                                             delete it. Now you have a
                                             sphere where you can
                                             clearly see the inside and
                                             the outside. You will use this surface to test your double sided
                                             shading group.


                                                STEP THREE

                                             Open the Hypershade.
                                             Select Create > Create
                                             Render Node. Under the
                                             Materials tab choose a
                                             Blinn material. Make sure
                                             with shading group is
                                             checked.
                                             Using the Attribute Editor
                                             Change the color of the Blinn material to a red then Assign the
                                             shading group to the sphere. The color will help you distinguish
                                             it from the inside material later.


                                                STEP FOUR

                                             From the Hypershade, select Create > Create Render Node
                                             and choose the following:
                                             Materials:
                                             • a Phong material With Shading Group turned Off.
                                             Utilities:
                                             • Condition
                                             • Sampler Info
                                             The Phong will be used for the second surface while the utility
                                             nodes will be used to build the two-sided nature of the shading
                                             group.




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                                                STEP FIVE

                                             With your middle mouse
                                             button, drag the
                                             samplerInfo node onto the
                                             condition node. This will
                                             open the Connection
                                             Editor.
                                             Connect the samplerInfo
                                             node's flipped Normal
                                             attribute to the condition                  Click here to view larger image
                                             node's First Term
                                             attribute.
                                             This will establish the surface normal as the driver of the
                                             condition. When the renderer sees a point on the inside of the
                                             surface, the samplerInfo node will tell it that there is a flipped
                                             normal and the condition node will know to change the
                                             material.


                                                STEP SIX

                                             With your middle mouse
                                             button drag the blinn node
                                             onto the condition node.
                                             Connect the blinn node's
                                             Out Color to the condition
                                             node's Color1.
                                             This establishes the blinn
                                             material as one side of the
                                                                                           Click here to view larger image
                                             shading group.


                                                STEP SEVEN

                                             With your middle mouse
                                             button drag the phong node
                                             onto the condition node.
                                             Connect the phong node's
                                             Out Color to the condition
                                             node's Color2.
                                             This establishes the phong
                                             material as the second side
                                                                              Click here to view larger image
                                             of the shading group. Leave
                                             the Connection Editor open for the next step.




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Assistant Online - Maya/How Tos/Rendering/Double Sided Shader

                                                STEP EIGHT

                                             Click the Clear All button in
                                             the Connection Editor.
                                             Delete the connection
                                             between the Blinn1 node
                                             and the BlinnSG node in the
                                             Hypershade.
                                             Select the Blinn node and
                                             click the Show Up and
                                                                                           Click here to view larger image
                                             DownStream Connection to
                                             view the blinn1SG.
                                             Use your middle mouse button to drag the condition node to the
                                             outputs section of the Connection Editor.
                                             With your middle mouse button drag the blinn1SG node to the
                                             Inputs section of the Connection Editor. Connect the condition
                                             node's Out Color attribute to the blinnSG node's Surface
                                             Shader attribute.
                                             This allows the underlying network to plug directly into the
                                             Shading Group node. The shader is now ready to be rendered.
                                             Note: If you have hardware texturing turned on you will not see
                                             the shading group displayed properly. You will have to render to
                                             see the results.


                                                STEP NINE

                                             You can now add lights to
                                             your scene, set up your
                                             Render Globals and render
                                             the scene to see the two
                                             sided surface.
                                             Note: If you want to reverse
                                             which surface is on the
                                             inside and which is on the
                                             outside then open up the condition node in the Attribute editor
                                             and change the Operation from Equal to Not Equal.




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Assistant Online - Maya/How Tos/Rendering/Double Sided Shader

                                                STEP TEN

                                             Because you now have two
                                             material nodes feeding the
                                             inside and outside of the
                                             shading group, you can
                                             apply various texture maps
                                             to the different materials.
                                             For instance you could
                                             apply a color map, specular
                                             map and bump map to Blinn material node to give it a look of
                                             wood then apply different maps to the Phong material to create
                                             a bumpy stone pattern.


                                                CONCLUSION

                                             Creating a double-sided shading group that offers different
                                             material qualities on the two sides is a great way of working with
                                             certain kinds of surfaces. Clothing is a good example where you
                                             might want a rough wool fabric on the outside and a shiny silk
                                             lining on the inside.
                                             You can download the shading group from this lesson assign it
                                             to your own objects. You can even use this shading group as a
                                             template and replace the textures to create your own look.
                                             Note: One limitation of
                                             double-sided surfaces is that
                                             the inside surface will not
                                             reflect or refract when
                                             raytraced. The image shown
                                             to the right is a two-sided
                                             surface that is reflected in a
                                             mirror. You can see that the
                                             grainy interior of the sphere is
                                             not reflected in the mirror.
                                             Download shader: double.ma[~4kb]


                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Environment Sky




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Environment Sky




                                                 HOW TO CREATE A REALISTIC
                                                                                                                By Steve Christov
                                                 SKY WITH THE ENVSKY TEXTURE
                                                Maya Complete
                                                Rendering
                                                The environment sky is a
                                                powerful procedural
                                                texture that you can
                                                quickly and easily add to
                                                your scene to give the
                                                appearance of a sky
                                                overhead.
                                                In this first part of a three
                                                part lesson you will learn                      Play Movie [~800k]
                                                how to create an
                                                environment sky and set attributes that will create a realistic
                                                looking sky.
                                                In the next lesson - How to create realistic shadows using
                                                envSky - you will learn how to achieve realistic shadows using
                                                the position of the sun on the EnvSky texture. In the final lesson
                                                you will learn how to "grow" a tree in Paint Effects from a simple
                                                black brush stroke - How to create a tree using Paint Effects.

                                                After these three lessons, you will be able to combine these
                                                elements to produce an animation similar to the one above
                                                where you create a time lapse animation of a sunset.


                                                  STEP ONE

                                                You will first need to
                                                create a new camera
                                                and then attach an
                                                image plane to it.
                                                Create a new camera by
                                                selecting Create >
                                                Camera.
                                                   q Translate the
                                                      camera 2 units in
                                                      the Y axis and 6 in

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Assistant Online - Maya/How Tos/Rendering/Environment Sky

                                                      the Z axis.
                                                  q   Open the Attribute
                                                      Editor for the new
                                                      camera, and open
                                                      the Environment
                                                      section. Click on
                                                      the Create button
                                                      next to Image
                                                      Plane. The
                                                      Attribute Editor
                                                      window will now
                                                      switch to the
                                                      Attribute Editor for
                                                      the Image Plane.
                                                  q   Open the
                                                      Placement section
                                                      and click on Fit to
                                                      Resolution Gate.
                                                      This will ensure
                                                      that your image
                                                      plane will fill the
                                                      entire rendered
                                                      scene.


                                               STEP TWO

                                             While you are still in the
                                             Attribute Editor for the
                                             Image Plane, Click on

                                             the Map      button
                                             next to Texture and
                                             map an EnvSky.
                                             The EnvSky node is
                                             located in the
                                             Environment Textures
                                             section of the Create
                                             Render Node window.




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                                               STEP THREE

                                             You will now set the
                                             colors for your
                                             environment. In the
                                             Attribute Editor for the
                                             EnvSky, Set the
                                             following attributes:
                                                 q Sun Brightness
                                                   to 1, 1, 0.5
                                                 q Halo Brightness
                                                   to 0.35, 0.36, 0.5
                                                 q Under
                                                   Atmospheric
                                                   Settings, Set the
                                                   Sky Brightness to
                                                   0.56, 0.617, 1.0
                                             To change any of the color values, select the color icon next to
                                             the attribute. This will open the Color Chooser. Make sure you
                                             are using the RGB values by checking the RGB box near the
                                             bottom of the window. You can then type the values in manually.
                                             NOTE: To open the Attribute Editor for the EnvSky, select the
                                             3D Icon for the EnvSky texture and open the Attribute Editor.
                                             Click the Goto Output Selection Button             at the top right
                                             side. This will take you to the EnvSky Attribute Editor.


                                               STEP FOUR

                                             Open the Floor
                                             Attributes section for the
                                             EnvSky, Map the color
                                             of the floor to a 2D
                                             Fractal texture.
                                             Change the Color Gain
                                             to a Dark Green and the
                                             Color Offset to a Dark
                                             Brown. This will be your
                                             floor.
                                             Select Camera 1 and
                                             Select > Panels > Look
                                             Through Selected. Turn
                                             on the Resolution Gate
                                             by selecting View >
                                             Camera Settings >
                                             Resolution Gate.
                                             Render this view by
                                             selecting Render > Render into New Window.


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                                               STEP FIVE

                                             When you render with
                                             the floor turned on, you
                                             may encounter a bright
                                             red surface for part of
                                             the floor. This is due to
                                             the fact that your
                                             camera is rendering a
                                             point that is below the
                                             Floor Altitude. You can
                                             fix this by either lowering the Floor Altitude, raising the look at
                                             point of the camera, or scaling the 3D icon. In this case we are
                                             going to scale the icon.
                                             Select the EnvSky icon in the perspective view window. In the
                                             Channel Box set the Scale X Y Z to 5.
                                             Re-Render your
                                             scene. You should now
                                             have a floor that
                                             extends to a vanishing
                                             point.




                                               STEP SIX

                                             You are now ready to
                                             add clouds to the
                                             scene. Open the Cloud
                                             Attributes section in the
                                             Attribute Editor for the
                                             EnvSky. Click the box
                                             next to Use Texture to
                                             turn it on.
                                             Click the Map button next to Cloud Texture. This will open the
                                             Create Render Node window. Select a Cloud Texture.




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                                               STEP SEVEN

                                             Preview your sky by
                                             rendering the Camera 1
                                             view.
                                             You will notice clouds in
                                             the scene but they are
                                             faint. You can make
                                             them more pronounced
                                             by setting the density.
                                             Set the Density under
                                             the Cloud Attribute of the EnvSky to 2.0.
                                             Render your scene. You
                                             should now see clouds in
                                             the sky.




                                               STEP EIGHT

                                             Switch to your persp camera.
                                             If you take a close look at the
                                             3D icon for the EnvSky, you
                                             will notice that there is a point
                                             that represents the sun. By
                                             adjusting the Elevation,
                                             Azimuth and Size, you will change the position and size of this
                                             point.
                                             Set the Elevation to 90 degrees. This will position the sun
                                             directly in the middle of the sky and also produce the brightest
                                             light. Notice on the 3D icon, that the sun icon has moved directly
                                             to the top middle of your icon.
                                             Render the scene. You
                                             should now see a bright
                                             blue sky.




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                                               STEP NINE

                                             You will now position the
                                             sun so that it appears in
                                             your scene. To do this you
                                             will need to align the line
                                             that represents the sun to
                                             intersect a point in your
                                             image plane. Make the
                                             following changes to position and size of the sun so that it will
                                             be seen in the image plane.
                                                 q Elevation to 10

                                                 q Azimuth to 0

                                                 q Size to 3.0

                                             If you imagine the line on the
                                             3D icon representing the sun
                                             going off to infinity, it will
                                             intersect the image plane
                                             which in turn will render the
                                             sun in your image. You may
                                             need to switch to your persp
                                             view and zoom out to see this.
                                             Render the Scene. Notice how the color of the sky changes in
                                             relation to the elevation of the sun. At an elevation of 90, you
                                             get an image that has the brightest possible sky. At a lower
                                             elevation your sky begins to change to a darker color.
                                             However the appearance of the sun does not seem quite
                                             bright enough. In this case we will increase the total
                                             brightness to get a nice sunset.
                                             Increase the Total Brightness to 3.0.
                                             Render the Scene. You should now have a decent looking
                                             sunset.
                                             Save your File.


                                               CONCLUSION

                                             You have now setup an
                                             EnvSky texture that will
                                             produce an
                                             environment complete
                                             with sun and clouds.
                                             There are many
                                             attributes to experiment
                                             with on this texture. You
                                             can achieve some
                                             interesting results by adjusting the some of the Atmospheric
                                             and Cloud attributes.



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                                             In the next lesson you will use this file and learn how-to achieve
                                             realistic shadows based on the position of the sun.
                                             Download the completed envSky.ma [~60k]

                                             Go to How to create realistic shadows using envSky.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Environment Sky Shadows




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / EnvSky_Shadows




                                               HOW TO CREATE REALISTIC
                                                                                                               By Steve Christov
                                               SHADOWS WITH ENVSKY
                                               Maya Complete
                                               Rendering
                                               This lesson is a
                                               continuation of How to
                                               create a realistic sky
                                               using envSky.

                                               In this lesson you will
                                               use your environment
                                               sky texture from the last
                                               lesson and link a
                                               directional light to the                      Play Movie [~800k]
                                               elevation and azimuth that will simulate the shadows cast when
                                               you animate the position of the sun.
                                               In the final lesson you will learn how to "grow" a tree in Paint
                                               Effects from a simple black brush stroke - How to create a tree
                                               using Paint Effects.


                                                STEP ONE

                                               Open Env_Sky.ma file that
                                               you saved from the last
                                               lesson.
                                               In the Attribute Editor for the
                                               EnvSky, Set the Elevation
                                               and Azimuth to 0. Set the
                                               Total Brightness to 1.0.
                                               Providing you have not moved or rotated the 3D icon the sun
                                               position should be lined up along the Z axis.




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                                              STEP TWO

                                            You are now ready to create
                                            a directional light and link it
                                            into the attributes of the
                                            EnvSky texture.
                                            Create a Directional Light
                                            by selecting Lights ->
                                            Create Directional Light.
                                            You will want this light to cast shadows so you will need to turn
                                            on shadows. Open the Attribute Editor for the light. In the
                                            shadows section, Click the box next to the Use Depth Map
                                            Shadows.
                                            You will notice that the light is pointing at the sun rather than
                                            away from it. Rotate the light 180 in the Y axis. This will align it
                                            properly.


                                              STEP THREE

                                            With the light
                                            selected, Group it to itself by selecting Edit > Group.
                                            In the Attribute Editor Rename this node lightLinker.


                                              STEP FOUR

                                            Open the Hypergraph
                                            window and holding
                                            the shift key, Select
                                            the lightLinker node
                                            and the place3dTexture node for EnvSky.
                                            Select Graph > Up and Downstream Connections.
                                            With the Middle Mouse Button, Drag the EnvSky1 node onto
                                            the lightLinker node.
                                            In the Connection Window that opens, click on Elevation on
                                            the left side, then click on Rotate X on the right. This connects
                                            the Elevation on the EnvSky node to the Rotate X attributes on
                                            the lightLinker node.
                                            Close the Connection Editor window.




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Assistant Online - Maya/How Tos/Rendering/Environment Sky Shadows

                                              STEP FIVE

                                            In the
                                            Hypergraph
                                            window, click
                                            on
                                            Rendering > Create Render Node window.
                                            If you were to directly connect the azimuth to the directional
                                            light you would find that as you adjust the azimuth your light
                                            would rotate in the opposite direction. In this case a reverse
                                            node will be used to correct this.
                                            In the Create Render Node window, click on the Utilities tab.
                                            Under General Utilities section, Create a Reverse node.


                                              STEP SIX

                                            In the Hypergraph
                                            window, Drag with
                                            the Middle Mouse Button, the EnvSky1 node onto the Reverse
                                            node. This will open the Connection Editor.
                                            Connect the Azimuth on the left side, with the Input X on the
                                            right side.
                                            In Hypergraph, Drag the Reverse node onto the lightLinker
                                            node. In the Connection Editor, Connect Output X to the
                                            Rotate Y.
                                            Test your light connection by opening the Attribute Editor for
                                            the EnvSky node, and changing the Elevation and Azimuth
                                            settings.
                                            You should now notice that the directional light will rotate along
                                            with the Elevation and Azimuth.


                                              STEP SEVEN

                                            Create a plane, by
                                            selecting Create >
                                            NURBS Primitive >
                                            Plane.
                                            Because you are
                                            unable to cast
                                            shadows on the floor
                                            of the EnvSky, you will
                                            need to turn it off. Open the Attribute Editor and Uncheck the
                                            box next to Has Floor. Scale the Plane out to roughly 35 units.
                                            Create a new Lambert material in the Hypershade, Change the
                                            color of the new Lambert to white. This will make it easier to
                                            see the shadow.

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Assistant Online - Maya/How Tos/Rendering/Environment Sky Shadows

                                            Assign this material to the Plane.
                                            Select Create > NURBS Primitive > Sphere. Move the
                                            sphere up in the Y axis. This will be your shadow casting object
                                            and will make it easier to see where the shadow will fall.
                                            Assign a new material to the sphere. Move the sphere so that
                                            it sits just above the floor.
                                            Select Lights > Create Ambient Light. Move the light to a
                                            point in front of the cone. Set the Intensity to 0.5.


                                              STEP EIGHT

                                            Position Camera1 in
                                            your scene. The most
                                            effective positioning
                                            of the camera when
                                            using an EnvSky is to
                                            point the camera
                                            slightly towards the
                                            sky.
                                            Move the camera away from the cone to see a good portion of
                                            the floor in front of it. This is where your shadow will be cast.
                                            Make sure that the camera is not positioned past the edge of
                                            the plane.


                                              STEP NINE

                                            You are now are going to
                                            animate the clouds.
                                            Select the 3D icon for the
                                            cloud. Move it 6 units in the Z
                                            axis. Set a key at time 1 by
                                            selecting Translate Z in the
                                            channel box and with the right
                                            mouse button select Key
                                            Selected from the drop down
                                            menu. Set another key for the Rotate X attribute value at
                                            time 1.
                                            Move the time slider to time 100. Change the Translate Z of
                                            the icon to 0 and set a key. Change the Rotate X to 60 and
                                            set another key.




