On Thu, 08 Sep 2011 10:53:45 -0700, Ian Romanick <i...@freedesktop.org> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 09/06/2011 03:21 PM, Roland Scheidegger wrote: > > EXT_blend_equation_separate allows some unholy combinations which the > > r200 (possibly other hw too) can't handle correctly. Namely this > > combination makes it possible to have logic ops on rgb or alpha channels > > and color blending on the other channels. > > I know that at least sometime in the past this driver did not advertize > > EXT_blend_logic_op, since OpenGL 1.1 style logic ops do not have that > > problem and EXT_blend_logic_op wasn't really all that important. I guess > > though it's not exactly a severe problem since surely apps old enough to > > use EXT_blend_logic_op wouldn't try to use EXT_blend_equation_separate > > (though in theory some app could be clever and really want to do that...). > > That's a good point. I suspect that no hardware actually handles this > case correctly. I seem to recall that this is the reason NVIDIA doesn't > support GL_EXT_blend_logic_op in their drivers. I know the non-Quadro > cards don't support it, anyway. > > Does this work on later chips in the Radeon family? > > I don't think anyone will miss GL_EXT_blend_logic_op if we just remove > it altogether.
Sadly, for the purpose of doing X on top of GL, we actually do want logic ops.
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