FTicker和FTickableGameObject

FTicker

FTicker運作于GameThread，提供了一個靜态方法CORE_API static FTicker& GetCoreTicker()，在FEngineLoop::Tick時會調用CORE_API void Tick(float DeltaTime)來對注冊的FTickerDelegate進行Tick。

FTicker可以設定tick的delay time。

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "UObject/NoExportTypes.h"
#include "Ticker.h"

#include "MyTickerObject.generated.h"

/**
 * 
 */
UCLASS(BlueprintType)
class MYPROJECT_API UMyTickerObject : public UObject
{
	GENERATED_BODY()
	
public:

	FDelegateHandle MyTickerHandle;

	UFUNCTION(BlueprintCallable)
	void Start()
	{
		MyTickerHandle = FTicker::GetCoreTicker().AddTicker(FTickerDelegate::CreateUObject(this, &UMyTickerObject::Tick));;
	}

	UFUNCTION(BlueprintCallable)
	void End()
	{
		FTicker::GetCoreTicker().RemoveTicker(MyTickerHandle);
	}

	bool Tick(float DeltaTime)
	{
		UE_LOG(LogTemp, Display, TEXT("UMyTickerObject Tick, %f."), DeltaTime);
		return true;
	}
};
           

FTickableGameObject

FTickableGameObject在GEngine::Tick中被調用，FTickableGameObject::TickObjects(nullptr, LEVELTICK_All, false, DeltaSeconds)。

FTickableGameObject在構造函數中會把自身加到NewTickableObjects清單中，是以一建立就有可能tick。如果子類繼承自UObject，那麼CDO也會tick，但是可以通過virtual bool IsTickable() const來控制tick的時機。

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "UObject/NoExportTypes.h"
#include "Tickable.h"
#include "MyTickableGameObject.generated.h"

/**
 * 
 */
UCLASS(BlueprintType)
class MYPROJECT_API UMyTickableGameObject : public UObject, public FTickableGameObject
{
	GENERATED_BODY()
	

public:

	virtual UWorld* GetTickableGameObjectWorld() const
	{
		return GetOuter()->GetWorld();
	}

	/**
	 * Used to determine if an object should be ticked when the game is paused.
	 * Defaults to false, as that mimics old behavior.
	 *
	 * @return true if it should be ticked when paused, false otherwise
	 */
	virtual bool IsTickableWhenPaused() const
	{
		return false;
	}

	/**
	 * Used to determine whether the object should be ticked in the editor.  Defaults to false since
	 * that is the previous behavior.
	 *
	 * @return	true if this tickable object can be ticked in the editor
	 */
	virtual bool IsTickableInEditor() const
	{
		return false;
	}

	/**
	 * Pure virtual that must be overloaded by the inheriting class. It will
	 * be called from within LevelTick.cpp after ticking all actors or from
	 * the rendering thread (depending on bIsRenderingThreadObject)
	 *
	 * @param DeltaTime	Game time passed since the last call.
	 */
	virtual void Tick(float DeltaTime)
	{
		UE_LOG(LogTemp, Display, TEXT("UMyTickableGameObject Tick, %f."), DeltaTime);

		TArray<UObject*> ReferredToObjects;				//req outer, ignore archetype, recursive, ignore transient
		FReferenceFinder ObjectReferenceCollector(ReferredToObjects, this, false, true, true, false);
		ObjectReferenceCollector.FindReferences(this);

		for (auto* object: ReferredToObjects)
		{
			UE_LOG(LogTemp, Display, TEXT("%s"), *object->GetName());
		}
	}

	/**
	* Virtual that can be overloaded by the inheriting class. It is
	* used to determine whether an object will ever be able to tick, and if not,
	* it will not get added to the tickable objects array. If the tickable tick type
	* is Conditional then the virtual IsTickable will be called to determine whether
	* to tick the object on each given frame
	*
	* @return	true if object will ever want to be ticked, false otherwise.
	*/
	virtual ETickableTickType GetTickableTickType() const { return ETickableTickType::Conditional; }

	/**
	 * Virtual that can be overloaded by the inheriting class. It is
	 * used to determine whether an object is ready to be ticked. This is
	 * required for example for all UObject derived classes as they might be
	 * loaded async and therefore won't be ready immediately.
	 *
	 * @return	true if object is ready to be ticked, false otherwise.
	 */
	virtual bool IsTickable() const { return !HasAnyFlags(EObjectFlags::RF_ClassDefaultObject); }

	/** return the stat id to use for this tickable **/
	virtual TStatId GetStatId() const { return TStatId(); }
};
           

轉載于:https://www.cnblogs.com/haisong1991/p/11532455.html