HLODRuntimeSubsystem.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "Subsystems/WorldSubsystem.h"
#include "Containers/Array.h"
#include "Containers/Map.h"
#include "UObject/ObjectKey.h"
#include "Containers/Ticker.h"
#include "Templates/Function.h"
#include "HLODRuntimeSubsystem.generated.h"
 
class IWorldPartitionHLODObject;
class AWorldPartitionHLOD;
class FSceneViewFamily;
class FHLODResourcesResidencySceneViewExtension;
class UWorldPartition;
class UWorldPartitionRuntimeCell;
class URuntimeHashExternalStreamingObjectBase;
class UWorld;
 
DECLARE_MULTICAST_DELEGATE_OneParam(FWorldPartitionHLODObjectRegisteredEvent, IWorldPartitionHLODObject* /* InHLODObject */);
DECLARE_MULTICAST_DELEGATE_OneParam(FWorldPartitionHLODObjectUnregisteredEvent, IWorldPartitionHLODObject* /* InHLODObject */);
DECLARE_MULTICAST_DELEGATE_TwoParams(FWorldPartitionHLODForEachHLODObjectInCellEvent, const UWorldPartitionRuntimeCell* /* InCell */, TFunction<void(IWorldPartitionHLODObject*)> /* InFunc */);
 
UE_DEPRECATED(5.6, "Use FWorldPartitionHLODObjectRegisteredEvent instead")
DECLARE_MULTICAST_DELEGATE_OneParam(FWorldPartitionHLODActorRegisteredEvent, AWorldPartitionHLOD* /* InHLODActor */);
UE_DEPRECATED(5.6, "Use FWorldPartitionHLODObjectUnregisteredEvent instead")
DECLARE_MULTICAST_DELEGATE_OneParam(FWorldPartitionHLODActorUnregisteredEvent, AWorldPartitionHLOD* /* InHLODActor */);
 
UCLASS(MinimalAPI)
class UWorldPartitionHLODRuntimeSubsystem : public UWorldSubsystem
{
    GENERATED_BODY()
 
public:
    ENGINE_API UWorldPartitionHLODRuntimeSubsystem();
 
    //~ Begin USubsystem Interface.
    ENGINE_API virtual void Initialize(FSubsystemCollectionBase& Collection) override;
    ENGINE_API virtual void Deinitialize() override;
    //~ End USubsystem Interface.
 
    //~ Begin UWorldSubsystem Interface.
    ENGINE_API virtual bool DoesSupportWorldType(const EWorldType::Type WorldType) const override;
    //~ End UWorldSubsystem Interface.
 
    ENGINE_API void RegisterHLODObject(IWorldPartitionHLODObject* InWorldPartitionHLOD);
    ENGINE_API void UnregisterHLODObject(IWorldPartitionHLODObject* InWorldPartitionHLOD);
 
    ENGINE_API void OnCellShown(const UWorldPartitionRuntimeCell* InCell);
    ENGINE_API void OnCellHidden(const UWorldPartitionRuntimeCell* InCell);
 
    ENGINE_API bool CanMakeVisible(const UWorldPartitionRuntimeCell* InCell);
    ENGINE_API bool CanMakeInvisible(const UWorldPartitionRuntimeCell* InCell);
 
    ENGINE_API FWorldPartitionHLODForEachHLODObjectInCellEvent& GetForEachHLODObjectInCellEvent();
 
    static ENGINE_API bool IsHLODEnabled();
 
    ENGINE_API const TArray<IWorldPartitionHLODObject*>& GetHLODObjectsForCell(const UWorldPartitionRuntimeCell* InCell) const;
    FWorldPartitionHLODObjectRegisteredEvent& OnHLODObjectRegisteredEvent() { return HLODObjectRegisteredEvent; }
    FWorldPartitionHLODObjectUnregisteredEvent& OnHLODObjectUnregisteredEvent() { return HLODObjectUnregisteredEvent; }
 
    ENGINE_API void OnExternalStreamingObjectInjected(URuntimeHashExternalStreamingObjectBase* ExternalStreamingObject);
    ENGINE_API void OnExternalStreamingObjectRemoved(URuntimeHashExternalStreamingObjectBase* ExternalStreamingObject);
 
    ENGINE_API void OnCVarsChanged();
 
#if !UE_BUILD_SHIPPING
    uint32 GetNumOutdatedHLODObjects() const { return OutdatedHLODObjects.Num(); }
#endif
 
    UE_DEPRECATED(5.6, "Use RegisterHLODObject instead")
    void RegisterHLODActor(AWorldPartitionHLOD* InWorldPartitionHLOD) {}
    UE_DEPRECATED(5.6, "Use UnregisterHLODObject instead")
    void UnregisterHLODActor(AWorldPartitionHLOD* InWorldPartitionHLOD) {}
 
    UE_DEPRECATED(5.6, "Use GetHLODObjectsForCell instead")
    const TArray<AWorldPartitionHLOD*>& GetHLODActorsForCell(const UWorldPartitionRuntimeCell* InCell) const
    {
        static TArray<AWorldPartitionHLOD*> Empty;
        return Empty;
    }
 
#if !UE_BUILD_SHIPPING
    UE_DEPRECATED(5.6, "Use GetNumOutdatedHLODObjects instead")
    uint32 GetNumOutdatedHLODActors() const { return 0; }
#endif
 
