965: Fix incorrect backface culling

Fix incorrect backface culling for OGL tunnel in wireframe and
point mode.

src/mesa/drivers/dri/i965/brw_clip.h

@@ -167,4 +167,9 @@ void brw_clip_copy_colors( struct brw_clip_compile *c,
 
 void brw_clip_init_clipmask( struct brw_clip_compile *c );
 
+struct brw_reg get_tmp( struct brw_clip_compile *c );
+
+void brw_clip_project_position(struct brw_clip_compile *c,
+             struct brw_reg pos );
+
 #endif

src/mesa/drivers/dri/i965/brw_clip_tri.c

@@ -42,16 +42,6 @@
 #include "brw_util.h"
 #include "brw_clip.h"
 
-static struct brw_reg get_tmp( struct brw_clip_compile *c )
-{
-   struct brw_reg tmp = brw_vec4_grf(c->last_tmp, 0);
-
-   if (++c->last_tmp > c->prog_data.total_grf)
-      c->prog_data.total_grf = c->last_tmp;
-
-   return tmp;
-}
-
 static void release_tmps( struct brw_clip_compile *c )
 {
    c->last_tmp = c->first_tmp;

src/mesa/drivers/dri/i965/brw_clip_unfilled.c

@@ -58,10 +58,30 @@ static void compute_tri_direction( struct brw_clip_compile *c )
    struct brw_reg v2 = byte_offset(c->reg.vertex[2], c->offset[VERT_RESULT_HPOS]); 
 
 
+   struct brw_reg v0n = get_tmp(c);
+   struct brw_reg v1n = get_tmp(c);
+   struct brw_reg v2n = get_tmp(c);
+
+   /* Convert to NDC.
+    * NOTE: We can't modify the original vertex coordinates,
+    * as it may impact further operations.
+    * So, we have to keep normalized coordinates in temp registers.
+    *
+    * TBD-KC
+    * Try to optimize unnecessary MOV's.
+    */
+   brw_MOV(p, v0n, v0);
+   brw_MOV(p, v1n, v1);
+   brw_MOV(p, v2n, v2);
+
+   brw_clip_project_position(c, v0n);
+   brw_clip_project_position(c, v1n);
+   brw_clip_project_position(c, v2n);
+
    /* Calculate the vectors of two edges of the triangle:
     */
-   brw_ADD(p, e, v0, negate(v2)); 
-   brw_ADD(p, f, v1, negate(v2)); 
+   brw_ADD(p, e, v0n, negate(v2n)); 
+   brw_ADD(p, f, v1n, negate(v2n)); 
 
    /* Take their crossproduct:
     */

src/mesa/drivers/dri/i965/brw_clip_util.c

@@ -46,8 +46,7 @@
 
 
 
-
-static struct brw_reg get_tmp( struct brw_clip_compile *c )
+struct brw_reg get_tmp( struct brw_clip_compile *c )
 {
    struct brw_reg tmp = brw_vec4_grf(c->last_tmp, 0);
 
@@ -90,7 +89,7 @@ void brw_clip_init_planes( struct brw_clip_compile *c )
 
 /* Project 'pos' to screen space (or back again), overwrite with results:
  */
-static void brw_clip_project_position(struct brw_clip_compile *c, struct brw_reg pos )
+void brw_clip_project_position(struct brw_clip_compile *c, struct brw_reg pos )
 {
    struct brw_compile *p = &c->func;