Porting Color, Shading, and Writemask Code

When porting color, shading, and writemask code to OpenGL, keep the following points in mind:

  • Though you can set color-map indexes with the OpenGL glIndex function, OpenGL does not have a function for loading color-map indexes.
  • Color values are normalized to their data type. (For information about color values, see glColor).
  • There is no simple equivalent for cpack.
  • You may have to translate code that includes the c or color functions to glClearColor or glClearIndex instead of glColor or glIndex.
  • The RGBA writemask applies to each component but not for each bit.
  • IRIS GL provides defined color constants: BLACK, BLUE, RED, GREEN, MAGENTA, CYAN, YELLOW, and WHITE. OpenGL does not provide these constants.

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