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  3. ULevelStreaming

ULevelStreaming

Abstract base class of container object encapsulating data required for streaming and providing interface for when a level should be streamed in and out of memory.

API > API/Runtime > API/Runtime/Engine

Abstract base class of container object encapsulating data required for streaming and providing interface for when a level should be streamed in and out of memory.

   
Name ULevelStreaming
Type class
Header File /Engine/Source/Runtime/Engine/Classes/Engine/LevelStreaming.h
Include Path #include "Engine/LevelStreaming.h"

Syntax

UCLASS (Abstract, EditInlineNew, BlueprintType, Within=World, MinimalAPI)  
class ULevelStreaming : public UObject

Inheritance Hierarchy

Derived Classes

Constructors

Name Remarks Include Path Unreal Specifiers

ULevelStreaming ( const FObjectInitializer& ObjectInitializer
)

   Engine/LevelStreaming.h  

Structs

Name Remarks
FLevelAnnotation Annotation for fast inverse lookup.
FPackageNameMatcher Matcher for searching streaming levels by PackageName

Enums

Public

Name Remarks
EReqLevelBlock  

Constants

Name Type Remarks Include Path
LevelAnnotations FUObjectAnnotationSparse< FLevelAnnotation, false >   Engine/LevelStreaming.h

Variables

Public

Name Type Remarks Include Path Unreal Specifiers
pad0 ECurrentState   Engine/LevelStreaming.h  
bClientOnlyVisible bool Applied to LoadedLevel Engine/LevelStreaming.h  
bDisableDistanceStreaming uint8 Whether this level streaming object should be ignored by world composition distance streaming, so streaming state can be controlled by other systems (ex: in blueprints) Engine/LevelStreaming.h
  • Transient
  • Category=LevelStreaming
  • BlueprintReadWrite
bDrawOnLevelStatusMap uint8 If true, will be drawn on the 'level streaming status' map (STAT LEVELMAP console command) Engine/LevelStreaming.h
  • EditAnywhere
  • AdvancedDisplay
  • Category=LevelStreaming
bGarbageCollectionClusteringEnabled uint8 If true, allows garbage collection clustering for the level. Engine/LevelStreaming.h  
bIsStatic uint8 Whether this level only contains static actors that aren't affected by gameplay or replication. Engine/LevelStreaming.h
  • EditDefaultsOnly
  • Category=LevelStreaming
bLocked uint8 Whether this level is locked; that is, its actors are read-only. Engine/LevelStreaming.h  
bShouldBlockOnLoad uint8 Whether we want to force a blocking load Engine/LevelStreaming.h
  • Category=LevelStreaming
  • BlueprintReadWrite
bShouldBlockOnUnload uint8 Whether we want to force a blocking unload Engine/LevelStreaming.h
  • Category=LevelStreaming
  • BlueprintReadWrite
EditorPathOwner TWeakObjectPtr< UObject > Applied to LoadedLevel Engine/LevelStreaming.h
  • Transient
EditorStreamingVolumes TArray< TObjectPtr< ALevelStreamingVolume > > The level streaming volumes bound to this level. Engine/LevelStreaming.h
  • EditAnywhere
  • Category=LevelStreaming
  • Meta=(DisplayName="Streaming Volumes", NoElementDuplicate)
FailedToLoad ECurrentState   Engine/LevelStreaming.h  
Keywords TArray< FString > List of keywords to filter on in the level browser Engine/LevelStreaming.h  
LastVolumeUnloadRequestTime float Time of last volume unload request. Used in preventing spurious unload requests. Engine/LevelStreaming.h  
LevelColor FLinearColor The level color used for visualization. (Show -> Advanced -> Level Coloration) Engine/LevelStreaming.h
  • EditAnywhere
  • Category=LevelStreaming
LevelTransform FTransform Transform applied to actors after loading. Engine/LevelStreaming.h
  • EditAnywhere
  • Category=LevelStreaming
  • BlueprintReadWrite
LoadedNotVisible ECurrentState   Engine/LevelStreaming.h  
LoadedVisible ECurrentState   Engine/LevelStreaming.h  
Loading ECurrentState   Engine/LevelStreaming.h  
LODPackageNames TArray< FName > LOD versions of this level Engine/LevelStreaming.h  
LODPackageNamesToLoad TArray< FName > LOD package names on disk Engine/LevelStreaming.h  
MakingInvisible ECurrentState   Engine/LevelStreaming.h  
MakingVisible ECurrentState   Engine/LevelStreaming.h  
MinTimeBetweenVolumeUnloadRequests float Cooldown time in seconds between volume-based unload requests. Engine/LevelStreaming.h
  • EditAnywhere
  • AdvancedDisplay
  • Category=LevelStreaming
  • Meta=(ClampMin="0", UIMin="0", UIMax="10")
OnLevelHidden FLevelStreamingVisibilityStatus Called when level is no longer visible, may not be removed from world yet Engine/LevelStreaming.h
  • BlueprintAssignable
OnLevelLoaded FLevelStreamingLoadedStatus Called when level is streamed in Engine/LevelStreaming.h
  • BlueprintAssignable
OnLevelShown FLevelStreamingVisibilityStatus Called when level is added to the world and is visible Engine/LevelStreaming.h
  • BlueprintAssignable
OnLevelUnloaded FLevelStreamingLoadedStatus Called when level is streamed out Engine/LevelStreaming.h
  • BlueprintAssignable
PackageNameToLoad FName If this isn't Name_None, then we load from this package on disk to the new package named PackageName Engine/LevelStreaming.h  
Unloaded ECurrentState   Engine/LevelStreaming.h  

