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> Unreal Engine API Reference > Runtime > Engine > Engine > ULevel

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ULevel

The level object.

Inheritance Hierarchy

UObjectBase

UObjectBaseUtility

UObject

ULevel

References

Module	Engine
Header	/Engine/Source/Runtime/Engine/Classes/Engine/Level.h
Include	#include "Engine/Level.h"

Syntax

class ULevel :
    public UObject,
    public IInterface_AssetUserData,
    public ITextureStreamingContainer

Remarks

The level object. Contains the level's actor list, BSP information, and brush list. Every Level has a World as its Outer and can be used as the PersistentLevel, however, when a Level has been streamed in the OwningWorld represents the World that it is a part of. A Level is a collection of Actors (lights, volumes, mesh instances etc.). Multiple Levels can be loaded and unloaded into the World to create a streaming experience.

Variables

	Name	Description
TObjectPtr< ULe...	ActorCluster
EActorPackaging...	ActorPackagingScheme
TArray< AActor ...	Actors	Array of all actors in this level, used by FActorIteratorBase and derived classes
TArray< AActor ...	ActorsForGC	Array of actors to be exposed to GC in this level.
TMap< FName, TO...	ActorsModifiedForPIE	List of modified, unsaved actors that needs to be duplicated for PIE
TArray< TObject...	AssetUserData	Array of user data stored with the asset
uint8: 1	bActorClusterCreated	Whether the level had its actor cluster created.
uint8: 1	bAlreadyAssociatedStreamableResources	Whether we already associated streamable resources.
uint8: 1	bAlreadyClearedActorsSeamlessTravelFlag	Whether we already cleared AActor::bActorSeamlessTraveled.
uint8: 1	bAlreadyInitializedNetworkActors	Whether we already initialized network actors.
uint8: 1	bAlreadyMovedActors	The below variables are used temporarily while making a level visible.
uint8: 1	bAlreadyShiftedActors	Whether we already shift actors positions according to world composition.
uint8: 1	bAlreadySortedActorList	Whether we already sorted the actor list.
uint8: 1	bAlreadyUpdatedComponents	Whether we already updated components.
uint8: 1	bAreComponentsCurrentlyRegistered	Whether components are currently registered or not.
uint8: 1	bClientOnlyVisible	Whether this level is specific to client, visibility state will not be replicated to server
uint8: 1	bContainsStableActorGUIDs	Whether the level has been saved after introducing actor GUIDs
uint8: 1	bFixupActorFoldersAtLoad	Whether the level should call FixupActorFolders on its actors when loading the level/actors (only used when level is using actor folder objects)
uint8: 1	bGeometryDirtyForLighting	Whether the geometry needs to be rebuilt for correct lighting
uint8: 1	bHasCurrentActorCalledPreRegister	Whether the actor referenced by CurrentActorIndexForUpdateComponents has called PreRegisterAllComponents
uint8: 1	bHasRerunConstructionScripts	Whether this level has gone through a complete rerun construction script pass.
uint8: 1	bIsAssociatingLevel	Whether this level is in the process of being associated with its world (i.e. we are within AddToWorld for this level
uint8: 1	bIsBeingRemoved	Whether the level is currently being removed from the world
uint8: 1	bIsDisassociatingLevel	Whether this level is in the process of being disassociated with its world (i.e. we are within RemoveFromWorld for this level
uint8: 1	bIsLightingScenario	Whether the level is a lighting scenario.
uint8: 1	bIsPartitioned	Whether the level is partitioned or not.
uint8: 1	bIsVisible	Whether the level is currently visible/ associated with the world.
uint8: 1	bLocked	Whether this level is locked; that is, its actors are read-only Used by WorldBrowser to lock a level when corresponding ULevelStreaming does not exist
bool	bPromptWhenAddingToLevelBeforeCheckout
bool	bPromptWhenAddingToLevelOutsideBounds
uint8: 1	bRequireFullVisibilityToRender	Whether this level should be fully added to the world before rendering its components
uint8: 1	bStaticComponentsRegisteredInStreamingManager	Whether the level has finished registering all static components in the streaming manager.