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Assistant Online - Maya/How Tos/Rendering/Environment Sky Shadows

                                              STEP TEN

                                            You are now ready to
                                            animate the setting of
                                            the sun.
                                            Move your time slider
                                            to 1. Set the elevation
                                            attribute on the
                                            EnvSky to 75 and click
                                            the attribute with your
                                            right mouse button and select Set Key.
                                            Change the time slider to 100. Change the elevation to 0 and
                                            Set a Key.
                                            Press Play, you should now see the EnvSky icon animate the
                                            elevation over time.
                                            Set up your Render Globals to render out 100 frames from
                                            Camera1. Save your file and then render out the frames.

                                              CONCLUSION

                                            You have now
                                            constructed an EnvSky
                                            that will cast accurate
                                            shadows according to
                                            the position of the sun.
                                            Click on the image to
                                            get a "time lapse"
                                            animation of a setting
                                            sun. Pay attention to
                                            the length and direction
                                                                                                                   Play Movie[~800k]
                                            of the shadow as the
                                            sun sets.
                                            You can further enhance the animation by keying the size and
                                            total brightness of your sun as it sets to produce a more
                                            dramatic sunset. You may also want to key the ambient light
                                            slowly to zero intensity at around frame 80 so that your objects
                                            fade completely to black.
                                            In the next lesson you are going to replace the primitive sphere
                                            with a black stroke painted onto the plane and adjust attributes
                                            in Paint Effects until you produce a tree similar to the one
                                            above. You will then assemble all the elements to produce an
                                            animation like the one above.
                                            Go to - How to create a tree using Paint Effects.

                                            Use of this file confirms your agreement to the Terms and Conditions
                                            set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Ghost Shader




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Ghost Shader




                                                HOW TO CREATE A GHOST SHADER                                   by Terry Stoeger
                                                Maya Complete
                                                Rendering
                                                In this lesson, you will learn
                                                how to create a shading
                                                network that has a soft,
                                                fuzzy look.
                                                You will be using the
                                                SamplerInfo utility node and
                                                a Ramp texture to achieve a
                                                transparent drop-off effect.                                Play Movie {433 k}


                                                   STEP ONE

                                                Select Window -> Hypershade to open it.
                                                Create the following nodes:
                                                   q Lambert Surface Material (With Shading Group turned
                                                     on)
                                                   q SamplerInfo utility node

                                                   q Ramp texture (With New Texure Placement turned off)



                                                   STEP TWO

                                                You will be connecting the Facing Ratio attribute of the
                                                samplerInfo to the V Coord of the Ramp. The Facing Ratio
                                                produces a value that ranges between 0 and 1 depending on
                                                the normal of the surface to the camera eye (normal facing
                                                Camera Eye = 1; perpendicular to Camera Eye = 0).
                                                In the Hypershade, Drag and Drop with MMB samplerInfo onto
                                                the ramp texture. This will open the Connection Editor with the
                                                samplerInfo in the Outputs column and the ramp texture in the
                                                inputs column.
                                                Expand the UV Coord in the Inputs column. Click on the Facing
                                                Ratio attribute in the Outputs column and then click on V Coord.
                                                This Connects the samplerInfo's FacingRatio to the Ramp's V
                                                Coord. Close the connection editor.



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Assistant Online - Maya/How Tos/Rendering/Ghost Shader


                                                STEP THREE

                                             Double click on the Lambert Shading Group to open the
                                             Attribute Editor.
                                             Change the Color to a light gray, green, or blue for the ghost's
                                             color.
                                             You will now map the ramp to the transparency. Drag and
                                             Drop with MMB the ramp texture to the Transparency slider of
                                             the Lambert Shading Group.




                                                STEP FOUR

                                             Double click on the Ramp
                                             Texture to open the
                                             Attribute Editor.
                                             Change the ramp colors to
                                             a dark grey and white as
                                             show in this figure. Also
                                             change the Interpolation
                                             to Smooth.
                                             For a more ghostly result,
                                             make the material node's Incandescence a dark blue and add
                                             a glow by opening the Special Effects section and increasing
                                             the Glow to .6.
                                             Do a test render and experiment with different ramp settings.


                                             CONCLUSION

                                             You have now constructed
                                             a Shading Network that
                                             creates some interesting
                                             transparent effects. This
                                             technique could also be
                                             used for other attributes
                                             (Incandescence, Specular
                                             Color, Diffusion, etc...).
                                             The ramp colors could                                          Play Movie {433 k}
                                             also be mapped with a
                                             Fractal or a file texture


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Assistant Online - Maya/How Tos/Rendering/Ghost Shader

                                             (image) for a broken, cloudy effect. Try changing the colors for
                                             a different look. This works well for glass (like a jelly jar).
                                             Shift-Click to download the finished ghost shader.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Gobo




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Gobo




                                                 HOW TO CREATE A LIGHT
                                                                                                                 by Robert Magee
                                                 GOBO WITH BARN DOORS
                                                MAYA Complete
                                                Rendering
                                                In this lesson, you will
                                                learn how to simulate the
                                                shadow coming from a
                                                window with blinds using
                                                a light gobo.
                                                You will create the blinds
                                                by texture mapping the
                                                color of your spotlight,
                                                then you will set up the                                    Play Movie [~160kb]
                                                spotlight's barn doors to
                                                complete the effect.


                                                   STEP ONE

                                                Create a spotlight. Use
                                                the Show Manipulator
                                                tool to reposition the light
                                                so that it is looking down
                                                at your scene.
                                                In the Attribute editor,
                                                change the light's Cone
                                                Angle to 80.




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Assistant Online - Maya/How Tos/Rendering/Gobo

                                                 STEP TWO

                                              In the Attribute editor,
                                              click on the Map button
                                              next to Color. Choose a
                                              grid texture. This texture
                                              will act as the gobo which
                                              will render the window
                                              blind effect.
                                              Change the Grid's U
                                              Width to 0 and it's V Width to 0.5.
                                              Click on the place2DTexture tab and change the Repeat V to
                                              16. Now you have more blinds.
                                              Test render your scene to see how the gobo is working. The
                                              blinds are working fine but the shape of the window needs to be
                                              more rectangular. You will need to set up the spotlight's barn
                                              doors.


                                                 STEP THREE

                                              In the Attribute editor,
                                              click on the
                                              spotLightShape node and
                                              go to the Light Effects
                                              section. Turn Barn Doors
                                              to On.
                                              With the light selected,
                                              select Panels -> Look
                                              through selected. You are now looking through the spotlight.
                                              This will make it easier to preview the barn doors.
                                              Select the Show Manipulator tool. Now barn door
                                              manipulators are available in the view. Click drag on them to
                                              set up the shape of your window. You may need to increase
                                              your light's view angle to set up the shape you want. This
                                              example used a View angle of 100.


                                                 STEP FOUR

                                              Test render the scene.
                                              Now the window has a
                                              rectangular shape.
                                              If you want to animate
                                              the blinds opening and
                                              closing then you can set
                                              keys on the grid
                                              texture's V width.
                                              Animate it from a value of 1.0 to 0.25.



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Assistant Online - Maya/How Tos/Rendering/Gobo


                                                 CONCLUSION

                                              You can combine barn doors and a texture mapped light to
                                              create a number of gobo effects. The shadow from the
                                              leaves of a tree, as well as other effects, can be easily
                                              simulated using a similar technique.

                                              Your use of this file confirms your agreement to the
                                              Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Aliasing Overview




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Aliasing Overview




                                                  ALIASING ARTIFACTS IN MAYA:
                                                                                                                 by Andrew Woo
                                                  A TECHNICAL OVERVIEW
                                                 This document describes some of
                                                 the key issues to be addressed
                                                 which affect the quality of an
                                                 image's aliasing when rendering in
                                                 Maya.
                                                 You will learn how to look for
                                                 some of the causes of aliasing
                                                 then address these issues while
                                                 maintaining good aliasing and
                                                 faster rendering times.
                                                 The Maya renderer offers many
                                                 attributes to help you solve
                                                 aliasing problems on a project by
                                                 project basis. This technical overview discusses several ways
                                                 you can efficiently improve image quality when rendering.
                                                 This document is a PDF file and can be viewed/printed using
                                                 Adobe Acrobat Reader.
                                                 PDF file [~619 k]
                                                 Your use of this file confirms your agreement to the
                                                 Terms and Conditions set out in the Terms and Conditions page.




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                                              images by Chris Beaumont




Aliasing Artifacts in Maya:
     A Technical Overview
           Maya 1.0.1 IRIX and Maya 1.0 NT

                           By Andrew Woo

                            Alias|Wavefront
                a Silicon Graphics Company
                                 AP-M-AA-01
Aliasing Artifacts in Maya: A Technical Overview

Algorithms: Maya Rendering Version 1.0, March 1998
ã September 1998, Alias|Wavefront, a division of Silicon Graphics Limited.
Printed in U S A, All rights reserved.


Assist Publishing Group:
Robert Magee, Tracy Barber
Maya 1.0 Rendering Team:
Sanjay Bakshi, Silviu Borac, Josh Cameron, Jim Craighead, Renaud Dumeur, Antoine Galbrun, Philippe Limantour,
Ryan Meredith, Chris Patmore, Andrew Pearce, Joe Spampinato, Kelvin Sung, Chris Thorne, Mamoudou Traore, Greg
Veres, Gianluca Vezzadini, Changyaw Wang, Andrew Woo.

A document by Andrew Woo

Cover image credit: Chris Beaumont


The following are trademarks of Alias|Wavefront, a division of Silicon Graphics Limited:
    AliasÔ                      MELÔ                        Alias PowerTracerÔ         Alias RayTracingÔ
    MayaÔ                       Alias MetamorphÔ            Alias QuickRenderÔ         Alias SDLÔ
    Maya ArtisanÔ               OpenAliasÔ                  Alias QuickShadeÔ          Alias ShapeShifterÔ
    Maya F/XÔ                   Alias OpenModelÔ            Alias QuickWireÔ           Alias StudioPaintÔ
    Maya PowerModelerÔ          Alias OpenRenderÔ           Alias RayCastingÔ          ZaPiT!Ô

The following are trademarks of Alias|Wavefront, Inc.:
    Advanced VisualizerÔ        ExploreÔ                    MediaStudioÔ               3DesignÔ
    Wavefront ComposerÔ         Wavefront IPRÔ              MultiFlipÔ
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Graph Layout Toolkit Copyright ã 1992-1996 Tom Sawyer Software, Berkeley, California, All Rights Reserved.
All other product names mentioned are trademarks or registered trademarks of their respective holders.
Any forward looking statements in this document are speculative and are based on current assumptions and in no way
imply Alias|Wavefront will at any future time act upon said statements. This document contains proprietary and
conÞdential information of Alias|Wavefront, a division of Silicon Graphics Limited, and is protected by Federal
copyright law. The contents of this document may not be disclosed to third parties, translated, copied, or duplicated in
any form, in whole or in part, without the express written permission of Alias|Wavefront, a division of Silicon
Graphics Limited.
The information contained in this document is subject to change without notice. Neither Alias|Wavefront, a division of
Silicon Graphics Limited, nor its employees shall be responsible for incidental or consequential damages resulting
from the use of this material or liable for technical or editorial omissions made herein.




          Alias|Wavefront „ 210 King Street East „ Toronto, Canada M5A 1J7
                     Aliasing Artifacts
                      When rendering in Maya, the quality of an imageÕs aliasing is one of
                      the key issues that must be addressed. Aliasing artifacts can impact
                      the look of an image and create unsatisfactory results.
                      One method of dealing with these artifacts is to increase the Shading
                      samples in MayaÕs Render Globals. While this may solve the aliasing
Technical Overview



                      problem, it is often not the most efficient way for the Maya renderer
                      to deal with the aliasing artifacts. This means that renderings take
                      longer when in fact it may have been possible to solve the problem
                      another way.
                      As well, if you find that the problem can be fixed using another
                      method which does not require increased shading samples, it is very
                      easy to forget to reset the original anti-aliasing values. Thus, the
                      Maya renderer will continue to run a lot slower than needed.
                      This paper has been written to help you identify and classify typical
                      aliasing artifacts, with some understanding of the technical
                      algorithms, so that you can optimally solve these artifacts with
                      minimal impact to the performance of the renderer. This document
                      will also help you recognize those cases where eventually the
                      shading samples will need to be increased.
                      It can be argued that all the aliasing artifacts should be taken care of
                      automatically, without much user intervention. Our experience has
                      found that automatic solutions may limit what you can achieve and
                      prevent you from finding the desired balance between quality and
                      performance. The Maya renderer therefore offers many attributes to
                      help you solve the aliasing problems on an project by project basis.
                      These attributes ensure that you do not hit a wall when a certain
                      image quality is desired, or when a certain performance limit needs
                      to be satisfied. Better automated solutions will be sought through
                      continued research.

                      THE CAUSES OF ALIASING
                      Following is a series of the most common aliasing artifacts, with
                      visual examples so that you can easily identify the type of artifacts
                      for future references.
Introduction
Edge Aliasing




                               Edge Aliasing
                               The Maya renderer employs a 32-bit, A-buffer to anti-alias polygon edges.
                               This provides an analytic solution for producing very high quality edge
                               anti-aliasing results. Thus edge anti-aliasing is separated from shading
                               anti-aliasing, which also buys some performance gains, because usually a
                               lot less shading samples are required for good overall anti-aliasing.
                               Once you identify that the problem is that of edge aliasing, you can go to
                               Render Globals ® Render Quality ® Edge Anti-aliasing to set the attribute
                               to either High Quality or Highest Quality. The following image shows two
                               sphere images that show high and low quality edge aliasing.




                                Poor quality aliasing                     Good quality aliasing

                                                        High and low quality edge aliasing
                               Since it is difficult to see the jagged effects well, the images are resized to
                               show the aliasing more closely.




                                  Poor quality aliasing                     Good quality aliasing
                                                 Close-up of high and low quality edge aliasing

                               Thin Geometry Aliasing:
                               In cases of very thin pieces of geometry, the 32-bit mask for edge anti-
                               aliasing may not be adequate. This usually occurs when the polygons
                               themselves are less than one tenth of a pixel wide. Under such situations,
                               the problem gets worse as you see flicker over an animation. Therefore a
                               multi-resolution bit mask will be implemented in Maya 1.5 IRIX and Maya
                               2.0 NT to help deal with thin geometry.




2 Aliasing Artifacts in Maya
                                                                                             The Causes of Aliasing
                                                                                   Aliased Edges Through Transparency




Aliased Edges Through Transparency
The 32-bit, A-buffer mask only applies to the first visible fragments in a
pixel. If there are surfaces behind a transparent surface, the mask does not
apply, and the renderer needs to resort to point sampling. Thus the
Shading samples attribute for that surface needs to be increased to
improve both the shading and the edge anti-aliasing of those surfaces.
Unfortunately, the same limitation exists for raytracing.

Specular Highlight Aliasing
The material used for rendering is also a very important consideration.
The more common (isotropic) materials used by our customers include:
        s   Phong
        s   PhongE
        s   Blinn (based on the Torrance-Sparrow model)

Note:       It is mathematically provable that the highlight hotspots for the above
            materials all sit in the same spot. So the main difference between those
            models are how their highlights decay.


The following image has 3 thin cylinders with materials, from top to
bottom, Phong, Blinn + PhongE (with diffuse set to 0). It is important to
note that the Phong model results in a very sharp, hard edge for its
specular highlight. With such a hard highlight, animations with thin-curvy
or (nosily) bump mapped surfaces can usually result in extreme changes
in the specular behavior, and thus resulting in flickering. The PhongE
model is slightly better in its harsh edges. The Blinn model is the best in
terms of a soft highlight. As a result, the same thin-curvy or bump mapped
surface will appear much cleaner when animated.




    Phong




            Blinn




                 PhongE
                                 Material highlights


                                                                                                 Technical Overview 3
Introduction
File Texture Aliasing




                               Tip:      Increasing the shading samples may not help entirely; the shading
                                         samples will need to be very high, until the artifacts go away. The choice
                                         of the material can be a much more efficient alternative.



                               File Texture Aliasing
                               When particular file textured surfaces are shimmering (or flickering) over
                               an animation, it is also best not to play with the shading samples first. The
                               first choice should be to play with the File texture ® Filter ® Filter and File
                               texture ® Filter ® Filter offset values. First, it is recommended that you do
                               not set the Filter attribute to 0, because the defaults for Filter and Filter
                               offset are set so that in most cases, you get the best quality images.

                               In this case, filtering means that there is a mipmap structure for texture
                               mapping. In other words, the renderer stores multiple resolutions of the
                               same texture. For example, if you have a 256x256 image - the renderer
                               stores the 256x256, then 128x128, then 64x64, then 32x32, etc. The Maya
                               renderer computes, internally, a filter size value so the renderer knows
                               when to access which level (which resolution) to get the good quality
                               results. The user can play with the Filter and Filter offset attributes, which
                               act as multiplier and adder to the filter size values, respectively, to get
                               smoother or crisper pictures. Think of it conceptually as FILTER *
                               filter_size + FILTER_OFFSET. By setting Filter to 0 or a very small value,
                               you're telling the renderer to ignore the internal filter size computation so
                               that it completely relies on the Filter offset to get you to the right resolution
                               levels.
                               However, in some situations, playing with the Filter values will not help.
                               Then the more optimal solution would be to employ a higher order filter,
                               such as the quadratic filter (File texture ® filter ® quadratic). The following
                               image has a file texture mapped with the default mipmap filter (on the left)
                               and a quadratic filter (on the right). The quadratic filter does more
                               computations in projecting pixel information to texture space, thus
                               resulting in much cleaner results. Be sure to note that this method also
                               increases rendering time, and should not be invoked unless the filter
                               alternative is not useful.




