i965: Set the correct provoking vertex for clipped first-mode trifans.

Bug #24470: glean clipFlat test.

diff --git a/src/mesa/drivers/dri/i965/brw_clip_tri.c b/src/mesa/drivers/dri/i965/brw_clip_tri.c
index b27fe65..916a99e 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_clip_tri.c
+++ b/src/mesa/drivers/dri/i965/brw_clip_tri.c
@@ -177,7 +177,7 @@ void brw_clip_tri_init_vertices( struct brw_clip_compile *c )
 void brw_clip_tri_flat_shade( struct brw_clip_compile *c )
 {
    struct brw_compile *p = &c->func;
-   struct brw_instruction *is_poly;
+   struct brw_instruction *is_poly, *is_trifan;
    struct brw_reg tmp0 = c->reg.loopcount; /* handy temporary */
 
    brw_AND(p, tmp0, get_element_ud(c->reg.R0, 2), brw_imm_ud(PRIM_MASK)); 
@@ -195,8 +195,22 @@ void brw_clip_tri_flat_shade( struct brw_clip_compile *c )
    is_poly = brw_ELSE(p, is_poly);
    {
       if (c->key.pv_first) {
-         brw_clip_copy_colors(c, 1, 0);
-         brw_clip_copy_colors(c, 2, 0);
+        brw_CMP(p,
+                vec1(brw_null_reg()),
+                BRW_CONDITIONAL_EQ,
+                tmp0,
+                brw_imm_ud(_3DPRIM_TRIFAN));
+        is_trifan = brw_IF(p, BRW_EXECUTE_1);
+        {
+           brw_clip_copy_colors(c, 0, 1);
+           brw_clip_copy_colors(c, 2, 1);
+        }
+        is_trifan = brw_ELSE(p, is_trifan);
+        {
+           brw_clip_copy_colors(c, 1, 0);
+           brw_clip_copy_colors(c, 2, 0);
+        }
+        brw_ENDIF(p, is_trifan);
       }
       else {
          brw_clip_copy_colors(c, 0, 2);