uint8: 1	bTextureStreamingRotationChanged	Whether a level transform rotation was applied since the texture streaming builds.
bool	bUseExternalActors	Use external actors, new actor spawned in this level will be external and existing external actors will be loaded on load.
uint8: 1	bWasDuplicated	Whether this level was duplicated
uint8: 1	bWasDuplicatedForPIE	Whether this level was duplicated for PIE
int32	CurrentActorIndexForIncrementalUpdate	Current index into actors array for updating components.
int32	CurrentActorIndexForUnregisterComponents	Current index into actors array for updating components.
std::atomic< ui...	FixupOverrideVertexColorsCount
std::atomic< ui...	FixupOverrideVertexColorsTimeMS
EIncrementalCom...	IncrementalComponentState	The current stage for incrementally updating actor components in the level
TWeakObjectPtr<...	InstancedFoliageActor	Cached pointer to Foliage actor
TWeakObjectPtr<...	LevelBoundsActor	Actor which defines level logical bounding box
FGuid	LevelBuildDataId	Identifies map build data specific to this level, eg lighting volume samples.
FLinearColor	LevelColor	The level color used for visualization.
TObjectPtr< cla...	LevelScriptActor	The level scripting actor, created by instantiating the class from LevelScriptBlueprint.
TObjectPtr< cla...	LevelScriptBlueprint	Reference to the blueprint for level scripting
FLevelSimplific...	LevelSimplification	Level simplification settings for each LOD
FIntVector	LightBuildLevelOffset	Level offset at time when lighting was built
float	LightmapTotalSize	Total number of KB used for lightmap textures in the level.
TObjectPtr< UMa...	MapBuildData	Registry for data from the map build.
TObjectPtr< cla...	Model	BSP UModel.
TArray< TObject...	ModelComponents	BSP Model components used for rendering.
TArray< TObject...	NavDataChunks	Navigation related data that can be stored per level
TObjectPtr< cla...	NavListEnd
TObjectPtr< cla...	NavListStart	Start and end of the navigation list for this level, used for quickly fixing up when streaming this level in/out.
int32	NumTextureStreamingDirtyResources	Num of resources that have changed since the last texture streaming build. Updated in map check.
int32	NumTextureStreamingUnbuiltComponents	Num of components missing valid texture streaming data. Updated in map check.
FLevelTransform...	OnApplyLevelTransform
FLevelCleanupEv...	OnCleanupLevel
FLoadedActorAdd...	OnLoadedActorAddedToLevelEvent
FLoadedActorRem...	OnLoadedActorRemovedFromLevelEvent
TObjectPtr< UWo...	OwningWorld	The World that has this level in its Levels array.
uint32	PackedTextureStreamingQualityLevelFeatureLevel	Packed quality level and feature level used when building texture streaming data.
AActor *	PlayFromHereActor
FPrecomputedLig...	PrecomputedLightVolume	The precomputed light information for this level.
FPrecomputedVis...	PrecomputedVisibilityHandler	Contains precomputed visibility data for this level.
FPrecomputedVol...	PrecomputedVolumeDistanceField	Precomputed volume distance field for this level.
FPrecomputedVol...	PrecomputedVolumetricLightmap	The volumetric lightmap data for this level.
FRenderCommandF...	RemoveFromSceneFence	Fence used to track when the rendering thread has finished referencing this ULevel's resources.
float	ShadowmapTotalSize	Total number of KB used for shadowmap textures in the level.
TArray< FVector...	StaticNavigableGeometry	Threes of triangle vertices - AABB filtering friendly.
TArray< FGuid >	StreamingTextureGuids	The Guid of each streamable texture refered by FStreamingTextureBuildInfo::TextureLevelIndex
TArray< FName >	StreamingTextures	The name of each streamable texture referred by FStreamingTextureBuildInfo::TextureLevelIndex
TArray< FGuid >	TextureStreamingResourceGuids	The Guid list of all materials and meshes Guid used in the last texture streaming build.
FTickTaskLevel ...	TickTaskLevel	Data structures for holding the tick functions
FURL	URL	URL associated with this level.

Constructors

	Name	Description
	ULevel ( const FObjectInitializer& ObjectIn... )
	ULevel ( FVTableHelper& Helper )	DO NOT USE. This constructor is for internal usage only for hot-reload purposes.

