[Mesa-dev] [Mesa-stable] [PATCH 3/3] i965: Fix component mask and varying_to_slot mapping for gl_ViewportIndex

[Kenneth Graunke]

On 04/14/2014 06:59 PM, Chris Forbes wrote:
> Are the streamout values allowed to be restricted to the ranges of the
> vertex header fields, or do they have to reflect exactly what the
> shader wrote?
> 
> (I ran into a similar issue with ARB_fragment_layer_viewport, and
> while nothing has been done about it, the consensus was that the FS
> had to see exactly what the previous stage wrote, and so a real slot
> would be necessary)

I'm not sure.  It sounds like there aren't any conformance tests for
that behavior, or else Anuj would have come across them.  It always
seemed like a stupid behavior to me, which is just wasteful for no
benefit (if you want to output arbitrary values, define your own
varying, seriously).  Personally, I would have landed your
ARB_fragment_layer_viewport patches.

At any rate, Anuj's patches make in-range values actually work, instead
of nothing working at all, so I think we should take them regardless.
If we absolutely have to support out-of-range values being copied
unmodified, then we can revisit this.

--Ken

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