[d3d11] Added option to limit tessellation factors

d3d11.maxTessFactor accepts values ranging from 8 to 64, and limits
the maximum tessellation factor accordingly.

src/d3d11/d3d11_device.cpp

@@ -612,6 +612,7 @@ namespace dxvk {
 
     DxbcModuleInfo moduleInfo;
     moduleInfo.options = m_dxbcOptions;
+    moduleInfo.tess    = nullptr;
     
     if (FAILED(this->CreateShaderModule(&module,
         pShaderBytecode, BytecodeLength, pClassLinkage,
@@ -636,6 +637,7 @@ namespace dxvk {
     
     DxbcModuleInfo moduleInfo;
     moduleInfo.options = m_dxbcOptions;
+    moduleInfo.tess    = nullptr;
 
     if (FAILED(this->CreateShaderModule(&module,
         pShaderBytecode, BytecodeLength, pClassLinkage,
@@ -679,6 +681,7 @@ namespace dxvk {
     
     DxbcModuleInfo moduleInfo;
     moduleInfo.options = m_dxbcOptions;
+    moduleInfo.tess    = nullptr;
 
     if (FAILED(this->CreateShaderModule(&module,
         pShaderBytecode, BytecodeLength, pClassLinkage,
@@ -701,8 +704,15 @@ namespace dxvk {
     InitReturnPtr(ppHullShader);
     D3D11CommonShader module;
     
+    DxbcTessInfo tessInfo;
+    tessInfo.maxTessFactor = float(m_d3d11Options.maxTessFactor);
+
     DxbcModuleInfo moduleInfo;
     moduleInfo.options = m_dxbcOptions;
+    moduleInfo.tess    = nullptr;
+
+    if (tessInfo.maxTessFactor >= 8.0f)
+      moduleInfo.tess = &tessInfo;
 
     if (FAILED(this->CreateShaderModule(&module,
         pShaderBytecode, BytecodeLength, pClassLinkage,
@@ -727,6 +737,7 @@ namespace dxvk {
     
     DxbcModuleInfo moduleInfo;
     moduleInfo.options = m_dxbcOptions;
+    moduleInfo.tess    = nullptr;
 
     if (FAILED(this->CreateShaderModule(&module,
         pShaderBytecode, BytecodeLength, pClassLinkage,
@@ -751,6 +762,7 @@ namespace dxvk {
     
     DxbcModuleInfo moduleInfo;
     moduleInfo.options = m_dxbcOptions;
+    moduleInfo.tess    = nullptr;
 
     if (FAILED(this->CreateShaderModule(&module,
         pShaderBytecode, BytecodeLength, pClassLinkage,

src/d3d11/d3d11_options.cpp

@@ -7,6 +7,7 @@ namespace dxvk {
   D3D11Options::D3D11Options(const Config& config) {
     this->allowMapFlagNoWait    = config.getOption<bool>("d3d11.allowMapFlagNoWait",    false);
     this->fakeStreamOutSupport  = config.getOption<bool>("d3d11.fakeStreamOutSupport",  false);
+    this->maxTessFactor         = config.getOption<int32_t>("d3d11.maxTessFactor",      0);
   }
   
 }

src/d3d11/d3d11_options.h

@@ -23,6 +23,13 @@ namespace dxvk {
     /// well enough without it. Will be removed once
     /// Stream Output is properly supported in DXVK.
     bool fakeStreamOutSupport;
+
+    /// Maximum tessellation factor.
+    ///
+    /// Limits tessellation factors in tessellation
+    /// control shaders. Values from 8 to 64 are
+    /// supported, other values will be ignored.
+    int32_t maxTessFactor;
   };
   
 }

src/dxbc/dxbc_compiler.cpp

@@ -5631,10 +5631,17 @@ namespace dxvk {
         = m_module.constu32(tessFactor.index);
       
       // Apply global tess factor limit
+      float maxTessFactor = m_hs.maxTessFactor;
+
+      if (m_moduleInfo.tess != nullptr) {
+        if (m_moduleInfo.tess->maxTessFactor < maxTessFactor)
+          maxTessFactor = m_moduleInfo.tess->maxTessFactor;
+      }
+
       DxbcRegisterValue tessValue = emitRegisterExtract(value, mask);
       tessValue.id = m_module.opFClamp(getVectorTypeId(tessValue.type),
         tessValue.id, m_module.constf32(0.0f),
-        m_module.constf32(m_hs.maxTessFactor));
+        m_module.constf32(maxTessFactor));
       
       DxbcRegisterPointer ptr;
       ptr.type.ctype  = DxbcScalarType::Float32;

src/dxbc/dxbc_modinfo.h

@@ -4,6 +4,17 @@
 
 namespace dxvk {
 
+  /**
+   * \brief Tessellation info
+   * 
+   * Stores the maximum tessellation factor
+   * to export from tessellation shaders.
+   */
+  struct DxbcTessInfo {
+    float maxTessFactor;
+  };
+
+
   /**
    * \brief Shader module info
    * 
@@ -12,6 +23,7 @@ namespace dxvk {
    */
   struct DxbcModuleInfo {
     DxbcOptions   options;
+    DxbcTessInfo* tess;
   };
 
 }