[i965] gl_FrontFacing support

1 files changed, 30 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_sf_emit.c b/src/mesa/drivers/dri/i965/brw_sf_emit.c
index 080a02b7304..ad1527e5193 100644
--- a/src/mesa/drivers/dri/i965/brw_sf_emit.c
+++ b/src/mesa/drivers/dri/i965/brw_sf_emit.c
@@ -59,6 +59,35 @@ static GLboolean have_attr(struct brw_sf_compile *c,
    return (c->key.attrs & (1<<attr)) ? 1 : 0;
 }
 
+/**
+ * Sets VERT_RESULT_FOGC.Y  for gl_FrontFacing
+ *
+ * This is currently executed if the fragment program uses VERT_RESULT_FOGC
+ * at all, but this could be eliminated with a scan of the FP contents.
+ */
+static void
+do_front_facing( struct brw_sf_compile *c )
+{
+   struct brw_compile *p = &c->func; 
+   int i;
+
+   if (!have_attr(c, VERT_RESULT_FOGC))
+      return;
+
+   brw_push_insn_state(p);
+   brw_CMP(p, brw_null_reg(), 
+        c->key.frontface_ccw ? BRW_CONDITIONAL_G : BRW_CONDITIONAL_L,
+        c->det, brw_imm_f(0));
+   brw_set_predicate_control(p, BRW_PREDICATE_NONE);
+   for (i = 0; i < 3; i++) {
+       struct brw_reg fogc = get_vert_attr(c, c->vert[i],FRAG_ATTRIB_FOGC);
+       brw_MOV(p, get_element(fogc, 1), brw_imm_f(0));
+       brw_set_predicate_control(p, BRW_PREDICATE_NORMAL);
+       brw_MOV(p, get_element(fogc, 1), brw_imm_f(1));
+       brw_set_predicate_control(p, BRW_PREDICATE_NONE);
+   }
+   brw_pop_insn_state(p);
+}
 
 			 
 /*********************************************************************** 
@@ -355,6 +384,7 @@ void brw_emit_tri_setup( struct brw_sf_compile *c, GLboolean allocate)
 
    invert_det(c);
    copy_z_inv_w(c);
+   do_front_facing(c);
 
    if (c->key.do_twoside_color) 
       do_twoside_color(c);