[Mesa-dev] [PATCH] mesa: initialize renderbuffer fields even if AllocStorage fails

[Marek Olšák]

On Mon, May 14, 2012 at 4:40 PM, Brian Paul <brianp at vmware.com> wrote:
> On 05/12/2012 10:11 AM, Marek Olšák wrote:
>>
>> It may fail with an unsupported format, but that's not an allowed case
>> where
>> RenderbufferStorage may fail.
>
>
> I've read your comment several times but I still can't quite understand the
> whole issue.
>
> The intention was that AllocStorage() should never fail because of the
> internalFormat value.  We do error checking of internalFormat earlier in
> renderbuffer_storage().  Then the driver chooses a hw format that best
> matches the requested internalFormat.

The driver is r600g and the format is GL_RGB9_E5
(EXT_texture_shared_exponent). There is sampler support, but no
colorbuffer support. The format is quite special, no other format
matches it well, though I guess any RGB float format would work.
However the spec doesn't require renderbuffer support despite the fact
the format is accepted in glRenderbufferStorage.

The problem is st_choose_renderbuffer_format returns PIPE_FORMAT_NONE,
because it looks for GL_RGB9_E5 with PIPE_BIND_RENDER_TARGET support.

I don't think we should allocate a renderbuffer if we know the user
won't be able to render to it. The other option is to pretend that we
allocated something, so that glCheckFramebufferStatus can fail later.

Marek