[Mesa-dev] [PATCH 02/12] spirv: Flip the tessellation winding order

[Jason Ekstrand]

It's not SPIR-V that's backwards from GLSL, it's Vulkan that's backwards
from GL.  Let's make NIR consistent with the source language and do the
flipping inside the Vulkan driver instead.

Cc: Kenneth Graunke <kenneth at whitecape.org>
Cc: Dave Airlie <airlied at redhat.com>
---
 src/compiler/spirv/spirv_to_nir.c |  9 ++-------
 src/intel/vulkan/genX_pipeline.c  | 13 ++++++++++++-
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/compiler/spirv/spirv_to_nir.c b/src/compiler/spirv/spirv_to_nir.c
index 8653685..6ce9d1a 100644
--- a/src/compiler/spirv/spirv_to_nir.c
+++ b/src/compiler/spirv/spirv_to_nir.c
@@ -2951,17 +2951,12 @@ vtn_handle_execution_mode(struct vtn_builder *b, struct vtn_value *entry_point,
    case SpvExecutionModeVertexOrderCw:
       assert(b->shader->stage == MESA_SHADER_TESS_CTRL ||
              b->shader->stage == MESA_SHADER_TESS_EVAL);
-      /* Vulkan's notion of CCW seems to match the hardware backends,
-       * but be the opposite of OpenGL.  Currently NIR follows GL semantics,
-       * so we set it backwards here.
-       */
-      b->shader->info.tess.ccw = true;
+      b->shader->info.tess.ccw = false;
       break;
    case SpvExecutionModeVertexOrderCcw:
       assert(b->shader->stage == MESA_SHADER_TESS_CTRL ||
              b->shader->stage == MESA_SHADER_TESS_EVAL);
-      /* Backwards; see above */
-      b->shader->info.tess.ccw = false;
+      b->shader->info.tess.ccw = true;
       break;
    case SpvExecutionModePointMode:
       assert(b->shader->stage == MESA_SHADER_TESS_CTRL ||
diff --git a/src/intel/vulkan/genX_pipeline.c b/src/intel/vulkan/genX_pipeline.c
index 6dfa49b..844c118 100644
--- a/src/intel/vulkan/genX_pipeline.c
+++ b/src/intel/vulkan/genX_pipeline.c
@@ -1217,7 +1217,18 @@ emit_3dstate_hs_te_ds(struct anv_pipeline *pipeline)
 
    anv_batch_emit(&pipeline->batch, GENX(3DSTATE_TE), te) {
       te.Partitioning = tes_prog_data->partitioning;
-      te.OutputTopology = tes_prog_data->output_topology;
+
+      /* Vulkan has its winding order backwards from GL so TRI_CCW becomes
+       * TRI_CW and vice versa.
+       */
+      if (tes_prog_data->output_topology == OUTPUT_TRI_CCW) {
+         te.OutputTopology = OUTPUT_TRI_CW;
+      } else if (tes_prog_data->output_topology == OUTPUT_TRI_CW) {
+         te.OutputTopology = OUTPUT_TRI_CCW;
+      } else {
+         te.OutputTopology = tes_prog_data->output_topology;
+      }
+
       te.TEDomain = tes_prog_data->domain;
       te.TEEnable = true;
       te.MaximumTessellationFactorOdd = 63.0;
-- 
2.5.0.400.gff86faf