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					Designing Computer Game
         Graphics
   (color & animation)
           From Ari Feldman’s book
 “Designing Arcade Computer Game Graphics”
             Wordware Publishing
              Brian Malloy, PhD
         Screen Resolution

 640 x 480
 800 x 600
 an image that looks nice on 800x600
  may look blocky on 640x480




                                        2
                     color depth

color depth           No. of               common name
                      colors
-----------------------------------------------------------------
1 bit/pixel           2                    monochrome
8 bits/pixel          256                  Palette mode
16 bits/pixel         65,536               16-bit high color
24 bits/pixel         16,777,216           true color


                                                             3
             color display

 video consoles can display millions of
  colors
 computers understand colors as a
  combination of 3 primary colors (r, g, b)
 actual no. of colors that can be
  displayed at once is limited by hardware


                                              4
                    color palettes

   collections of colors from which one or more
    may be selected
   two types:
       physical – contain all possible colors
       logical – contain small portion of possible colors
        (window into actual hardware palette)
   No. of colors in logical palette is determine by
    color depth
   logical palettes do not exist in display modes
    above 8-bit
                                                             5
          common denominator

   images that use 8-bit color are guaranteed to
    display properly on any display
   images that use 8-bit color tend to require less
    disk space than 16 or 24 bit
   palettes are easy to manipulate & give the
    artist more control over color choice
   color palettes can support special effects


                                                   6
             palette organization
 arranged as an array of palette entries
 each entry has an index and an (r,g,b)
  value
 most tools will dither colors that can’t be
  reproduced in current display mode
     blending   a pattern of 2 colors to produce a 3rd
      color
     used to simulate colors that are missing from
      palette
                                                      7
         Creating a color palette

   palettes can differ greatly
   to create your own, need careful planning
   can set the mood of the game
   need some kind of painting program
   after creating a palette, you save it as a .PAL
    file
   There are versions of .PAL files
   can later load the palette
                                                      8
               Animation

 process that produces the illusion of
  movement
 by displaying 2 or more frames
 ability to focus on subtle details of how
  objects move
 every object exhibits different actions
  when it moves

                                              9
     characteristics of movement:
             motion lines

     invisible line created by an objects as it
    performs a series of sequential movements
   an even motion line will create a smooth
    animation
   some objects produce different shaped motion
    line
   to follow an object, locate its center of gravity


                                                    10
               key frames

 the actions needed to produce an
  animation
 there is a direct relationship between the
  number of key frames and the
  smoothness of the animation
     moreframes = smoother animation &
     longer time to design and build

                                           11
   common frame requirements
object:                   min #   max #
4-legged animal running   4       16
animal biting             2       5
crawling                  2       12
explosions                5       16
falling                   3       5
flying                    2       12
jumping                   2       10
kicking                   2       6
punching                  2       6
rotating/spinning         4       16
running                   2       12
throwing                  2       8
walking                   2       12
                    tempo

 number of frames per second
 human eye can perceive movement in
  as few as 12 frames per second (fps)
 thus, we want more than 12 fps
 some common values
     television     30 fps
     motion  pic    24 fps
     action game    30
                                         13
                 sprites

 special graphic objects that can move
  independently of the background
 they can be animated or static
 most challenging aspect of game
  graphics
 need to maintain size consistency – grid
  squares help to do this

                                         14
16x16




        15
128x128




          16
    7 game animation primitives

 cylindrical primitive
 rotational
 disintegration
 color flash
 scissors
 growing
 shrinking
                                  17
      graphics creation tools

 painting programs
 screen capture utilities
 image viewers/converters
 palette tools




                                18
      game artwork required

 title screen
 menu screens
 background
 background objs
 sprites




                              19
       paint program features
             brush tools

 pencil tool – paint pixels in freehand;
  nice to be able to zoom
 brush tool – paint pixels in soft strokes;
  want brush strokes to be antialiased
 airbrush – paint pixels as if you were
  using a spray can; nice to be able to
  adjust the width and flow of “can”

                                               20
                    other tools
   shape tools: lines, curves, rectangles, ellipse,
    polygon, fill
   lasso tool: allows you to to select an irregular
    portion of an image and store it for later
    manipulation
   zoom tool
   palette selection tool
   image processing tool: brighten, darken,
    smooth, smear
   anti-alias tool
   colorize tool                                      21
recommended dos painting programs

 Deluxe Paint Iie
 GrafX2
 Improcess
 NeoPaint




                                22
    recommended windows painting programs

 NeoPaint (www.neosoftware.com)
 Paint Shop Pro (www.jasc.com)
 Pro Motion
  (www.cosmigo.com/promotion/)




                                            23
sample sprite file




                     24
action sprites




                 25
space sprites 1




                  26
space sprites 2




                  27
space sprites 3




                  28

				
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posted:10/22/2011
language:English
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