[dxvk] Implement backend support for D3D11 forced sample count

We don't support rasterization with a sample count different from
the framebuffer sample count, but if there are no attachments, any
sample count is allowed.

src/d3d11/d3d11_rasterizer.cpp

@@ -47,12 +47,10 @@ namespace dxvk {
     m_state.depthBiasClamp    = desc.DepthBiasClamp;
     m_state.depthBiasSlope    = desc.SlopeScaledDepthBias;
     m_state.depthClampEnable  = desc.DepthClipEnable ? VK_FALSE : VK_TRUE;
+    m_state.sampleCount       = VkSampleCountFlags(desc.ForcedSampleCount);
     
     if (desc.AntialiasedLineEnable)
       Logger::err("D3D11RasterizerState: Antialiased lines not supported");
-    
-    if (desc.ForcedSampleCount)
-      Logger::err("D3D11RasterizerState: Forced sample count not supported");
   }
   
   

src/dxvk/dxvk_constant_state.h

@@ -48,6 +48,7 @@ namespace dxvk {
     float               depthBiasConstant;
     float               depthBiasClamp;
     float               depthBiasSlope;
+    VkSampleCountFlags  sampleCount;
   };
   
   

src/dxvk/dxvk_context.cpp

@@ -1562,6 +1562,7 @@ namespace dxvk {
     m_state.gp.state.rsPolygonMode       = rs.polygonMode;
     m_state.gp.state.rsCullMode          = rs.cullMode;
     m_state.gp.state.rsFrontFace         = rs.frontFace;
+    m_state.gp.state.rsSampleCount       = rs.sampleCount;
 
     m_state.ds.depthBiasConstant = rs.depthBiasConstant;
     m_state.ds.depthBiasClamp    = rs.depthBiasClamp;

src/dxvk/dxvk_framebuffer.h

@@ -79,11 +79,17 @@ namespace dxvk {
     }
     
     /**
-     * \brief Sample count
+     * \brief Framebuffer sample count
+     * 
+     * Returns the sample count of the color
+     * and depth-stencil attachments, or 0 if
+     * there are no attachments.
      * \returns Sample count
      */
-    VkSampleCountFlagBits getSampleCount() const {
+    VkSampleCountFlags getSampleCount() const {
-      return m_renderPass->getSampleCount();
+      return m_attachmentCount != 0
+        ? m_renderPass->getSampleCount()
+        : 0;
     }
     
     /**

src/dxvk/dxvk_graphics.cpp

@@ -160,9 +160,18 @@ namespace dxvk {
       VK_DYNAMIC_STATE_BLEND_CONSTANTS,
       VK_DYNAMIC_STATE_STENCIL_REFERENCE,
     };
+
+    // Figure out the actual sample count to use
+    VkSampleCountFlagBits sampleCount = VK_SAMPLE_COUNT_1_BIT;
+
+    if (state.msSampleCount)
+      sampleCount = VkSampleCountFlagBits(state.msSampleCount);
+    else if (state.rsSampleCount)
+      sampleCount = VkSampleCountFlagBits(state.rsSampleCount);
     
+    // Set up some specialization constants
     DxvkSpecConstantData specData;
-    specData.rasterizerSampleCount = uint32_t(state.msSampleCount);
+    specData.rasterizerSampleCount = uint32_t(sampleCount);
     
     for (uint32_t i = 0; i < MaxNumActiveBindings; i++)
       specData.activeBindings[i] = state.bsBindingMask.isBound(i) ? VK_TRUE : VK_FALSE;
@@ -272,7 +281,7 @@ namespace dxvk {
     msInfo.sType                  = VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO;
     msInfo.pNext                  = nullptr;
     msInfo.flags                  = 0;
-    msInfo.rasterizationSamples   = state.msSampleCount;
+    msInfo.rasterizationSamples   = sampleCount;
     msInfo.sampleShadingEnable    = m_common.msSampleShadingEnable;
     msInfo.minSampleShading       = m_common.msSampleShadingFactor;
     msInfo.pSampleMask            = &state.msSampleMask;

src/dxvk/dxvk_graphics.h

@@ -52,8 +52,9 @@ namespace dxvk {
     VkCullModeFlags                     rsCullMode;
     VkFrontFace                         rsFrontFace;
     uint32_t                            rsViewportCount;
+    VkSampleCountFlags                  rsSampleCount;
     
-    VkSampleCountFlagBits               msSampleCount;
+    VkSampleCountFlags                  msSampleCount;
     uint32_t                            msSampleMask;
     VkBool32                            msEnableAlphaToCoverage;
     VkBool32                            msEnableAlphaToOne;