Destructors

	Name	Description
	~ULevel()

Functions

	Name	Description
void	AddLoadedActor ( AActor* Actor, const FTransform* TransformToA... )	Add a dynamically loaded actor to this level, as if it was part of the original map load process.
void	AddLoadedActors ( const TArray< AActor* >& Acto..., const FTransform* TransformToA... )	Add a dynamically loaded actor to this level, as if it was part of the original map load process.
void	AddReferencedObjects ( UObject* InThis, FReferenceCollector& Collector )
void	ApplyWorldOffset ( const FVector& InWorldOffset, bool bWorldShift )	Shift level actors by specified offset The offset vector will get subtracted from all actors positions and corresponding data structures
void	BroadcastLevelBoundsActorUpdated()	Broadcasts that Level bounds actor has been updated
void	BuildStreamingData ( UWorld* World, ULevel* TargetLevel, UTexture2D* TargetTexture )	Rebuilds static streaming data for all levels in the specified UWorld.
void	CleanupDeletedAndUnreferencedActorFolders()	Deletes all actor folders marked as deleted and unreferenced by neither an actor nor another actor folder
void	CleanupLevel ( bool bCleanupResources, bool bUnloadFromEditor )	Flag this level instance for destruction.
void	CleanupLevelScriptBlueprint()	Nulls certain references related to the LevelScriptBlueprint.
void	CleanupReferences()	Cleans all references from and to this level that may be preventing it from being Garbage Collected
void	ClearActorsSeamlessTraveledFlag()
void	ClearLevelComponents()	Clears all components of actors associated with this level (aka in Actors array) and also the BSP model components.
void	CommitModelSurfaces()	Commits changes made to the UModel's surfaces.
void	ConvertAllActorsToPackaging ( bool bExternal )	Convert this level actors to the specified loading strategy
UPackage ...	CreateActorPackage ( UPackage* InLevelPackage, EActorPackagingScheme ActorPackagin..., const FString& InActorPath )	Create an package for this actor
UPackage ...	CreateMapBuildDataPackage()
void	CreateModelComponents()	Called to create ModelComponents for BSP rendering
void	CreateOrUpdateActorFolders()	Updates all actors/folders that refer to folders marked as deleted, reparent to valid folder, deletes folders marked as deleted.
void	CreateReplicatedDestructionInfo ( AActor*const Actor )	Populate an entry for Actor in the DestroyedReplicatedStaticActors list
void	DetachAttachAllActorsPackages ( bool bReattach )	Detach or reattach all level actors to from/to their external package
void	FixupForPIE ( int32 PIEInstanceID, TFunctionRef< void(int32, FSoftObje... )	Call on a level that was loaded from disk instead of PIE-duplicating, to fixup actor references
void	FixupForPIE ( int32 PIEInstanceID )	Call on a level that was loaded from disk instead of PIE-duplicating, to fixup actor references
void	ForEachActorFolder ( TFunctionRef< bool(UActorFolder..., bool bSkipDeleted )	Iterates on all valid level actor folders.
UActorFolder...	GetActorFolder ( const FGuid& InGuid, bool bSkipDeleted )	Finds the level actor folder by its guid. Returns null if not found.
UActorFolder...	GetActorFolder ( const FName& InPath )	Finds the level actor folder by its path. Returns null if not found.
FString	GetActorPackageName ( const FString& InBaseDir, EActorPackagingScheme ActorPackagin..., const FString& InActorPath )	Get the package name for this actor
FString	GetActorPackageName ( UPackage* InLevelPackage, EActorPackagingScheme ActorPackagin..., const FString& InActorPath )	Get the package name for this actor
EActorPackag...	GetActorPackagingScheme()	Returns the level's actor packaging scheme
EActorPackag...	GetActorPackagingSchemeFromActorPackageName ( const FStringView InActorPackageNam... )	Extract the packaging Scheme used by an external actor package based on the name of the package
FLevelCollec...	GetCachedLevelCollection()	Returns the cached collection that contains this level, if any. May be null.
ABrush *	GetDefaultBrush()	Returns the default brush for this level.
const TArray...	GetDestroyedReplicatedStaticActors()
FString	GetExternalActorPackageInstanceName ( const FString& LevelPackageName, const FString& ActorPackageName )	Get a properly formated external actor package instance name for this level package to be used in FLinkerInstancingContext
const TCHAR ...	GetExternalActorsFolderName()	Get the folder name from which all external actors paths are created
FString	GetExternalActorsPath ( UPackage* InLevelPackage, const FString& InPackageShortName )	Get the folder containing the external actors for this level
