[Mesa-dev] [PATCH v2 1/2] swr: perform perspective division on clip distances

[Rowley, Timothy O]

Reviewed-by: Tim Rowley <timothy.o.rowley at intel.com<mailto:timothy.o.rowley at intel.com>>

On Dec 8, 2016, at 8:21 PM, Ilia Mirkin <imirkin at alum.mit.edu<mailto:imirkin at alum.mit.edu>> wrote:

Clip distances need to be perspective-divided. This fixes all the
interpolation-*-{distance,vertex} piglits.

Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu<mailto:imirkin at alum.mit.edu>>
---
src/gallium/drivers/swr/rasterizer/core/binner.cpp | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/gallium/drivers/swr/rasterizer/core/binner.cpp b/src/gallium/drivers/swr/rasterizer/core/binner.cpp
index 6f9259f..1538020 100644
--- a/src/gallium/drivers/swr/rasterizer/core/binner.cpp
+++ b/src/gallium/drivers/swr/rasterizer/core/binner.cpp
@@ -383,7 +383,7 @@ PFN_PROCESS_ATTRIBUTES GetProcessAttributesFunc(uint32_t NumVerts, bool IsSwizzl
/// @param clipDistMask - mask of enabled clip distances
/// @param pUserClipBuffer - buffer to store results
template<uint32_t NumVerts>
-void ProcessUserClipDist(PA_STATE& pa, uint32_t primIndex, uint8_t clipDistMask, float* pUserClipBuffer)
+void ProcessUserClipDist(PA_STATE& pa, uint32_t primIndex, uint8_t clipDistMask, float *pRecipW, float* pUserClipBuffer)
{
    DWORD clipDist;
    while (_BitScanForward(&clipDist, clipDistMask))
@@ -407,11 +407,12 @@ void ProcessUserClipDist(PA_STATE& pa, uint32_t primIndex, uint8_t clipDistMask,

        // setup plane equations for barycentric interpolation in the backend
        float baryCoeff[NumVerts];
+        float last = vertClipDist[NumVerts - 1] * pRecipW[NumVerts - 1];
        for (uint32_t e = 0; e < NumVerts - 1; ++e)
        {
-            baryCoeff[e] = vertClipDist[e] - vertClipDist[NumVerts - 1];
+            baryCoeff[e] = vertClipDist[e] * pRecipW[e] - last;
        }
-        baryCoeff[NumVerts - 1] = vertClipDist[NumVerts - 1];
+        baryCoeff[NumVerts - 1] = last;

        for (uint32_t e = 0; e < NumVerts; ++e)
        {
@@ -834,7 +835,7 @@ endBinTriangles:
        {
            uint32_t numClipDist = _mm_popcnt_u32(rastState.clipDistanceMask);
            desc.pUserClipBuffer = (float*)pArena->Alloc(numClipDist * 3 * sizeof(float));
-            ProcessUserClipDist<3>(pa, triIndex, rastState.clipDistanceMask, desc.pUserClipBuffer);
+            ProcessUserClipDist<3>(pa, triIndex, rastState.clipDistanceMask, &desc.pTriBuffer[12], desc.pUserClipBuffer);
        }

        for (uint32_t y = aMTTop[triIndex]; y <= aMTBottom[triIndex]; ++y)
@@ -1184,8 +1185,9 @@ void BinPoints(
            if (rastState.clipDistanceMask)
            {
                uint32_t numClipDist = _mm_popcnt_u32(rastState.clipDistanceMask);
+                float one[2] = {1.0f, 1.0f};
                desc.pUserClipBuffer = (float*)pArena->Alloc(numClipDist * 2 * sizeof(float));
-                ProcessUserClipDist<2>(pa, primIndex, rastState.clipDistanceMask, desc.pUserClipBuffer);
+                ProcessUserClipDist<2>(pa, primIndex, rastState.clipDistanceMask, one, desc.pUserClipBuffer);
            }

            MacroTileMgr *pTileMgr = pDC->pTileMgr;
@@ -1396,7 +1398,7 @@ void BinPostSetupLines(
        {
            uint32_t numClipDist = _mm_popcnt_u32(rastState.clipDistanceMask);
            desc.pUserClipBuffer = (float*)pArena->Alloc(numClipDist * 2 * sizeof(float));
-            ProcessUserClipDist<2>(pa, primIndex, rastState.clipDistanceMask, desc.pUserClipBuffer);
+            ProcessUserClipDist<2>(pa, primIndex, rastState.clipDistanceMask, &desc.pTriBuffer[12], desc.pUserClipBuffer);
        }

        MacroTileMgr *pTileMgr = pDC->pTileMgr;
--
2.7.3


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