                                                                Texture aliasing



4 Aliasing Artifacts in Maya
                                                                                                             The Causes of Aliasing
                                                                                                           Depth Map Shadow Aliasing:




The intention of the filter attributes, discussed earlier, is not to blur the
images as a special effect. It may work in certain circumstances for the
mipmap setting coincidentally, but likely will not work for the other
settings. The attributes are meant as an adjustment factor to get the best
image quality. For example, the following images show an exaggerated
Filter of 2.6 when applied with mipmap and quadratic filters, respectively.
Notice that exaggerated filter values will result in blockiness of the
quadratic (and higher order filters) textures.




                                                                                images by Chris Beaumont
                                Mipmap texture




                               Quadratic texture

Depth Map Shadow Aliasing:
The Maya 1.0 renderer had image quality problems where the depth map
shadows often display very blocky, shadow borders. Thus as a
workaround, it is recommended that the resolution of the shadow depth
map be increased. This workaround is not ideal since it can increase both
rendering time and memory usage. This problem has been fixed since
Maya IRIX 1.0.1 and Maya NT 1.0, and you should not be employing such
high resolutions any more.
The following example shows a 256x256 resolution shadow depth map,
casting a shadow from a sphere. Note the jaggies at the shadow borders.
Increasing the shading samples will not help the situation.




                                                                                                                  Technical Overview 5
Introduction
Depth Map Shadow Aliasing:




                                                       Poor depth map shadow aliasing
                               To improve the anti-aliasing of such shadow border jaggies, first increase
                               the light's Shape ® Dmap Filter Size. The below image uses a filter size of 3.
                               The filter size indicates the level of neighboring shadow map pixels that
                               are used to filter the shadow borders.


                               Note:     A larger Filter size beyond 4 is not recommended. If more than 4, each
                                         shadow sample will need to evaluate far too many neighboring shadow
                                         map pixels. The final image shows even better anti-aliasing, when the
                                         Shape ® Dmap Resolution is set at 512x512.




                                                         Filtered depth map shadow




                                                      High resolution depth map shadow


6 Aliasing Artifacts in Maya
                                                                               The Causes of Aliasing
                                                                               Light Fog Shadow Aliasing:




Finally, if your scene allows you to narrow the cone angle for the spotlight
(or reduce the orthographic width of a directional light) without adversely
affecting the outcome of the lighting, then you will get crisper shadows
without having to increase the shadow map resolution. This is because the
resolution of the shadow depth map will be focused in a smaller region,
which, in effect, gives it much better resolution.

Light Fog Shadow Aliasing:
Light fog shadows only work with depth map shadows. This is because
the algorithm for calculating light fog shadows projects the view vector
onto the shadow depth map. Then, for each shadow map pixel that the
projected view vector visits, it asks whether it is in shadow or not.
However, since this is needed for each view vector, and traversing the
many shadow depth map pixels can increase rendering time, the renderer
stochastically samples the shadow depth map pixels, capped by the Shape
® Depth Map Shadow Attributes ® Volume shadow samples value.
Note the first image below, where the Depth map resolution is set at
512x512, but the Volume shadow samples is set at only 15. Notice the
dicing artifact with respect to the light fog shadows, sometimes capturing
the occluding surface's shadow, sometimes not. In an animation, this may
cause flickering artifacts as well. Increasing the shading samples will not
help this situation either. But increasing the Volume shadow samples to 50
will produce a much cleaner image, as seen in the second image below.
Note that you should only worry about this attribute when you have small
or skinny surfaces which may miss/hit the light fog shadow computations
For example, if the occluding surface is a big sphere, there would not have
been any artifacts.




    Aliasing artifacts                    Improved aliasing
                         Aliasing artifacts in fog shadow




                                                                                     Technical Overview 7
Introduction
Motion Blur Visibility Aliasing:




                                   Motion Blur Visibility Aliasing:
                                   To anti-alias motion blurred images properly can be tricky. The renderer
                                   does not use the standard distributed raytracing because it relies on
                                   raytracing and dicing artifacts that are significant. Alias|Wavefront
                                   invented a new (and patented) approach which produces an analytical
                                   solution to the edge anti-aliasing during motion blur.
                                   The following image shows the progression of image quality when certain
                                   attributes are increased. The first image indicates what happens when the
                                   Edge anti-aliasing is set at Low. In this case, all aliasing contains artifacts.
                                   With the next image, the Edge anti-aliasing is set at High. With the next
                                   image, Edge anti-aliasing is set at Highest which invokes more shading
                                   samples that do a much better job at spatial anti-aliasing. In the final image
                                   which uses higher initial Shading samples, and sometimes Visibility
                                   samples, the image contains well aliased motion blur. This is elaborated in
                                   Maya Software Rendering, Assistant Online [Pearce, Sung].

                                                 Low Quality                      High Quality
                                                             Geometric Aliasing




                                                                          Spatial
                                                                          Shading
                                                                          Aliasing




                                                 Highest Quality      Temporal    Highest Quality
                                                                      Shading
                                                                      Aliasing    (With 16 shading samples)




                                                      Geometric vs. spatial vs. temporal aliasing

                                   Image Plane Aliasing:
                                   If your image plane appears aliased, increasing the global shading samples
                                   will not help. The only way to improve the anti-aliasing of the image
                                   planes would be to increase the attribute values of Imageplane ® Shading
                                   samples and Imageplane ® Max shading samples. If the image of the image
                                   plane matches the resolution of the rendering, then additional anti-aliasing
                                   will not be required.




8 Aliasing Artifacts in Maya
                                                                                         The Causes of Aliasing
                                                           Check List for other Common Animation Aliasing Artifacts:




Check List for other Common Animation Aliasing Artifacts:
s   Flicker due to screen space or min-screen tessellation. With a surface set
    at screen space or min-screen tessellation, the tessellation per frame
    can be different. When different, you can see flickering, for example,
    due to solid textures receiving very different (x,y,z) coordinates to
    texture map.
s   Flicker due to filter or filter offset set to very small numbers. This was
    explained in the file texture section above.
s   Flicker due to very noisy texture(s). With very noisy textures (other
    than file textures), usually the texture does not know how to anti-
    alias itself. If it does, it usually has Filter and Filter offset attributes,
    which you can tweak, as discussed in the file texture section. The
    other option is to apply a convert-solid-to-2d-texture operation, in
    which a snapshot of the noisy texture is completed to create a file
    texture that matches the procedural texture. Rendering with this file
    texture, and its ability to anti-alias, may resolve the flickering
    problems.
s   Exaggerated aliasing due to incorrect usage of multi-pixel filtering. If your
    non-filtered rendering already looks aliased, having multi-pixel
    filtering turned on will exaggerate the aliasing even more. The multi-
    pixel filtering is meant to improve the quality of thinline situations
    and when smoothing a good image quality result is needed.
s   Flicker or dicing due to raytracing soft shadows with small number of
    shadow samples. Soft shadows occur when Light ® Shadows ® Light
    radius is non-zero. If soft shadows are desired, it is best to use
    shadow depth maps instead of raytrace soft shadows. It will require
    many samples to avoid flicker in the raytrace soft shadows, which
    becomes very time consuming for the renderer. Raytrace shadows are
    useful, as opposed to depth map shadows, mainly when shadows
    from transparent objects need to show colored shadows.




                            Raytraced aliasing artifacts

Check List for Mistaken Aliasing Artifacts:
s   Aliasing due to composite rendering. It is very common mistake to set
    the Render Globals ®ÊComposite render to On, then noticed that the
    rendered results look very aliased. This is because the composite
    render option is intended to look aliased before compositing, but
    should be perfect after compositing. This means that a composite
    render does not want to add the residue of the background color into
    the pixel result.


                                                                                               Technical Overview 9
Introduction
Conclusion




                                s   Nickeling artifacts with tessellation. It is very easy to mistake the
                                    nickeling found at the edge of a surface as an anti-aliasing problem.
                                    This problem is in fact a tessellation issue and increasing the shading
                                    samples will not help. Rather, select the surface, and increase its
                                    tessellation parameters.



                                             Nickeling




                                                         Nickeling at the edge of an object
                                s   Terminator problem. This is a common artifact in computer graphics,
                                    not particular to our software. This staircase of black polygons is due to
                                    the combination of coarse tessellation of the surface, and raytracing
                                    shadows. The only workaround for this problem is to increase the
                                    tessellation of the surface.




                                         Staircase
                                         effect




                                s
                                    You're out of options... Even if you need to increase the Shading
                                    samples, don't do it globally yet if this is only a problem for a small,
                                    select number of surfaces. Instead, select the troubled surfaces, then
                                    edit the Shape ® Render Stats ® Shading Samples Override ® Shading
                                    Samples so that only those surfaces will have their shading samples
                                    increased, without having to affect the entire scene.

                                Conclusion
                                When setting up a rendering it is important to remember that aliasing may
                                occur for all of the reasons mentioned in this document. Be sure to try the
                                various methods outlined here to fix aliasing issues before increasing the
                                shading samples and slowing down rendering time. These tips should help
                                you find the right balance between quality and performance.




10 Aliasing Artifacts in Maya
Assistant Online - Maya/How Tos/Rendering/SW Rendering Overview




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / SW Rendering Overview




                                                MAYA SOFTWARE RENDERING:                                  by Andrew Pearce
                                                A TECHNICAL OVERVIEW                                        and Kelvin Sung
                                               This document describes some of
                                               the technical details of the Maya
                                               1.0 Software Renderer. It
                                               assumes some technical
                                               knowledge of the inner workings of
                                               a renderer. There are many
                                               sections of this document which
                                               can be helpful to non-technical
                                               people as well.
                                               The document is laid out in two
                                               sections:
                                               The Rendering Pipeline: This section outlines the algorithms
                                               that the renderer uses from the moment it is invoked to the final
                                               pixel output.
                                               Understanding shading networks describes the power of the
                                               Maya shading network and how to tap that power interactively.
                                               It is hoped that this document will give you the knowledge that
                                               will help you to effectively, efficiently and optimally use the
                                               Maya 1.0 Renderer for your production’s needs.
                                               This document is a PDF file and can be view/printed using
                                               Adobe Acrobat Reader.
                                               PDF file [720 k]
                                               Your use of this file confirms your agreement to the
                                               Terms and Conditions set out in the Terms and Conditions page.




http://www.aw.sgi.com/assistant_online/entertain/maya/how_tos/rendering/overview_rendering/ [3/7/2000 14:47:46]
Maya Software Rendering:
   A Technical Overview
          By Andrew Pearce and Kelvin Sung


                            Alias|Wavefront
                a Silicon Graphics Company
                               AP-M-SWR-01
Maya Rendering: A Technical Overview

Algorithms: Maya Rendering Version 1.0, March 1998
ã September 1998, Alias|Wavefront, a division of Silicon Graphics Limited.
Printed in U S A, All rights reserved.


Assist Publishing Group:
Bob Gundu, Robert Magee
Maya 1.0 Rendering Team:
Sanjay Bakshi, Silviu Borac, Josh Cameron, Jim Craighead, Renaud Dumeur, Antoine Galbrun, Philippe Limantour,
Ryan Meredith, Chris Patmore, Andrew Pearce, Joe Spampinato, Kelvin Sung, Chris Thorne, Mamoudou Traore, Greg
Veres, Gianluca Vezzadini, Changyaw Wang, Andrew Woo.

A document by Andrew Pearce & Kelvin Sung

Cover image credit: Balloon Girl by Chris Landreth, and the Alias|Wavefront Bingo Team.


The following are trademarks of Alias|Wavefront, a division of Silicon Graphics Limited:
    AliasÔ                      MELÔ                        Alias PowerTracerÔ         Alias RayTracingÔ
    MayaÔ                       Alias MetamorphÔ            Alias QuickRenderÔ         Alias SDLÔ
    Maya ArtisanÔ               OpenAliasÔ                  Alias QuickShadeÔ          Alias ShapeShifterÔ
    Maya F/XÔ                   Alias OpenModelÔ            Alias QuickWireÔ           Alias StudioPaintÔ
    Maya PowerModelerÔ          Alias OpenRenderÔ           Alias RayCastingÔ          ZaPiT!Ô

The following are trademarks of Alias|Wavefront, Inc.:
    Advanced VisualizerÔ        ExploreÔ                    MediaStudioÔ               3DesignÔ
    Wavefront ComposerÔ         Wavefront IPRÔ              MultiFlipÔ
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Graph Layout Toolkit Copyright ã 1992-1996 Tom Sawyer Software, Berkeley, California, All Rights Reserved.
All other product names mentioned are trademarks or registered trademarks of their respective holders.
Any forward looking statements in this document are speculative and are based on current assumptions and in no way
imply Alias|Wavefront will at any future time act upon said statements. This document contains proprietary and
conÞdential information of Alias|Wavefront, a division of Silicon Graphics Limited, and is protected by Federal
copyright law. The contents of this document may not be disclosed to third parties, translated, copied, or duplicated in
any form, in whole or in part, without the express written permission of Alias|Wavefront, a division of Silicon
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The information contained in this document is subject to change without notice. Neither Alias|Wavefront, a division of
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from the use of this material or liable for technical or editorial omissions made herein.




          Alias|Wavefront „ 210 King Street East „ Toronto, Canada M5A 1J7
                     Maya Software Rendering
                          This document describes some of the technical details of the Maya
                          1.0 Software Renderer. It assumes some technical knowledge of the
                          inner workings of a renderer. There are many sections of this
                          document which can be helpful to non-technical people as well.
                          The document is laid out in two sections:
Technical Overview



                          s   The Rendering Pipeline
                          s   Understanding the Shading Network.
                          The Rendering Pipeline on page 1 outlines the algorithms that the
                          renderer uses from the moment it is invoked to the final pixel output.
                          Understanding shading networks on page 21 describes the power of
                          the Maya shading network and how to tap that power interactively.
                          It is hoped that this document will give you the knowledge that will
                          help you to effectively, efficiently and optimally use the Maya 1.0
                          Renderer for your productionÕs needs.
                          The Rendering Pipeline assumes you have a basic understanding of
                          rendering algorithms.
                          Understanding the Shading Network assumes your are familiar with
                          basic Maya Dependency Graph connections, nodes and attributes.

                          THE RENDERING PIPELINE
                          This section outlines the phases and algorithms the Maya 1.0
                          Renderer uses in order to produce a final image.
                          Before discussing the steps involved in Maya Rendering, a high-level
                          overview of the algorithm is in order. The Maya Renderer is a hybrid
                          renderer. It uses an EAS (Exact Area Sampling) or A-buffer
                          algorithm for primary visibility from the eye, and then ray traces any
                          secondary rays.
                          EAS computes a coverage mask for the geometry in a pixel, which is
                          more precise than point sampling can produce in all but the most
                          extreme cases. The improved coverage mask results in better edge
                          anti-aliasing of the objects in a scene.
                          Part of the philosophy of the Maya Renderer is that it attempts to
                          solve each part of the rendering process independently, using the
The Rendering Pipeline
Step One: Initialize the camera




                                  best method for each rendering problem. Geometric anti-aliasing is solved
                                  with EAS completely before the shading is solved, which is solved
                                  separately from glow, etc.
                                  The Maya Renderer also takes advantage of data cache and instruction
                                  cache locality by making each shading call with a vector of samples. If the
                                  shader is called with a single sample, the instructions for the shader must
                                  be brought into the instruction cache by the computerÕs CPU, and any data
                                  that that shader uses must be brought into the data cache. Cache memory
                                  works best (fastest) if the next instruction or next data are in the cache. By
                                  providing each shader with a vector, or array, of samples, MayaÕs renderer
                                  takes advantage of the computerÕs built-in caching mechanism.
                                  When an object is encountered that requires ray tracing to compute some
                                  component of its shading (ray traced shadows, reflections, and/or
                                  refractions), the ray tracer is invoked.
                                  The steps involved in rendering are:

                                  1 Initialize the camera

                                  2 Perform shadow depth map computations

                                  3 Compute geometries that are potentially visible for rendering

                                  4 Compute the tile system

                                  5 Render each tile
                                    a) Compute visibility for stationary objects
                                    b) Compute visibility for moving objects (only if motion blur is selected)
                                    c) Compute shading (moving and stationary objects)
                                    d) If highestQuality is selected:
                                                i) Compute Contrast
                                                ii) Compute Extra Shading

                                  6 Composite shaded results

                                  Step One: Initialize the camera
                                  The 3D coordinates of the camera to be rendered are determined by
                                  evaluating the Dependency Graph (DG) at the current time value. The
                                  evaluated parameters of the camera are used to compute the perspective
                                  (or orthographic) matrix, and the coordinates of the camera are used to
                                  construct the WorldToEye matrix. Image planes to be used during the
                                  rendering phase are tested for existence.

                                  Step Two: Perform shadow depth map computations
                                  Because the Maya Renderer is a hybrid renderer containing both EAS and
                                  ray tracing code, you have the option to either ray trace shadows or to use
                                  depth map shadows. This section deals with depth map shadows only,
                                  since the depth maps must be computed as a first pass before rendering,
                                  while ray traced shadows are computed during the rendering phase.



