On 05/14/2014 11:52 AM, Matt Turner wrote: > On Wed, May 14, 2014 at 10:00 AM, Aras Pranckevicius <a...@unity3d.com> wrote: >> Hi, >> >> Mesa's ast_to_hir.cpp does a check like: >> >> state->check_version(120, 0, &initializer_loc, >> "cannot initialize uniforms"); >> >> i.e. it does not allow uniform initializers on GLSL ES 3.00. >> >> Upon my reading of the spec, I can't find any place where that would be >> disallowed. ES 3.00 seems to be based on GLSL 3.3, with a bunch of stuff >> removed and added. Uniform initializers aren't listed in the "removed" >> section (spec 3.00.4, section 1.1.4). So maybe the check should be changed >> to allow 300 in the ES min version? > > The GLSL 3.30 spec says > >> All uniform variables are read-only and are initialized externally either at >> link time or through the API. The link time initial value is either the >> value of the variable's initializer, if present, or 0 if no initializer is >> present. Sampler types cannot have initializers. > > While the GLSL ES 3.00 (.4) spec says (The GLSL ES 3.1 spec contains > this wording too) > >> All uniform variables are read-only. They are initialized to 0 at link time >> and may be updated through the API. > > So I think we're correct in disallowing it. > > Chalk it up to another trivial divergence of ES in unexpected way. > > Ian, does it seem like we can make a really trivial extension that > gives you back the wording in the Desktop GLSL spec? Are there other > interactions we need to think about? There's already wording > explicitly disallowing initializing samplers in a shader.
I don't see any reason that we couldn't. It would probably take longer to spec it than to implement it. :) It's /probably/ more than just adding that one sentence. Applications would still need to enable that extension in the shader... and the work-arounds for drivers that don't support it would be ugly. I think I'd want to have at least one other vendor agree to implement the extension before it would be worth the effort for anyone involved (us or ISV). _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