    PRAGMA_DISABLE_DEPRECATION_WARNINGS
    UE_DEPRECATED(5.6, "Use OnHLODObjectRegisteredEvent instead")
    FWorldPartitionHLODActorRegisteredEvent& OnHLODActorRegisteredEvent() { return HLODActorRegisteredEvent; }
    UE_DEPRECATED(5.6, "Use OnHLODObjectUnregisteredEvent instead")
    FWorldPartitionHLODActorUnregisteredEvent& OnHLODActorUnregisteredEvent() { return HLODActorUnregisteredEvent; }
    PRAGMA_ENABLE_DEPRECATION_WARNINGS
 
#if WITH_EDITOR
    UE_DEPRECATED(5.5, "Use UWorldPartitionHLODEditorSubsystem::WriteHLODStatsCSV()")
    static bool WriteHLODStatsCSV(UWorld* InWorld, const FString& InFilename) { return false; }
#endif
 
    UE_DEPRECATED(5.4, "You should perform this logic on the game side.")
    void SetHLODAlwaysLoadedCullDistance(int32 InCullDistance) {}
    
private:
    void ForEachHLODObjectInCell(const UWorldPartitionRuntimeCell* InCell, TFunction<void(IWorldPartitionHLODObject*)> InFunc);
    FWorldPartitionHLODForEachHLODObjectInCellEvent ForEachHLODObjectInCellEvent;
 
    struct FCellData
    {
        bool bIsCellVisible = false;
        TArray<IWorldPartitionHLODObject*> LoadedHLODs; // HLOD representation of the cell itself
    };
 
    struct FWorldPartitionHLODRuntimeData
    {
        TMap<FGuid, FCellData> CellsData;
    };
 
    TMap<TObjectPtr<UWorldPartition>, FWorldPartitionHLODRuntimeData> WorldPartitionsHLODRuntimeData;
    ENGINE_API const FCellData* GetCellData(const UWorldPartitionRuntimeCell* InCell) const;
    ENGINE_API FCellData* GetCellData(const UWorldPartitionRuntimeCell* InCell);
    ENGINE_API FCellData* GetCellData(IWorldPartitionHLODObject* InWorldPartitionHLOD);
    ENGINE_API FCellData* GetCellData(const UWorldPartition* InWorldPartition, const FGuid& InCellGuid);
 
    // Keep track of the state of warmup for an HLOD object
    struct FWorldPartitionHLODWarmupState
    {       
        uint32 WarmupLastRequestedFrame = INDEX_NONE;
        uint32 WarmupCallsUntilReady = INDEX_NONE;
        FBox WarmupBounds;
    };
    typedef TMap<IWorldPartitionHLODObject*, FWorldPartitionHLODWarmupState> FHLODWarmupStateMap;
    FHLODWarmupStateMap HLODObjectsToWarmup;
    
    // Keep track of all HLOD objects currently warming up for a given level
    // If there are any, the OnCleanupLevelDelegateHandle member should be bound
    struct FHLODLevelState
    {
        TSet<IWorldPartitionHLODObject*> HLODObjectsWarmingUp;
        FDelegateHandle OnCleanupLevelDelegateHandle;
    };
    typedef TMap<ULevel*, FHLODLevelState> FHLODLevelStateMap;
    FHLODLevelStateMap HLODLevelWarmupStates;
 
    FWorldPartitionHLODWarmupState& AddHLODObjectToWarmup(IWorldPartitionHLODObject* InHLODObject);
    void RemoveHLODObjectFromWarmup(IWorldPartitionHLODObject* InHLODObject);
    void OnCleanupLevel(ULevel* InCell);
 
    ENGINE_API void OnBeginRenderViews(const FSceneViewFamily& InViewFamily);
    ENGINE_API bool PrepareToWarmup(const UWorldPartitionRuntimeCell* InCell, IWorldPartitionHLODObject* InHLODObject);
    ENGINE_API bool ShouldPerformWarmup() const;
    ENGINE_API bool ShouldPerformWarmupForCell(const UWorldPartitionRuntimeCell* InCell) const;
    bool bCachedShouldPerformWarmup;
 
    static ENGINE_API class FAutoConsoleCommand EnableHLODCommand;
 
    static ENGINE_API bool WorldPartitionHLODEnabled;
 
    friend class FHLODResourcesResidencySceneViewExtension;
    TSharedPtr<FHLODResourcesResidencySceneViewExtension, ESPMode::ThreadSafe> SceneViewExtension;
 
    ENGINE_API void OnWorldPartitionInitialized(UWorldPartition* InWorldPartition);
    ENGINE_API void OnWorldPartitionUninitialized(UWorldPartition* InWorldPartition);
 
    FWorldPartitionHLODObjectRegisteredEvent    HLODObjectRegisteredEvent;
    FWorldPartitionHLODObjectUnregisteredEvent  HLODObjectUnregisteredEvent;
 
    PRAGMA_DISABLE_DEPRECATION_WARNINGS
    FWorldPartitionHLODActorRegisteredEvent     HLODActorRegisteredEvent;
    FWorldPartitionHLODActorUnregisteredEvent   HLODActorUnregisteredEvent;
    PRAGMA_ENABLE_DEPRECATION_WARNINGS
 
    // Referenced Cell GUID -> HLOD Actor
    TMap<FGuid, TSet<IWorldPartitionHLODObject*>> StandaloneHLODObjectsReferencingUnloadedCells;
    
    // Cell GUID -> WorldPartition
    TMap<FGuid, TObjectPtr<UWorldPartition>> StandaloneHLODCellToWorldPartitionMap;
 
#if !UE_BUILD_SHIPPING
    TSet<IWorldPartitionHLODObject*> OutdatedHLODObjects;
#endif
};