[Mesa-dev] [PATCH 1/3] glsl/linker: fix varying packing for non-flat integer varyings.

[Paul Berry]

On 7 April 2013 11:12, Jordan Justen <jljusten at gmail.com> wrote:

> On Sat, Apr 6, 2013 at 7:49 PM, Paul Berry <stereotype441 at gmail.com>
> wrote:
> > +   if (consumer_var == NULL) {
> > +      /* Since there is no consumer_var, the interpolation type of this
> > +       * varying cannot possibly affect rendering.  Also, since the GL
> spec
> > +       * only requires integer varyings to be "flat" when they are
> fragment
> > +       * shader inputs, it is possible that this variable is non-flat
> and is
> > +       * (or contains) an integer.
> > +       *
> > +       * lower_packed_varyings requires all integer varyings to flat,
> > +       * regardless of where they appear.  We can trivially satisfy that
> > +       * requirement by changing the interpolation type to flat here.
> > +       */
> > +      producer_var->centroid = false;
> > +      producer_var->interpolation = INTERP_QUALIFIER_FLAT;
>
> Should we check if producer_var's type is an integer?
>

Yeah, that's a good point.  It shouldn't affect correctness, but it will
make the patch less invasive, and that seems worthwhile since I'm hoping
this can be cherry-picked back to 9.1.  I'll follow up with a v2 of the
series.


>
> Could this cause issues if the producer stage is later linked to
> another consumer?
>

That shouldn't be a problem, since at this stage of linking, we are
operating on a copy of the IR that is private to this particular linked
program.
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