FTicker
FTicker运行于GameThread，提供了一个静态方法CORE_API static FTicker& GetCoreTicker()，在FEngineLoop::Tick时会调用CORE_API void Tick(float DeltaTime)来对注册的FTickerDelegate进行Tick。
FTicker可以设定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中被调用，FTickableGameObject::TickObjects(nullptr, LEVELTICK_All, false, DeltaSeconds)。
FTickableGameObject在构造函数中会把自身加到NewTickableObjects列表中，因此一创建就有可能tick。如果子类继承自UObject，那么CDO也会tick，但是可以通过virtual bool IsTickable() const来控制tick的时机。
// 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(); }
};