85 lines
2.9 KiB
Markdown
85 lines
2.9 KiB
Markdown
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# GetterContext
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- **功能描述：** 继续限定AnimGetter函数在哪个地方才可以使用，如果不填，则默认都可以用。
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- **使用位置：** UFUNCTION
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- **引擎模块：** AnimationGraph
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- **元数据类型：** string="abc"
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- **限制类型：** UAnimInstance及子类的AnimGetter函数
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- **关联项：** [AnimGetter](../AnimGetter/AnimGetter.md)
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- **常用程度：** ★★
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继续限定AnimGetter函数在哪个地方才可以使用，如果不填，则默认都可以用。
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选项有：Transition，CustomBlend，AnimGraph。
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## 源码注释：
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```cpp
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* A context string can be provided in the GetterContext metadata and can contain any (or none) of the
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* following entries separated by a pipe (|)
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* Transition - Only available in a transition rule
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* AnimGraph - Only available in an animgraph (also covers state anim graphs)
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* CustomBlend - Only available in a custom blend graph
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```
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## 测试代码：
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```cpp
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UFUNCTION(BlueprintPure, Category = "Animation|Insider", meta = (BlueprintThreadSafe))
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float MyGetStateWeight(int32 MachineIndex, int32 StateIndex);
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public:
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UFUNCTION(BlueprintPure, Category = "Animation|Insider", meta = (BlueprintInternalUseOnly = "true", AnimGetter, GetterContext = "Transition", BlueprintThreadSafe))
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float MyGetStateWeight_AnimGetter_OnlyTransition(int32 MachineIndex, int32 StateIndex);
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UFUNCTION(BlueprintPure, Category = "Animation|Insider", meta = (BlueprintInternalUseOnly = "true", AnimGetter, GetterContext = "CustomBlend", BlueprintThreadSafe))
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float MyGetTransitionTimeElapsed_AnimGetter_OnlyCustomBlend(int32 MachineIndex, int32 TransitionIndex);
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```
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## 测试效果：
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这个图要对比AnimGetter里的图来查看。
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关注点一是在AnimGraph里的MyGetStateWeight_AnimGetter_OnlyTransition，如果不标GetterContext 则是可以调用的，但标上就只能在Transition里调用。同时也发现该函数不能在CustomBlend里调用。
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二是在CustomBlend里。操作步骤是在Rule上右侧细节面板改为Custom然后进入CustomBlend的蓝图。在该蓝图下，MyGetStateWeight可以调用，因为并没有填写GetterContext。而MyGetTransitionTimeElapsed_AnimGetter_OnlyCustomBlend可以开始调用了。
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## 原理：
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判断能否调用的函数如下。
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```cpp
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bool UK2Node_AnimGetter::IsContextValidForSchema(const UEdGraphSchema* Schema) const
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{
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if(Contexts.Num() == 0)
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{
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// Valid in all graphs
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return true;
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}
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for(const FString& Context : Contexts)
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{
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UClass* ClassToCheck = nullptr;
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if(Context == TEXT("CustomBlend"))
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{
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ClassToCheck = UAnimationCustomTransitionSchema::StaticClass();
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}
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if(Context == TEXT("Transition"))
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{
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ClassToCheck = UAnimationTransitionSchema::StaticClass();
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}
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if(Context == TEXT("AnimGraph"))
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{
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ClassToCheck = UAnimationGraphSchema::StaticClass();
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}
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return Schema->GetClass() == ClassToCheck;
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}
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return false;
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}
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```
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