gallium: rework provoking vertex code

Builds on commit ddb0e18f6c5582d4d2cc59ffd16ad9c4639ed059 and fixes
regressions in glean clipFlat test.

We assume that Gallium drivers observe flatshade_first for all triangles
and that all the assorted per-triangle calls in the 'draw' module also
follow flatshade_first.  Everything else builds on those rules.

Gallium does not use follow flatshade_first for GL quads, quad strips
and polygons; the "last" vertex is always the provoking vertex for those
prims.  So now there are separate QUAD_FIRST_PV and QUAD_LAST_PV macros
in the draw primitive decomposition code instead of one QUAD macro.

1 files changed, 2 insertions, 13 deletions

diff --git a/src/gallium/auxiliary/draw/draw_pipe_vbuf.c b/src/gallium/auxiliary/draw/draw_pipe_vbuf.c
index abbf6247ab..1fd083e54d 100644
--- a/src/gallium/auxiliary/draw/draw_pipe_vbuf.c
+++ b/src/gallium/auxiliary/draw/draw_pipe_vbuf.c
@@ -159,19 +159,8 @@ vbuf_tri( struct draw_stage *stage,
 
    check_space( vbuf, 3 );
 
-   if (vbuf->stage.draw->rasterizer->flatshade_first) {
-      /* Put provoking vertex in position expected by the driver.
-       * Emit last provoking vertex in first pos.
-       * Swap verts 0 & 1 to preserve polygon winding.
-       */
-      vbuf->indices[vbuf->nr_indices++] = emit_vertex( vbuf, prim->v[2] );
-      vbuf->indices[vbuf->nr_indices++] = emit_vertex( vbuf, prim->v[0] );
-      vbuf->indices[vbuf->nr_indices++] = emit_vertex( vbuf, prim->v[1] );
-   }
-   else {
-      for (i = 0; i < 3; i++) {
-         vbuf->indices[vbuf->nr_indices++] = emit_vertex( vbuf, prim->v[i] );
-      }
+   for (i = 0; i < 3; i++) {
+      vbuf->indices[vbuf->nr_indices++] = emit_vertex( vbuf, prim->v[i] );
    }
 }