On 07/22/2013 03:58 PM, Marek Olšák wrote:
There are a couple of reasons why this was missed:
1) The depth texture mode doesn't exist in the core profile, so the
core spec doesn't and cannot specify what the default should be, so
that's why nobody updated it. However the 4.1 core spec says:
"3.8.9 Depth Component Textures
Depth textures and the depth components of depth/stencil textures can
be treated as RED textures during texture filtering and application
(see section 3.8.16). The initial state for depth and depth/stencil
textures treats them as RED textures."
2) The default TBO format is LUMINANCE8 according to the ARB_tbo spec,
so apparently the default value was copied from there. However the GL
core spec is different again and says R8 is the default format.
You're right - the OpenGL 3.1 spec says R8, but ARB_tbo says L8.
This
was also missed because the piglit test expects LUMINANCE8 and also
because proprietary drivers don't support 3.1 without
ARB_compatibility (I assume the piglit tests had been tested on
proprietary drivers first).
I guess we should stop exposing ARB_tbo, because it conflicts with the
GL core spec.
Hmm, and since we don't currently expose ARB_tbo in the legacy profile
(extensions.c:133 - due to having to support the crazy A/L/LA formats),
that means not exposing it at all. Which means your second patch could
simply change it to R8 universally. Slightly tidier.
BTW I have also sent some fixes for piglit. We just lack a test for
the depth textures being treated as RED by default.
Marek
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