[Mesa-dev] [PATCH 3/5] glsl: Mark gl_ViewportIndex and gl_Layer varyings as flat.

[Kenneth Graunke]

On Monday, October 26, 2015 05:02:07 PM Ian Romanick wrote:
> On 10/26/2015 11:03 AM, Kenneth Graunke wrote:
> > Integer varyings need to be flat qualified - all others were already.
> > I think we just missed this.  Presumably some hardware passes this via
> > sideband and ignores attribute interpolation, so no one has noticed.
> > 
> > Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> > Cc: Chris Forbes <chrisf at ijw.co.nz>
> > ---
> >  src/glsl/builtin_variables.cpp | 39 ++++++++++++++++++++++++++-------------
> >  1 file changed, 26 insertions(+), 13 deletions(-)
> > 
> > diff --git a/src/glsl/builtin_variables.cpp b/src/glsl/builtin_variables.cpp
> > index a6ad105..07aacd4 100644
> > --- a/src/glsl/builtin_variables.cpp
> > +++ b/src/glsl/builtin_variables.cpp
> > @@ -887,16 +887,22 @@ builtin_variable_generator::generate_uniforms()
> >  void
> >  builtin_variable_generator::generate_vs_special_vars()
> >  {
> > +   ir_variable *var;
> > +
> >     if (state->is_version(130, 300))
> >        add_system_value(SYSTEM_VALUE_VERTEX_ID, int_t, "gl_VertexID");
> >     if (state->ARB_draw_instanced_enable)
> >        add_system_value(SYSTEM_VALUE_INSTANCE_ID, int_t, "gl_InstanceIDARB");
> >     if (state->ARB_draw_instanced_enable || state->is_version(140, 300))
> >        add_system_value(SYSTEM_VALUE_INSTANCE_ID, int_t, "gl_InstanceID");
> > -   if (state->AMD_vertex_shader_layer_enable)
> > -      add_output(VARYING_SLOT_LAYER, int_t, "gl_Layer");
> > -   if (state->AMD_vertex_shader_viewport_index_enable)
> > -      add_output(VARYING_SLOT_VIEWPORT, int_t, "gl_ViewportIndex");
> > +   if (state->AMD_vertex_shader_layer_enable) {
> > +      var = add_output(VARYING_SLOT_LAYER, int_t, "gl_Layer");
> > +      var->data.interpolation = INTERP_QUALIFIER_FLAT;
> > +   }
> > +   if (state->AMD_vertex_shader_viewport_index_enable) {
> > +      var = add_output(VARYING_SLOT_VIEWPORT, int_t, "gl_ViewportIndex");
> > +      var->data.interpolation = INTERP_QUALIFIER_FLAT;
> > +   }
> >     if (compatibility) {
> >        add_input(VERT_ATTRIB_POS, vec4_t, "gl_Vertex");
> >        add_input(VERT_ATTRIB_NORMAL, vec3_t, "gl_Normal");
> > @@ -954,11 +960,16 @@ builtin_variable_generator::generate_tes_special_vars()
> >  void
> >  builtin_variable_generator::generate_gs_special_vars()
> >  {
> > -   add_output(VARYING_SLOT_LAYER, int_t, "gl_Layer");
> > -   if (state->is_version(410, 0) || state->ARB_viewport_array_enable)
> > -      add_output(VARYING_SLOT_VIEWPORT, int_t, "gl_ViewportIndex");
> > +   ir_variable *var;
> > +
> > +   var = add_output(VARYING_SLOT_LAYER, int_t, "gl_Layer");
> > +   var->data.interpolation = INTERP_QUALIFIER_FLAT;
> > +   if (state->is_version(410, 0) || state->ARB_viewport_array_enable) {
> > +      var = add_output(VARYING_SLOT_VIEWPORT, int_t, "gl_ViewportIndex");
> > +      var->data.interpolation = INTERP_QUALIFIER_FLAT;
> > +   }
> >     if (state->is_version(400, 0) || state->ARB_gpu_shader5_enable)
> > -      add_system_value(SYSTEM_VALUE_INVOCATION_ID, int_t, "gl_InvocationID");
> > +      var = add_system_value(SYSTEM_VALUE_INVOCATION_ID, int_t, "gl_InvocationID");
> 
> Shouldn't this set var->data.interpolation?  It looks like you only made
> half the change.

I actually meant to leave that alone, as I don't think it makes sense to
set interpolation modes on system values (they aren't varyings!).  Good
catch, though, I got a bit overzealous in my "var" adding :)

I've dropped that one line of diff locally.  Thanks!
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