Protected

Name Type Remarks Include Path Unreal Specifiers
bHasCachedLoadedLevelPackageName uint8 Whether CachedLoadedLevelPackageName is valid Engine/LevelStreaming.h  
bHasCachedWorldAssetPackageFName uint8 Whether CachedWorldAssetPackageFName is valid Engine/LevelStreaming.h  
bIsRequestingUnloadAndRemoval uint8 Whether this level streaming object's level should be unloaded and the object be removed from the level list. Engine/LevelStreaming.h  
bShouldBeVisible uint8 Whether the level should be visible if it is loaded Engine/LevelStreaming.h
  • Category=LevelStreaming
  • BlueprintSetter=SetShouldBeVisible
bShouldBeVisibleInEditor uint8 Whether this level should be visible in the Editor Engine/LevelStreaming.h  
CachedLoadedLevelPackageName FName The cached package name of the currently loaded level. Engine/LevelStreaming.h  
CachedWorldAssetPackageFName FName The cached package name of the world asset that is loaded by the levelstreaming Engine/LevelStreaming.h  
CurrentState ELevelStreamingState What the current streamed state of the streaming level is Engine/LevelStreaming.h  
CurrentStateLock FTransactionallySafeRWLock Used to get the CurrentState from an async task while it can be modified by the gamethread Engine/LevelStreaming.h  
FolderPath FName The folder path for this level within the world browser. Engine/LevelStreaming.h  
LevelLODIndex int32 Requested LOD. Non LOD sub-levels have Index = -1 Engine/LevelStreaming.h
  • Transient
  • Category=LevelStreaming
  • BlueprintSetter=SetLevelLODIndex
NetVisibilityState FNetLevelVisibilityState State for server handshake of NetLevelVisibilty requests Engine/LevelStreaming.h  
StreamingPriorityOverrideBackup TOptional< int32 >   Engine/LevelStreaming.h  
TargetState ELevelStreamingTargetState What streamed state the streaming level is transitioning towards Engine/LevelStreaming.h  

Functions

Public

Name Remarks Include Path Unreal Specifiers

void AddLevelToCollectionAfterReload()

   Engine/LevelStreaming.h  

void BeginClientNetVisibilityRequest ( bool bInShouldBeVisible
)

 Begin a client instigated NetVisibility request Engine/LevelStreaming.h  

virtual bool CanReplicateStreamingStatus()

 Returns whether level status can be replicated from the server to the client Engine/LevelStreaming.h  

void ClearLoadedLevel()

 Sets the LoadedLevel value to NULL Engine/LevelStreaming.h  

ULevelStreaming * CreateInstance ( const FString& UniqueInstanceName
)

 Creates a new instance of this streaming level with a provided unique instance name Engine/LevelStreaming.h
  • BlueprintCallable
  • Category="Game"

const TArray< int32 > & GetAsyncRequestIDs ()