FString	GetExternalActorsPath ( const FString& InLevelPackageName, const FString& InPackageShortName )	Get the folder containing the external actors for this level path
TArray< FStr...	GetExternalObjectsPaths ( const FString& InLevelPackageName, const FString& InPackageShortName )	Get the folders containing the external objects for this level path
bool	GetIsLevelPartitionedFromAsset ( const FAssetData& Asset )
bool	GetIsLevelPartitionedFromPackage ( FName LevelPackage )
bool	GetIsLevelUsingExternalActorsFromAsset ( const FAssetData& Asset )
bool	GetIsLevelUsingExternalActorsFromPackage ( FName LevelPackage )
bool	GetIsStreamingDisabledFromAsset ( const FAssetData& Asset )
bool	GetIsStreamingDisabledFromPackage ( FName LevelPackage )
bool	GetIsUsingActorFoldersFromAsset ( const FAssetData& Asset )
bool	GetIsUsingActorFoldersFromPackage ( FName LevelPackage )
bool	GetLevelBoundsFromAsset ( const FAssetData& Asset, FBox& OutLevelBounds )
bool	GetLevelBoundsFromPackage ( FName LevelPackage, FBox& OutLevelBounds )
FVector	GetLevelInstancePivotOffsetFromAsset ( const FAssetData& Asset )
FVector	GetLevelInstancePivotOffsetFromPackage ( FName LevelPackage )
const ILevel...	GetLevelPartition()	Get the level partition assigned to this level, if any
ILevelPartit...	GetLevelPartition()	Get the level partition assigned to this level, if any
ALevelScript...	GetLevelScriptActor()	Returns the level scripting actor associated with this level
ULevelScript...	GetLevelScriptBlueprint ( bool bDontCreate )	Grabs a reference to the level scripting blueprint for this level.
bool	GetLevelScriptExternalActorsReferencesFromAsset ( const FAssetData& Asset, TArray< FGuid >& OutLevelScriptExt... )
bool	GetLevelScriptExternalActorsReferencesFromPackage ( FName LevelPackage, TArray< FGuid >& OutLevelScriptExt... )
TArray< UPac...	GetLoadedExternalObjectPackages()	Get the list of (loaded) external object packages (actors/folders) associated with this level
TArray< FStr...	GetOnDiskExternalActorPackages ( bool bTryUsingPackageLoadedPath )	Get the list of (on disk) external actor packages associated with this level
TArray< FStr...	GetOnDiskExternalActorPackages ( const FString& ExternalActorsPath )	Get the list of (on disk) external actor packages associated with this external actors path
UMapBuildDat...	GetOrCreateMapBuildData()
bool	GetPartitionedLevelCanBeUsedByLevelInstanceFromAsset ( const FAssetData& Asset )
bool	GetPartitionedLevelCanBeUsedByLevelInstanceFromPackage ( FName LevelPackage )
bool	GetPromptWhenAddingToLevelBeforeCheckout()
bool	GetPromptWhenAddingToLevelOutsideBounds()
TArray< FVec...	GetStaticNavigableGeometry()
UWorld *	GetWorld()
AWorldDataLa...	GetWorldDataLayers()	Returns the world data layers info for this level.
UWorldPartit...	GetWorldPartition()	Returns the UWorldPartition for this level.
const IWorld...	GetWorldPartitionRuntimeCell()	Returns the RuntimeCell associated with this Level if it is a level representing a cell of a WorldPartition World.
AWorldSettin...	GetWorldSettings ( bool bChecked )	Returns the world info for this level.
void	HandleLegacyMapBuildData()	Creates UMapBuildDataRegistry entries for legacy lightmaps from components loaded for this level.
bool	HasAnyActorsOfType ( UClass* SearchType )	Utility searches this level's actor list for any actors of the specified type.
bool	HasStaticMeshCompilationPending()	Returns true if the level contains static meshes that have not finished compiling yet.
bool	HasVisibilityChangeRequestPending()	Whether the level is currently pending being made invisible or visible.
bool	IncrementalUnregisterComponents ( int32 NumComponentsToUnregister )	Incrementally unregisters all components of actors associated with this level.
void	IncrementalUpdateComponents ( int32 NumComponentsToUpdate, bool bRerunConstructionScripts, FRegisterComponentContext* Con... )	Incrementally updates all components of actors associated with this level.
void	Initialize ( const FURL& InURL )	Constructor.
void	InitializeNetworkActors()	Handles network initialization for actors in this level
void	InitializeRenderingResources()	Initializes rendering resources for this level.
void	InvalidateModelGeometry()	Invalidates the cached data used to render the level's UModel.
void	InvalidateModelSurface()	Discards the cached data used to render the level's UModel.
bool	IsCurrentLevel()	Is this the current level in the world it is owned by
bool	IsFinishedRouteActorInitialization()	Returns whether the level has completed routing actor initialization.
bool	IsInstancedLevel()	Is this a level instance
