[Mesa-dev] [PATCH] i965: Allow the blorp blit between BGR and RGB

[Kenneth Graunke]

On Monday, June 23, 2014 07:02:59 PM Neil Roberts wrote:
> Previously the blorp blitter would only be used if the format is identical 
or
> there is only a difference between whether there is an alpha component or 
not.
> This patch makes it also allow the blorp blitter if the only difference is 
the
> ordering of the RGB components (ie, RGB or BGR).
> 
> This is particularly useful since commit 61e264f4fcdba3623 because Mesa now
> prefers RGB ordering for textures but the window system buffers are still
> created as BGR. That means that the blorp blitter won't be used for the
> (probably) common case of blitting from a texture to the window system 
buffer.
> 
> This doesn't cause any regressions in the FBO piglit tests on Haswell. On
> Sandybridge it causes the fbo-blit-stretch test to fail but that is only
> because it was failing anyway before the above commit and that commit hid 
the
> problem.
> 
> https://bugs.freedesktop.org/show_bug.cgi?id=68365

FWIW, I relaxed the format restrictions in brw_blorp_copytexsubimage, so it 
can handle general format conversions as well (i.e. RGBA_FLOAT16 -> 
RGBA8888_UNORM).  There's no reason we couldn't do that for BlitFramebuffer as 
well, I just forgot to do it (and then we decided to make it a newbie task, 
and then the newbie didn't do said task, and...oops.)

A couple of games do BlitFramebuffer with format conversions, IIRC.  I think 
DOTA 2 does 1010102 -> 8888 blits.

--Ken
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