[dxvk] Patch fragment shader for dual-source blending

src/dxvk/dxvk_compute.cpp

@@ -36,7 +36,10 @@ namespace dxvk {
       slotMapping.bindingInfos(),
       VK_PIPELINE_BIND_POINT_COMPUTE);
     
-    m_cs = cs->createShaderModule(m_vkd, slotMapping);
+    DxvkShaderModuleCreateInfo moduleInfo;
+    moduleInfo.fsDualSrcBlend = false;
+
+    m_cs = cs->createShaderModule(m_vkd, slotMapping, moduleInfo);
   }
   
   

src/dxvk/dxvk_graphics.cpp

@@ -61,11 +61,18 @@ namespace dxvk {
       slotMapping.bindingInfos(),
       VK_PIPELINE_BIND_POINT_GRAPHICS);
     
-    if (vs  != nullptr) m_vs  = vs ->createShaderModule(m_vkd, slotMapping);
-    if (tcs != nullptr) m_tcs = tcs->createShaderModule(m_vkd, slotMapping);
-    if (tes != nullptr) m_tes = tes->createShaderModule(m_vkd, slotMapping);
-    if (gs  != nullptr) m_gs  = gs ->createShaderModule(m_vkd, slotMapping);
-    if (fs  != nullptr) m_fs  = fs ->createShaderModule(m_vkd, slotMapping);
+    DxvkShaderModuleCreateInfo moduleInfo;
+    moduleInfo.fsDualSrcBlend = true;
+    
+    DxvkShaderModuleCreateInfo moduleInfoDualSrc;
+    moduleInfoDualSrc.fsDualSrcBlend = true;
+    
+    if (vs  != nullptr) m_vs  = vs ->createShaderModule(m_vkd, slotMapping, moduleInfo);
+    if (tcs != nullptr) m_tcs = tcs->createShaderModule(m_vkd, slotMapping, moduleInfo);
+    if (tes != nullptr) m_tes = tes->createShaderModule(m_vkd, slotMapping, moduleInfo);
+    if (gs  != nullptr) m_gs  = gs ->createShaderModule(m_vkd, slotMapping, moduleInfo);
+    if (fs  != nullptr) m_fs  = fs ->createShaderModule(m_vkd, slotMapping, moduleInfo);
+    if (fs  != nullptr) m_fs2 = fs ->createShaderModule(m_vkd, slotMapping, moduleInfoDualSrc);
     
     m_vsIn  = vs != nullptr ? vs->interfaceSlots().inputSlots  : 0;
     m_fsOut = fs != nullptr ? fs->interfaceSlots().outputSlots : 0;
@@ -200,12 +207,20 @@ namespace dxvk {
     specInfo.pData                = &specData;
     
     std::vector<VkPipelineShaderStageCreateInfo> stages;
-    
+
+    bool useDualSrcBlend = state.omBlendAttachments[0].blendEnable && (
+      util::isDualSourceBlendFactor(state.omBlendAttachments[0].srcColorBlendFactor) ||
+      util::isDualSourceBlendFactor(state.omBlendAttachments[0].dstColorBlendFactor) ||
+      util::isDualSourceBlendFactor(state.omBlendAttachments[0].srcAlphaBlendFactor) ||
+      util::isDualSourceBlendFactor(state.omBlendAttachments[0].dstAlphaBlendFactor));
+
+    Rc<DxvkShaderModule> fs = useDualSrcBlend ? m_fs2 : m_fs;
+
     if (m_vs  != nullptr) stages.push_back(m_vs->stageInfo(&specInfo));
     if (m_tcs != nullptr) stages.push_back(m_tcs->stageInfo(&specInfo));
     if (m_tes != nullptr) stages.push_back(m_tes->stageInfo(&specInfo));
     if (m_gs  != nullptr) stages.push_back(m_gs->stageInfo(&specInfo));
-    if (m_fs  != nullptr) stages.push_back(m_fs->stageInfo(&specInfo));
+    if (fs    != nullptr) stages.push_back(fs->stageInfo(&specInfo));
 
