[Mesa-dev] [PATCH v5 0/3] Add and enable extension EXT_sRGB_write_control

[Ilia Mirkin]

On Wed, Nov 7, 2018 at 7:45 AM Gert Wollny <gert.wollny at collabora.com> wrote:
>
> Am Dienstag, den 06.11.2018, 15:28 -0500 schrieb Ilia Mirkin:
> > On Tue, Nov 6, 2018 at 3:15 PM Gert Wollny <gert.wollny at collabora.com
> > > wrote:
> > >
> > >
> > > The extension has the status "not complete" but after reading is it
> > > seems to describe what is needed from ARB_framebuffer_sRGB in GLES
> > > 3.0,
>
> Well, after starting to hacking it up and reading the finer details  it
> turns out that EXT_sRGB is not providing what GLES 3.0 needs:
>
> EXT_sRGB says
> """
> Accepted by the <format> and <internalformat> parameter of TexImage2D,
> and     TexImage3DOES.  These are also accepted by <format> parameter
> of TexSubImage2D and TexSubImage3DOES:
>
>     SRGB_EXT                                       0x8C40
>     SRGB_ALPHA_EXT                                 0x8C42
>
> Accepted by the <internalformat> parameter of RenderbufferStorage:
>
>     SRGB8_ALPHA8_EXT                               0x8C43
> """
>
> whereas GLES 3.0 only knows the internal formats  SRGB8 and
> SRGB8_ALPHA8 but it doesn't use the unsized SRGB_EXT and SRGB_ALPHA_EXT
> at all, and certainaly not as accepted formats.
>
> Also there is
>
> """
>  4) What is the expectation for mipmap generation on SRGB textures?
> Issue 24 from EXT_texture_sRGB gives two possible ways, will we leave
> it similarly undefined, or is this not intended to be supported at all?
>
> No.  This in not likely to be used much so for simplicity let's not
> require it.  This will generate an INVALID_OPERATION error.
> """
>
> which is also in conflict with GLES 3.0.
>
> Which brings me back to what I was talking about yesterday: For
> properly calculating GLES 3.0 support a flag is needed that says sRGB
> render targets are supported without the need that such a fbo
> attachment can switch between linear and sRGB.
>
> Well, I'll think of something and send an RFC

Those are just small API-level differences, not differences in
functionality. If you don't feel like actually doing those, you could
create the EXT_sRGB enable flag, but not hook it up to an actual
extension being enabled.

  -ilia