78 lines
3.3 KiB
Markdown
78 lines
3.3 KiB
Markdown
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# SequencerBindingResolverLibrary
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- **功能描述：** 把具有SequencerBindingResolverLibrary标记的UBlueprintFunctionLibrary作为动态绑定的类。
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- **使用位置：** UCLASS
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- **引擎模块：** Sequencer
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- **元数据类型：** bool
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- **限制类型：** UClass上，但一般是UBlueprintFunctionLibrary
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- **常用程度：** ★★
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把具有SequencerBindingResolverLibrary标记的UBlueprintFunctionLibrary作为动态绑定的类。只把它里面的函数添加到右键菜单里。
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动态绑定是Sequencer的一个新功能，简单来说就是允许设定好的轨迹变化动态应用到运行时的其他Actor上，用来做Gameplay和Sequence的过度切换会很有用。更细致用法可以参考官方文档：[https://dev.epicgames.com/documentation/zh-cn/unreal-engine/dynamic-binding-in-sequencer](https://dev.epicgames.com/documentation/zh-cn/unreal-engine/dynamic-binding-in-sequencer)
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## 测试代码：
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```cpp
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UCLASS(meta=(SequencerBindingResolverLibrary), MinimalAPI)
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class UMySequencerBindingResolverLibrary : public UBlueprintFunctionLibrary
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{
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GENERATED_BODY()
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public:
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/** Resolve the bound object to the player's pawn */
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UFUNCTION(BlueprintPure, Category="Sequencer|Insider", meta=(WorldContext="WorldContextObject"))
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static FMovieSceneDynamicBindingResolveResult ResolveToMyActor(UObject* WorldContextObject, FString ActorTag);
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};
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```
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源码：
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```cpp
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UCLASS(meta=(SequencerBindingResolverLibrary), MinimalAPI)
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class UBuiltInDynamicBindingResolverLibrary : public UBlueprintFunctionLibrary
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{
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GENERATED_BODY()
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public:
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/** Resolve the bound object to the player's pawn */
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UFUNCTION(BlueprintPure, Category="Sequencer|Dynamic Binding", meta=(WorldContext="WorldContextObject"))
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static MOVIESCENE_API FMovieSceneDynamicBindingResolveResult ResolveToPlayerPawn(UObject* WorldContextObject, int32 PlayerControllerIndex = 0);
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};
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```
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## 测试结果：
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在没有定义UMySequencerBindingResolverLibrary 之前，引擎里有个内建的ResolveToPlayerPawn，可以把PlayerControllerIndex 解析为Pawn来动态绑定到玩家的Pawn。
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因此我们也可以定义自己的动态绑定函数，来解析一个FString为一个Actor，如代码里ResolveToMyActor所示。
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## 原理：
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FMovieSceneDynamicBindingCustomization会搜索引擎里的所有类，但为了缩减范围，因此只有在标有SequencerBindingResolverLibrary的类下面才去发现Resolver函数。
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```cpp
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void FMovieSceneDynamicBindingCustomization::CollectResolverLibraryBindActions(UBlueprint* Blueprint, FBlueprintActionMenuBuilder& MenuBuilder, bool bIsRebinding)
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{
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// Add any class that has the "SequencerBindingResolverLibrary" meta as a target class.
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//
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// We don't consider *all* blueprint function libraries because there are many, many of them that expose
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// functions that are, technically speaking, compatible with bound object resolution (i.e. they return
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// a UObject pointer) but that are completely non-sensical in this context.
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const static FName SequencerBindingResolverLibraryMeta("SequencerBindingResolverLibrary");
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for (TObjectIterator<UClass> ClassIt; ClassIt; ++ClassIt)
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{
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UClass* CurrentClass = *ClassIt;
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if (CurrentClass->HasMetaData(SequencerBindingResolverLibraryMeta))
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{
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FBlueprintActionFilter::Add(MenuFilter.TargetClasses, CurrentClass);
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}
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}
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}
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```
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