 Returns the RequestIDs for the async load requests required to load the level. Engine/LevelStreaming.h  

PRAGMA_DISABLE_DEPRECATION_WARNINGS ECurrentState GetCurrentState()

 Returns the current loaded/visible state of the streaming level. Engine/LevelStreaming.h  

const FName & GetFolderPath()

 Get the folder path for this level for use in the world browser. Only available in editor builds Engine/LevelStreaming.h  

virtual TOptional< FFolder::FRootObject > GetFolderRootObject()

   Engine/LevelStreaming.h  

bool GetIsRequestingUnloadAndRemoval()

 Returns if the streaming level has requested to be unloaded and removed. Engine/LevelStreaming.h
  • BlueprintPure
  • Category=LevelStreaming

int32 GetLevelLODIndex()

 Returns the world composition level LOD index. Engine/LevelStreaming.h  

ALevelScriptActor * GetLevelScriptActor()

 Returns the Level Script Actor of the level if the level is loaded and valid Engine/LevelStreaming.h
  • BlueprintPure
  • Meta=(BlueprintInternalUseOnly="true")

ELevelStreamingState GetLevelStreamingState()

   Engine/LevelStreaming.h  

EStreamingStatus GetLevelStreamingStatus()

 Used for debugging Level's status Engine/LevelStreaming.h  

ULevel * GetLoadedLevel()

 Gets a pointer to the LoadedLevel value Engine/LevelStreaming.h
  • BlueprintCallable
  • Category="Game"

int32 GetPriority ()

 Sets the relative priority of considering the streaming level. Engine/LevelStreaming.h  
Returns the value of bShouldBeVisible. Engine/LevelStreaming.h  

bool GetShouldBeVisibleInEditor()

 Returns if the streaming level should be visible in the editor. Engine/LevelStreaming.h  

FBox GetStreamingVolumeBounds()

 Get a bounding box around the streaming volumes associated with this LevelStreaming object Engine/LevelStreaming.h  

virtual UWorld * GetStreamingWorld()

 Returns the UWorld that triggered the streaming of this streaming level. Engine/LevelStreaming.h  

virtual UWorld * GetWorld()

   Engine/LevelStreaming.h  

const TSoftObjectPtr< UWorld > & GetWorldAsset()

 Returns a constant reference to the world asset this streaming level object references Engine/LevelStreaming.h  

virtual FName GetWorldAssetPackageFName()

 Gets the package name for the world asset referred to by this level streaming as an FName Engine/LevelStreaming.h
  • BlueprintCallable
  • Category="Game"

FString GetWorldAssetPackageName()

 Gets the package name for the world asset referred to by this level streaming Engine/LevelStreaming.h  

virtual const IWorldPartitionCell * GetWorldPartitionCell()

   Engine/LevelStreaming.h  

bool HasLoadedLevel()

 Returns whether the streaming level has loaded a level. Engine/LevelStreaming.h  

bool HasLoadRequestPending()

 Returns whether the streaming level is in the loading state. Engine/LevelStreaming.h  

bool IsLevelLoaded()

 Returns whether streaming level is loaded Engine/LevelStreaming.h
  • BlueprintCallable
  • Category="Game"

bool IsLevelVisible()

 Returns whether streaming level is visible Engine/LevelStreaming.h
  • BlueprintCallable
  • Category="Game"

bool IsStreamingStatePending()

 Returns whether level has streaming state change pending Engine/LevelStreaming.h
  • BlueprintCallable
  • Category="Game"

virtual bool IsUserManaged()

 Returns if the streaming level can be modified by user Engine/LevelStreaming.h  

bool IsValidStreamingLevel()

 Returns false if the level package associated to that streaming level is invalid. Engine/LevelStreaming.h  

bool IsWaitingForNetVisibilityTransactionAck ( ENetLevelVisibilityRequest InRequestType
) const

 Check if we are waiting for a making visible or invisible streaming transaction Engine/LevelStreaming.h  

void RemoveLevelFromCollectionForReload()

 After a sub level is reloaded in the editor the cache state needs to be refreshed. Engine/LevelStreaming.h  

void RemoveStreamingVolumeDuplicates()

 Remove duplicates in EditorStreamingVolumes list Engine/LevelStreaming.h  

void RenameForPIE ( int PIEInstanceID,
bool bKeepWorldAssetName
)

