LightWeightInstanceSubsystem.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "UObject/ObjectMacros.h"
#include "GameFramework/LightWeightInstanceManager.h"
#include "Misc/TransactionallySafeRWLock.h"
#include "Templates/SharedPointer.h"
 
 
ENGINE_API DECLARE_LOG_CATEGORY_EXTERN(LogLightWeightInstance, Log, All);
 
class FAutoConsoleVariableRef;
 
struct FLightWeightInstanceSubsystem
{
    static FLightWeightInstanceSubsystem& Get()
    {
        static TSharedPtr<FLightWeightInstanceSubsystem, ESPMode::ThreadSafe> LWISubsystemSingleton = []
        {
            return MakeShareable(new FLightWeightInstanceSubsystem());
        }();
        return *LWISubsystemSingleton;
    }
 
    ENGINE_API FLightWeightInstanceSubsystem();
    ENGINE_API ~FLightWeightInstanceSubsystem();
 
    // Returns the instance manager that handles the given handle
    ENGINE_API ALightWeightInstanceManager* FindLightWeightInstanceManager(const FActorInstanceHandle& Handle) const;
 
    // Returns the instance manager that handles actors of type ActorClass in level Level
    UE_DEPRECATED(5.3, "Use the version that takes in a position.")
    ENGINE_API ALightWeightInstanceManager* FindLightWeightInstanceManager(UClass* ActorClass, const UDataLayerInstance* Layer, UWorld* World) const;
 
    // Returns the instance manager that handles instances of type Class that live in Level
    UE_DEPRECATED(5.3, "Use the version that takes in a position.")
    ENGINE_API ALightWeightInstanceManager* FindOrAddLightWeightInstanceManager(UClass* ActorClass, const UDataLayerInstance* DataLayer, UWorld* World);
 
    // Returns the instance manager that handles actors of type ActorClass in level Level
    ENGINE_API ALightWeightInstanceManager* FindLightWeightInstanceManager(UClass& ActorClass, UWorld& World, const FVector& InPos, const UDataLayerInstance* DataLayer = nullptr) const;
 
    // Returns the instance manager that handles instances of type Class that live in Level
    ENGINE_API ALightWeightInstanceManager* FindOrAddLightWeightInstanceManager(UClass& ActorClass, UWorld& World, const FVector& InPos, const UDataLayerInstance* DataLayer = nullptr);
 
    // Returns the actor specified by Handle if it exists. Returns nullptr if it doesn't
    ENGINE_API AActor* GetActor_NoCreate(const FActorInstanceHandle& Handle) const;
 
    // Returns the class of the actor specified by Handle.
    ENGINE_API UClass* GetActorClass(const FActorInstanceHandle& Handle);
 
    ENGINE_API FVector GetLocation(const FActorInstanceHandle& Handle);
 
    ENGINE_API FString GetName(const FActorInstanceHandle& Handle);
 
    ENGINE_API ULevel* GetLevel(const FActorInstanceHandle& Handle);
 
    // Returns true if the object represented by Handle is in InLevel
    ENGINE_API bool IsInLevel(const FActorInstanceHandle& Handle, const ULevel* InLevel);
 
    // Returns a handle to a new light weight instance that represents an object of type ActorClass
    ENGINE_API FActorInstanceHandle CreateNewLightWeightInstance(UClass* ActorClass, FLWIData* InitData, UDataLayerInstance* Layer, UWorld* World);
 
    // deletes the instance identified by Handle
    ENGINE_API void DeleteInstance(const FActorInstanceHandle& Handle);
 
    // Helper that converts a position (world space) into a coordinate for the LWI grid.
    UE_DEPRECATED(5.3, "Use LWI Managers version of ConvertPositionToCoord()")
    static ENGINE_API FInt32Vector3 ConvertPositionToCoord(const FVector& InPosition);
 
    // Add a manager to the subsystem, thread safe.
    ENGINE_API bool AddManager(ALightWeightInstanceManager* Manager);
 
    // Remove a manager from the subsystem, thread safe.
    ENGINE_API bool RemoveManager(ALightWeightInstanceManager* Manager);
 
protected:
    // Returns the class of the instance manager best suited to support instances of type ActorClass
    ENGINE_API UClass* FindBestInstanceManagerClass(const UClass* ActorClass);
 
    // Returns the index associated with Manager
    ENGINE_API int32 GetManagerIndex(const ALightWeightInstanceManager* Manager) const;
 
    // Returns the light weight instance manager at index Index
    ENGINE_API const ALightWeightInstanceManager* GetManagerAt(int32 Index) const;
 
private:
    // TODO: preallocate the size of this based on a config variable
    TArray<ALightWeightInstanceManager*> LWInstanceManagers;
 
    // Mutex to make sure we don't change the LWInstanceManagers array while reading/writing it.
    mutable FTransactionallySafeRWLock LWIManagersRWLock;
 
#ifdef WITH_EDITOR
private:
    FDelegateHandle OnLevelActorAddedHandle;
    FDelegateHandle OnLevelActorDeletedHandle;
#endif // WITH_EDITOR
};