U++ Tag

在UE中Tag用于给对象添加一个名称标记之后可以通过标签来判断对象属于哪一类。一、Actor Tag用于给整个Actor添加标签。AActor内部已经定义TArrayFName Tags;不需要自己重新声明 Tags。官方将它描述为用于对 Actor 进行分组和分类的 FName 数组。1.在蓝图细节面板中添加Actor TagDetails→ Actor→ Tags2.在cpp中添加Actor Tag一般构造函数中添加Tags.Add(TEXT(Interactable));不过更推荐用AddUnique()Tags.AddUnique(TEXT(Interactable));前者会添加重名标签后者不会。3.检查Actor是否拥有TagActorHasTag()返回布尔值例检查自身if (ActorHasTag(TEXT(Interactable))) { UE_LOG(LogTemp, Warning, TEXT(当前 Actor 可以交互)); }检查其他对象void AMyActor::CheckActor(AActor* OtherActor) { if (OtherActor OtherActor-ActorHasTag(TEXT(Enemy))) { UE_LOG(LogTemp, Warning, TEXT(发现敌人)); } }ActorHasTag() 会检查该 Actor 的 Tags 数组中是否包含指定的 FName。4.在碰撞事件中检查Tag例如角色碰到不同物体时根据 Tag 执行不同逻辑void AMyActor::OnBeginOverlap( UPrimitiveComponent* OverlappedComponent, AActor* OtherActor, UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult SweepResult) { if (!OtherActor) { return; } if (OtherActor-ActorHasTag(TEXT(Enemy))) { UE_LOG(LogTemp, Warning, TEXT(碰到了敌人)); } else if (OtherActor-ActorHasTag(TEXT(Pickup))) { UE_LOG(LogTemp, Warning, TEXT(碰到了可拾取物)); } }5.在射线检测中检查TagFHitResult HitResult; bool bHit GetWorld()-LineTraceSingleByChannel( HitResult, Start, End, ECC_Visibility ); if (bHit) { AActor* HitActor HitResult.GetActor(); if (HitActor HitActor-ActorHasTag(TEXT(Interactable))) { UE_LOG( LogTemp, Warning, TEXT(射线检测到可交互物体%s), *HitActor-GetName() ); } }6.运行时添加和删除TagOtherActor-Tags.AddUnique(TEXT(Selected));OtherActor-Tags.Remove(TEXT(Selected));OtherActor-Tags.Empty();7.查找所有拥有某个Tag的Actor#include Kismet/GameplayStatics.h TArrayAActor* EnemyActors; UGameplayStatics::GetAllActorsWithTag( GetWorld(), TEXT(Enemy), EnemyActors ); for (AActor* EnemyActor : EnemyActors) { if (EnemyActor) { UE_LOG( LogTemp, Warning, TEXT(找到敌人%s), *EnemyActor-GetName() ); } }注意头文件该操作属于较慢操作不应该放在Tick中没帧调用。二、ComponentTag一个Actor中通常包括多个组件Actor├── BoxCollision├── BodyMesh├── HeadMesh└── CameraUActorComponent 自带TArrayFName ComponentTags;1.给组件添加TagAMyActor::AMyActor() { MyMesh CreateDefaultSubobjectUStaticMeshComponent( TEXT(MyMesh) ); SetRootComponent(MyMesh); MyMesh-ComponentTags.AddUnique(TEXT(Body)); }2.检查组件Tagif (MyMesh-ComponentHasTag(TEXT(Body))) { UE_LOG(LogTemp, Warning, TEXT(这个组件是身体网格)); }3.射线检测判断命中组件HeadMesh-ComponentTags.AddUnique(TEXT(Head)); BodyMesh-ComponentTags.AddUnique(TEXT(Body)); LegMesh-ComponentTags.AddUnique(TEXT(Leg)); if (bHit) { AActor* HitActor HitResult.GetActor(); UPrimitiveComponent* HitComponent HitResult.GetComponent(); if (HitActor HitActor-ActorHasTag(TEXT(Robot))) { UE_LOG(LogTemp, Warning, TEXT(命中了机器人)); } if (HitComponent) { if (HitComponent-ComponentHasTag(TEXT(Head))) { UE_LOG(LogTemp, Warning, TEXT(命中了机器人的头部)); } else if (HitComponent-ComponentHasTag(TEXT(Body))) { UE_LOG(LogTemp, Warning, TEXT(命中了机器人的身体)); } else if (HitComponent-ComponentHasTag(TEXT(Leg))) { UE_LOG(LogTemp, Warning, TEXT(命中了机器人的腿部)); } } }4.根据Tag查找Actor内的组件FindComponentByTag()UActorComponent* FoundComponent FindComponentByTag( UStaticMeshComponent::StaticClass(), TEXT(Head) );三、Gameplay TagsUE 官方将 Gameplay Tag 定义为一种用户自定义的、具有层级结构的概念标签可以像布尔值或标志位一样驱动游戏逻辑。