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authorChris Forbes <chrisf@ijw.co.nz>2013-07-07 21:42:39 +1200
committerChris Forbes <chrisf@ijw.co.nz>2013-08-01 20:58:59 +1200
commit3f6fb5e1dd684434979ffca418184574e5c086f3 (patch)
treef2a897a2a38f13105c57c53aec951a14dd78cbb0 /src/mesa/drivers/dri/i965/brw_clip_util.c
parentf0feb32eaf8d4b35e5c3a47ef90aa876b231ada6 (diff)
i965 Gen4/5: clip: Add support for noperspective varyings
Adds support for interpolating noperspective varyings linearly in screen space when clipping. Based on Olivier Galibert's patch from last year: http://lists.freedesktop.org/archives/mesa-dev/2012-July/024341.html At this point all -fixed and -vertex interpolation tests work. V5: Add brw_clip_compile.has_noperspective_shading rather than another key flag. V6: Real bools. [V1-2]: Signed-off-by: Olivier Galibert <galibert at pobox.com> Signed-off-by: Chris Forbes <chrisf@ijw.co.nz> Acked-by: Paul Berry <stereotype441@gmail.com> Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Diffstat (limited to 'src/mesa/drivers/dri/i965/brw_clip_util.c')
-rw-r--r--src/mesa/drivers/dri/i965/brw_clip_util.c120
1 files changed, 110 insertions, 10 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_clip_util.c b/src/mesa/drivers/dri/i965/brw_clip_util.c
index 9d77d1e1b4..b188bf7738 100644
--- a/src/mesa/drivers/dri/i965/brw_clip_util.c
+++ b/src/mesa/drivers/dri/i965/brw_clip_util.c
@@ -128,6 +128,8 @@ static void brw_clip_project_vertex( struct brw_clip_compile *c,
/* Interpolate between two vertices and put the result into a0.0.
* Increment a0.0 accordingly.
+ *
+ * Beware that dest_ptr can be equal to v0_ptr!
*/
void brw_clip_interp_vertex( struct brw_clip_compile *c,
struct brw_indirect dest_ptr,
@@ -137,7 +139,7 @@ void brw_clip_interp_vertex( struct brw_clip_compile *c,
bool force_edgeflag)
{
struct brw_compile *p = &c->func;
- struct brw_reg tmp = get_tmp(c);
+ struct brw_reg t_nopersp, v0_ndc_copy;
GLuint slot;
/* Just copy the vertex header:
@@ -148,12 +150,107 @@ void brw_clip_interp_vertex( struct brw_clip_compile *c,
*/
brw_copy_indirect_to_indirect(p, dest_ptr, v0_ptr, 1);
- /* Iterate over each attribute (could be done in pairs?)
+
+ /* First handle the 3D and NDC interpolation, in case we
+ * need noperspective interpolation. Doing it early has no
+ * performance impact in any case.
+ */
+
+ /* Take a copy of the v0 NDC coordinates, in case dest == v0. */
+ if (c->has_noperspective_shading) {
+ GLuint offset = brw_varying_to_offset(&c->vue_map,
+ BRW_VARYING_SLOT_NDC);
+ v0_ndc_copy = get_tmp(c);
+ brw_MOV(p, v0_ndc_copy, deref_4f(v0_ptr, offset));
+ }
+
+ /* Compute the new 3D position
+ *
+ * dest_hpos = v0_hpos * (1 - t0) + v1_hpos * t0
+ */
+ {
+ GLuint delta = brw_varying_to_offset(&c->vue_map, VARYING_SLOT_POS);
+ struct brw_reg tmp = get_tmp(c);
+ brw_MUL(p, vec4(brw_null_reg()), deref_4f(v1_ptr, delta), t0);
+ brw_MAC(p, tmp, negate(deref_4f(v0_ptr, delta)), t0);
+ brw_ADD(p, deref_4f(dest_ptr, delta), deref_4f(v0_ptr, delta), tmp);
+ release_tmp(c, tmp);
+ }
+
+ /* Recreate the projected (NDC) coordinate in the new vertex header */
+ brw_clip_project_vertex(c, dest_ptr);
+
+ /* If we have noperspective attributes,
+ * we need to compute the screen-space t
+ */
+ if (c->has_noperspective_shading) {
+ GLuint delta = brw_varying_to_offset(&c->vue_map,
+ BRW_VARYING_SLOT_NDC);
+ struct brw_reg tmp = get_tmp(c);
+ t_nopersp = get_tmp(c);
+
+ /* t_nopersp = vec4(v1.xy, dest.xy) */
+ brw_MOV(p, t_nopersp, deref_4f(v1_ptr, delta));
+ brw_MOV(p, tmp, deref_4f(dest_ptr, delta));
+ brw_set_access_mode(p, BRW_ALIGN_16);
+ brw_MOV(p,
+ brw_writemask(t_nopersp, WRITEMASK_ZW),
+ brw_swizzle(tmp, 0, 1, 0, 1));
+
+ /* t_nopersp = vec4(v1.xy, dest.xy) - v0.xyxy */
+ brw_ADD(p, t_nopersp, t_nopersp,
+ negate(brw_swizzle(v0_ndc_copy, 0, 1, 0, 1)));
+
+ /* Add the absolute values of the X and Y deltas so that if
+ * the points aren't in the same place on the screen we get
+ * nonzero values to divide.