 Rename package name to PIE appropriate name Engine/LevelStreaming.h  

void ResetPriorityOverride()

 Restore the original streaming level priority after a call to SetPriorityOverride(). Engine/LevelStreaming.h  

void SetFolderPath ( const FName& InFolderPath
)

 Sets the folder path for this level in the world browser. Only available in editor builds Engine/LevelStreaming.h  

void SetIsRequestingUnloadAndRemoval ( bool bInIsRequestingUnloadAndRemoval
)

 Sets if the streaming level should be unloaded and removed. Engine/LevelStreaming.h
  • BlueprintCallable
  • Category=LevelStreaming

void SetLevelLODIndex ( int32 LODIndex
)

 Sets the world composition level LOD index and marks the streaming level as requiring consideration. Engine/LevelStreaming.h
  • BlueprintSetter

void SetPriority ( int32 NewPriority
)

 Sets the relative priority of considering the streaming level. Engine/LevelStreaming.h
  • BlueprintSetter

void SetPriorityOverride ( int32 PriorityOverride
)

 Provide a temporary priority override for the streaming level. Engine/LevelStreaming.h  

virtual void SetShouldBeLoaded ( bool bInShouldBeLoaded
)

 Virtual that can be overridden to change whether a streaming level should be loaded. Engine/LevelStreaming.h
  • BlueprintSetter

void SetShouldBeVisible ( bool bInShouldBeVisible
)

 Sets the should be visible flag and marks the streaming level as requiring consideration. Engine/LevelStreaming.h
  • BlueprintSetter

void SetShouldBeVisibleInEditor ( bool bInShouldBeVisibleInEditor
)

 Sets if the streaming level should be visible in the editor. Engine/LevelStreaming.h  

virtual void SetWorldAsset ( const TSoftObjectPtr< UWorld >& NewWorldAsset
)

 Setter for WorldAsset. Engine/LevelStreaming.h  

void SetWorldAssetByPackageName ( FName InPackageName
)

 Sets the world asset based on the package name assuming it contains a world of the same name. Engine/LevelStreaming.h  

virtual bool ShouldBeAlwaysLoaded()

   Engine/LevelStreaming.h  

virtual bool ShouldBeLoaded ()

 Return whether this level should be present in memory which in turn tells the streaming code to stream it in. Engine/LevelStreaming.h
  • BlueprintGetter

virtual bool ShouldBeVisible()

 Return whether this level should be visible/ associated with the world if it is loaded. Engine/LevelStreaming.h  

virtual bool ShouldBlockOnUnload()

   Engine/LevelStreaming.h  

virtual bool ShouldRequireFullVisibilityToRender()

 Returns whether level should start to render only when it will be fully added to the world or not. Engine/LevelStreaming.h  

virtual bool ShowInLevelCollection()

 Returns if the streaming level is visible in LevelCollectionModel Engine/LevelStreaming.h  

void UpdateNetVisibilityTransactionState ( bool bInShouldBeVisible,
FNetLevelVisibilityTransactionId TransactionId
)

 Set the current state of the current visibility/streaming transaction Engine/LevelStreaming.h  

Overridden from UObject

Name Remarks Include Path Unreal Specifiers

virtual void PostEditChangeProperty ( FPropertyChangedEvent& PropertyChangedEvent
)

   Engine/LevelStreaming.h  

virtual void PostEditUndo()

 Override Pre/PostEditUndo functions to handle editor transform Engine/LevelStreaming.h  

virtual void PostLoad()

   Engine/LevelStreaming.h  

virtual void Serialize ( FArchive& Ar
)

   Engine/LevelStreaming.h  

Protected

Name Remarks Include Path Unreal Specifiers

bool CanMakeInvisible()

 Returns whether the streaming level can make invisible (can call RemoveFromWorld). Engine/LevelStreaming.h  

bool CanMakeVisible()

 Returns whether the streaming level can make visible (can call AddToWorld). Engine/LevelStreaming.h  

FName GetLoadedLevelPackageName()

   Engine/LevelStreaming.h  

virtual void OnCurrentStateChanged ( ELevelStreamingState OldState,
ELevelStreamingState NewState
)

