Tickable.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
    Tickable.h: Interface for tickable objects.
 
=============================================================================*/
 
#pragma once
 
#include "CoreMinimal.h"
#include "Stats/Stats.h"
#include "Misc/ScopeLock.h"
#include "Misc/TransactionallySafeCriticalSection.h"
#include "Engine/EngineBaseTypes.h"
 
enum class ETickableTickType : uint8
{
    Conditional,
 
    Always,
 
    Never,
 
    NewObject
};
 
class FTickableObjectBase
{
protected:  
    struct FTickableObjectEntry
    {
        FTickableObjectBase* TickableObject = nullptr;
        ETickableTickType TickType = ETickableTickType::NewObject;
 
        bool operator==(FTickableObjectBase* OtherObject) const { return TickableObject == OtherObject; }
    };
 
    struct FTickableStatics
    {
        FTransactionallySafeCriticalSection TickableObjectsCritical;
 
        TArray<FTickableObjectBase::FTickableObjectEntry> TickableObjects;
 
        FTransactionallySafeCriticalSection NewTickableObjectsCritical;
 
        TMap<FTickableObjectBase*, ETickableTickType> NewTickableObjects;
 
        bool bIsTickingObjects = false;
 
        bool bNeedsCleanup = false;
 
 
        ENGINE_API void QueueTickableObjectForAdd(FTickableObjectBase* InTickable, ETickableTickType NewTickType = ETickableTickType::NewObject);
 
        ENGINE_API void SetTickTypeForTickableObject(FTickableObjectBase* TickableObject, ETickableTickType NewTickType);
 
 
        ENGINE_API void StartTicking();
 
        ENGINE_API void FinishTicking();
    };
 
    static ENGINE_API void SimpleTickObjects(FTickableStatics& Statics, TFunctionRef<void(FTickableObjectBase*)> TickFunc);
 
public:
    virtual void Tick( float DeltaTime ) = 0;
 
    virtual ETickableTickType GetTickableTickType() const { return ETickableTickType::Conditional; }
 
    virtual bool IsTickable() const { return true; }
 
    UE_DEPRECATED(5.5, "Use IsTickable for conditional ticks and SetTickableTickType to change the tick type after initial registration")
    virtual bool IsAllowedToTick() const { return true; }
 
    virtual TStatId GetStatId() const = 0;
};
 
class FTickableGameObject : public FTickableObjectBase
{
    static ENGINE_API FTickableStatics& GetStatics();
 
public:
    UE_NONCOPYABLE(FTickableGameObject);
 
    ENGINE_API FTickableGameObject(ETickableTickType StartingTickType = ETickableTickType::NewObject);
 
    ENGINE_API virtual ~FTickableGameObject();
 
    virtual bool IsTickableWhenPaused() const
    {
        return false;
    }
 
    virtual bool IsTickableInEditor() const
    {
        return false;
    }
 
    virtual UWorld* GetTickableGameObjectWorld() const 
    { 
        return nullptr;
    }
 
    ENGINE_API void SetTickableTickType(ETickableTickType NewTickType);
 
    static ENGINE_API void TickObjects(UWorld* World, ELevelTick LevelTickType, bool bIsPaused, float DeltaSeconds);
};