+ *
+ * After that, we have vert1 - vert0 in t_nopersp.x and
+ * vertnew - vert0 in t_nopersp.y
+ *
+ * t_nopersp = vec2(|v1.x -v0.x| + |v1.y -v0.y|,
+ * |dest.x-v0.x| + |dest.y-v0.y|)
+ */
+ brw_ADD(p,
+ brw_writemask(t_nopersp, WRITEMASK_XY),
+ brw_abs(brw_swizzle(t_nopersp, 0, 2, 0, 0)),
+ brw_abs(brw_swizzle(t_nopersp, 1, 3, 0, 0)));
+ brw_set_access_mode(p, BRW_ALIGN_1);
+
+ /* If the points are in the same place, just substitute a
+ * value to avoid divide-by-zero
+ */
+ brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_EQ,
+ vec1(t_nopersp),
+ brw_imm_f(0));
+ brw_IF(p, BRW_EXECUTE_1);
+ brw_MOV(p, t_nopersp, brw_imm_vf4(VF_ONE, VF_ZERO, VF_ZERO, VF_ZERO));
+ brw_ENDIF(p);
+
+ /* Now compute t_nopersp = t_nopersp.y/t_nopersp.x and broadcast it. */
+ brw_math_invert(p, get_element(t_nopersp, 0), get_element(t_nopersp, 0));
+ brw_MUL(p, vec1(t_nopersp), vec1(t_nopersp),
+ vec1(suboffset(t_nopersp, 1)));
+ brw_set_access_mode(p, BRW_ALIGN_16);
+ brw_MOV(p, t_nopersp, brw_swizzle(t_nopersp, 0, 0, 0, 0));
+ brw_set_access_mode(p, BRW_ALIGN_1);
+
+ release_tmp(c, tmp);
+ release_tmp(c, v0_ndc_copy);
+ }
+
+ /* Now we can iterate over each attribute
+ * (could be done in pairs?)
*/
for (slot = 0; slot < c->vue_map.num_slots; slot++) {
int varying = c->vue_map.slot_to_varying[slot];
GLuint delta = brw_vue_slot_to_offset(slot);
+ /* HPOS, NDC already handled above */
+ if (varying == VARYING_SLOT_POS || varying == BRW_VARYING_SLOT_NDC)
+ continue;
+
+
if (varying == VARYING_SLOT_EDGE) {
if (force_edgeflag)
brw_MOV(p, deref_4f(dest_ptr, delta), brw_imm_f(1));
@@ -173,20 +270,27 @@ void brw_clip_interp_vertex( struct brw_clip_compile *c,
*
* New = attr0 + t*attr1 - t*attr0
*/
+ struct brw_reg tmp = get_tmp(c);
+ struct brw_reg t =
+ c->key.interpolation_mode.mode[slot] == INTERP_QUALIFIER_NOPERSPECTIVE ?
+ t_nopersp : t0;
+
brw_MUL(p,
vec4(brw_null_reg()),
deref_4f(v1_ptr, delta),
- t0);
+ t);
brw_MAC(p,
tmp,
negate(deref_4f(v0_ptr, delta)),
- t0);
+ t);
brw_ADD(p,
deref_4f(dest_ptr, delta),
deref_4f(v0_ptr, delta),
tmp);
+
+ release_tmp(c, tmp);
}
}
@@ -196,12 +300,8 @@ void brw_clip_interp_vertex( struct brw_clip_compile *c,
brw_MOV(p, deref_4f(dest_ptr, delta), brw_imm_f(0));
}
- release_tmp(c, tmp);
-
- /* Recreate the projected (NDC) coordinate in the new vertex
- * header:
- */
- brw_clip_project_vertex(c, dest_ptr );
+ if (c->has_noperspective_shading)
+ release_tmp(c, t_nopersp);
}
void brw_clip_emit_vue(struct brw_clip_compile *c,