2 Maya Rendering
                                                                                       The Rendering Pipeline
                                                                 Step Two: Perform shadow depth map computations




The shadow depth map computation is similar to shadow depth map
computations for other renderers you are familiar with. A ÒdepthÓ
rendering is done from the point of view of the light source, and later used
during the rendering phase to determine if that light illuminates a given
point (i.e., if the point is obscured by any other object closer to the light,
then it is in shadow). For an excellent introduction and overview of depth
map shadowing techniques, see SIGGRAPH Ô87 Reeves, Salesin and Cook,
ÒRendering Antialiased Shadows with Depth MapsÓ, pp. 283-291. This section
discusses what is unique about the Maya Depth Map Shadows.
In Maya, Depth Map Shadows are available from each of pointLights,
directionalLights, and spotLights.

In the attribute editor for these lights, the Depth Map Shadow section
contains settings to allow you to Read/Write/Reuse Dmap. In all dealings
with Depth Map Shadows in the UI, Dmap means Depth Map. These
settings cause the depth maps to be written to or read from disk and
should be enabled when doing iterative render tests on a scene with many
shadows, or when there is only a camera fly-by of the scene (i.e., no
objects move in the area visible to the light). Be aware that if you set these
flags when moving objects or moving lights are present, it may cause your
shadows to remain stationary while your objects move in your animation.
Another feature of Depth Map Shadows in Maya is the ability to cast
volume shadows through fog. The shadowing of the fog is done by
examining the shadow map a number of times across the fog volume. The
number of times the fog is sampled is controlled by the attribute
volumeShadowSamples.


                          Light
                                              Fog Volume



                                                  Geometry


                                                     Shadow

                                                          Viewing Ray




                           volumeShadowSamples

   Figure 1: A side view of a ray penetrating a shadow volume for a spot light.
        volumeShadowSamples are taken across the penetration interval.
To automatically get the best resolution out of your depth map, there is an
attribute called useDmapAutoFocus. When this attributeÕs value is true, the
renderer automatically computes a bounding volume for the objects in the
view from the light source and uses the smallest possible field of view to
render the shadow map. This can, however, create artifacts over an


                                                                                           Technical Overview3
The Rendering Pipeline
Step Two: Perform shadow depth map computations




                                animation if the bounding box of the objects in your scene changes; the
                                area covered by a shadow map changes, possibly creating aliasing artifacts
                                in your shadows, or unwanted softening or noise in the shadows.
                                Those familiar with Depth Maps for shadowing know that there are self-
                                shadowing artifacts that can occur due to the finite resolution of the
                                shadow map. Only one depth value is stored per pixel and if you happen
                                to be shading a point on a surface that lies between samples in the depth
                                map, there is the possibility that the averaged depth from the depth map
                                will incorrectly shadow the point being shaded. In classical depth map
                                shadow algorithms, a jitter or bias is added to the depths before
                                comparison in order to alleviate this artifact. This is also done in Maya.
                                However, Maya has an additional option called useMidDistDmap which
                                modifies the depth map calculation and eventual use. useMidDistMap is on
                                by default. If the depth map is to be used for purposes other than
                                shadowing, then it is best to turn this option off. For those with an interest
                                in the specifics of the algorithm, please refer to Graphics Gems III (Academic
                                Press, ISBN 0-12-409670-0) p. 338.
                                Essentially, Mid Dist attempts to eliminate the need for the jitter or bias
                                parameters by storing the midpoint between the first and second surfaces
                                visible to the light source in the depth map, rather than simply storing the
                                distance to the nearest surface. By doing this, a larger margin for error is
                                provided, thereby mitigating the incorrect self-shadowing problem. Figure
                                2 shows a simple side view of a depth map situation. The light source is
                                shining on a sphere and a plane. In a normal depth map, Z1 (the distance
                                to the Closest Intersection) is stored in the depth map. When Mid Dist is
                                enabled, Zmid (the halfway point between Z1 and Z2) is stored in the
                                depth map.


                                                                                     Distance Stored


                                                              z2
                                                                   zMid                               Light
                                                                       z1
                                                                                        De
                                                                                          pt
                                                                                              h
                                                                                                  M
                                                                                                   ap
                                           Next Closest                        Closest
                                           Intersection                        Intersection



                                      Figure2: Diagram of the value stored for the mid distance depth map.
                                Directional lights can cast depth map shadows in Maya. They have two
                                possible behaviors. Since directional lights are assumed to be at an infinite
                                distance from the scene (hence the parallel light rays), by default
                                directional lights will cast shadows on the entire scene. The bounding box
                                of the scene is taken and an orthogonal depth map region is created, which
                                contains the entire scene. This can result in shadow depth map resolution
                                problems if the scene is very large, but only a small section of the scene is


4 Maya Rendering
                                                                                    The Rendering Pipeline
                                                                           Shadow Computation and Motion Blur




being viewed, or if the scene changes size dramatically over an animation.
To limit the number of objects that are involved in a directional lightÕs
depth map, an attribute named useLightPosition is provided at the top of
the Attribute Editor for directional lights. Setting this attribute to true
makes the directional light take its position (the location of the directional
light icon in the modeling view) into account. Objects in the half space
defined by the lightÕs position and direction are affected by the directional
light and are used in the creation of the shadow depth map. Any objects
ÒbehindÓ the directional light are not lit and do not participate in the
generation of the shadow depth map. The useLightPosition attribute is not
on by default because this is a new behavior which may be unexpected by
people coming from other software where directional lights were
infinitely far away regardless of icon position in the scene.
Another way to optimize shadows is to link the lights only to those objects
which you wish to cast and receive shadows. You can also avoid casting
shadows from some objects by going to the objectÕs attribute editor and
turning the castsShadows flag off under Render Stats.
Point lights can cast depth map shadows in the Maya Renderer. By
default, these shadows are produced by casting 6 depth maps in each of
the cardinal axes directions (+X, -X, +Y, -Y, +Z, and -Z) from the point
lightÕs position in space. Be aware that if you specify a large shadow depth
map resolution, there will be 6 depth maps of that large resolution
generated. Maya does try to compact the depth maps as much as possible,
but large depth maps can still occupy a great deal of memory and take
valuable time to render. To further optimize your shadow depth maps
from point lights, you can turn individual directions off or on. For
example, if there is nothing of interest to cast shadows on the ceiling of
your room, you could disable the +Y depth map by un-checking the
useY+Dmap attribute in the Depth Map Shadow Attributes section of the
point lightÕs Attribute Editor.
Spot lights by default use only one depth map. Using only one depth map
has limitations when the angle of the spot light exceeds 90 degrees; the
resolution of the depth map must be increased dramatically to keep the
shadow quality high. Maya allows you to use up to six depth maps for
spot lights by setting the useOnlySingleDmap check box to false in the
Attribute Editor for spotlights. When this attribute is set to false, and the
cone angle of the spot light exceeds 90 degrees, five or six depth maps are
created around the spot light, tiling the faces of an axis-aligned cube with
faces in each of the axis directions - much the same as for a point light. The
only difference is that a spotlight will only cast five depth maps if the spot
light does not shine onto one of the six faces. Just as cubic reflection maps
avoid aliasing at the boundaries between faces of the cube, the cubic
shadow map is also filtered to avoid artifacts.

Shadow Computation and Motion Blur
Basically, shadows do not motion blur in the current renderer. MayaÕs
renderer takes only one geometric position (shutter mid) when sampling
the shadow map, so even though the geometry moves from A to B to C,
the shadow only falls at position B.


                                                                                         Technical Overview5
The Rendering Pipeline
Step Three: Compute potentially visible geometries




                                   Methods to work-around this limitation are to use the Mid-distance
                                   shadow depth map algorithm, or to output the shadow depth map and
                                   process it to add blur before using it in a render.
                                   Ray traced shadows will not work in almost every motion blur instance.

                                                                                                                            Light



                                                                                             e.g. Shading this position
                                                                                                 at Time = 0.7




                                                       Position        Position         Position
                                                       at Time = 1.0   at Time = 0.5    at Time = 0




                                                                                       Geometry used to compute shadow

                                   Step Three: Compute potentially visible geometries
                                   Gathering the objects to be rendered starts by going to all of the Shading
                                   Groups and collecting all of the objects contained in each group. Figure 3
                                   shows that there is a ÒhiddenÓ list associated with each shading group
                                   which is a list of objects or geometries to be shaded using that shading
                                   group. A consequence of this is that if an object is not a member of any
                                   shading group, it is not rendered. Figure 3 also shows that there is a hidden
                                   partition (much like a partition which you as a user can create) called the
                                   renderPartition which contains the shading groups. The renderPartition is
                                   hidden from direct manipulation in the interface; changing an objectÕs
                                   group membership in the renderPartition is done using shading group
                                   assignment in the Multilister.

                                            Displacement
                                            Material
                                                                                              May or may not
                                            Surface                                           be connected
                                            Material                                          to Shaders
                                                                                              (material)
                                            Volume
                                            Material

                                            defaultLightList                                  List of active lights

                                                                                              List of connected geometries


                                           renderPartition
                                                                            SG
                                                                                       SG
                                                       SG        SG
                                                                                                Pre-defined partition
                                                                                                contains all the ÒactiveÓ
                                                            SG         SG         SG            shadingGroups



                                                              Figure 3: Shading Group Relationships



6 Maya Rendering
                                                                                      The Rendering Pipeline
                                                                 Step Three: Compute potentially visible geometries




Given this background, and now that the shadow depth maps have been
computed, the rendering pipeline continues as follows:

Computation of Visible Geometries For Rendering
    For each shadingGroup in renderPartition
        For each geometry in shadingGroup
             compute geometryÕs boundingBox in screen space
             if (boundingBox touches cameraÕs viewing frustum)
                 initialize shadingGroupÕs shading network
                 if (initialization succeeds)
                     keep the geometry in the renderableGeometrySet
                 endif
             endif
        endfor
    endfor
Note that the Maya renderer will only initialize a shading network at most
once per material. Initializing shading networks does not load file
textures. At this point, the renderer is identifying geometries and their
associated shading networks that may be visible in this frame.


Note:     A similar computation occurs for computing the shadow depth maps;
          however, shading networks are not initialized at that point, and
          visibility determination also includes light linking criteria.
          Displacement shading networks are the exception to this rule - the
          displacement must be evaluated during a shadow depth map
          computation to generate the proper shadowing.


For determining which geometries possibly intersect the cameraÕs frustum
(frustum is a technical word describing a volume the shape of a pyramid
with its point cut off) MayaÕs renderer looks at the near and far clipping
planes. Geometry that penetrates the near clipping plane will be clipped to
the near clipping plane. Any part of the geometry nearer to the camera
than the near clipping plane is eliminated from being rendered. Geometry
is not clipped at the far clipping plane in the Maya 1.0 Renderer. If a piece
of geometry spans the far clipping plane, it will be rendered in its entirety.
If a piece of geometry is beyond the far clipping plane it will not be
rendered at all. So there is a type of clipping occurring at the far clipping
plane, but it is at the object level, not at the triangle level. Figure 4 shows
this clipping relationship. Geometry O1 will be cut by the near clipping
plane so that only the portion beyond the near clipping plane is rendered.
Geometry O3 will not be rendered at all since it is beyond the far clipping
plane, and geometry O2 will be completely rendered because part of it lies
between the camera and the far clipping plane.




                                                                                            Technical Overview7
The Rendering Pipeline
Step Three: Compute potentially visible geometries




                                                                                                                                         O2 (Object 2)




                                                                   Near Clipping Plane




                                                                                                                 Far Clipping Plane
                                                                                     O1 (Object 1)

                                                                                                                                                                O3 (Object 3)




                                       Figure 4: Near and Far plane clipping; O1 is partially rendered, O3 is not
                                                        rendered, O2 is completely rendered.
                                   Since MayaÕs renderer uses the bounding box to cull or accept geometry, it
                                   is possible that pathological geometries (such as the one diagrammed in
                                   Figure 5) can be unnecessarily placed into the renderableGeometrySet. This
                                   will not produce incorrect images, merely waste the time needed to
                                   process the geometry. In Figure 5, the gray ÒCÓ shaped geometry is
                                   unnecessarily placed into the renderable set because its bounding box
                                   intersects the viewing frustum even though the geometry itself does not.
                                   Break the object up into three separate geometries to solve this problem.
                                   Smaller objects shrink the size of the bounding boxes so that they do not
                                   contain the interior of the ÒCÓ.
                                                                                           Near Clipping Plane




                                                                                                                                           Far Clipping Plane




                                                                                                                                      Bounding Box




                                      Figure 5: A grey ÒCÓ shaped object which will incorrectly be placed into the
                                                                   renderable set.




8 Maya Rendering
                                                                                         The Rendering Pipeline
                                                                                   Step 4: Computing the tile system




Step 4: Computing the tile system
The Maya Renderer ÒtilesÓ the image to be rendered into smaller pixel
rectangles. If you have watched the Maya Renderer while it is rendering,
you have seen this tiling pattern; areas of low complexity are rendered
with larger tiles than areas with high complexity. This section describes
why this occurs and how the decision is made about tile sizes.
A goal of the Maya Renderer is to keep the amount of memory used to a
minimum. One of the ways the renderer attempts to achieve that is by
estimating the memory cost of rendering a single tile scanline. A tile is a
subsection of an image, and a tile scanline is a single row of pixels in a tile.
The Maya Renderer first uses a number of variables to compute the
maximum allowable number of triangles that can render in a tile scanline.
Factors used in the computation of this number include:
s   is ray tracing enabled?
s   is motion blur enabled?
s   is edgeAntiAliasing enabled?
s   what is the number of shading samples?
s   what is the setting of the Render Globals maxMemoryUse attribute?
s   is multi-pixel filtering on?
s   what is the vector length (the number of samples passed into the
    shading nodes)?
From these factors a maxTileCost is derived which represents the
maximum number of triangles believed to be renderable in a single
scanline while still maintaining the given memory limit. Factors that are
not included in the estimation of tile cost are shading network complexity
and the size of any file textures required to render the geometry in the tile.
Each object in Maya has a method to estimate how much memory is
required to render it (in terms of triangle counts, number of particles, etc.)
in a given screen space window.
The Maya Renderer starts by tiling the screen into four tiles to start with,
each one quarter of the image resolution. It then estimates the cost of
rendering each of the tiles in terms of the most complicated scanline
(geometrically speaking) in the tile. If the estimated number of triangles in
the most complicated scanline exceeds the maxTileCost, then the tile is
subdivided into four new tiles and the same process is applied to each of
them in turn. This continues until the maxTileCost criteria is met, or the
tile has reached the minimum tile size of 16x16 pixels.
Note that at this point, no tessellation has occurred; the renderer has
merely collected bounding boxes of the objects in screen space, and gotten
estimates from those objects regarding their geometric rendering
complexity. From this information, a tile pattern is created to use when
rendering the scene.




                                                                                             Technical Overview9
The Rendering Pipeline
Step 5: Render each tile




                           The following pseudo-code describes the tile generation procedure:
                               create four tiles based on the input image resolution
                               Foreach geometry in renderableGeometrySet
                                   Foreach tile in tileList
                                        approximate tileCost of geometry
                                        put geometry into the tile, and update the tileCost
                                        if tileCost > maxTileCost
                                            Subdivide tile to create new smaller tiles
                                            put new tiles in tileList
                                        endif
                                   endFor
                               endFor


                           Note:     To save memory, the subdivision of tiles is not really done until
                                     rendering begins, but is included in this code for clarity



                           Step 5: Render each tile
                           So far, you have learned about the generation of shadow depth maps, the
                           determination of renderable geometries, and the computation of the image
                           tiling pattern. The next step in the rendering process is to perform the
                           visible surface determination given the tile and a list of objects visible in
                           that tile. The visible surface and shading computation is broken down as
                           follows:
                              a) Compute visibility for stationary objects
                              b) Compute visibility for moving objects
                              c) Compute shading
                              d) Highest quality setting
                                        - compute contrast
                                        - compute extra shading samples if necessary

                           Note:     The following sections will discuss non-moving objects and their
                                     shading first (step a), then discuss how adaptive sampling works (steps
                                     c + d), and finally return to discuss computing visibility for moving
                                     objects (step b).


                           Step a: Compute visibility for stationary objects
                              The Maya Renderer does not tessellate geometries until it has to.
                              Tessellation is the process of approximating a NURB surface with
                              triangles. Tessellation is a required step because the renderer only
                              knows how to render triangles and volumes, not NURB surfaces. The
                              process of avoiding tessellation until the renderer knows it will have to
                              render the object is called lazy tessellation. By doing lazy tessellation,


10 Maya Rendering
                                                                                       The Rendering Pipeline
                                                                                          Step 5: Render each tile




   the renderer hopes to avoid tessellating some objects, thus saving on
   the associated time and memory consumption that would otherwise be
   incurred. So how does lazy tessellation work? First the
   renderableGeometrySet is sorted for the tile in order of depth from the
   camera. Then the renderer only tessellates the front-most surface (or
   surfaces if two or more surfaces overlap in Z depth from the camera) in
   the hopes that they will fully occlude the more distant surfaces. If this is
   wrong, then the renderer will continue and tessellate the more distant
   surfaces, but in many cases, this saves some amount of work. Figure 6
   shows a case where the renderer would first tessellate objects O1 and
   O2 - because they overlap in Z depth from the camera, the renderer
   must first determine inter-object occlusions, hence the need to tessellate
   them both - object O3 would not be tessellated since objects O1 and O2
   can potentially occlude O3. Tessellation generally applies only to
   NURB surfaces, but in the case of displacement mapping, it can also
   apply to polymeshes.


