[Mesa-dev] [PATCH 3/3] st/mesa: automatically set per-sample interpolation if using SampleID/Pos

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

---
 src/mesa/state_tracker/st_atom_shader.c | 8 +++++++-
 src/mesa/state_tracker/st_program.c     | 4 +++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/mesa/state_tracker/st_atom_shader.c b/src/mesa/state_tracker/st_atom_shader.c
index dc03156..1e880a1 100644
--- a/src/mesa/state_tracker/st_atom_shader.c
+++ b/src/mesa/state_tracker/st_atom_shader.c
@@ -70,9 +70,15 @@ update_fp( struct st_context *st )
    key.clamp_color = st->clamp_frag_color_in_shader &&
                      st->ctx->Color._ClampFragmentColor;
 
-   /* Ignore sample qualifier while computing this flag. */
+   /* Don't set it if the driver can force the interpolation by itself.
+    * If SAMPLE_ID or SAMPLE_POS are used, the interpolation is set
+    * automatically.
+    * Ignore sample qualifier while computing this flag.
+    */
    key.persample_shading =
       !st->can_force_persample_interp &&
+      !(stfp->Base.Base.SystemValuesRead & (SYSTEM_BIT_SAMPLE_ID |
+                                            SYSTEM_BIT_SAMPLE_POS)) &&
       _mesa_get_min_invocations_per_fragment(st->ctx, &stfp->Base, true) > 1;
 
    st->fp_variant = st_get_fp_variant(st, stfp, &key);
diff --git a/src/mesa/state_tracker/st_program.c b/src/mesa/state_tracker/st_program.c
index 9c27147..a07f8fe 100644
--- a/src/mesa/state_tracker/st_program.c
+++ b/src/mesa/state_tracker/st_program.c
@@ -619,7 +619,9 @@ st_translate_fragment_program(struct st_context *st,
          else
             interpLocation[slot] = TGSI_INTERPOLATE_LOC_CENTER;
 
-         if (key->persample_shading)
+         if (stfp->Base.Base.SystemValuesRead & (SYSTEM_BIT_SAMPLE_ID |
+                                                 SYSTEM_BIT_SAMPLE_POS) ||
+             key->persample_shading)
             interpLocation[slot] = TGSI_INTERPOLATE_LOC_SAMPLE;
 
          switch (attr) {
-- 
2.1.4