Mesa (master): i965/clip: Use clip distances for all user clipping

[Chris Forbes]

Module: Mesa
Branch: master
Commit: 45540921eceed47688493e93a003f86ccbe9038c
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=45540921eceed47688493e93a003f86ccbe9038c

Author: Chris Forbes <chrisf at ijw.co.nz>
Date:   Sun Aug  4 18:31:56 2013 +1200

i965/clip: Use clip distances for all user clipping

V2: Adjust explanation of load_clip_distance()

Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
Reviewed-by: Paul Berry <stereotype441 at gmail.com>

---

 src/mesa/drivers/dri/i965/brw_clip_tri.c |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_clip_tri.c b/src/mesa/drivers/dri/i965/brw_clip_tri.c
index bf221ca..090d203 100644
--- a/src/mesa/drivers/dri/i965/brw_clip_tri.c
+++ b/src/mesa/drivers/dri/i965/brw_clip_tri.c
@@ -228,9 +228,7 @@ void brw_clip_tri_flat_shade( struct brw_clip_compile *c )
  * a comparison of it to zero with the condition `cond`.
  *
  * - If using a fixed plane, the distance is dot(hpos, plane).
- * - If using a user clip plane, the distance is dot(clipvertex, plane).
- *     Elsewhere we arrange for clipvertex to be mapped to hpos if no
- *     explicit clipvertex value was provided by the previous shader.
+ * - If using a user clip plane, the distance is directly available in the vertex.
  */
 static inline void
 load_clip_distance(struct brw_clip_compile *c, struct brw_indirect vtx,
@@ -244,16 +242,19 @@ load_clip_distance(struct brw_clip_compile *c, struct brw_indirect vtx,
    brw_AND(p, vec1(brw_null_reg()), c->reg.vertex_src_mask, brw_imm_ud(1));
    brw_IF(p, BRW_EXECUTE_1);
    {
-      brw_MOV(p, dst, deref_4f(vtx, clip_offset));
+      struct brw_indirect temp_ptr = brw_indirect(7, 0);
+      brw_ADD(p, get_addr_reg(temp_ptr), get_addr_reg(vtx), c->reg.clipdistance_offset);
+      brw_MOV(p, vec1(dst), deref_1f(temp_ptr, 0));
    }
    brw_ELSE(p);
    {
       brw_MOV(p, dst, deref_4f(vtx, hpos_offset));
+      brw_DP4(p, dst, dst, c->reg.plane_equation);
    }
    brw_ENDIF(p);
 
    brw_set_conditionalmod(p, cond);
-   brw_DP4(p, dst, dst, c->reg.plane_equation);
+   brw_CMP(p, brw_null_reg(), cond, vec1(dst), brw_imm_f(0.0f));
 }