                                   O1 (Object 1)            O3 (Object 3)



                                                                                   Z
                          Tile




                                                         Objects in this zone
                                                         may not have to be
                                 O2 (Object 2)           tessellated


       Figure 6: Depth sorting objects in tiles. Objects O1 and O2 are initially
            tessellated, while O3 is not, pending visibility determination.
   Because the renderer is trying to fully determine visibility before
   moving onto the shading phase, if objects O1 or O2 are potentially
   transparent (i.e., they have a transparency map or have their
   transparency set to a constant, non-zero value) then the renderer has to
   assume that they will be transparent and compute the visibility of
   object O3.

Tip:        It helps the renderer optimize the scene if you do not attach any nodes
            to the transparency channel of a texture when that object can never be
            transparent. That way, the shader initialization can flag the objects as
            completely opaque and use this optimization.


   The visibility of the objects is determined by a method that has a close
   analogy to the pushpin array of nails novelty toy you often see in
   ÒscienceÓ stores or higher-end games stores. It consists of an array of
   blunt nails pushed through a plastic board with a plexiglass front
   shield to prevent the nails from being pushed all the way out of the
   board. You press your hand or face into the blunt end of the nails, and
   the nails on the other side of board take on the shape of your hand or
   face.
   The EAS algorithm used in Maya is very much like a pushpin approach
   where the renderer pushes the triangles into a digital pushpin array.


                                                                                          Technical Overview11
The Rendering Pipeline
Step 5: Render each tile




                              The digital pushpin array is many times more dense than the pixel,
                              which gives us good geometrical anti-aliasing, and our digital pushpin
                              array remembers which triangle pushed it the furthest towards the
                              camera so that it can be shaded correctly. The portions of each triangle
                              that remain visible in each pixel after all this digital pin-pushing are
                              called fragments. A fragment is simply the shape left by clipping the
                              triangle to the pixel.

                           Note:     Step b will be explained at the end of this section.


                           Step c: Compute shading (for stationary objects)
                              Now that the visibility of all non-moving objects in the scene has been
                              determined, the renderer needs to shade those objects which still remain
                              visible in each pixel. Before the renderer starts to shade, though, it must
                              first attempt to merge any triangle fragments from the same object into
                              a larger fragment. This is done because it is important to shade each
                              surface as few times as possible in each pixel. However, there are a
                              number of cases where it is not possible or desirable to do the merging.
                              If the fragments are from the same surface, but they have different
                              depths (say you can see the front and back lip of a bowl in the same
                              pixel, these need to be shaded differently; so the fragments cannot be
                              merged) or if the triangles are on either side of a sharp edge on an object
                              (say there is a degree one surface or an object which is not smooth
                              shaded), then it is important to preserve the sharp edges and again, it is
                              not possible to merge these fragments.
                              Once the fragments are merged, the renderer then shades the merged
                              fragment shadingSample a number of times as specified in renderQuality
                              or overridden by each object in the Attribute Editor under Render Stats.
                              The following pseudo-code briefly outlines the merging and shading
                              process;
                               For each pixel in the tile scanline
                                   merge all possible fragments for the same object
                                   shade the mergedFragments shadingSample number of times.
                               endFor
                              The initialization and evaluation of the shading network is handled in a
                              different section. For now, the renderer can almost consider the shading
                              of each fragment as complete.

                           Note:     If you have animated the camera in Maya then all objects are considered
                                     to be moving since the Maya renderer treats the camera as the stationary
                                     point. Therefore if you animate the camera, you must consider the issues
                                     in Step b.


                           Step d: Highest quality setting
                              The shading is not complete if highestQuality has been selected in
                              renderQuality. The Maya Renderer tries to shade each object only once


12 Maya Rendering
                                                                                   The Rendering Pipeline
                                                                                      Step 5: Render each tile




 per pixel; however, this is not always a high enough sampling
 frequency to properly anti-alias some shading events like thin speculars
 or shadow edges. To catch these shading events, the Maya Renderer
 provides an adaptive shading option that is enabled when
 highestQuality is selected. The Maya Renderer examines the contrast
 between this pixel and its five already-computed neighboring pixels
 (the next scanline is not yet rendered, so all 8 cannot be examined).
 Figure 7 shows the five neighboring pixels involved in the contrast
 computation.




     Current Scanline




                                    Current Pixel


        Figure 7: The 5 neighboring pixels used to compute contrast.
 If the contrast exceeds the contrast threshold specified in the Contrast
 Threshold Attributes section of renderQuality, then additional shading
 samples are taken. The number of additional shading samples taken
 varies between shadingSamples and maxShadingSamples as specified in
 renderQuality and is overrideable on a per-object basis in the Render
 Stats portion of the Attribute Editor. A simple linear function is used to
 determine the number of shading samples. Figure 8 shows a chart of
 the function used to determine the number of additional samples to
 take. The number of samples starts at shadingSamples (SS) and remains
 at that number until the contrast threshold is reached. At that point, as
 the distance above the threshold increases, so does the number of
 shading samples taken until the full contrast of 1.0 is reached and
 maxShadingSamples are taken.

 Shading
 Samples

    MaxSS
                                                    MaxSS - Max shading samples.
                                                    (defined in renderQuality)
   Extra                                            can be overridden by object
   Shading
   Samples
   taken                                            SS - shading samples
                                                    (defined in renderQuality)
        SS                                          can be overridden by object




                        threshold         1.0
                                                               Contrast

Figure 8: Graph showing how the number of extra shading samples for highest
                          quality is computed.



                                                                                      Technical Overview13
The Rendering Pipeline
Step 5: Render each tile




                           If you look at the default contrast settings you will see that they are:
                                     Red = 0.4
                                     Green = 0.3
                                     Blue = 0.6
                           These settings were chosen because they roughly correspond to the
                           human eyeÕs responsiveness to these wavelengths of light. The human
                           eye is very sensitive to changes in green, but not very sensitive to
                           changes in blue.
                           The computation of contrast is physically based on the contrast
                           recognition abilities of a monkey eye. While not wanting to start a
                           debate regarding evolution vs. creation, it is generally accepted that the
                           human eye is very similar to the monkey eye, genetically speaking. The
                           contrast is computed with the following formula for each of R, G and B:


                                                    max       min
                                                   I           ÐI
                                                                           -
                                                   ------------------------- = contrast
                                                     max              min
                                                   I           +I

                           The algorithm for determining if additional samples should be taken is
                           outlined in the following pseudo-code:
                            Foreach pixel
                                examine the pixelÕs 5 neighbors
                                Foreach object shaded in this pixel
                                     collect (RGBmax) (RGBmin)
                                     compute contrast
                                     if (contrast > threshold)
                                         take additional shading samples
                                     endif
                                endFor
                            endFor
                           Figure 9 shows a simple example for non-moving objects. There are four
                           images of a spot light shining on a plane. With low quality, both the
                           geometric edge of the object and the shaded edge of the spot light are
                           aliased. When high quality is selected, the geometric edges of the object
                           are anti-aliased; however, the shading edge of the spotlight is still
                           aliased because no adaptive shading was invoked. When highest quality
                           is set, both the geometric edge of the object and the shading edge of the
                           spot light are properly anti-aliased. The final image shows the same
                           image generated with multi-pixel filtering on. This is a true multi-pixel
                           filter applied at the sub-pixel level and not a post-process low pass filter
                           that is applied to the pixels. Multi-pixel filtering is discussed further on
                           page 18 of this document.




14 Maya Rendering
                                                                                   The Rendering Pipeline
                                                                                      Step 5: Render each tile




             Low Quality                         High Quality
                        Spatial/Geometric         (No adaptive shading)
                        Aliasing




                                        Shading Aliasing


              Highest Quality                    Highest Quality
              (With adaptive shading)             (With multi-pixel filtering)




                 Figure 9: Geometric vs. shading anti-aliasing.
Step b: Compute visibility for moving objects
  You have learned how non-moving objects have their visible surfaces
  calculated and subsequently shaded, and touched on the methods the
  Maya Renderer uses for anti-aliasing stationary geometry and shading.
  In this section, you will learn about the rendering of moving objects
  and motion blur.
  Motion blur is solved with point sampling using a process unique to
  Alias|Wavefront. The Maya Renderer chooses pseudo-random
  locations on each pixel where it will sample the moving objects as
  illustrated in Figure 10.




            Current Scanline




                                            Current Pixel

Figure 10: Example sample locations (not actual) for motion blur point sampling.
  The number of sample points in each pixel is under user control. The
  number of visibility sample points for motion blur is determined by the
  motionBlurVisibilitySamples attribute in renderQuality.
  The number of motion blur visibility samples cannot be overridden on
  a per object basis; however, the contrast is used to increase the number
  of visibility samples for motion blur. For highest quality, the five
  neighboring samples are examined to compute the coverageContrast,


                                                                                      Technical Overview15
The Rendering Pipeline
Step 5: Render each tile




                           and additional visibility samples are taken (up to maxVisibilitySamples
                           from the renderQualityÕs Motion Blur Visibility section). While the
                           minimum number of motion blur visibility samples cannot be
                           overridden on a per-object basis, the maximum number of visibility
                           samples can be overridden. The Render Stats section of the Attribute
                           Editor for an object contains a Motion Blur section where this override
                           can be set.
                           To compute the coverage and visible surfaces for motion blurred
                           objects, the Maya Renderer holds the ray stationary, and moves the
                           triangle across it to see when and where the ray intersects the triangle.
                           Figure 11 diagrams this procedure. A ray (a point sample) is sent
                           through the pixel and checked for intersection with a moving triangle
                           that moves from the left of the pixel at shutter open time, to the right of
                           the pixel at shutter close time. By looking at the triangle itself, you can
                           see that the triangle first intersects the ray at time = .2 and stops
                           intersecting the triangle at time = .7. These intersection points allow us
                           to form a line in the space of the triangle that describes where the
                           triangle intersects our point sample. The renderer can then sample this
                           line (and thus the triangle) at multiple times during the time it covers
                           this pixel, which is how it supersamples the shading of moving objects.
                           There are other optimizations which are used in computing motion blur
                           that are not covered in this document. The important thing to learn
                           from this section is that in the case of motion blurred objects, the
                           meaning of shadingSamples is overloaded, which means it is used to
                           control a different type of sampling when motion blur is on versus the
                           type of sampling it controls when motion blur is off. In the case of
                           motion blurred objects, shadingSamples controls the number of shading
                           samples in time across the moving triangle(s), as represented by the ÔXÕs
                           on the triangle in the upper left of Figure 11.


                                t=0.7         t=0.2
                                        xxx




                                                 Pixel




                                                                  !!shadingSampleÕs meaning
                                                                  is overloaded!!

                                    Figure 11: Motion blur coverage and shading sampling.
                           There is no adaptive shading sampling for time-based samples.
                           Figure 12 shows a simple example of the differences between geometric,
                           spatial and temporal aliasing, and how various Maya Renderer
                           parameters anti-alias each of these artifacts. At low quality, all types of
                           aliasing are present; going to high quality eliminates the geometric
                           aliasing problem. Going to highest quality with one shading sample



16 Maya Rendering
                                                                                    The Rendering Pipeline
                                                                                       Step 5: Render each tile




   eliminates the spatial aliasing, and going to 16 shading samples
   completely eliminates the temporal aliasing.The checkered plane is
   moving from left to right.


Tip:      It is not recommended that you set the shading sample frequency to 16
          for all your motion blur scenes, only that you increase the number of
          shading samples on objects that display this type of temporal aliasing.


               Low Quality                      High Quality
                           Geometric Aliasing




                                        Spatial
                                        Shading
                                        Aliasing




               Highest Quality     Temporal     Highest Quality
                                   Shading
                                   Aliasing     (With 16 shading samples)




              Figure 12: Geometric vs. spatial vs. temporal aliasing.
   In general, it is not possible to separately anti-alias or see if the spatial
   or the temporal aliasing is causing the artifact; the example in Figure 12
   is a bit contrived to be able to show this. Figure 13 shows a more
   common case where both the spatial and temporal aliasing are seen in
   the same location. In Figure 13, the texture mapped plane is rotated 45
   degrees and then moved from left to right across the screen.




                                                                                       Technical Overview17
The Rendering Pipeline
Step 5: Render each tile




                                         Low Quality                         High Quality
                                                       Geometric Aliasing




                                                                  Spatial/ Temporal
                                                                  Shading Aliasing

                                         Highest Quality          Temporal   Highest Quality
                                         (performs spatial        Shading     (With 10 shading samples)
                                         shading anti-aliasing)   Aliasing




                                 Figure 13: Spatial and temporal aliasing can not always be separated.

                           Step 6: Composite shaded results
                           At this point the renderer has a list of shaded fragments for each pixel. The
                           next task is to composite the fragments together to form a single pixel color
                           that represents the geometry visible in that pixel.
                           If multi-pixel filtering is not enabled, the result is simply a box filtering of
                           the fragments. The fragmentÕs color is multiplied by the amount of the
                           pixel it covers, and then all fragments are added together, or to put it a
                           different way, the fragment colors are weighted by their coverage
                           contribution and then summed.
                           If, however, multi-pixel filtering is enabled, then a 3x3 pixel filter kernel is
                           used to combine the fragments. The 3X3 pixel filter kernel is a cubic spline
                           filter kernel derived by convolving a square pulse with itself three times.
                           The shape of this filter roughly approximates a gaussian filter. Figure 14
                           shows a graphic diagram of this filter. The fragment marked with the bold
                           circle inscribed with an ÔXÕ is weighted according to the volume contained
                           between it and the projection of the fragment onto the filter kernel. This is
                           a true multi-pixel filter and not a post-filter; the fragments for all of the 3x3
                           pixels are weighted before pixel composition.




18 Maya Rendering
                                                                                          The Rendering Pipeline
                                                                            Working with BOT or Cached File Textures




                                                      Pixel



                      Figure 14: The 3x3 multi-pixel filter

Working with BOT or Cached File Textures
BOT (Block Order Textures) are enabled by selecting useTextureCache on
each file texture. If this flag is ON and the file textures are not already
BOT format files, then Maya will automatically create BOT textures from
your images files in the TMPDIR (temporary directory).
If the textures are already in BOT format (you can convert them using the
stand-alone utility makebot) then no conversion is required, the state of the
useTextureCache flag is irrelevant, and BOT textures will be used.
A BOT texture on disk is a compressed MIPMAP structure with 8x8 texel
pages. (A texel is a texture element derived in much the same way as pixel
is a picture element). The textureCache is a 256 texel page cache in memory;
that is, it can hold 256 of the 8x8 texel pages. There is only one textureCache
for the entire rendering session, and the cache is shared between all file
textures.
The textureCache is demand loaded. When a part of a texture is required, if
it is not already in the cache, then it is loaded from disk. If the textureCache
is full, then the least recently accessed pages are removed and replaced
with the pages being loaded.


Tip:      BOT textures have the advantage of reducing the amount of memory
          required to keep textures in memory, and they employ algorithms that
          help ensure a high hit ratio when looking for a part of a texture. If the
          image file has already been converted to a BOT texture file, then the
          Maya renderer can use it much more quickly than when it has to
          convert the file to BOT texture on its own. If you have lots of textures,
          or very big textures, then converting to BOT textures may be a useful
          way of conserving memory.


BOT textures do have some limitations as well. The image viewing
utilities fcheck and wrl do not know how to display a BOT texture as it is
not a standard image format. If multiple renderers are using the same
BOT file (whether those renderers are on a multi-processor machine or on


                                                                                             Technical Overview19
The Rendering Pipeline
Other renderGlobal Optimization Parameters




                                a separate machines.), there can be an I/O bandwidth problem as all of
                                these renderers attempt to access the same file on the same disk. This will
                                cause the renderers to slow down. The only solution to this problem is to
                                ensure each renderer is accessing it's own local copy of the BOT texture,
                                where each BOT texture resides on a separate hard disk from all the other
                                BOT textures. If the image files are not BOT texture files to begin with,
                                then TMPDIR can get full quickly with all of the temporary BOT files.

                                                                                 BOT file
                                                                                 (on disk)


                                                               8x8
                                                               page




                                                                              256 slots

                                                 textureCache (in Memory)


                                Other renderGlobal Optimization Parameters
                                useFileCache swaps the least recently used (LRU) render data in memory
                                out to a disk file in TMPDIR. At the start of rendering, Maya will compute
                                the maximum size this swap file can become by setting its maximum size
                                to 80% of the free space on TMPDIR. This is done to avoid filling up the
                                disk and leaving no space for other processes which require TMPDIR
                                space.
                                As the renderer consumes more memory,the least recently used sections of
                                data are swapped out to the swap file by the renderer. This does not
                                involve any operating system context switch or swapping.
                                Data items which are candidates for swapping are tessellated triangles and
                                raytracing spatial subdivision structures (voxels).
                                If, for some reason, swapping data to this swap file fails (i.e., the swap file
                                has reached its maximum size), then the data is simply thrown away and
                                re-calculated if required again at a later stage of the rendering.
                                By having Maya do the swapping, it should be a little more intelligent
                                about it than the operating system, which has no knowledge of what the
                                renderer is doing.
                                Disadvantages are I/O bandwidth problems, which get worse if there are
                                multiple processes on a single multi-processor machine and they are all
                                accessing the same TMPDIR. You could run out of disk space and not be
                                able to save your images.
                                Therefore, if the rendererÕs output image directory and TMPDIR are on the
                                same disk partition, saving of image files may fail. The likelihood of this
                                data loss increases as more frames of the animation are rendered.




