[Mesa-dev] can we have gl_framebuffer _NumColorDrawBuffers = 1 and all the entries in the array NULL

[Jose Fonseca]

If drivers has issues dealing with NULL cbufs, then we could have the state trackers using dummy rendertargets.  But probably it's more efficent to handle in the pipe drivers.

My concern is that this ends up being a rare condition in practice, and that pipe drivers end up having a lot of bugs handling it.  So even though it's less efficient, its more piece of mind there won't be exploits here.

Jose

----- Original Message -----
> Hi Dave,
> 
> Yes, it's legal. Drivers should handle NULL color buffer bindings and
> there is a test for it:
> https://urldefense.proofpoint.com/v1/url?u=http://cgit.freedesktop.org/piglit/commit/?id%3Dff2398a4e3c4805e7d1bea38f4ae6f9811b42ede&k=oIvRg1%2BdGAgOoM1BIlLLqw%3D%3D%0A&r=NMr9uy2iTjWVixC0wOcYCWEIYhfo80qKwRgdodpoDzA%3D%0A&m=5XVVc6HPMBuXPEd7Z6EjczrwK%2FCkUYUHD7AIExEK7Yw%3D%0A&s=cf39ce3ddd6d3fcabef701dc10f6ee54e18d1a6ad1cc03348ca3e2e668c93697
> 
> I fixed it just recently.
> 
> That said, I think we don't have to bind NULL color buffers which
> appear at the end of the color buffer list.
> 
> Marek
> 
> On Tue, Jan 28, 2014 at 7:33 AM, Dave Airlie <airlied at gmail.com> wrote:
> >  I've just been playing with layered rendering on r600g and the depth
> > test Marek wrote, and I noticed I'm sometimes getting a gallium
> > framebuffer state with 1 cbuf but no defined cbuf,
> >
> > this comes direct from the Mesa state in the gl_framebuffer object, is
> > this legal?
> >
> > Dave.
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