[Mesa-dev] [PATCH 1/2] swr: [rasterizer core] allow an OpenGL driver to specify halfz clipping

[Ilia Mirkin]

With ARB_clip_control, GL may also do 0..1 depth clipping, not just
-1..1. For backwards compatibility, preserve the existing driver type
check for DX as well.

Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
---
 src/gallium/drivers/swr/rasterizer/core/clip.h  | 6 +++---
 src/gallium/drivers/swr/rasterizer/core/state.h | 1 +
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/gallium/drivers/swr/rasterizer/core/clip.h b/src/gallium/drivers/swr/rasterizer/core/clip.h
index 43bc522..78dbcf0 100644
--- a/src/gallium/drivers/swr/rasterizer/core/clip.h
+++ b/src/gallium/drivers/swr/rasterizer/core/clip.h
@@ -90,7 +90,7 @@ void ComputeClipCodes(DRIVER_TYPE type, const API_STATE& state, const simdvector
     {
         // FRUSTUM_NEAR
         // DX clips depth [0..w], GL clips [-w..w]
-        if (type == DX)
+        if (type == DX || state.rastState.clipHalfZ)
         {
             vRes = _simd_cmplt_ps(vertex.z, _simd_setzero_ps());
         }
@@ -640,7 +640,7 @@ private:
         case FRUSTUM_BOTTOM:    t = ComputeInterpFactor(_simd_sub_ps(v1[3], v1[1]), _simd_sub_ps(v2[3], v2[1])); break;
         case FRUSTUM_NEAR:      
             // DX Znear plane is 0, GL is -w
-            if (this->driverType == DX)
+            if (this->driverType == DX || this->state.rastState.clipHalfZ)
             {
                 t = ComputeInterpFactor(v1[2], v2[2]);
             }
@@ -708,7 +708,7 @@ private:
         case FRUSTUM_RIGHT:     return _simd_cmple_ps(v[0], v[3]);
         case FRUSTUM_TOP:       return _simd_cmpge_ps(v[1], _simd_mul_ps(v[3], _simd_set1_ps(-1.0f)));
         case FRUSTUM_BOTTOM:    return _simd_cmple_ps(v[1], v[3]);
-        case FRUSTUM_NEAR:      return _simd_cmpge_ps(v[2], this->driverType == DX ? _simd_setzero_ps() : _simd_mul_ps(v[3], _simd_set1_ps(-1.0f)));
+        case FRUSTUM_NEAR:      return _simd_cmpge_ps(v[2], this->driverType == DX || this->state.rastState.clipHalfZ ? _simd_setzero_ps() : _simd_mul_ps(v[3], _simd_set1_ps(-1.0f)));
         case FRUSTUM_FAR:       return _simd_cmple_ps(v[2], v[3]);
         default:
             SWR_ASSERT(false, "invalid clipping plane: %d", ClippingPlane);
diff --git a/src/gallium/drivers/swr/rasterizer/core/state.h b/src/gallium/drivers/swr/rasterizer/core/state.h
index 93e4565..5ee12e8 100644
--- a/src/gallium/drivers/swr/rasterizer/core/state.h
+++ b/src/gallium/drivers/swr/rasterizer/core/state.h
@@ -932,6 +932,7 @@ struct SWR_RASTSTATE
     uint32_t frontWinding           : 1;
     uint32_t scissorEnable          : 1;
     uint32_t depthClipEnable        : 1;
+    uint32_t clipHalfZ              : 1;
     uint32_t pointParam             : 1;
     uint32_t pointSpriteEnable      : 1;
     uint32_t pointSpriteTopOrigin   : 1;
-- 
2.7.3