[Mesa-dev] Switching to the GL 4.4 sRGB rules for glBlitFramebuffer().

[Ian Romanick]

Patches 1 through 5 and 7 through 9 are

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

I sent one trivial comment on patch 9.

On 08/04/2016 04:14 PM, Kenneth Graunke wrote:
> Hello,
> 
> This combined patch series updates both Piglit and Mesa to implement
> the modern GL 4.4+ rules for sRGB encoding/decoding in BlitFramebuffer().
> 
> The new GL 4.4 rules make it possible to match the behavior of ES 3.x
> (always encode and decode), and the old behavior (never encode or decode).
> If GL_FRAMEBUFFER_SRGB is enabled, encode and decode happen.  If not,
> no conversions apply.  This is a change in behavior, which could break
> applications.
> 
> Paul Berry wrote Piglit tests in 2012 which matched the NVIDIA driver
> behavior at the time, which was to never apply conversions.  It appears
> that NVIDIA has changed their behavior, and now implements the GL 4.4
> rules.  They fail the Piglit tests, but begin passing after my patches.
> I'm told that AMD/Catalyst follows the 4.4+ rules too, but I haven't
> tested that personally.
> 
> Left 4 Dead 2 used to require the old behavior, but I retested with
> these patches, and it seems to be working fine.  I'm assuming they
> updated their application when the closed drivers changed behavior.
> 
> I've updated Gallium, Meta, and i965/blorp.  Please review - this
> will impact everyone.  I highly recommend reading patch 3, as it
> summarizes the changes in all GL 4.x specs.
> 
> Because working on sRGB drives people insane, here's an ode to
> non-linear colorspaces:
> 
>     sRGB rules, GL broke
>     some rendering glistened brightly
>     some rendering grew bleak
>     spec reformulations greatly bewilder
>     surprisingly reasonable GL became
> 
>     should review go badly,
>     submitter's rationality goes b'bye
> 
> Thanks,
> --Ken
> 
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