[Mesa-dev] ARB_fragment_layer_viewport in gallium

[Roland Scheidegger]

Am 18.09.2014 00:28, schrieb Roland Scheidegger:
> ARB_fragment_layer_viewport is enabled unconditionally if geometry
> shaders / multiple viewports are also enabled. This seems reasonable,
> though I noticed at least it won't work for llvmpipe - entirely due to
> the requirement of the viewport/layer value being zero if it wasn't
> output by the gs (or if no gs is present).
> I couldn't actually figure out if that would be required for d3d10
> (which has this functionality as well) too, though tests don't seem to
> require it (or we otherwise get lucky).
> I'm wondering if other drivers have a problem with that as well? I
> thought it would be trivial to fix but not so actually for llvmpipe.
> (Essentially would need to note if fs reads layer/vp_index when scanning
> the shader, then inject some appropriate zero output in draw somewhere,
> probably draw_prepare_shader_outputs(). At this point the extension
> doesn't seem worth it anymore at least if d3d10 would not require that
> behavior neither since it isn't in any GL core version.)
> But I guess if it's just draw having a problem with that it's not worth
> a cap bit neither...
> 
> Roland


Hmm actually it's in glsl 4.30 so I guess it's worth fixing...

Roland