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

[Eric Anholt]

On Thu, 08 Sep 2011 20:13:45 +0200, Roland Scheidegger <sroland at vmware.com> wrote:
> Am 08.09.2011 19:59, schrieb Eric Anholt:
> > On Thu, 08 Sep 2011 10:53:45 -0700, Ian Romanick <idr at freedesktop.org> wrote:
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> >> 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.
> 
> Yes but do we need GL_EXT_blend_logic_op and not the GL 1.1 style logic ops?

Oh, I guess what I was looking for was just GL 1.1 logic ops.  I assumed
that was what this was.

None of the apps I have extension usage for used this one, so I wouldn't
miss it.
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