[Mesa-dev] [PATCH 2/2] gallivm: handle srgb-to-linear and linear-to-srgb conversions

[Jose Fonseca]

----- Original Message -----
> Am 11.07.2013 15:50, schrieb Jose Fonseca:
> > 
> > 
> > ----- Original Message -----
> >> From: Roland Scheidegger <sroland at vmware.com>
> >>
> >> srgb-to-linear is using 3rd degree polynomial for now which should be
> >> _just_
> >> good enough. Reverse is using some rational polynomials and is quite
> >> accurate,
> >> though not hooked into llvmpipe's blend code yet and hence unused
> >> (untested).
> >> Using a table might also be an option (for srgb-to-linear especially).
> >> This does not enable any new features yet because EXT_texture_srgb was
> >> already
> >> supported via util_format fallbacks, but performance was lacking probably
> >> due
> >> to the external function call (the table used by the util_format_srgb code
> >> may
> >> not be all that much slower on its own).
> >> Some performance figures (taken from modified gloss, replaced both base
> >> and
> >> sphere texture to use GL_SRGB instead of GL_RGB, measured on 1Ghz Sandy
> >> Bridge,
> >> the numbers aren't terribly accurate):
> >>
> >> normal gloss, aos, 8-wide: 47 fps
> >> normal gloss, aos, 4-wide: 48 fps
> >>
> >> normal gloss, forced to soa, 8-wide: 48 fps
> >> normal gloss, forced to soa, 4-wide: 47 fps
> >>
> >> patched gloss, old code, soa, 8-wide: 21 fps
> >> patched gloss, old code, soa, 4-wide: 24 fps
> >>
> >> patched gloss, new code, soa, 8-wide: 41 fps
> >> patched gloss, new code, soa, 4-wide: 38 fps
> > 
> > Indeed, not a big difference.  Though these figures seem low overall -- I
> > get 72.5275 on my machine.  This was with release/profile build, right?
> Yes with release build - I get less than half that with debug build. You
> got 72.5 on a 1Ghz Sandy Bridge using 1 thread? I was also using llvm 3.1.
> 
> > 
> > Eitherway the patch looks good.
> Actually it does not I forgot to include the actual conversion code.
> I'll send out another version :-(.

That's embarrassing! How did I miss that.

Jose