[Mesa-dev] WebGL WG interested in 1.0.1 conformance test results on real drivers

[Benoit Jacob]

> GL_MAX_SAMPLES tells you how many samples you can ask for from a
> multisample renderbuffer (GL 3.0 spec page 285), while to ask about
> the
> number of samples in a particular GLX visuals you have to check the
> GLX_SAMPLE_BUFFERS_ARB of the visual (GL_ARB_multisample spec).  We
> currently expose GL_MAX_SAMPLES of 4 (GL 3.0 spec page 391), but
> that's
> a lie and if you ask for a 4-sample renderbuffer we don't actually
> multisample it.  We don't expose any GLX visuals with nonzero
> GLX_SAMPLE_BUFFERS_ARB, which is conformant but disappointing.

Thanks for that information. WebGL antialiasing relies in multisample renderbuffers (ARB_framebuffer_multisample), not on multisample GLX visuals. So GL_MAX_SAMPLES is really what we care about. If the value returned by Mesa for getIntegerv(GL_MAX_SAMPLES) can't be used to tell whether multisample renderbuffers are actually supported, then how can we determine that?

Benoit