[Mesa-dev] [PATCH] i965: handle stencil_bits parameter for MESA_FORMAT_B8G8R8X8_UNORM format.

[Ilia Mirkin]

On Wed, Dec 9, 2015 at 11:23 AM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> On Wed, Dec 9, 2015 at 11:18 AM, Deve <deveee at gmail.com> wrote:
>> This patch indeed seems to not have a sense. I just added it to the bug
>> report as a suggestion that it works for me after this modification. Emil
>> Velikov said that I should send it to the mailing list.
>>
>> Here is how it works in Supertuxkart:
>> We create rtt with following parameters:
>>
>> DepthStencilTexture = generateRTT(res, GL_DEPTH24_STENCIL8,
>> GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8);
>>
>> Then, during rendering scene, we do:
>>
>>     glEnable(GL_FRAMEBUFFER_SRGB);
>>     glBindFramebuffer(GL_FRAMEBUFFER, 0);
>
> OK, so this is the "winsys" framebuffer (GL has some term for it,
> sorry, I don't remember what it is... perhaps it's even winsys). This
> is created based on parameters of your selected GLX visual. For
> example, when I run glxinfo, I see (on nouveau; the list on intel will
> be different but comparable):
>
> 480 GLX Visuals
>     visual  x   bf lv rg d st  colorbuffer  sr ax dp st accumbuffer  ms  cav
>   id dep cl sp  sz l  ci b ro  r  g  b  a F gb bf th cl  r  g  b  a ns b eat
> ----------------------------------------------------------------------------
> 0x021 24 tc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
> 0x022 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
> ...
> 0x343 24 tc  0  32  0 r  . .   8  8  8  8 .  s  0  0  0  0  0  0  0  0 0 None
> 0x344 24 tc  0  32  0 r  . .   8  8  8  8 .  s  0  0  0 16 16 16 16  0 0 Slow
> 0x345 24 tc  0  32  0 r  y .   8  8  8  8 .  s  0  0  0  0  0  0  0  0 0 None
> 0x346 24 tc  0  32  0 r  y .   8  8  8  8 .  s  0  0  0 16 16 16 16  0 0 Slow
>
> Note how some of them have srgb, others don't (and have various
> differences in their various other properties). EGL has something
> similar I believe, but tbh I don't remember the specifics. That's the
> mesaVis->sRGBCapable bit below. If you need an sRGB-capable visual,
> are you sure you're picking one? This would be somewhere well before
> any actual rendering takes place.
>
> If you're not sure whether you need an sRGB-capable visual or not, try
> making sure you pick a *non-srgb* visual in a working configuration
> and see if it breaks.

Right, so looking at your code with in more detail, you probably just
require a stencil visual, which, in combination with this patch, makes
you skip this one.

However I noticed that i965/hsw and probably others don't expose *any*
sRGB-capable GLX visuals/fb configs! Pretty sure that's not good...
but GLX, sRGB, and visuals are not exactly my strong point, hopefully
someone a bit more clued in can comment.

Cheers,

  -ilia