Module: Mesa
Branch: master
Commit: 023ea3772dfcd81e6a5822a1812ff991d68cccd8
URL:
http://cgit.freedesktop.org/mesa/mesa/commit/?id=023ea3772dfcd81e6a5822a1812ff991d68cccd8
Author: Iago Toral Quiroga <ito...@igalia.com>
Date: Thu Mar 23 11:54:16 2017 +0100
nir/lower_wpos_center: support adding sample position to fragment coordinate
According to section 14.6 of the Vulkan specification:
"When sample shading is enabled, the x and y components of FragCoord
reflect the location of the sample corresponding to the shader
invocation."
So add a boolean parameter to the lowering pass to select this behavior
when we need it.
Reviewed-by: Jason Ekstrand <ja...@jlekstrand.net>
---
src/compiler/nir/nir.h | 2 +-
src/compiler/nir/nir_lower_wpos_center.c | 31 ++++++++++++++++++++++++-------
src/intel/vulkan/anv_pipeline.c | 2 +-
3 files changed, 26 insertions(+), 9 deletions(-)
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index d032787a2a..f88707a31a 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2518,7 +2518,7 @@ typedef struct nir_lower_wpos_ytransform_options {
bool nir_lower_wpos_ytransform(nir_shader *shader,
const nir_lower_wpos_ytransform_options
*options);
-bool nir_lower_wpos_center(nir_shader *shader);
+bool nir_lower_wpos_center(nir_shader *shader, const bool for_sample_shading);
typedef struct nir_lower_drawpixels_options {
int texcoord_state_tokens[5];
diff --git a/src/compiler/nir/nir_lower_wpos_center.c
b/src/compiler/nir/nir_lower_wpos_center.c
index 5a70848eb8..478818d8d6 100644
--- a/src/compiler/nir/nir_lower_wpos_center.c
+++ b/src/compiler/nir/nir_lower_wpos_center.c
@@ -39,11 +39,14 @@
* hardware which provides an integer pixel center. Vulkan mandates that
* the pixel center must be half-integer, and also that the coordinate
* system's origin must be upper left. This means that there's no need
- * for a uniform - we can always just add a constant.
+ * for a uniform - we can always just add a constant. In the case that
+ * sample shading is enabled, Vulkan expects FragCoord to include sample
+ * positions.
*/
static void
-add_half_to_fragcoord(nir_builder *b, nir_intrinsic_instr *intr)
+update_fragcoord(nir_builder *b, nir_intrinsic_instr *intr,
+ const bool for_sample_shading)
{
nir_ssa_def *wpos = &intr->dest.ssa;
@@ -51,14 +54,27 @@ add_half_to_fragcoord(nir_builder *b, nir_intrinsic_instr
*intr)
b->cursor = nir_after_instr(&intr->instr);
- wpos = nir_fadd(b, wpos, nir_imm_vec4(b, 0.5f, 0.5f, 0.0f, 0.0f));
+ if (!for_sample_shading) {
+ wpos = nir_fadd(b, wpos, nir_imm_vec4(b, 0.5f, 0.5f, 0.0f, 0.0f));
+ } else {
+ nir_ssa_def *spos =
+ nir_load_system_value(b, nir_intrinsic_load_sample_pos, 0);
+
+ wpos = nir_fadd(b, wpos,
+ nir_vec4(b,
+ nir_channel(b, spos, 0),
+ nir_channel(b, spos, 1),
+ nir_imm_float(b, 0.0f),
+ nir_imm_float(b, 0.0f)));
+ }
nir_ssa_def_rewrite_uses_after(&intr->dest.ssa, nir_src_for_ssa(wpos),
wpos->parent_instr);
}
static bool
-lower_wpos_center_block(nir_builder *b, nir_block *block)
+lower_wpos_center_block(nir_builder *b, nir_block *block,
+ const bool for_sample_shading)
{
bool progress = false;
@@ -73,7 +89,7 @@ lower_wpos_center_block(nir_builder *b, nir_block *block)
var->data.location == VARYING_SLOT_POS) {
/* gl_FragCoord should not have array/struct derefs: */
assert(dvar->deref.child == NULL);
- add_half_to_fragcoord(b, intr);
+ update_fragcoord(b, intr, for_sample_shading);
progress = true;
}
}
@@ -84,7 +100,7 @@ lower_wpos_center_block(nir_builder *b, nir_block *block)
}
bool
-nir_lower_wpos_center(nir_shader *shader)
+nir_lower_wpos_center(nir_shader *shader, const bool for_sample_shading)
{
bool progress = false;
nir_builder b;
@@ -96,7 +112,8 @@ nir_lower_wpos_center(nir_shader *shader)
nir_builder_init(&b, function->impl);
nir_foreach_block(block, function->impl) {
- progress = lower_wpos_center_block(&b, block) || progress;
+ progress = lower_wpos_center_block(&b, block, for_sample_shading)
||
+ progress;
}
nir_metadata_preserve(function->impl, nir_metadata_block_index |
nir_metadata_dominance);
diff --git a/src/intel/vulkan/anv_pipeline.c b/src/intel/vulkan/anv_pipeline.c
index 23274ef2a8..8ad2d48536 100644
--- a/src/intel/vulkan/anv_pipeline.c
+++ b/src/intel/vulkan/anv_pipeline.c
@@ -158,7 +158,7 @@ anv_shader_compile_to_nir(struct anv_device *device,
nir_var_shader_in | nir_var_shader_out | nir_var_system_value);
if (stage == MESA_SHADER_FRAGMENT)
- NIR_PASS_V(nir, nir_lower_wpos_center);
+ NIR_PASS_V(nir, nir_lower_wpos_center, false);
/* Now that we've deleted all but the main function, we can go ahead and
* lower the rest of the constant initializers.
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