[Mesa-dev] [PATCH v2 1/8] st/mesa: don't force per-sample interp if only sampleid/pos are used

[Ilia Mirkin]

The OES extensions clarify this behaviour to differentiate between
per-sample invocation and per-sample interpolation. Using sampleid/pos
will force per-sample invocation but not per-sample interpolation.

See https://www.khronos.org/bugzilla/show_bug.cgi?id=1462

Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
---
 src/mesa/state_tracker/st_atom_shader.c | 4 ----
 src/mesa/state_tracker/st_program.c     | 4 ----
 2 files changed, 8 deletions(-)

diff --git a/src/mesa/state_tracker/st_atom_shader.c b/src/mesa/state_tracker/st_atom_shader.c
index a88f035..f261ce3 100644
--- a/src/mesa/state_tracker/st_atom_shader.c
+++ b/src/mesa/state_tracker/st_atom_shader.c
@@ -71,14 +71,10 @@ update_fp( struct st_context *st )
                      st->ctx->Color._ClampFragmentColor;
 
    /* 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->force_persample_in_shader &&
-      !(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 2e21d02..c9f390a 100644
--- a/src/mesa/state_tracker/st_program.c
+++ b/src/mesa/state_tracker/st_program.c
@@ -573,10 +573,6 @@ st_translate_fragment_program(struct st_context *st,
          else
             interpLocation[slot] = TGSI_INTERPOLATE_LOC_CENTER;
 
-         if (stfp->Base.Base.SystemValuesRead & (SYSTEM_BIT_SAMPLE_ID |
-                                                 SYSTEM_BIT_SAMPLE_POS))
-            interpLocation[slot] = TGSI_INTERPOLATE_LOC_SAMPLE;
-
          switch (attr) {
          case VARYING_SLOT_POS:
             input_semantic_name[slot] = TGSI_SEMANTIC_POSITION;
-- 
2.4.10