[Mesa-dev] [PATCH 4/9] r200: Enable extensions by just setting the flags

[Roland Scheidegger]

Am 06.09.2011 22:13, schrieb Ian Romanick:
> From: Ian Romanick <ian.d.romanick at intel.com>
> 
> Core Mesa already does the dispatch offset remapping for every
> function that could possibly ever be supported.  There's no need to
> continue using that cruft in the driver.
> 
> Since the call to _mesa_enable_imaging_extensions (via
> driInitExtensions) is removed, EXT_blend_logic_op is explicitly added
> to the list.  EXT_blend_color is also added, but it depends on the
> drmSupportsBlendColor flag.

Hmm, I don't think EXT_blend_logic_op was advertized before. The reason
for this is that EXT_blend_logic_op together with
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...).

Roland