1 files changed, 30 insertions, 5 deletions

diff --git a/src/mesa/pipe/draw/draw_twoside.c b/src/mesa/pipe/draw/draw_twoside.c
index c7e268f11e..da8e7bd90d 100644
--- a/src/mesa/pipe/draw/draw_twoside.c
+++ b/src/mesa/pipe/draw/draw_twoside.c
@@ -30,12 +30,15 @@
 
 #include "pipe/p_util.h"
 #include "pipe/p_defines.h"
+#include "pipe/p_shader_tokens.h"
 #include "draw_private.h"
 
 
 struct twoside_stage {
    struct draw_stage stage;
    float sign;         /**< +1 or -1 */
+   uint attrib_front0, attrib_back0;
+   uint attrib_front1, attrib_back1;
 };
 
 
@@ -48,6 +51,29 @@ static INLINE struct twoside_stage *twoside_stage( struct draw_stage *stage )
 static void twoside_begin( struct draw_stage *stage )
 {
    struct twoside_stage *twoside = twoside_stage(stage);
+   const struct pipe_shader_state *vs = stage->draw->vertex_shader->state;
+   uint i;
+
+   twoside->attrib_front0 = 0;
+   twoside->attrib_front1 = 0;
+   twoside->attrib_back0 = 0;
+   twoside->attrib_back1 = 0;
+
+   /* Find which vertex shader outputs are front/back colors */
+   for (i = 0; i < vs->num_outputs; i++) {
+      if (vs->output_semantic_name[i] == TGSI_SEMANTIC_COLOR) {
+         if (vs->output_semantic_index[i] == 0)
+            twoside->attrib_front0 = i;
+         else
+            twoside->attrib_front1 = i;
+      }
+      if (vs->output_semantic_name[i] == TGSI_SEMANTIC_BCOLOR) {
+         if (vs->output_semantic_index[i] == 0)
+            twoside->attrib_back0 = i;
+         else
+            twoside->attrib_back1 = i;
+      }
+   }
 
    /*
     * We'll multiply the primitive's determinant by this sign to determine
@@ -76,13 +102,12 @@ static struct vertex_header *copy_bfc( struct twoside_stage *twoside,
 				       unsigned idx )
 {   
    struct vertex_header *tmp = dup_vert( &twoside->stage, v, idx );
-   const struct draw_context *draw = twoside->stage.draw;
    
-   if (draw->attrib_front0 && draw->attrib_back0) {
-      copy_attrib(draw->attrib_front0, draw->attrib_back0, tmp);
+   if (twoside->attrib_front0 && twoside->attrib_back0) {
+      copy_attrib(twoside->attrib_front0, twoside->attrib_back0, tmp);
    }
-   if (draw->attrib_front1 && draw->attrib_back1) {
-      copy_attrib(draw->attrib_front1, draw->attrib_back1, tmp);
+   if (twoside->attrib_front1 && twoside->attrib_back1) {
+      copy_attrib(twoside->attrib_front1, twoside->attrib_back1, tmp);
    }
 
    return tmp;