vault backup: 2024-10-12 17:19:45

03-UnrealEngine/Gameplay/UObject/UnrealSpecifiers/Meta/Material/MaterialNewHLSLGenerator/MaterialNewHLSLGenerator.md

@@ -0,0 +1,76 @@
+# MaterialNewHLSLGenerator
+
+- **功能描述：** 标识该UMaterialExpression为采用新HLSL生成器的节点，当前在材质蓝图右键菜单中隐藏。
+- **使用位置：** UCLASS
+- **引擎模块：** Material
+- **元数据类型：** bool
+- **限制类型：** UMaterialExpression子类
+- **常用程度：** ★
+
+标识该UMaterialExpression为采用新HLSL生成器的节点，当前在材质蓝图右键菜单中隐藏。
+
+## 源码例子：
+
+```cpp
+
+UCLASS(MinimalAPI, meta = (MaterialNewHLSLGenerator))
+class UMaterialExpressionLess : public UMaterialExpressionBinaryOp
+{
+	GENERATED_UCLASS_BODY()
+#if WITH_EDITOR
+	virtual UE::HLSLTree::EOperation GetBinaryOp() const override { return UE::HLSLTree::EOperation::Less; }
+#endif // WITH_EDITOR
+};
+```
+
+## 测试效果：
+
+材质蓝图里无法调用Less。
+
+![Untitled](Untitled.png)
+
+## 原理：
+
+在遍历所有可用FMaterialExpression的时候，如果有MaterialNewHLSLGenerator则略过。当前引擎下r.MaterialEnableNewHLSLGenerator是只读的，且实现未完全。
+
+```cpp
+static TAutoConsoleVariable<int32> CVarMaterialEnableNewHLSLGenerator(
+	TEXT("r.MaterialEnableNewHLSLGenerator"),
+	0,
+	TEXT("Enables the new (WIP) material HLSL generator.\n")
+	TEXT("0 - Don't allow\n")
+	TEXT("1 - Allow if enabled by material\n")
+	TEXT("2 - Force all materials to use new generator\n"),
+	ECVF_RenderThreadSafe | ECVF_ReadOnly);
+
+void MaterialExpressionClasses::InitMaterialExpressionClasses()
+{
+		static const auto CVarMaterialEnableNewHLSLGenerator = IConsoleManager::Get().FindTConsoleVariableDataInt(TEXT("r.MaterialEnableNewHLSLGenerator"));
+		const bool bEnableControlFlow = AllowMaterialControlFlow();
+		const bool bEnableNewHLSLGenerator = CVarMaterialEnableNewHLSLGenerator->GetValueOnAnyThread() != 0;
+	
+		for( TObjectIterator<UClass> It ; It ; ++It )
+		{
+			if( Class->IsChildOf(UMaterialExpression::StaticClass()) )
+			{
+					// Hide node types related to control flow, unless it's enabled
+					if (!bEnableControlFlow && Class->HasMetaData("MaterialControlFlow"))
+					{
+									continue;
+					}
+					
+					if (!bEnableNewHLSLGenerator && Class->HasMetaData("MaterialNewHLSLGenerator"))
+					{
+									continue;
+					}
+					
+					// Hide node types that are tagged private
+					if(Class->HasMetaData(TEXT("Private")))
+					{
+									continue;
+					}
+				AllExpressionClasses.Add(MaterialExpression);
+			}
+		}
+}
+```