On Wed, Jul 15, 2009 at 12:29:31AM +0200, Nicolai Hähnle wrote: | The test exactRGBA is motivated by a paragraph in the section "Final Color | Processing" (2.19.9 in glspec3.0). This is, as far as I know, the only support | for this test in the entire spec.
Some OpenGL semantics were motivated by the desire to maintain compatibility with important applications that were written for IrisGL. This is one of them. Some apps implemented picking (selecting the object under a cursor) by drawing depth-buffered objects using object IDs instead of colors, then choosing the object whose ID appeared in the color channels of the pixel under the cursor. For this to work, there had to be a well-defined mapping between an integral object ID and a color value stored in the framebuffer. That's the reason for the language in "Final Color Processing." At the time this was written, 12-bit color channels were considered high-end, floating-point color channels didn't exist, and the conversion requirements weren't unreasonable. Nowadays the constraints are different, and some slop is much more justifiable. But as you say, changing the spec requires some agreement from the ARB. Allen ------------------------------------------------------------------------------ Enter the BlackBerry Developer Challenge This is your chance to win up to $100,000 in prizes! For a limited time, vendors submitting new applications to BlackBerry App World(TM) will have the opportunity to enter the BlackBerry Developer Challenge. See full prize details at: http://p.sf.net/sfu/Challenge _______________________________________________ Mesa3d-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
