[Piglit] [PATCH] util: Fix visual selection when using waffle

[Chad Versace]

On 10/16/2012 05:12 PM, Ian Romanick wrote:
> On 10/16/2012 03:37 PM, Marek Olšák wrote:
>> There is one test fdo25614-genmipmap which reproduces a bug only
>> occuring with a framebuffer without alpha. If we enforce RGBA
>> everywhere, not only would the test be useless, but also we'd end up
>> with the RGBX framebuffer config mostly untested.
>>
>> While it's useful to have RGBA framebuffers in most tests, we should
>> not remove support for RGBX framebuffers entirely.
> 
> We should modify this test to complain if it gets a visual that has alpha.
> 
>     glGetIntegerv(GL_ALPHA_BITS, &v)
>     if (v != 0)
>         skip? warn? other?

>From my understanding of the EGL spec, if an app does not request alpha, then
it's guaranteed to not get alpha. Test's that don't request alpha may as well do
this:
  glGetIntegerv(GL_ALPHA_BITS, &v);
  assert(v == 0);

>From page 15 of the EGL 1.4 spec:

    If the depth of a buffer in an EGLConfig is zero, then an EGLSurface
    created with respect to that EGLConfig will not contain the corresponding
    buffer.

(I don't hold a position on whether fs-texelFetchOffset should support alpha
configs. I'm just pointing out that tests that don't request alpha need not
expect it).