RegisterGameplayTagEvent——UE4 GAS API

API//AbilitySystemComponent.h/** Allow events to be registered for specific gameplay tags being added or removed */FOnGameplayEffectTagCountChanged& RegisterGameplayTagEvent(FGameplayTag Tag, EGam

Endless丶Go

528人浏览 · 2021-12-01 14:52:36

Endless丶Go · 2021-12-01 14:52:36 发布

API


//AbilitySystemComponent.h
	/** Allow events to be registered for specific gameplay tags being added or removed */
	FOnGameplayEffectTagCountChanged& RegisterGameplayTagEvent(FGameplayTag Tag, EGameplayTagEventType::Type EventType=EGameplayTagEventType::NewOrRemoved);

允许对指定的GameplayTag在新增或删除时注册事件。

参数	类型	含义
Tag	FGameplayTag Tag	指定的GameplayTag
EventType	EGameplayTagEventType::Type	注册的事件类型
返回值	FOnGameplayEffectTagCountChanged&	委托的引用

以下详细解释下UAbilitySystemComponent::RegisterGameplayTagEvent

功能：向GameplayTag的委托（新增或删除/数量变化两种委托）中注册回调函数，当GameplayTag发生变化时（委托会进行广播，进而）触发回调函数中的逻辑。

两种委托动态多播委托：新增或删除/数量变化

//GameplayEffectTypes.h
DECLARE_MULTICAST_DELEGATE_TwoParams(FOnGameplayEffectTagCountChanged, const FGameplayTag, int32);

	struct FDelegateInfo
	{
		FOnGameplayEffectTagCountChanged	OnNewOrRemove;
		FOnGameplayEffectTagCountChanged	OnAnyChange;
	};

两种注册的事件类型

//GameplayEffectTypes.h
UENUM(BlueprintType)
namespace EGameplayTagEventType
{
	/** Rather a tag was added or removed, used in callbacks */
	enum Type
	{		
		/** Event only happens when tag is new or completely removed */
		NewOrRemoved,

		/** Event happens any time tag "count" changes */
		AnyCountChange		
	};
}

用法，参考GASShooter代码中的KnockedDownTag和AGSPlayerState::KnockDownTagChanged回调函数。

//GSPlayerState.cpp
void AGSPlayerState::BeginPlay()
{
	Super::BeginPlay();

	if (AbilitySystemComponent)
	{
		// Attribute change callbacks
		HealthChangedDelegateHandle = AbilitySystemComponent->GetGameplayAttributeValueChangeDelegate(AttributeSetBase->GetHealthAttribute()).AddUObject(this, &AGSPlayerState::HealthChanged);

		// Tag change callbacks
		AbilitySystemComponent->RegisterGameplayTagEvent(KnockedDownTag, EGameplayTagEventType::NewOrRemoved).AddUObject(this, &AGSPlayerState::KnockDownTagChanged);
	}
}

void AGSPlayerState::KnockDownTagChanged(const FGameplayTag CallbackTag, int32 NewCount)
{
	AGSHeroCharacter* Hero = Cast<AGSHeroCharacter>(GetPawn());
	if (!IsValid(Hero))
	{
		return;
	}

	if (NewCount > 0)
	{
		Hero->PlayKnockDownEffects();
	}
	else if (NewCount < 1 && !AbilitySystemComponent->HasMatchingGameplayTag(DeadTag))
	{
		Hero->PlayReviveEffects();
	}
}