 Called when the current state changes Engine/LevelStreaming.h  

virtual void OnLevelLoadedChanged ( ULevel* Level
)

 Called by SetLoadedLevel Engine/LevelStreaming.h  

void OnLoadingFinished()

   Engine/LevelStreaming.h  

void OnLoadingStarted()

   Engine/LevelStreaming.h  

void PrepareLoadedLevel ( ULevel* InLevel,
UPackage* InLevelPackage,
int32 InPIEInstanceID
)

 Sets loaded level, fixups for PIE, notifies level is loaded, apply necessary modifications on level once loaded. Engine/LevelStreaming.h  

virtual bool RequestLevel ( UWorld* PersistentWorld,
bool bAllowLevelLoadRequests,
EReqLevelBlock BlockPolicy
)

 Try to find loaded level in memory, issue a loading request otherwise Engine/LevelStreaming.h  

virtual bool RequestVisibilityChange ( bool bVisible
)

 Prepare the transition to the new state. Engine/LevelStreaming.h  

void SetCurrentState ( ELevelStreamingState NewState
)

 Updates the current state of the streaming level and notifies any observers. Engine/LevelStreaming.h  

virtual void SetLoadedLevel ( ULevel* Level
)

 Sets the value of LoadedLevel Engine/LevelStreaming.h  

bool ValidateUniqueWorldAsset ( UWorld* PersistentWorld
)

 Called by RequestLevel to detect existing streaming level with same world asset Engine/LevelStreaming.h  

Static

Name Remarks Include Path Unreal Specifiers

static bool AllowIncrementalRemovalWhilePendingVisibility()

 Whether incremental removal of a streaming level can be done while there's a pending visible streaming level being processed. Engine/LevelStreaming.h  

static void BroadcastLevelLoadedStatus ( UWorld* PersistentWorld,
FName LevelPackageName,
bool bLoaded
)

 Traverses all streaming level objects in the persistent world and in all inner worlds and calls appropriate delegate for streaming objects that refer specified level Engine/LevelStreaming.h  

static void BroadcastLevelVisibleStatus ( UWorld* PersistentWorld,
FName LevelPackageName,
bool bVisible
)

 Traverses all streaming level objects in the persistent world and in all inner worlds and calls appropriate delegate for streaming objects that refer specified level Engine/LevelStreaming.h  

static void DebugDrawLegend ( const UWorld* World,
UCanvas* Canvas,
const FVector2D& Offset
)

 Utility that draws a legend of level streaming status Engine/LevelStreaming.h  

static bool DefaultAllowClientUseMakingInvisibleTransactionRequests()

 Whether client should be using making invisible transaction requests to the server (default value). Engine/LevelStreaming.h  

static bool DefaultAllowClientUseMakingVisibleTransactionRequests()

 Whether client should be using making visible transaction requests to the server (default value). Engine/LevelStreaming.h  

static PRAGMA_DISABLE_DEPRECATION_WARNINGS const TCHAR * EnumToString ( ECurrentState InCurrentState
)

   Engine/LevelStreaming.h  

static ULevelStreaming * FindStreamingLevel ( const ULevel* Level
)

   Engine/LevelStreaming.h  

static FColor GetLevelStreamingStatusColor ( EStreamingStatus Status
)

 Utility that gets a color for a particular level status Engine/LevelStreaming.h  

static const TCHAR * GetLevelStreamingStatusDisplayName ( EStreamingStatus Status
)

 Utility that returns a string for a streaming level status Engine/LevelStreaming.h  

static void RemoveLevelAnnotation ( const ULevel* Level
)

   Engine/LevelStreaming.h  

static bool ShouldReuseUnloadedButStillAroundLevels ( const ULevel* InLevel
)

 If true level streaming can reuse an unloaded level that wasn't GC'd yet. Engine/LevelStreaming.h  

static bool ShouldServerUseMakingVisibleTransactionRequest()

 If true server will wait for client acknowledgment before making treating streaming levels as visible for the client Engine/LevelStreaming.h  

Deprecated Variables

Name Type Remarks Include Path Unreal Specifiers
DrawColor_DEPRECATED FColor Deprecated level color used for visualization. Engine/LevelStreaming.h  
PackageName_DEPRECATED FName Deprecated name of the package containing the level to load. Engine/LevelStreaming.h  

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