20 Maya Rendering
                                                                                 Understanding shading networks
                                                                           Other renderGlobal Optimization Parameters




Tip:       When using useFileCache, it is better to therefore render to a different
           disk than the disk containing the TMPDIR.



UNDERSTANDING SHADING NETWORKS
This section describes basic concepts that are important to make the most
use of the power of the Maya RendererÕs shading network.
First, let us define some terms.
s   shading network - a connected graph of nodes that can be used to
    shade objects. These networks generally contain what Maya classifies
    as materials and textures, but they do not have to contain these
    nodes.
s
    shadingGroup - a collection of objects to be shaded with the shading
    network attached to the surfaceMaterial port of the shadingGroup if the
    object is a surface, or with the shading network attached to the
    volumeMaterial port of the shadingGroup if the object is a volume.
s
    port - an attribute on the shadingGroup, which acts as an input for
    shading networks. These attributes differ from normal connected
    input attributes because the renderer evaluates these inputs for
    required connections.
s
    material - these are similar to what were called shaders in Alias and
    Explore. They are called materials in Maya to avoid any functional
    associations that the word ÔshaderÕ might imply.
The shading network is designed as a data flow network. As you look at
shading networks in the Hypergraph, data is fed in the left side of the
network and a final shaded result emerges from the right-most node.
A Shading Group can have a different shading network attached to both
the surfaceMaterial port and the volumeMaterial port. Surfaces that are in
this shadingGroup are shaded with the network attached to the
surfaceMaterial port, while volumes that are in this Shading Group are
shaded with the network attached to the volumeMaterial port. A shading
network assigned to the displacementMaterial port affects only surfaces and
only during tessellation (unless it is otherwise connected to the surface
shading network as well as being attached to the displacementMaterial
port).


Note:      The Maya Renderer uses specially named attributes to supply shading
           networks with information about the sample point being shaded.




                                                                                              Technical Overview21
Understanding shading networks
Other renderGlobal Optimization Parameters




                                Note:        For a list of the specially named attributes that the Maya Renderer uses
                                             to supply information to a shading network, see the Maya online
                                             documentation ® Maya DeveloperÕs Tool Kit ® Maya API Overview
                                             for writing Shading Nodes ® Appendix C, ÒRendering attributesÓ.

                                If a shader declares an attribute with one of these special names, the
                                attribute is automatically fed that information at shading time during
                                rendering. This is called an implicit connection and is similar to accessing
                                global variables in RenderManÕs shading language.
                                For example, if an attribute on a node is called pointCamera and that
                                attribute is not connected, then when that attribute is queried during the
                                shading computation, the intersection point in camera space will be
                                provided to that attribute, since this is a specially named attribute.
                                If an unconnected attribute exists anywhere in the shading network and
                                the attribute has one of the special names listed in the appendix, the
                                attribute will be filled with the requested information at shading time
                                during rendering.


                                Tip:         You can override the implicit behavior of any specially named attribute
                                             simply by explicitly connecting something to that attribute.



                                                      outAlpha   bumpValue     outNormal   normalCamera



                                                                      normalCamera


                                              Figure 15: Overriding normalCamera for bump mapping.
                                Bump mapping in Maya works by overriding the normalCamera attribute
                                on materials. The normalCamera is the normal of the surface in camera
                                space. A similar naming convention is followed for other Maya specially
                                named attributes. Figure 15 shows the manner in which the normalCamera
                                for a material is overridden. Maya supplied materials have an attribute
                                called normalCamera; usually normalCamera is unconnected and the normal
                                in camera space of the intersection point is supplied to the shader. When
                                the material is bump mapped, a bump node is connected to the
                                normalCamera attribute. The bump node has two input attributes:
                                normalCamera, which will normally be unconnected, and a bumpValue
                                attribute. The final outNormal from the bump node will be the normal in
                                camera space modified (bump mapped) by the texture map.


                                Note:        Because of the way Maya supplies data to unconnected, specially named
                                             attributes, the bump node must also be connected to any reflection maps
                                             you have on your material, so that both the material and the reflection
                                             map are using the same bumped normal. This type of connection is




22 Maya Rendering
                                                                                     Understanding shading networks
                                                                               Other renderGlobal Optimization Parameters




         shown in Figure 16. The attribute outNormal of the bump node is fed
         both into the materialÕs normalCamera as well as the environment
         textureÕs normalCamera.




                             normalCamera   outNormal

                                                            normalCamera

                outAlpha     bumpValue      outNormal

                                                              reflectedColor




                            normalCamera

                                                        outColor


     Figure 16: Material and environment map sharing the same bump map.

Note:    You do not need to program API shading nodes to access all the
         attributes provided to the shaders.


You can access any of the specially named attributes by adding a dynamic
attribute onto any node, provided that the attribute has the same name
and data type as listed in the appendix.
Adding all of these dynamic attributes can be time-consuming, and may
result in many different nodes with the same dynamic attributes defined,
so to make accessing sample data easier, there is a helpful node provided
in the Create Render Node window called sampleData, which is simply a
node with many of the specially-named attributes already defined on it.
You can create just one of these sampleData nodes and connect from its
attributes to every place in your shading network that requires the
information. Any attribute you require that is not already defined on the
sampleData node can be added as a dynamic attribute of the same name
and type.
Creating just one sampleData node with all the attributes you require is an
effective way to create a kind of global variable list. Of course, there is
nothing wrong with creating multiple sampleData nodes to reduce
confusion, if the attributes will be connected into many shading networks.



                           normalCamera     input1
                                                                       outValue


                            rayDirection    input2




  Figure 17: Using sample data to take the dot product of the ray and normal.


                                                                                                  Technical Overview23
Understanding shading networks
Other renderGlobal Optimization Parameters




                                In Figure 17, the normal in camera space and the incident ray direction are
                                supplied by the sampleData node and connected to the two inputs of a
                                dotProduct node, the results of which are to be used elsewhere in the
                                shading network.
                                Since the dot product is an important component of many shading models,
                                it can be seen that Maya allows for the prototyping of shaders without
                                actually coding them in C++.


                                Note:        Just as there are specially named input attributes, there are specially
                                             named output attributes.


                                A node must have at least one of the following specially named output
                                attributes to be a valid node to directly connect to a surfaceMaterial port of a
                                shadingGroup:
                                s
                                    outColor
                                s
                                    outTransparency
                                s
                                    outGlowColor
                                If the node connected to the surfaceMaterial port of a shadingGroup does
                                not have at least one of the above attributes, none of the surface objects
                                assigned to that shadingGroup will render.
                                It does not matter which attribute of a node is connected to the
                                surfaceMaterial port of a shadingGroup; only the outColor, outTransparency
                                and outGlowColor attributes of the connected node will be used. Even if the
                                message port is used to attach a node to the surfaceMaterial port, the
                                shadingGroup will look for outColor, outTransparency and outGlowColor
                                attributes on the attached node.
                                A node must have at least one of the following specially named output
                                attributes to be a valid node to connect to the volumeMaterial port of a
                                shadingGroup:
                                s
                                    outColor
                                s   outTransparency
                                Creating special effects, such as inverting a materialÕs color after shading,
                                requires that you attach a special node with outColor, outTransparency and/
                                or outGlowColor attributes to the surfaceMaterial port of the shadingGroup.
                                A special node called surfaceShader is provided in the Create Render Node
                                window available in the multilister. This is a light weight Òpass-throughÓ
                                node that simply allows you to translate the names of the nodeÕs outputs
                                to the names required for it to be a valid surfaceShader.




24 Maya Rendering
                                                                           Understanding shading networks
                                                                     Other renderGlobal Optimization Parameters




  in                     out




                               outColor
                               outTransparency
                               outGlowColor




              outColor
       outTransparency
          outGlowColor




       Figure 18: Renaming output attributes using a surfaceShader node.
In Figure 18, the shading group is attached to a surfaceShader node.
Although most of the attributes have the same names, the outColor of the
material is passed through an invert node which does not have a properly
named attribute, so the surfaceShader node is required to rename that one
attribute. The surfaceShaderÕs outTransparency and outGlowColor are
attached directly to the materialÕs outTransparency and outGlowColor, so
these values go to the shadingGroup unchanged, directly from the
material. The outColor of the material, however, is first passed to the in
attribute of an imaginary (a node made up for this example) invert node,
which inverts the color and then places the result in the out attribute. The
out attribute is then connected to the outColor of the surfaceShader node
where it is passed through to the shadingGroup.
The surfaceShader node is simply a means to translate an arbitrary network
of Maya or user-written nodes with arbitrarily named output attributes
into what the renderer will recognize as a shading network with which it
can render objects. Of course, you can always create three dynamic
attributes on the invert node and make connections from the material and a
loop back connection from the out attribute to the dynamic outColor
attribute on the invert node, as shown in Figure 19.



                outColor       in                out
                               outColor
         outTransparency       outTransparency
            outGlowColor       outGlowColor




       Figure 19: Invert node with 3 dynamic Òpass-throughÓ attributes.
There is also a volumeShader node provided for the same reasons.




                                                                                        Technical Overview25
Understanding shading networks
Other renderGlobal Optimization Parameters




26 Maya Rendering
Assistant Online - Maya/How Tos/Rendering/Realistic Glass




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Realistic Glass




                                                  HOW TO CREATE
                                                                                                           by Alias|Wavefront
                                                  REALISTIC GLASS
                                                 Maya Complete
                                                 Rendering
                                                 In this lesson, you will learn
                                                 how to create a glass shader
                                                 that uses a samplerInfo
                                                 node and several blendColor
                                                 nodes to add more realism
                                                 than is possible with the
                                                 material node alone.
                                                                                                            Play Movie [~246kb]


                                                    STEP ONE

                                                 Create a profile curve for
                                                 the glass. Make the profile
                                                 so that it creates a surface
                                                 for both the inside and
                                                 outside of the glass. This
                                                 double surface will create a
                                                 more realistic effect when
                                                 you later add refraction to
                                                 your scene.


                                                    STEP TWO

                                                 Revolve the curve to create
                                                 the glass.
                                                 Set up a simple scene with
                                                 some props. These will be
                                                 useful to evaluate the
                                                 refractive qualities of the
                                                 surface.
                                                 Don't forget to add lights to your scene.




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                                                 STEP THREE

                                              Open the Hypershade. Select Create -> Material -> Phong to
                                              create a phong material node. Open up the node in the
                                              Attribute editor and set the following:
                                                      Color to Black;
                                                      Transparency to White;
                                                      Diffuse to 0;
                                                      Translucence to 0;
                                                      Cosine Power to 50;
                                              Under Raytrace Options set the following:
                                                      Refractions to On;
                                                      Refractive Index to 1.33;
                                                      Refraction Limit to 6;
                                                      Reflection Limit to 1.
                                              These settings offer the desired qualities for glass.


                                                 STEP FOUR

                                              Assign the phong shading
                                              group to the glass. Now you
                                              can test render the scene to
                                              evaluate this basic glass
                                              shader.
                                              To raytrace the glass, you
                                              must follow the steps
                                              outlined in How to set up reflections and refractions. The
                                              reflections and refractions lesson will teach you how to set up
                                              critical attributes on your various props to ensure that they are
                                              reflected and refracted properly. You will also learn how to set
                                              up your Render Globals for raytracing.


                                                 STEP FIVE

                                              In the Hypershade, select Create -> Create Render Node. This
                                              will open the Create Render Node window. and under the
                                              Utilities tab, create the following utility nodes:
                                                      3 Blend Color nodes,
                                                      1 Sampler Info node
                                              The Sampler Info node is a special utility node that returns
                                              values when a point is sampled on a surface during rendering.
                                              These values can be mapped to other nodes to create unique
                                              effects. In this lesson, the Sampler info node will control the
                                              blending of two colors in each of the three Blend Color nodes.
                                              Rename the three Blend Color nodes to the following:
                                                      colorBC, reflectBC, transpBC


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                                              This will help you distinguish the purpose of these nodes as you
                                              build the glass shading network.


                                                 STEP SIX

                                              In the Hypershade, drag the
                                              samplerInfo node onto the
                                              colorBC node. The
                                              Connection editor will open.
                                              Connect the Facing Ratio
                                              attribute to the Blender
                                              attribute.
                                              The Facing Ratio attribute
                                              returns a value between 0
                                              and 1 based on how much
                                              the sampled point is facing
                                              the camera. If you were
                                              looking at a cylindrical glass
                                              head on, the Facing Ratio values would go from 0 at the sides of
                                              the glass to 1 at the center.
                                              Repeat this step two more times to connect the samplerInfo
                                              node's Facing Ratio attribute to the Blender attribute belonging
                                              to the reflectBC and the transpBC nodes. Now the samplerInfo
                                              node is connected to all three Blend color nodes.


                                                 STEP SEVEN

                                              Open up the transpBC node
                                              in the Attribute editor. Set
                                              Color1 and Color2 as
                                              shown here. This will create
                                              a blend from light gray to
                                              white.
                                              Drag the transpBC node
                                              onto the phong shading
                                              group.
                                              In the Connection editor,
                                              connect the transpBCs
                                              Output attribute to the
                                              phong's Transparency Attribute.
                                              Now the transparency of the glass will appear stronger at the
                                              center of the glass and slightly less transparent at the edges.
                                              Test render to compare the results. You may want to darken
                                              the gray blend color to make the edges even less transparent.
                                              Note: The value of the blending colors [1.0 for white and
                                              approximately 0.8 for the light gray] will be used to set the
                                              transparency value. To find out the value of a color that you
                                              choose, open the Color editor and look at the Value that is

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                                              shown as part of Hue, Saturation and Value. A similar mapping
                                              of color values will apply to setting the reflectivity of the glass.


                                                 STEP EIGHT

                                              Open up the reflectBC node
                                              in the Attribute editor. Set
                                              the Color1 and Color2 as
                                              shown here. This will create
                                              a blend from white to light
                                              gray.
                                              Drag the reflectBC node
                                              onto the phong shading
                                              group.
                                              In the Connection editor,
                                              connect the reflectBC's
                                              Output R attribute to the
                                              phong's Reflectivity Attribute.
                                              Now the reflectivity of the glass will be strongest at the edges of
                                              the glass and slightly less strong where the glass faces the
                                              camera. Test render to compare the results. You may want to
                                              darken the two blend colors to lower the amount of reflection on
                                              the glass.


                                                 STEP NINE

                                              Open up the colorBC node
                                              in the Attribute editor. Set
                                              the Color1 and Color2 as
                                              shown here. This will create
                                              a blend from black to dark
                                              gray.
                                              Drag the colorBC node onto
                                              the phong shading group.
                                              In the Connection editor,
                                              connect the colorBC's
                                              Output R attribute to the
                                              phong's Color Attribute.
                                              Now the color of the glass will be black at the edges of the
                                              glass and a dark grey where the glass faces the camera. Test
                                              render to compare the results. You may want to change the two
                                              blend colors to alter the colors of the glass.




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                                                 CONCLUSION

                                              You now have a glass rendering that uses Maya's utility nodes
                                              to create subtle reflection and refraction effects. You can easily
                                              alter the look of the glass by editing the various blend colors to
                                              suit your needs.
                                              To view the completed scene, download the following file:
                                              glassScene.ma

                                              Your use of this file confirms your agreement to the
                                              Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Reflections + Refractions




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Reflections + Refractions




                                                 HOW TO SET UP RAYTRACED
                                                                                                                    by Robert Magee
                                                 REFLECTIONS AND REFRACTIONS
                                                 Maya Complete
                                                 Rendering
                                                 In this lesson, you will
                                                 learn how to set up a
                                                 scene for reflections and
                                                 refractions.
                                                 Both of these effects
                                                 require Raytracing and
                                                 they also require that
                                                 objects in the scene be
                                                 set up properly.                                           Play Movie [~576kb]
                                                 This example will deal with both these qualities at the same
                                                 time. In other cases you might want only reflections or only
                                                 refractions. The workflow would be similar. You would only
                                                 have to focus your attention on the effect that you are most
                                                 concerned with.


                                                    STEP ONE

                                                 Create or import a shader
                                                 that has reflective and
                                                 refractive qualities. Take a
                                                 look at the Glass shaders
                                                 in the library for some
                                                 examples. Shown below
                                                 is a sample image before
                                                 it has been prepared for
                                                 reflections and
                                                 refractions.
                                                 You will require a material node that has either Reflectivity for
                                                 reflections or Transparency for refractions. Phong and Blinn
                                                 have both of these attributes.
                                                 For reflections, you must set the Reflectivity attribute on the
                                                 material node of your shader. You need to also set the number
                                                 of reflections in the Raytrace Options section of the material


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                                              node. In most cases 1 or maybe 2 reflections will be all that are
                                              required.
                                              For refractions, your material will require Transparency and,
                                              under Raytrace Options, you will need to turn on Refractions
                                              and set the Refractive Index. The refractive index should be
                                              set based on the material you are trying to simulate. Below are
                                              some guidelines for Index values:
                                                          Material                                   Refractive Index
                                                          Standard Glass                             1.2
                                                          Quartz                                     1.46
                                                          Crown Glass                                1.52
                                                          Diamond                                    2.4

                                              The Refraction Limit should be set to at least the number of
                                              refractive surfaces that will overlap at any one time in the
                                              rendering. A simple sphere would have the front and back
                                              surface, therefore a setting of 2 would be required. If you had
                                              two spheres overlapping then you would need a setting of 4.