     // Fix up color write masks using the component mappings
     std::array<VkPipelineColorBlendAttachmentState, MaxNumRenderTargets> omBlendAttachments;

src/dxvk/dxvk_graphics.h

@@ -229,6 +229,7 @@ namespace dxvk {
     Rc<DxvkShaderModule>    m_tes;
     Rc<DxvkShaderModule>    m_gs;
     Rc<DxvkShaderModule>    m_fs;
+    Rc<DxvkShaderModule>    m_fs2;
     
     uint32_t m_vsIn  = 0;
     uint32_t m_fsOut = 0;

src/dxvk/dxvk_shader.cpp

@@ -91,11 +91,22 @@ namespace dxvk {
     
     // Gather the offsets where the binding IDs
     // are stored so we can quickly remap them.
+    uint32_t o1VarId = 0;
+    
     for (auto ins : m_code) {
-      if (ins.opCode() == spv::OpDecorate
-       && ((ins.arg(2) == spv::DecorationBinding)
-        || (ins.arg(2) == spv::DecorationSpecId)))
-        m_idOffsets.push_back(ins.offset() + 3);
+      if (ins.opCode() == spv::OpDecorate) {
+        if (ins.arg(2) == spv::DecorationBinding
+         || ins.arg(2) == spv::DecorationSpecId)
+          m_idOffsets.push_back(ins.offset() + 3);
+        
+        if (ins.arg(2) == spv::DecorationLocation && ins.arg(3) == 1) {
+          m_o1LocOffset = ins.offset() + 3;
+          o1VarId = ins.arg(1);
+        }
+        
+        if (ins.arg(2) == spv::DecorationIndex && ins.arg(1) == o1VarId)
+          m_o1IdxOffset = ins.offset() + 3;
+      }
     }
   }
   
@@ -128,15 +139,21 @@ namespace dxvk {
   
   Rc<DxvkShaderModule> DxvkShader::createShaderModule(
     const Rc<vk::DeviceFn>&          vkd,
-    const DxvkDescriptorSlotMapping& mapping) {
+    const DxvkDescriptorSlotMapping& mapping,
+    const DxvkShaderModuleCreateInfo& info) {
     SpirvCodeBuffer spirvCode = m_code;
+    uint32_t* code = spirvCode.data();
     
     // Remap resource binding IDs
-    uint32_t* code = spirvCode.data();
     for (uint32_t ofs : m_idOffsets) {
       if (code[ofs] < MaxNumResourceSlots)
         code[ofs] = mapping.getBindingId(code[ofs]);
     }
+
+    // For dual-source blending we need to re-map
+    // location 1, index 0 to location 0, index 1
+    if (info.fsDualSrcBlend && m_o1IdxOffset && m_o1LocOffset)
+      std::swap(code[m_o1IdxOffset], code[m_o1LocOffset]);
     
     return new DxvkShaderModule(vkd, this, spirvCode);
   }

src/dxvk/dxvk_shader.h

@@ -101,6 +101,14 @@ namespace dxvk {
     uint32_t* m_data = nullptr;
 
   };
+
+
+  /**
+   * \brief Shader module create info
+   */
+  struct DxvkShaderModuleCreateInfo {
+    bool fsDualSrcBlend;
+  };
   
   
   /**
@@ -162,11 +170,13 @@ namespace dxvk {
      * Maps the binding slot numbers 
      * \param [in] vkd Vulkan device functions
      * \param [in] mapping Resource slot mapping
+     * \param [in] info Module create info
      * \returns The shader module
      */
     Rc<DxvkShaderModule> createShaderModule(
       const Rc<vk::DeviceFn>&          vkd,
-      const DxvkDescriptorSlotMapping& mapping);
+      const DxvkDescriptorSlotMapping& mapping,
+      const DxvkShaderModuleCreateInfo& info);
     
     /**
      * \brief Inter-stage interface slots
@@ -242,6 +252,9 @@ namespace dxvk {
     DxvkShaderOptions             m_options;
     DxvkShaderConstData           m_constData;
     DxvkShaderKey                 m_key;
+
+    size_t m_o1IdxOffset = 0;
+    size_t m_o1LocOffset = 0;
     
   };
   

src/dxvk/dxvk_util.cpp

@@ -149,4 +149,12 @@ namespace dxvk::util {
     }
   }
 
+
+  bool isDualSourceBlendFactor(VkBlendFactor factor) {
+    return factor == VK_BLEND_FACTOR_SRC1_COLOR
+        || factor == VK_BLEND_FACTOR_SRC1_ALPHA
+        || factor == VK_BLEND_FACTOR_ONE_MINUS_SRC1_COLOR
+        || factor == VK_BLEND_FACTOR_ONE_MINUS_SRC1_ALPHA;
+  }
+
 }

src/dxvk/dxvk_util.h

@@ -212,4 +212,7 @@ namespace dxvk::util {
           VkComponentSwizzle          component,
           uint32_t                    identity);
   
+  bool isDualSourceBlendFactor(
+          VkBlendFactor               factor);
+  
 }