[Mesa-dev] [PATCH] mesa: fix glGet size queries for L/LA/I color buffers

[Marek Olšák]

On Mon, Mar 10, 2014 at 6:07 PM, Brian Paul <brianp at vmware.com> wrote:
> On 03/09/2014 01:03 PM, Marek Olšák wrote:
>>
>> Do you have any opinion on this patch, anyone?
>>
>> Marek
>>
>> On Tue, Mar 4, 2014 at 12:32 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>>
>>> From: Marek Olšák <marek.olsak at amd.com>
>>>
>>> There is no API for returning the number of luminance and intensity bits
>>> and
>>> the 3.3 spec doesn't seem to specify any behavior for the queries if the
>>> format
>>> is one of L, LA, I. It seems to be a spec bug.
>
>
> I'm trying to piece together the background info on this.
>
> IIRC, in GL 3.3 core there are no luminance, l/a or intensity textures or
> surfaces anymore.  And yeah, I don't see a
> GL_FRAMEBUFFER_ATTACHMENT_LUMINANCE_SIZE query in the 3.3 compat profile
> spec.
>
> So basically your patch will return a non-zero value if, for example,
> GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE is called on a luminance buffer, right?

Correct.

>
> Is that what AMD and NVIDIA's drivers do?

For 8-bit luminance and intensity, AMD Catalyst returns
RED/GREEN/BLUE_BITS=(8,0,0), but the renderbuffer and framebuffer
attachment queries return (0,0,0).

I don't think (8,0,0) is correct, but the compatibility spec doesn't
say it's incorrect.

Marek