                                                 STEP TWO

                                              Once your material has
                                              been built and assigned
                                              to your object then you
                                              must set up the other
                                              objects in the scene.
                                              Select objects such as                Click to view larger version
                                              the wall or the floor that
                                              you want to reflect and refract through the glass.
                                              Using either the Attribute editor (one node at a time) or the
                                              Rendering Flags window (multiple nodes), turn the Visible in
                                              Reflections and Visible in Refractions to On.
                                              Note: This is a very easy step to forget therefore watch out for
                                              it when you want reflections/refractions. Also remember that the
                                              Visible in... settings are not required on the object that is doing
                                              the reflecting/refracting but rather on the surrounding objects
                                              that will be reflected/refracted by that object.




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                                                 STEP THREE

                                              Now open up the Render
                                              Globals and click on the
                                              Render Quality tab.
                                                                                                   Click to view larger version
                                              From the Raytracing
                                              section, set the following:
                                              Enable Raytracing to On;
                                              Reflections to 1;
                                              Refractions to 2.
                                              Earlier you set Reflections and Refractions for the shading
                                              group's material node. The renderer will use the lower of either
                                              the material node's setting or the Render Global setting. For
                                              example, if the material node had a reflection setting of 3 and
                                              the Render Globals set Reflections to 1 then only 1 reflection
                                              would occur.
                                              This lets you control these settings either locally at a material
                                              node by material node basis or globally using the Render
                                              Globals.


                                                 CONCLUSION

                                              Now you can render
                                              your scene with
                                              reflections and
                                              refractions. Remember
                                              that Maya's renderer is
                                              a selective raytracer.
                                              This means that only
                                              objects with shaders
                                              that exhibit raytrace
                                              qualities, such as                                         Play Movie [~576kb]
                                              reflectivity and
                                              refractions, will be raytraced.

                                              Your use of this file confirms your agreement to the
                                              Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Reflection Mapping




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Reflection Mapping




                                                 HOW TO CREATE A BALL ENV
                                                                                                             By Steve Christov
                                                 REFLECTION MAP
                                                Maya Complete
                                                Rendering
                                                In Maya, reflections can
                                                be achieved in one of two
                                                ways. You can either
                                                raytrace the scene or you
                                                can map the reflected
                                                color attribute using an
                                                environment shader.
                                                In this lesson, you will
                                                learn how to render realistic reflections without needing to
                                                raytrace every frame of the animation. Using a ball env. shader,
                                                you can raytrace one image then reapplied it as a map to the
                                                shader's reflectivity.
                                                This is an update for Maya from a previous Assistant article
                                                "Reflection Mapping" by Lorna Saunders, Assistant issue No 3,
                                                Winter 1997.


                                                  STEP ONE

                                                For any reflections you
                                                will need to use a
                                                digital set. The set
                                                must be enclosed in
                                                that it is not 3 sided,
                                                and needs to cover
                                                the area behind the
                                                camera.
                                                Download and
                                                uncompress the file:
                                                reflection.zip.
                                                [NT ~2 megs.] or,
                                                reflection.tar.gz
                                                [IRIX ~2megs.]


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                                             This is a simple set that will be used to demonstrate basic
                                             reflections.
                                             You will notice that the various objects are assigned to several
                                             layers. Select the ball layer and with your right mouse button
                                             select Template.


                                               STEP TWO

                                             Create a Sphere.
                                             Position the sphere so
                                             that it is in the same
                                             location as one of the
                                             balls for the pendulum.
                                             Scale the sphere to
                                             make it roughly the size
                                             of one of the balls.



                                               STEP THREE

                                             You now need to give this
                                             sphere a chrome-like
                                             shader.
                                             In the Hypershade, Create
                                             a Blinn material. Name it
                                             Reflector and assign it to
                                             the sphere. Set the
                                             following values in the
                                             Attribute Editor.
                                                 q Color to Black

                                                 q Diffuse to 0.0

                                                 q Eccentricity to 0.14

                                                 q Specular Roll off to
                                                   1.0
                                                 q Specular Color to
                                                   White
                                                 q Reflectivity to 1.0
                                                                                                 Click to view larger version




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                                               STEP FOUR

                                             Create a new camera and
                                             toggle a panel to look
                                             through it. It should be
                                             called camera 2.
                                             In your Render Globals,
                                             set up the globals to
                                             render from your new
                                             camera. In the Resolution
                                             section change the size to
                                             be 512 X 512. Turn off
                                             Lock Device Aspect
                                             Ratio. The reason for this
                                             is because the env sphere
                                             needs to be a square
                                             image with the chrome ball
                                             as its focus.
                                             Name the output image
                                             Reflection, and in the
                                             Raytracing section turn                              Click to view larger version
                                             Raytracing to On.
                                             Set camera 2 as your render camera.


                                               STEP FIVE

                                             In your persp view,
                                             Select the camera and
                                             move it using the move
                                             tool to position it to look
                                             directly at the ball. Open
                                             the Attribute Editor and
                                             set a narrow angle of
                                             view to around 20. This
                                             will decrease the
                                             distortion around the
                                             edges. Switch to the new camera view and select View ->
                                             Camera Settings -> Resolution Gate.
                                             Set up a two panel view where you can see the persp and
                                             Camera 4. Position your camera in the persp window so that
                                             the ball touches all four sides of the resolution gate of camera 1.
                                             It is important to keep the camera parallel to the ground so that
                                             it looks straight at the reflector. Make sure there is no Y
                                             rotation on the camera.
                                             Batch Render the image.




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                                               STEP SIX

                                             In your scene it
                                             is a good idea
                                             to put the
                                             camera and the
                                             chrome ball in
                                             its own layer so
                                             that you can
                                             hide them and
                                             come back to
                                             them later if you
                                             need to.
                                             Make sure your layer bar is shown by selecting Options ->
                                             Layer Bar.
                                             Create a new layer. Name it reflector. Select the camera and
                                             the chrome ball. In the layer bar move your mouse over the
                                             reflection layer, click with your right mouse button, and select
                                             Assign Selected. Again with your right mouse button, select
                                             Visible.
                                             This will hide the camera and chrome ball so that it does not
                                             clutter your scene.


                                               STEP SEVEN

                                             In the Hypershade window,
                                             select the reflector shader
                                             you made and select Edit ->
                                             Duplicate -> Shading
                                             Network. Rename the
                                             material to reflection_color.
                                             In the Attribute editor, click
                                             on the Map button beside
                                             Reflected Color. In the
                                             Environments Section,
                                             select Env Ball. In the


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                                             Attribute editor window, Click beside Image, and select File in
                                             the Create Node Window. In the Attribute editor for the File,
                                             click on the folder beside image name and Select the image
                                             reflection.iff. By default, this image will be located in the images
                                             folder in your project directory.
                                             NOTE: Many times reflections are not perfect, to achieve a
                                             blurred effect, import the file into a paint program to add some
                                             blur. For the final animation, the file was blurred slightly.


                                               STEP EIGHT

                                             At this point you should see
                                             the material node updated
                                             in the Hypershade. Notice
                                             that the color is not
                                             changed but enhanced
                                             when you add the effect of
                                             reflections.
                                             Untemplate the Newton
                                             layer by selecting it and
                                             using the right mouse
                                             button to click on
                                             Standard.
                                             Assign the new material to
                                             the balls layer.


                                               STEP NINE

                                             In the Render globals,
                                             turn Raytracing to Off.
                                             Rename the final render.
                                             Set your
                                             Frame/Animation Ext. to
                                             start at frame 1 and end
                                             at frame 165. Pick the
                                             camera1 as your
                                             renderable camera.
                                             You are now ready to
                                             render the scene.




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                                               CONCLUSION

                                             Final Animation
                                             [MPEG 800k]

                                             By using the ball method
                                             to create a reflection map
                                             you can save on total
                                             render time when
                                             rendering multiple frames
                                             for an animation. While this may not work in all cases, it does
                                             offer an alternative to raytracing a scene.
                                             You could also use different resolutions for your ball image
                                             depending on the size of the object and the distance from the
                                             camera, but generally you'll want to keep the resolution at
                                             either 256 x 256 or 1024 x 1024. In the final animation the
                                             shading samples have been increased to 4 instead of 1. This
                                             helps to reduce some flickering that was encountered when
                                             the final animation was rendered.
                                             Take a look at the following examples for rendering an
                                             animation of 165 frames on a Pentium III with 512 megs ram.
                                                q Scene using reflection mapping. Time: 1 hour 28
                                                  minutes.
                                                q Scene using selective raytracing only on the balls in the
                                                  pendulum. Time: 3 hours 19 minutes.
                                             One thing to keep in mind is that reflections are used to
                                             enhance realism and most times you only need to see
                                             general contrast and shapes to produce the effect of a true
                                             reflection as more often than not the viewer is concentrating
                                             on the animation rather than reflections.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Env Ball vs. Raytrace




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Env Ball vs. Raytrace




                                                   Env Ball Render vs. Raytracing                             By Steve Christov
                                                   Reflection Map

                                                 View the final animation using Reflection map - reflection.mpg
                                                 [800k]
                                                 Time to render 165 frames on Pentium III w/ 512 meg ram: 1 hr
                                                 28 min.




                                                   Raytracing

                                                 View final animation using Raytracing - raytrace.mpg [800k]

                                                 Time to render 165 frames on Pentium III w/ 512 meg ram: 3 hr
                                                 19 min.




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Assistant Online - Maya/How Tos/Rendering/Env Ball vs. Raytrace




                                             When you compare the reflections of the env. ball render to the
                                             raytraced render you will notice a few differences.
                                             The actual reflection in the mapped image shows a consistent
                                             reflection for each sphere. For instance, the black base is
                                             reflected in exactly the same way in all the spheres. Also, the
                                             perspective of the room becomes distorted.
                                             However, the decision whether to use raytracing or not
                                             depends on the level of detail needed for your reflections. Using
                                             a reflection map you can "fake" reflections and achieve almost
                                             the same results while shaving valuable time off your renders.

                                             Use of this file confirms your agreement to the Terms and Conditions
                                             set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Ripple




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Ripple




                                                  HOW TO MAKE WATER RIPPLE                                     by Steve Christov
                                                 Maya Complete
                                                 Rendering
                                                 In this lesson you will learn
                                                 how to create ripples on
                                                 water that appear to cross
                                                 over and float through each
                                                 other.
                                                 This will be done by using
                                                 multiple water textures that
                                                 will be layered to provide
                                                 information to a bump node                     Play Movie [~350kb]
                                                 to produce the ripples. You will map the textures to the
                                                 colorOffset attribute to layer the ripples onto surface of the
                                                 water.
                                                 This article is an update for Maya of a previous article "Texture
                                                 Mapping Aoffsets" by Erik Noteboom; Alias Assistant, Issue
                                                 #14.


                                                    STEP ONE

                                                 Open the Hypershade
                                                 window and Create a Blinn
                                                 material node.
                                                 Open the Attribute editor window for the Blinn.
                                                   q Set the Color to Light Blue.

                                                   q Map a Water texture to Bump Mapping.

                                                   q Rename this texture to Ripple.




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Assistant Online - Maya/How Tos/Rendering/Ripple

                                                 STEP TWO

                                              Create a NURBS Plane.
                                              Scale it out so that it covers
                                              the grid in your perspective
                                              window.
                                              Add and Position a
                                              Directional light so that it is
                                              illuminating the plane.
                                              Assign the Blinn to the
                                              Plane.


                                                 STEP THREE

                                              In the Attribute Editor for the
                                              Ripple set the following:
                                                  q Wave Amplitude to 0.0

                                                  q Ripple Amplitude to
                                                    2.0
                                                  q Spread Rate to 0.5

                                              This will be your main water texture that will have other water
                                              textures mapped into the Color Offset attribute.


                                                 STEP FOUR

                                              To animate the ripples, you will need to keyframe the Ripple
                                              Time attribute.
                                              Make sure your Timeslider is at 1. In the Attribute editor for
                                              your Ripple texture, set the Ripple Time to 0 and using the
                                              RMB set a key for it. Move your Time Slider to 40 and key the
                                              Ripple Time at 1.


                                                 STEP FIVE

                                              You will now duplicate the
                                              Ripple texture with the
                                              animation.
                                              With the Ripple node in
                                              the Hypershade selected,
                                              go to Edit -> Duplicate ->
                                              Shading Network.
                                              Rename this texture node Ripple1. This will create a new water
                                              node without any connections to the shading network.




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Assistant Online - Maya/How Tos/Rendering/Ripple

                                                 STEP SIX

                                              In the Attribute editor for
                                              Ripple1, change the Ripple
                                              Origin to 0.2 and 0.3. Finally
                                              with your MMB, drag the
                                              Ripple1 onto Ripple, and
                                              connect to Color Offset from
                                              the pop-up menu. Notice the
                                              updated water texture in the
                                              Hypershade.
                                              At this point you will notice that the original water texture
                                              becomes white. This is because the color offset channel is used
                                              to add color. By mapping a texture to it you are actually adding
                                              more color to it thus resulting in a white. This will still work with
                                              this example because the information for the bump is there
                                              even though you cannot see it.
                                              NOTE: To see the changes you are making in the Hypershade
                                              on the original water texture, you can remap the colors of the
                                              original water texture with a ramp.


                                                 STEP SEVEN

                                              Repeat the above steps to
                                              produce two more water
                                              textures. Rename these
                                              Ripple2 and Ripple3.
                                              Connect Ripple2 to
                                              Ripple1's colorOffset.
                                              Connect Ripple3 to
                                              Ripple2's colorOffset.
                                                                             Click here to view larger image
                                              For the Ripple2 change
                                              the Ripple Origin to 0.4 and 0.4.
                                              For the Ripple3 texture change the Ripple Origin to 0.3 and
                                              0.5.




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Assistant Online - Maya/How Tos/Rendering/Ripple

                                                 STEP EIGHT

                                              In the Hypershade window,
                                              select the Ripple3 texture.
                                              Select Window ->
                                              Animation Editors ->
                                              Graph Editor.
                                              Press W on the keyboard to
                                              select the Move tool. Click
                                              on the curve to select it.       Click here to view larger image
                                              Hold down the Shift key,
                                              Move the curve to the right so that the end Keyframe is set to
                                              around 70.
                                              Repeat for the Ripple2 and Ripple1, setting their end keys at 60
                                              and 55 respectively.


                                                 STEP NINE

                                              Render the Scene.
                                              You will notice in your render
                                              that only the Ripple node is
                                              rendered while the others do
                                              not render out. The reason for
                                              this is that the Bump node
                                              uses Alpha information which
                                              is not provided because you
                                              have only been mapping color information from the previous
                                              nodes. You will need to use color information to provide the
                                              bump information.
                                              To do this, Create a
                                              Luminance Node in the
                                              Hypershade under the
                                              Utilities menu.
                                              Highlight the connection
                                              between Ripple and the
                                              Bump Node and press
                                              Delete.
                                                                             Click here to view larger image
                                              Drag Ripple onto the
                                              Luminance node, the connection editor will open. Connect
                                              Ripple.outColor to Luminance.value.
                                              Drag Luminance on to the Bump Node, and Connect
                                              Luminance.outValue to Bump.bumpValue.




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Assistant Online - Maya/How Tos/Rendering/Ripple

                                                CONCLUSION

                                              Test Render your scene at
                                              a few diffrent frames. You
                                              should now see ripples on
                                              the surface.
                                              Mapping textures to the
                                              colorOffset of a texture
                                              offers a way to layer
                                              textures that will ultimately
                                              be used as a bump map. Keep in mind that you will need to
                                              use a luminance node to achieve this result.
                                              Another approach to this is instead of connecting Outcolor to
                                              colorOffset, connect outAlpha to the Alpha Offset for each
                                              texture thus keeping Alpha information intact which can
                                              connect directly to the Bump Node therefore eliminating the
                                              need for the Luminance node.
                                              Download ripple.ma. [~ 5kb]


                                              Use of this file confirms your agreement to the Terms and Conditions
                                              set out on the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Shading Networks




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Shading Networks




                                                 HOW SHADING NETWORKS OPERATE                                      by Robert Magee
                                                Maya: Base
                                                Rendering
                                                Maya's Shading networks allow you to build up a shader using
                                                various nodes. These nodes connect together to help
                                                determine the final look of the shader when it is applied to a
                                                surface.
                                                The descriptions in the Maya shader library are a great place to
                                                learn more about how different nodes come together to form a
                                                network. You can use these descriptions to help you work with
                                                the pre-built shaders and to analyze them for learning
                                                purposes.


                                                  Material Nodes

                                                Material nodes contain all the information that affects the
                                                overall shading of the network. Some of the common material
                                                types include:
                                                   q Lambert

                                                   q Phong

                                                   q PhongE

                                                   q Blinn

                                                There are attributes associated with these nodes that allow you
                                                to determine Common material attributes such as reflectivity,
                                                transparency and color. You can also determine the way in
                                                which the surface reacts to light using the Specular shading
                                                attributes.




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Assistant Online - Maya/How Tos/Rendering/Shading Networks

                                               Texture Maps

                                             In Maya, every attribute can be mapped to create more
                                             dynamic results. Some of the common mapping types include:
                                                q Color maps

                                                q Bump maps

                                                q Transparency maps

                                                q Specular maps

                                             In each of these mapping types, you will see that the normal
                                             value associated with an attribute is replaced by the values
                                             found in the map. In some cases, there are RGB values
                                             associated with the color of a map and in others cases it is the
                                             alpha information which is used in the map.


