74 lines
3.3 KiB
Markdown
74 lines
3.3 KiB
Markdown
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# MaterialParameterCollectionFunction
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- **功能描述：** 指定该函数是用于操作UMaterialParameterCollection，从而支持ParameterName的提取和验证
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- **使用位置：** UFUNCTION
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- **引擎模块：** Material
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- **元数据类型：** bool
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- **限制类型：** 带有UMaterialParameterCollection参数的函数
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- **常用程度：** ★★★
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指定该函数是用于操作UMaterialParameterCollection，从而支持ParameterName的提取和验证。
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## 测试代码：
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```cpp
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UCLASS(Blueprintable, BlueprintType)
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class INSIDER_API UMyFunction_Material :public UBlueprintFunctionLibrary
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{
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public:
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GENERATED_BODY()
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public:
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UFUNCTION(BlueprintCallable, meta=(WorldContext="WorldContextObject", MaterialParameterCollectionFunction))
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static void MySetScalarParameterValue(UObject* WorldContextObject, UMaterialParameterCollection* Collection, FName ParameterName, float ParameterValue);
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UFUNCTION(BlueprintCallable, meta=(WorldContext="WorldContextObject"))
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static void MySetScalarParameterValue_NoError(UObject* WorldContextObject, UMaterialParameterCollection* Collection, FName ParameterName, float ParameterValue);
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};
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```
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## 蓝图中效果：
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引擎自带的UKismetMaterialLibrary::SetScalarParameterValue和我们自己手动编写的MySetScalarParameterValue，会触发材质参数集合的蓝图节点验证检测。如果没有指定ParameterName，则会产生编译错误。而没有MaterialParameterCollectionFunction标记的MySetScalarParameterValue_NoError函数版本则只是当作一个普通的函数一样，一是不会自动提取MPC中的Parameters集合来选择，二是没有ParameterName为空的错误验证。
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## 原理：
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```cpp
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UBlueprintFunctionNodeSpawner* UBlueprintFunctionNodeSpawner::Create(UFunction const* const Function, UObject* Outer/* = nullptr*/)
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{
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bool const bIsMaterialParamCollectionFunc = Function->HasMetaData(FBlueprintMetadata::MD_MaterialParameterCollectionFunction);
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if (bIsMaterialParamCollectionFunc)
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{
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NodeClass = UK2Node_CallMaterialParameterCollectionFunction::StaticClass();
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}
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else
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{
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NodeClass = UK2Node_CallFunction::StaticClass();
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}
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}
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TSharedPtr<SGraphNode> FNodeFactory::CreateNodeWidget(UEdGraphNode* InNode)
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{
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if (UK2Node_CallMaterialParameterCollectionFunction* CallFunctionNode = Cast<UK2Node_CallMaterialParameterCollectionFunction>(InNode))
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{
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return SNew(SGraphNodeCallParameterCollectionFunction, CallFunctionNode);
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}
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}
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TSharedPtr<SGraphPin> SGraphNodeCallParameterCollectionFunction::CreatePinWidget(UEdGraphPin* Pin) const
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{
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//提取MPC中参数列表等操作
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if (Collection)
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{
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// Populate the ParameterName pin combobox with valid options from the Collection
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const bool bVectorParameters = CallFunctionNode->FunctionReference.GetMemberName().ToString().Contains(TEXT("Vector"));
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Collection->GetParameterNames(NameList, bVectorParameters);
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}
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}
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```
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MaterialParameterCollectionFunction这个标记的，会采用UK2Node_CallMaterialParameterCollectionFunction来验证材质函数的正确书写与否。同时UK2Node_CallMaterialParameterCollectionFunction这个蓝图节点也在引擎内部继续被识别以进一步定制化ParameterName的Pin节点。
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引擎源码内采用MaterialParameterCollectionFunction标记的函数只有UKismetMaterialLibrary里的函数。
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