From b56ec10deb2b6b9f03e2c5339143bf3c19938bd0 Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Fri, 16 Sep 2022 15:31:17 +0200
Subject: [PATCH] [d3d9] Add helpers for precise matrix-vector products

---
 src/d3d9/d3d9_fixed_function.cpp | 35 ++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/src/d3d9/d3d9_fixed_function.cpp b/src/d3d9/d3d9_fixed_function.cpp
index c54bdc422..6a9f5c7c2 100644
--- a/src/d3d9/d3d9_fixed_function.cpp
+++ b/src/d3d9/d3d9_fixed_function.cpp
@@ -764,6 +764,9 @@ namespace dxvk {
 
     void alphaTestPS();
 
+    uint32_t emitMatrixTimesVector(uint32_t rowCount, uint32_t colCount, uint32_t matrix, uint32_t vector);
+    uint32_t emitVectorTimesMatrix(uint32_t rowCount, uint32_t colCount, uint32_t vector, uint32_t matrix);
+
     bool isVS() { return m_programType == DxsoProgramType::VertexShader; }
     bool isPS() { return !isVS(); }
 
@@ -2390,6 +2393,38 @@ namespace dxvk {
   }
 
 
+  uint32_t D3D9FFShaderCompiler::emitMatrixTimesVector(uint32_t rowCount, uint32_t colCount, uint32_t matrix, uint32_t vector) {
+    uint32_t f32Type = m_module.defFloatType(32);
+    uint32_t vecType = m_module.defVectorType(f32Type, rowCount);
+    uint32_t accum = 0;
+
+    for (uint32_t i = 0; i < colCount; i++) {
+      std::array<uint32_t, 4> indices = { i, i, i, i };
+
+      uint32_t a = m_module.opVectorShuffle(vecType, vector, vector, rowCount, indices.data());
+      uint32_t b = m_module.opCompositeExtract(vecType, matrix, 1, &i);
+
+      accum = accum
+        ? m_module.opFFma(vecType, a, b, accum)
+        : m_module.opFMul(vecType, a, b);
+
+      m_module.decorate(accum, spv::DecorationNoContraction);
+    }
+
+    return accum;
+  }
+
+
+  uint32_t D3D9FFShaderCompiler::emitVectorTimesMatrix(uint32_t rowCount, uint32_t colCount, uint32_t vector, uint32_t matrix) {
+    uint32_t f32Type = m_module.defFloatType(32);
+    uint32_t vecType = m_module.defVectorType(f32Type, colCount);
+    uint32_t matType = m_module.defMatrixType(vecType, rowCount);
+
+    matrix = m_module.opTranspose(matType, matrix);
+    return emitMatrixTimesVector(colCount, rowCount, matrix, vector);
+  }
+
+
   D3D9FFShader::D3D9FFShader(
           D3D9DeviceEx*         pDevice,
     const D3D9FFShaderKeyVS&    Key) {