                                               Placement Nodes

                                             When you create a texture map, it needs to be created with
                                             some relationship to the surfaces on which it is mapped. You
                                             can choose a 2D or 3D mapping to achieve the final look.
                                             A 2D placement uses the surface's UV coordinates to place
                                             the texture. The texture can then be adjusted to fit the UV
                                             space accordingly.
                                             A 3D placement uses an external icon to determine the
                                             position of the texture in 3D space. You can position, scale and
                                             rotate the icon to get the mapping that you want. In fact, for
                                             many of the library shaders, you would want to adjust the icon
                                             to suit your own objects.
                                             If you want to animate your object, then the placement node
                                             must be parented to the object or the texture will swim on the
                                             surface. If you have a deforming surface then you will have to
                                             convert the 3D texture into a 2D texture which works better on
                                             the surface as it deforms.


                                               Utility Nodes

                                             Maya also includes utility nodes that can add important
                                             functionality to a shading network. For instance a BlendColors
                                             node can let you combine two textures. The Sampler Info node
                                             can get information from surfaces during the rendering process
                                             then use that information to affect the network.
                                             In the shader library, you will find some examples of utility
                                             nodes at work.




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Assistant Online - Maya/How Tos/Rendering/Shading Networks

                                               Conclusion

                                             This short synopsis of how shading networks operate is
                                             designed to help you make best use of the shader library.
                                             Reviewing how other people build shaders is one of the best
                                             ways to begin creating your own.

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Share Texture Nodes




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Share Texture Nodes




                                                HOW TO SHARE
                                                                                                          by Terry Stoeger
                                                TEXTURE NODES
                                                MAYA Complete
                                                Rendering
                                                In this lesson, you will learn
                                                how to use the same ramp
                                                texture node to define the
                                                transparency, specular color
                                                and bump maps.
                                                The advantage of using the
                                                same texture node for all
                                                three is the ease of making        Download Movie [~240 Kb]
                                                changes: you would only have to make changes to one ramp
                                                instead of three.
                                                For this example you will make a shading network that creates
                                                a shiny, perforated surface.


                                                   STEP ONE

                                                In the Hypershade menu select Create, and add the following:
                                                    q Materials -> Blinn Surface Material (With Shading
                                                      Group turned on)
                                                    q Textures -> 2D -> Ramp texture (Include Placement
                                                      turned on)
                                                    q Utilities -> General -> Reverse

                                                    q Utilities -> Color -> Clamp node.




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Assistant Online - Maya/How Tos/Rendering/Share Texture Nodes

                                                STEP TWO

                                             Begin by double clicking the
                                             ramp texture to open the
                                             attribute editor.
                                             Change the Type to
                                             Circular Ramp.
                                             Set the ramp colors to black
                                             and white and slide them
                                             closer together.
                                             Select the place2dTexture
                                             tab and change the Repeat UV to 5 and 5.


                                                STEP THREE

                                             Double click on the Blinn
                                             Shading Group to open the
                                             Attribute Editor.
                                             Change the Color to a dark
                                             blue.
                                             You will now map the ramp
                                             to the Transparency. Drag and Drop with MMB the ramp
                                             texture to the Transparency slider of the Blinn Shading
                                             Group.


                                                STEP FOUR

                                             If you were to map the ramp directly to the specular color, the
                                             transparent areas would have highlights instead of the opaque
                                             areas. This is because white is treated as transparent and black
                                             as opaque. To solve this, you will connect the reverse utility
                                             node to the ramp before mapping to the specular color.
                                             In the Hypershade, Drag and Drop with MMB the ramp onto the
                                             reverse node. This will open the Connection Editor with the
                                             ramp in the Outputs column and the Reverse node in the
                                             inputs column.
                                             In the left column, click on Out Color and then click on Input in
                                             the right column. This connects the Ramp node's Out Color to
                                             the Reverse node's Input.




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Assistant Online - Maya/How Tos/Rendering/Share Texture Nodes

                                               STEP FIVE

                                             If you map this new reverse node directly to the specular
                                             color, you will have no control over its color. This can be solved
                                             by inserting the clamp utility node.
                                             Drag and Drop with MMB the reverse node onto the clamp
                                             node. This will open the Connection Editor with the reverse
                                             node in the Outputs column and the clamp node in the inputs
                                             column.
                                             In the left column, click on Output and then click on Input in the
                                             right column. This connects the reverse nodes Output to the
                                             clamp nodes Input.


                                                STEP SIX

                                             Double click on the Blinn
                                             Shading Group to open the
                                             Attribute Editor.
                                             You will now map the clamp
                                             to the Specular Color.
                                             Drag and Drop with MMB the clamp utility node onto the
                                             Specular Color slider of the Blinn Shading Group. This
                                             connects the Clamp Output to the Blinn's Specular Color.


                                               STEP SEVEN

                                             The clamp node can now be used to control the intensity and
                                             color of the specular highlight.
                                             Double click on the clamp node to open the Attribute Editor. In
                                             the Clamp Color Attributes section, enter .75 in all three
                                             channels for Max. This will give you a 75% gray as the specular
                                             color. As you enter .75 in the channels, watch the Shading
                                             group in the Hypershade. You will see first red being added ,
                                             then green, then blue. This is the order of the min, max and
                                             input channels from left to right X-Y-Z = R-G-B . For
                                             example: If you want the specular color to be blue, lower the
                                             number in the red and green channels.


                                                STEP EIGHT

                                             Finally, the Ramp texture
                                             will also be used for a Bump
                                             Mapping.
                                             Drag and Drop with MMB
                                             the Ramp texture onto the
                                             Bump Mapping attribute in
                                             the Blinn attribute editor.


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                                               CONCLUSION

                                             You have now created a
                                             shading network that uses
                                             one texture for
                                             Transparency, Specular
                                             Color, and Bump Mapping.
                                             Any change to the texture
                                             or its placement, will be
                                             reflected in all three
                                             channels. This will also                            Click to view larger version
                                             minimize confusion and
                                             improve rendering performance.

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Soft Spotlight




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Soft Spotlight




                                                  HOW TO CREATE
                                                                                                      by Haskell Friedman
                                                  A SOFT SPOT LIGHT
                                                 MAYA Complete
                                                 Rendering
                                                 In this lesson, you will
                                                 learn how to create a spot
                                                 light with soft lighting and
                                                 shadows. This will involve
                                                 the setting of several light
                                                 attributes such as decay,
                                                 intensity and penumbra
                                                 angle as well as the use of
                                                 depth map shadows.                                  Default Lighting [~432kb]
                                                                                                       Soft Lighting [~416kb]
                                                 By default, Maya's spot
                                                 lights create strong sharp lighting. In this lesson, you will learn
                                                 how to soften the effect of the light by adjusting various light
                                                 attributes. Throughout this example, you will be shown how
                                                 changing each attribute affects the look of the scene. At the
                                                 end, you will learn how to use depth map shadows to further
                                                 enhance the soft lighting effect.


                                                    STEP ONE

                                                 Create a primitive NURBS
                                                 plane to act as a floor
                                                 surface. Set Scale X,
                                                 Scale Y,and Scale Z to
                                                 24.0, so that the plane
                                                 covers the perspective
                                                 grid. Rename the surface
                                                 floor.
                                                 If you would like to preview the scene using interactive
                                                 hardware lighting, set the surface's Patch U and V to 16.
                                                 Place a character into the scene. This lesson uses Primitive
                                                 man from Lesson 15 in the Learning Maya book. Place the
                                                 character at the origin (0, 0, 0) and set the character's height to
                                                 about 6 units.



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Assistant Online - Maya/How Tos/Rendering/Soft Spotlight

                                                 STEP TWO

                                              Create a spotlight then
                                              rename it softSpotLight.
                                              Use the Show
                                              Manipulator tool to place
                                              the eye-point manipulator
                                              above the character at
                                              roughly a 45 degree angle.
                                              Place the look-at
                                              manipulator at the origin.
                                              Create an ambient light to provide fill lighting for the scene. Edit
                                              the Intensity to a value of 0.25 and the Ambient Shade to 0.0.


                                                 STEP THREE

                                              In the Render Globals, set
                                              the Presets to Preview
                                              Quality in the Anti-aliasing
                                              Quality tab.
                                              Test render the scene to
                                              preview the lighting.
                                              Looking at the image, you
                                              will notice that the edge of the light, which is called the umbra,
                                              is very sharp. In this lesson, you will soften this edge. First you
                                              will tweak the color and angle of the light.


                                                 STEP FOUR

                                              Open the Attribute editor
                                              for softSpotLightShape.
                                              Click on the Color swatch
                                              and set the HSV to 44.0,
                                              0.06, 1.0. This creates a
                                              slightly off-white color.
                                              Now set the Cone Angle
                                              to around 45 degrees.
                                              Re-render the scene. Now the light's umbra is larger and covers
                                              more of the floor surface.




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Assistant Online - Maya/How Tos/Rendering/Soft Spotlight

                                                 STEP FIVE

                                              You will now add Decay to
                                              your light. This means that
                                              the intensity of the light will
                                              decrease as the distance
                                              away from the source
                                              increases.
                                              To add decay to the
                                              scene, set the light's Decay Rate to Quadratic.
                                              Re-render the scene. The scene has suddenly become very
                                              dark. This is because the intensity of the light is not strong
                                              enough for this decay setting.


                                                 STEP SIX

                                              To compensate for the
                                              new decay rate you will
                                              have to increase the
                                              amount of light in your
                                              scene. Set the spot light's
                                              Intensity to 500.
                                              Re-render the scene. Now
                                              your scene has more than enough illumination to compensate
                                              for the decay. In fact, the scene should be a little over-exposed
                                              since you will be further softening the light in the next step.


                                                 STEP SEVEN

                                              Earlier you noted that the
                                              light's umbra is too sharp.
                                              To soften it, you will need
                                              to set the light's Penumbra
                                              angle and Dropoff. The
                                              Penumbra angle defines a
                                              ring around the light's
                                              edge where the light will
                                              fade more quickly. The Dropoff will cause the light intensity to
                                              decrease from the center of the spot to the umbra.
                                              Set the Penumbra Angle to 5.0 and the Dropoff to 25.0.
                                              Re-render the scene. You should now see a softening effect
                                              that is a combination of the Penumbra, Dropoff and Decay.




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Assistant Online - Maya/How Tos/Rendering/Soft Spotlight

                                                 STEP EIGHT

                                              Now that you have soft
                                              lighting you will want soft
                                              shadows. You will use
                                              Depth map shadows to
                                              achieve the desired effect.
                                              In the Attribute Editor for
                                              your softSpotLight, open
                                              the Shadows section. Under Depth Map Shadow Attributes,
                                              turn Use Depth Map Shadows to On.
                                              Re-render your scene. With the default settings, the shadow
                                              appears sharp and pixelated compared to the light itself.


                                                 STEP NINE

                                              To fix the shadow, you will
                                              reduce the resolution of
                                              the depth map and apply a
                                              filter setting that will blur
                                              the effect of the shadow.
                                              You are going to use a
                                              very low resolution depth
                                              map so that it appears
                                              softer. If you were to                        View Movie [~416Kb]
                                              increase the resolution of
                                              the depth map, the shadow would appear sharper and you
                                              would require a higher filter setting to soften the shadow.
                                              In the Attribute editor, set the Dmap Filter Size to 4 and the
                                              Dmap Resolution to 256.
                                              Render your scene. Now the shadows match correctly with the
                                              type of lighting being produced. This completes the soft light
                                              effect.
                                              Note: You can increase the Dmap Filter Size for higher quality
                                              shadows but keep in mind that the higher the filter size the
                                              longer it will take your scene to render.


                                                 CONCLUSION

                                              You now know how to soften a spotlight by combining,
                                              decay, dropoff, penumbra and depth map shadows. Be sure
                                              to remember that the attribute values used in this lesson
                                              have been chosen because of the size of the scene. To use
                                              similar lighting in your work, you may have to increase or
                                              decrease the attribute values depending on the positioning of
                                              your lights and the size of your scene.




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                                              Your use of this file confirms your agreement to the
                                              Terms and Conditions set out in the Terms and Conditions page.




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Assistant Online - Maya/How Tos/Rendering/Toon Shader




 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Toon Shader




                                                 HOW TO MAKE A
                                                                                                        by Tom Kluyskens
                                                 CARTOON SHADER
                                                MAYA Complete
                                                Rendering
                                                In this lesson, you will
                                                learn how to create a
                                                cartoon shader. By
                                                combining several utility
                                                nodes to remap a Blinn
                                                material node using a
                                                Ramp, you will define the
                                                cartoonish look of the
                                                shader.
                                                                                          Play Movie [~485kb]
                                                This lesson will help you
                                                better understand how you can create custom shading
                                                networks using the Connection editor and utility nodes.


                                                   STEP ONE

                                                In the Hypershade, select Create -> Create Render Node..
                                                and create the following rendering nodes:
                                                Material nodes:                  Blinn (no Shading Group),
                                                                                 Surface Shader (with Shading Group)
                                                Texture nodes:                   Ramp (no Texture Placement, Normal)
                                                Utility nodes:                   Sampler Info
                                                                                 Clamp
                                                                                 Condition

                                                The Blinn material node will be used to catch highlights on the
                                                objects. Leave the color grey. The greyscale blinn shading
                                                (white = highlights) will be transformed into the cartoon shader
                                                effect by remapping the grey values into a sequence of colors
                                                using a ramp. The Sampler info node will be used to put a line
                                                at the objects' border.




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                                                STEP TWO

                                             In the Hypershade with the MMB, drag the Blinn node over the
                                             Clamp node to open the Connection Editor. Connect the Blinn
                                             node's Out Color to the Clamp node's Input.
                                             The Clamp node is going to reduce all greyscale values to
                                             values less than or equal to 1. The clamp cuts off all highlights
                                             that have a greyscale value greater than 1 (superwhite).
                                             Open the Attribute Editor for the Clamp node, and set the left
                                             Max field to 1. The left field represents the Red channel
                                             (middle = Green, right = Blue), but because grey is an equal
                                             mix of R G and B, you only need one channel (this lesson
                                             chooses R). Min should be set to 0.


                                                STEP THREE

                                             The same way, connect the Output R of the Clamp node to the
                                             V Coord of the Ramp node, using the Connection Editor.
                                             Make sure that your Ramp is a V Type ramp. The color output
                                             of the ramp is now going to be the color in the ramp that
                                             corresponds to the greyscale value (0 <= clamp Color R Output
                                             <= 1) of the input. This technique is called remapping.


                                                STEP FOUR

                                             Connect the Ramp node's Out Color to the Color1 of the
                                             Condition node. Also connect the Facing Ratio of the Sampler
                                             info node to the First Term of the Condition node.
                                             The Facing Ratio, is the degree to which a point on a surface is
                                             facing towards the camera. If the point is located on a part of
                                             the surface that is facing 90 degrees away from the camera
                                             (typically the border of a sphere), the Facing Ratio is 0. If the
                                             angle between the surface normal and the camera ray is 0, the
                                             Facing Ratio is 1. Check your online Maya manuals for more
                                             info.


                                                STEP FIVE

                                             Open the Attribute Editor for the Surface shader material.
                                             Select Add -> Add Attributes... and add following attributes
                                             (float, scalar):
                                             LineThickness : Min 0, Max 1, Default .2
                                             LineR
                                             LineG
                                             LineB
                                             These are the user-definable border thickness and color.



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                                                STEP SIX

                                             Connect the Line
                                                                            Diagram of final dependency graph
                                             Thickness and LineR G B
                                             of the Surface shader
                                             node to the Second Term and Color2 R G B of the Condition
                                             node.
                                             Set the Condition Operation to Greater Than.
                                             If the Facing Ratio (first term of the condition) is smaller than
                                             the line thickness (second term), the condition output will be
                                             Color2 (line color set in surface shader), else it will be Color1
                                             (ramp-blinn color).
                                             Connect the Condition node's Out Color to the Surface
                                             shader node's Out Color.


                                                STEP SEVEN

                                             Adjust your Ramp to use the colors that you want. Cartoon
                                             shaders normally may be designed to use no interpolation
                                             between the ramp colors in order to create hard uniform color
                                             zone edges. Shown below is a sample ramp and how the final
                                             shader appears. Here are some examples of how different
                                             positions, color zones and interpolation affect the final result.




                                             Other edits you can make include the following:
                                                q Adjust line thickness and color in the attributes of the
                                                  surface shader.
                                                q Adjust your blinn parameters to have different kinds of
                                                  highlights.
                                                q You can even put a bump map on the blinn. This
                                                  technique was used on the worm in the animation.
                                                q You can use another material (instead of blinn) to get
                                                  other kinds of highlight.
                                             You can now assign the shader to your objects.


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                                                CONCLUSION

                                             This lesson taught you how to build a cartoon shader as well as
                                             how to work with several utility nodes to build a complex
                                             shading network.
                                             Thanks to Michele Borghi and Duncan Brinsmead for the
                                             original design of the cartoon shader.

                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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 Alias|Wavefront / Assistant Online / Maya / How Tos / Rendering / Ramp Examples




                                                CARTOON SHADER: Ramp examples
                                               Shown below are some sample ramps that explore how the
                                               positions, number of color zones and ramp interpolation affect
                                               the final result:
                                               Example1: 2 colors, no interpolation




                                               Example2: 3 colors, no interpolation




                                               Example3: 5 colors, no interpolation




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                                             Example4: 2 colors, smooth interpolation




                                             Example5: 4 colors with transition zones, smooth interpolation




                                             Example6: 5 rainbow colors, linear interpolation




                                             Your use of this file confirms your agreement to the
                                             Terms and Conditions set out in the Terms and Conditions page.




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