[Mesa-dev] [RFC] [PATCH 0/3] Make Gallium aware of GL_TEXTURE_RECTANGLE

Marek Olšák maraeo at gmail.com
Wed Aug 11 19:06:44 PDT 2010

On Wed, Aug 11, 2010 at 10:07 PM, Luca Barbieri <luca at luca-barbieri.com>wrote:

> > Because all nvidia hardware seems to have the normalized bit as a
> property
> > of a resource (PIPE_TEXTURE_RECT or a flag would be okay here), and all
> > hardware has the normalized bit as part of the texture instruction (it's
> a
> > shader state, so a driver looks for TGSI_TEXTURE_RECT), I believe it
> would
> > really be best for everyone to have this RECT texture target type and
> > removing normalized_coords from pipe_sampler_state. Luca, you've already
> > done some work for this change. If you don't have time to finish
> > PIPE_TEXTURE_RECT, I'll do that.
> So no hardware at all supports specifying the normalization as part of
> the sampler state?
> One has to keep in mind OpenCL though, which has the following API:
> cl_sampler clCreateSampler (cl_context context,
>    cl_bool normalized_coords,
>    cl_addressing_mode addressing_mode,
>    cl_filter_mode filter_mode, cl_int *errcode_ret)
> If you put the bit in the resource itself, then it becomes impossible
> to change the normalization without copying the whole resource, which
> would seem to be a major problem for implementing OpenCL.
> A possible solution could be removing the bit from the sampler state
> and adding the bit to both TEX instructions and sampler views.
> This would seem to suit nv50, which has it in the hardware sampler
> view, and r300-r700 which has it in the hardware shader instruction
> (according to you).
> I'm not sure if it is good enough for OpenCL (i.e. whether the OpenCL
> state tracker can statically determine the sampler<->texture mapping),
> but I suppose it is, since it matches the hardware and the proprietary
> drivers manage to support OpenCL.
> A flag would need to be passed on resource creation anyway though,
> since nv30 needs to use different memory layouts.
> Also in this option, adding the resource hint and moving the bit out
> from the sampler state would be independent.

ACK for your patch series from me. Getting rid of that normalized_coords bit
in pipe_sampler_state would make implementing OpenCL really hard. I'll try
to come up with a sane way to rewrite shaders for all ATI hardware. Masking
should be enough to keep r600g in a working state.

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