[Mesa-dev] [PATCH 5/5] intel gen4-5: Make noperspective clipping work.
Olivier Galibert
galibert at pobox.com
Sat Jun 30 11:50:15 PDT 2012
At this point all interpolation tests with fixed clipping work.
Signed-off-by: Olivier Galibert <galibert at pobox.com>
---
src/mesa/drivers/dri/i965/brw_clip.c | 9 ++
src/mesa/drivers/dri/i965/brw_clip.h | 1 +
src/mesa/drivers/dri/i965/brw_clip_util.c | 133 ++++++++++++++++++++++++++---
3 files changed, 132 insertions(+), 11 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_clip.c b/src/mesa/drivers/dri/i965/brw_clip.c
index 952eb4a..6bfdf24 100644
--- a/src/mesa/drivers/dri/i965/brw_clip.c
+++ b/src/mesa/drivers/dri/i965/brw_clip.c
@@ -234,6 +234,15 @@ brw_upload_clip_prog(struct brw_context *brw)
break;
}
}
+ key.has_noperspective_shading = 0;
+ for (i = 0; i < BRW_VERT_RESULT_MAX; i++) {
+ if (brw_get_interpolation_mode(brw, i) == INTERP_QUALIFIER_NOPERSPECTIVE &&
+ brw->vs.prog_data->vue_map.slot_to_vert_result[i] != VERT_RESULT_HPOS) {
+ key.has_noperspective_shading = 1;
+ break;
+ }
+ }
+
key.pv_first = (ctx->Light.ProvokingVertex == GL_FIRST_VERTEX_CONVENTION);
brw_copy_interpolation_modes(brw, key.interpolation_mode);
/* _NEW_TRANSFORM (also part of VUE map)*/
diff --git a/src/mesa/drivers/dri/i965/brw_clip.h b/src/mesa/drivers/dri/i965/brw_clip.h
index 0ea0394..2a7245a 100644
--- a/src/mesa/drivers/dri/i965/brw_clip.h
+++ b/src/mesa/drivers/dri/i965/brw_clip.h
@@ -47,6 +47,7 @@ struct brw_clip_prog_key {
GLuint primitive:4;
GLuint nr_userclip:4;
GLuint has_flat_shading:1;
+ GLuint has_noperspective_shading:1;
GLuint pv_first:1;
GLuint do_unfilled:1;
GLuint fill_cw:2; /* includes cull information */
diff --git a/src/mesa/drivers/dri/i965/brw_clip_util.c b/src/mesa/drivers/dri/i965/brw_clip_util.c
index 7b0205a..5bdcef8 100644
--- a/src/mesa/drivers/dri/i965/brw_clip_util.c
+++ b/src/mesa/drivers/dri/i965/brw_clip_util.c
@@ -129,6 +129,8 @@ 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,
@@ -138,8 +140,9 @@ 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);
- GLuint slot;
+ struct brw_context *brw = p->brw;
+ struct brw_reg tmp, t_nopersp, v0_ndc_copy;
+ GLuint slot, delta;
/* Just copy the vertex header:
*/
@@ -148,13 +151,119 @@ void brw_clip_interp_vertex( struct brw_clip_compile *c,
* back on Ironlake, so needn't change it
*/
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 positioning, in case we need
+ * noperspective interpolation. Doing it early has no performance
+ * impact in any case.
+ */
+
+ /* Start by picking up the v0 NDC coordinates, because that vertex
+ * may be shared with the destination.
+ */
+ if (c->key.has_noperspective_shading) {
+ v0_ndc_copy = get_tmp(c);
+ brw_MOV(p, v0_ndc_copy, deref_4f(v0_ptr,
+ brw_vert_result_to_offset(&c->vue_map,
+ BRW_VERT_RESULT_NDC)));
+ }
+
+ /*
+ * Compute the new 3D position
+ */
+
+ delta = brw_vert_result_to_offset(&c->vue_map, VERT_RESULT_HPOS);
+ 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);
+
+ /* Then recreate the projected (NDC) coordinate in the new vertex
+ * header
*/
+ brw_clip_project_vertex(c, dest_ptr);
+
+ /*
+ * If we have noperspective attributes, we now need to compute the
+ * screen-space t.
+ */
+ if (c->key.has_noperspective_shading) {
+ delta = brw_vert_result_to_offset(&c->vue_map, BRW_VERT_RESULT_NDC);
+ t_nopersp = get_tmp(c);
+ tmp = get_tmp(c);
+
+ /* Build a register with coordinates from the second and new vertices */
+ 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));
+
+ /* Subtract the coordinates of the first vertex */
+ brw_ADD(p, t_nopersp, t_nopersp, negate(brw_swizzle(v0_ndc_copy, 0,1,0,1)));
+
+ /* Add the absolute value of the X and Y deltas so that if the
+ * points aren't in the same place on the screen we get non-zero
+ * values to divide.
+ *
+ * After that we have vert1-vert0 in t_nopersp.x and vertnew-vert0 in t_nopersp.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 (vert1-vert0 == 0), just
+ * substitute a value that will ensure that we don't divide by
+ * 0.
+ */
+ brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_EQ,
+ vec1(t_nopersp),
+ brw_imm_f(1));
+ 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?)
+ */
+ tmp = get_tmp(c);
for (slot = 0; slot < c->vue_map.num_slots; slot++) {
int vert_result = c->vue_map.slot_to_vert_result[slot];
GLuint delta = brw_vue_slot_to_offset(slot);
+ /* HPOS is already handled */
+ if(vert_result == VERT_RESULT_HPOS)
+ continue;
+
if (vert_result == VERT_RESULT_EDGE) {
if (force_edgeflag)
brw_MOV(p, deref_4f(dest_ptr, delta), brw_imm_f(1));
@@ -174,15 +283,20 @@ void brw_clip_interp_vertex( struct brw_clip_compile *c,
*
* New = attr0 + t*attr1 - t*attr0
*/
+
+ struct brw_reg t =
+ brw_get_interpolation_mode(brw, 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),
@@ -198,11 +312,8 @@ void brw_clip_interp_vertex( struct brw_clip_compile *c,
}
release_tmp(c, tmp);
-
- /* Recreate the projected (NDC) coordinate in the new vertex
- * header:
- */
- brw_clip_project_vertex(c, dest_ptr );
+ if (c->key.has_noperspective_shading)
+ release_tmp(c, t_nopersp);
}
void brw_clip_emit_vue(struct brw_clip_compile *c,
--
1.7.10.rc3.1.gb306
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