[Mesa-dev] gallium & texture rectangles

[Jakob Bornecrantz]

On 18 aug 2010, at 17.08, Luca Barbieri wrote:
>> I have a feeling that CL performance will not matter that much for
>> nvfx and r300, compared to nv50 and r600.
>
> Sure.
> The point is that if you can't use normalized coordinates at all on
> PIPE_TEXTURE_RECT, you can't implement OpenCL well on nv50 and r600.
> Hence, that should be allowed on OpenCL capable cards (and not on  
> others).

Well a prerequisite for OpenCL would be PIPE_CAP_ADVANCED_SAMPLERS and  
with that cap the state tracker shouldn't use PIPE_TEXTURE_RECT for  
GL_TEXTURE_RECT but instead normal 2D textures and then just use  
unnormalized/normalized as it see fit. Or just make  
PIPE_CAP_ADVANCED_SAMPLERS  also mean that PIPE_TEXTURE_RECT can be  
treated as normal 2D target. Either one is fine, but for now we don't  
have to worry about this.

>
>> r300 having to emit a shader instruction unconditionally in this case
>> really isn't that big of a deal.
> On nVidia cards, this doesn't matter, since they never prefer the
> normalization opposite to the OpenGL-required one.
> So if the maintainers of Radeon and software renderers, who might
> care, don't, I suppose we could as well not introduce the feature,
> even though I'm not totally convinced of this.


Cheers Jakob.