Soon the dp4 is only going to be used for fixed clip planes.
V2: Remove old inaccurate comment about the behavior of this function;
add a better explanation above.
Signed-off-by: Chris Forbes <chr...@ijw.co.nz>
Reviewed-by: Paul Berry <stereotype...@gmail.com>
---
src/mesa/drivers/dri/i965/brw_clip_tri.c | 39 ++++++++++++++++++--------------
1 file changed, 22 insertions(+), 17 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_clip_tri.c
b/src/mesa/drivers/dri/i965/brw_clip_tri.c
index dd750f5..bf221ca 100644
--- a/src/mesa/drivers/dri/i965/brw_clip_tri.c
+++ b/src/mesa/drivers/dri/i965/brw_clip_tri.c
@@ -223,18 +223,23 @@ void brw_clip_tri_flat_shade( struct brw_clip_compile *c )
}
+/**
+ * Loads the clip distance for a vertex into `dst`, and ends with
+ * 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.
+ */
static inline void
-load_vertex_pos(struct brw_clip_compile *c, struct brw_indirect vtx,
- struct brw_reg dst,
- GLuint hpos_offset, GLuint clip_offset)
+load_clip_distance(struct brw_clip_compile *c, struct brw_indirect vtx,
+ struct brw_reg dst, GLuint hpos_offset, GLuint clip_offset,
+ int cond)
{
struct brw_compile *p = &c->func;
- /*
- * Roughly:
- * dst = (vertex_src_mask & 1) ? src.hpos : src.clipvertex;
- */
-
+ dst = vec4(dst);
brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
brw_AND(p, vec1(brw_null_reg()), c->reg.vertex_src_mask, brw_imm_ud(1));
brw_IF(p, BRW_EXECUTE_1);
@@ -246,6 +251,9 @@ load_vertex_pos(struct brw_clip_compile *c, struct
brw_indirect vtx,
brw_MOV(p, dst, deref_4f(vtx, hpos_offset));
}
brw_ENDIF(p);
+
+ brw_set_conditionalmod(p, cond);
+ brw_DP4(p, dst, dst, c->reg.plane_equation);
}
@@ -313,17 +321,15 @@ void brw_clip_tri( struct brw_clip_compile *c )
*/
brw_MOV(p, get_addr_reg(vtx), deref_1uw(inlist_ptr, 0));
- load_vertex_pos(c, vtxPrev, vec4(c->reg.dpPrev), hpos_offset,
clipvert_offset);
+ load_clip_distance(c, vtxPrev, c->reg.dpPrev, hpos_offset,
clipvert_offset,
+ BRW_CONDITIONAL_L);
/* IS_NEGATIVE(prev) */
- brw_set_conditionalmod(p, BRW_CONDITIONAL_L);
- brw_DP4(p, vec4(c->reg.dpPrev), vec4(c->reg.dpPrev),
c->reg.plane_equation);
brw_IF(p, BRW_EXECUTE_1);
{
- load_vertex_pos(c, vtx, vec4(c->reg.dp), hpos_offset,
clipvert_offset);
+ load_clip_distance(c, vtx, c->reg.dp, hpos_offset,
clipvert_offset,
+ BRW_CONDITIONAL_GE);
/* IS_POSITIVE(next)
*/
- brw_set_conditionalmod(p, BRW_CONDITIONAL_GE);
- brw_DP4(p, vec4(c->reg.dp), vec4(c->reg.dp),
c->reg.plane_equation);
brw_IF(p, BRW_EXECUTE_1);
{
@@ -362,11 +368,10 @@ void brw_clip_tri( struct brw_clip_compile *c )
brw_ADD(p, get_addr_reg(outlist_ptr), get_addr_reg(outlist_ptr),
brw_imm_uw(sizeof(short)));
brw_ADD(p, c->reg.nr_verts, c->reg.nr_verts, brw_imm_ud(1));
- load_vertex_pos(c, vtx, vec4(c->reg.dp), hpos_offset,
clipvert_offset);
+ load_clip_distance(c, vtx, c->reg.dp, hpos_offset,
clipvert_offset,
+ BRW_CONDITIONAL_L);
/* IS_NEGATIVE(next)
*/
- brw_set_conditionalmod(p, BRW_CONDITIONAL_L);
- brw_DP4(p, vec4(c->reg.dp), vec4(c->reg.dp),
c->reg.plane_equation);
brw_IF(p, BRW_EXECUTE_1);
{
/* Going out of bounds. Avoid division by zero as we
--
1.8.3.4
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