[Mesa-dev] gallium scaled types

Ian Romanick idr at freedesktop.org
Tue Sep 13 09:30:13 PDT 2011

Hash: SHA1

On 09/13/2011 11:23 AM, Jose Fonseca wrote:

> ----- Original Message -----
>> I've attached a rough outline of a patch to add a
>> bind_as_integer flag for vertex elements, sampler views and
>> surfaces.
> I don't mind "as_integer" but I wonder if "as_float" (i.e. the
> negative), wouldn't be more generic (so it could be used for
> doubles too [1]).
>> I wonder if the sampler view and surfaces are always going to be
>> bind as integer for SCALED types, in which case maybe we can just
>> state that somewhere and move on.
> It looks like it.
> GLSL defines
> gvec4 texture (gsampler2D sampler, vec2 ...)
> where g is '', 'i', 'u'.
> But in section 8.7, "Texture Lookup Functions" of
> GLSLangSpec.3.30.6.clean.pdf it has a table relating texture
> internal formats with the vector types, and doesn't allow
> converting between different type.

Integer samplers can only be used with integer textures.  This is a
case just like shadow samplers.  If you use an integer texture with a
mismatched sampler type, you get undefined results, IIRC.  I know that
it's not expected to work, and I don't think it will generate any sort
of error (since that requires validation at glBegin).

>> I've also shown the clear color code in softpipe where it pick
>> the correct clear color depending on the surface type.
>> I've started hacking on u_blitter and r600g to no avail yet to
>> try and get some of the -integer tests passing.
> Jose
> [1] although this is academic, given that there doesn't seem to be
> double sample support.

Not yet, but there surely will be someday.
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