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【UE4C++】Tick的三种方式、异步蓝图节点、LatentAction

原作者: [db:作者] 来自: [db:来源] 收藏邀请

包括
- 默认 Tick （Actor、Component、UMG）
- TimerManager 定时器
- FTickableGameObject
  - 可以写原生 Object
  - 也可以继承UObject 使用
下面利用 AActor 直接实现三种 Tick

class  FTickableObject :public FTickableGameObject
{
public:
	bool bEnableTick = false;
	int32 TickCounter = 0;

	virtual void Tick(float DeltaTime)override {
		UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__"\t [TickCounter]%d"), TickCounter);
	}
	virtual bool IsTickable()const override { return bEnableTick; }
	virtual TStatId GetStatId() const override { RETURN_QUICK_DECLARE_CYCLE_STAT(UTickableObject, STATGROUP_Tickables); }
};

UCLASS()
class DESIGNPATTERNS_API AAsyncTickActor : public AActor
{
	GENERATED_BODY()
public:	
	// Sets default values for this actor's properties
	AAsyncTickActor();

	// Called every frame
	virtual void Tick(float DeltaTime) override;
	void TimerTick();
protected:
	// Called when the game starts or when spawned
	virtual void BeginPlay() override;

private:
	int32 TickCounter = 0;
	FTimerHandle TimeHandle;
	TSharedPtr<FTickableObject> TickableObject;
};

AAsyncTickActor::AAsyncTickActor()
{
 	// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
	PrimaryActorTick.bCanEverTick = true;	
}

// Called when the game starts or when spawned
void AAsyncTickActor::BeginPlay()
{
	Super::BeginPlay();
	TickableObject = MakeShareable(new FTickableObject());
	TickableObject->bEnableTick = true;
	GetWorld()->GetTimerManager().SetTimer(TimeHandle, this, &AAsyncTickActor::TimerTick, 0.1f, true);
}

// Called every frame
void AAsyncTickActor::Tick(float DeltaTime)
{
	Super::Tick(DeltaTime);
	UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__"\t[TickCounter]%d"), TickCounter);
	if (TickableObject.IsValid())
	{
		TickableObject->TickCounter = TickCounter;
	}

}

void AAsyncTickActor::TimerTick()
{
	TickCounter++;
	UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__"%\t [TickCounter]%d"), TickCounter);
}

异步蓝图节点

原博客地址

使用方法

继承 UBlueprintAsyncActionBase

成员函数 Activate 用于内部触发委托绑定的事件
成员函数 RegisterWithGameInstance 允许将该对象注册到 GameInstance，防止GC
注册后，调用成员方法 SetReadyToDestroy 销毁、释放，从 GameInstance 注销

源码

class UGameInstance;

UCLASS()
class ENGINE_API UBlueprintAsyncActionBase : public UObject
{
	GENERATED_UCLASS_BODY()

	/** Called to trigger the action once the delegates have been bound */
	UFUNCTION(BlueprintCallable, meta=(BlueprintInternalUseOnly="true"))
	virtual void Activate();

	/**
	 * Call to globally register this object with a game instance, it will not be destroyed until SetReadyToDestroy is called
	 * This allows having an action stay alive until SetReadyToDestroy is manually called, allowing it to be used inside loops or if the calling BP goes away
	 */
	virtual void RegisterWithGameInstance(UObject* WorldContextObject);
	virtual void RegisterWithGameInstance(UGameInstance* GameInstance);

	/** Call when the action is completely done, this makes the action free to delete, and will unregister it with the game instance */
	virtual void SetReadyToDestroy();

protected:
	TWeakObjectPtr<UGameInstance> RegisteredWithGameInstance;
};

声明静态函数
需要动态多播委托，作为多个输出节点

代码实现

代码

UCLASS()
class DESIGNPATTERNS_API AAsyncTickActor : public AActor
{
public:
	UPROPERTY(BlueprintReadWrite)
		TArray<int32>CountdownNums;
};

// 定义委托类型
DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(FCompleteHandleDelegate, int32, Result);

UCLASS()
class DESIGNPATTERNS_API UMyBPAsyncAction : public UBlueprintAsyncActionBase
{
	GENERATED_BODY()
public:
	UMyBPAsyncAction() { UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__"")); }
	~UMyBPAsyncAction() { UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__"")); }

	// 自定义的异步蓝图节点
	UFUNCTION(BlueprintCallable, meta = (WorldContext = "WorldContextObject"), Category = "MyBPAsyncAction")
		static UMyBPAsyncAction* AsyncCountdown(UObject* WorldContextObject, AAsyncTickActor* AsyncTickActor, int32 StartNum);
public:
	//输出节点
	UPROPERTY(BlueprintAssignable)
		FCompleteHandleDelegate OnSucceeded;
	
	//输出节点
	UPROPERTY(BlueprintAssignable)
		FCompleteHandleDelegate OnFailed;
private:
	FTimerHandle TimerHandle;
	
protected:
	virtual void Activate() override;
};

void UMyBPAsyncAction::Activate()
{
	// 开新的线程，测试 Activate 调用情况
	Async(EAsyncExecution::ThreadPool, [&]()
		{
			UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__" Start Delay 1s."));
			FPlatformProcess::Sleep(1.0f);
			UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__" Delay Finished."));
		});
}

UMyBPAsyncAction* UMyBPAsyncAction::AsyncCountdown(UObject* WorldContextObject, AAsyncTickActor* AsyncTickActor, int32 StartNum)
{
	if (WorldContextObject == nullptr)
	{
		FFrame::KismetExecutionMessage(TEXT("Invalid WorldContextObject"), ELogVerbosity::Error);
		UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__" Invalid WorldContextObject."));
		return nullptr;
	}

	UMyBPAsyncAction* MyBPAsyncActionNode = NewObject<UMyBPAsyncAction>();
	// Lambda 表达式
	auto CountdownFunc = [&,MyBPAsyncActionNode, WorldContextObject, AsyncTickActor, StartNum]() {
		if (IsValid(AsyncTickActor))
		{
			if (AsyncTickActor->CountdownNums.Num() == StartNum)
			{
				// OnSucceeded输出节点
				MyBPAsyncActionNode->OnSucceeded.Broadcast(1);	
				
				// 清空定时器
				WorldContextObject->GetWorld()->GetTimerManager().ClearTimer(MyBPAsyncActionNode->TimerHandle);
				
				// 如果不使用，则销毁
				MyBPAsyncActionNode->SetReadyToDestroy();
				UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__" Countdown Completed."));
			}
			else
			{
				int32 length = AsyncTickActor->CountdownNums.Num();
				AsyncTickActor->CountdownNums.Add(length + 1);
				UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__" Counting down... %d"), length + 1);
			}
		}
		else
		{
			// OnFailed 输出节点
			MyBPAsyncActionNode->OnFailed.Broadcast(-1);
			WorldContextObject->GetWorld()->GetTimerManager().ClearTimer(MyBPAsyncActionNode->TimerHandle);
			UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__" Invalid AsyncTickActor."));
			FFrame::KismetExecutionMessage(TEXT("Invalid AsyncTickActor"), ELogVerbosity::Error);
		}
	};
	
	// 设置定时器并开始
	WorldContextObject->GetWorld()->GetTimerManager().SetTimer(MyBPAsyncActionNode->TimerHandle, FTimerDelegate::CreateLambda(CountdownFunc), 1.0f, true);
	UE_LOG(LogTemp, Warning, TEXT(__FUNCTION__" Countdown Starting."));
	return MyBPAsyncActionNode;
}