65 lines
2.1 KiB
Markdown
65 lines
2.1 KiB
Markdown
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# NotPlaceable
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- **功能描述：** 标明该Actor不可被放置在关卡里
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- **引擎模块：** Behavior
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- **元数据类型：** bool
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- **作用机制：** 在ClassFlags中添加[CLASS_NotPlaceable](../../../../Flags/EClassFlags/CLASS_NotPlaceable.md)
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- **关联项：** Placeable (Placeable.md)
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- **常用程度：★★★**
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标明该Actor不可被放置在关卡里，没法拖放到场景里。使继承自基类的Placeable说明符无效。会在ClassFlagss里标记上CLASS_NotPlaceable，这个标记是可以继承的，意味着其所有的子类默认都不可放置。例如AWorldSettings其实就是一个notplaceable的Actor。
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但是注意该类依然可以通过SpawnActor动态生成到关卡中。
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NotPlaceable的类是不出现在PlaceMode的类选择里去的。
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## 示例代码：
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```cpp
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UCLASS(Blueprintable,BlueprintType, NotPlaceable)
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class INSIDER_API AMyActor_NotPlaceable :public AActor
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{
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GENERATED_BODY()
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};
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```
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## 示例效果：
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拖动到场景里会发现不能创建Actor。
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## 原理：
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如果直接是C++类AMyActor_NotPlaceable ，是可以直接从ContentBrowser拖到场景里去的。看源码可知，只有BP继承下来的子类才有受到这个限制。
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```cpp
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TArray<AActor*> FLevelEditorViewportClient::TryPlacingActorFromObject( ULevel* InLevel, UObject* ObjToUse, bool bSelectActors, EObjectFlags ObjectFlags, UActorFactory* FactoryToUse, const FName Name, const FViewportCursorLocation* Cursor )
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{
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bool bPlace = true;
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if (ObjectClass->IsChildOf(UBlueprint::StaticClass()))
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{
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UBlueprint* BlueprintObj = StaticCast<UBlueprint*>(ObjToUse);
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bPlace = BlueprintObj->GeneratedClass != NULL;
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if(bPlace)
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{
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check(BlueprintObj->ParentClass == BlueprintObj->GeneratedClass->GetSuperClass());
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if (BlueprintObj->GeneratedClass->HasAnyClassFlags(CLASS_NotPlaceable | CLASS_Abstract))
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{
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bPlace = false;
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}
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}
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}
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if (bPlace)
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{
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PlacedActor = FActorFactoryAssetProxy::AddActorForAsset( ObjToUse, bSelectActors, ObjectFlags, FactoryToUse, Name );
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if ( PlacedActor != NULL )
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{
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PlacedActors.Add(PlacedActor);
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PlacedActor->PostEditMove(true);
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}
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}
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}
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```
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