bool	IsNetActor ( const AActor* Actor )	Used internally to determine which actors should go on the world's NetworkActor list.
bool	IsPartitionedLevel()	Returns true if the current level is a partitioned level
bool	IsPartitionSubLevel()	Returns true if the current level is a sublevel (managed by a parent partitioned level)
bool	IsPersistentLevel()	Is this the persistent level
bool	IsUsingActorFolders()	Returns true if the level uses actor folders mode.
bool	IsUsingExternalActors()	Returns true if the level uses external actors mode.
bool	IsUsingExternalObjects()	Returns true if the level uses external objects.
bool	IsWorldPartitionRuntimeCell()	Returns if the level is a cell from a WorldPartition World.
FLevelBounds...	LevelBoundsActorUpdated()
void	MarkLevelBoundsDirty()	Marks level bounds as dirty so they will be recalculated
void	MarkLevelComponentsRenderStateDirty()	Marks all level components render state as dirty
void	OnApplyNewLightingData ( bool bLightingSuccessful )	Called after lighting was built and data gets propagated to this level
void	OnLevelLoaded()	Called when level is loaded.
void	OnLevelScriptBlueprintChanged ( ULevelScriptBlueprint* InBluep... )	Called when the level script blueprint has been successfully changed and compiled.
void	PushPendingAutoReceiveInput ( APlayerController* PC )	Push any pending auto receive input actor's input components on to the player controller's input stack
void	RebuildStaticNavigableGeometry()	Meant to be called only from editor, calculating and storing static geometry to be used with off-line and/or on-line navigation building
void	RegisterActorForAutoReceiveInput ( AActor* Actor, const int32 PlayerIndex )	Register an actor that should be added to a player's input stack when they are created
uint16	RegisterStreamableTexture ( const FString& InTextureName, const FGuid& InTextureGuid )
void	ReleaseRenderingResources()	Releases rendering resources for this level.
void	RemoveLoadedActor ( AActor* Actor, const FTransform* TransformToR... )	Remove a dynamically loaded actor from this level.
void	RemoveLoadedActors ( const TArray< AActor* >& Acto..., const FTransform* TransformToR... )	Remove a dynamically loaded actor from this level.
void	ResetNavList()	Resets the level nav list.
void	ResetRouteActorInitializationState()	Method for resetting routing actor initialization for the next time this level is streamed.
void	RouteActorInitialize ( int32 NumActorsToProcess )	Routes pre and post initialize to actors and also sets volumes.
void	ScanLevelAssets ( const FString& InLevelPackageName )	Scans/Updates all Level Assets (level package and external packages)
void	SetCachedLevelCollection ( FLevelCollection*const InCache... )	Sets the cached level collection that contains this level.
void	SetLevelPartition ( ILevelPartitionInterface* Leve... )	Assign a level partition to this level
void	SetLightingScenario ( bool bNewIsLightingScenario )	Sets whether this level is a lighting scenario and handles propagating the change.
void	SetPartitionSubLevel ( ULevel* SubLevel )	Setup the provided sublevel so that it is handled by this level's partition
bool	SetUseActorFolders ( bool bEnabled, bool bInteractive )	Sets if the level uses actor folders mode or not. Returns true if succeeded.
void	SetUseExternalActors ( bool bEnable )	Sets if the level uses external actors mode or not.
void	SetWorldDataLayers ( AWorldDataLayers* NewWorldData... )
void	SetWorldSettings ( AWorldSettings* NewWorldSettin... )
bool	ShouldCreateNewExternalActors()	Returns true if the level wants newly spawned actors to be external
void	SortActorList()	Sorts the actor list by net relevancy and static behaviour.
void	UpdateLevelComponents ( bool bRerunConstructionScripts, FRegisterComponentContext* Con... )	Updates all components of actors associated with this level (aka in Actors array) and creates the BSP model components.
void	UpdateModelComponents()	Updates the model components associated with this level

Overridden from UObject

	Name	Description
void	BeginCacheForCookedPlatformData ( const ITargetPlatform* TargetP... )	Starts caching of platform specific data for the target platform Called when cooking before serialization so that object can prepare platform specific data Not called during normal loading of objects
void	BeginDestroy()	Called before destroying the object.
bool	CanEditChange ( const FProperty* InProperty )	Called by the editor to query whether a property of this object is allowed to be modified.
void	FinishDestroy()	Called to finish destroying the object.
bool	IsNameStableForNetworking()	IsNameStableForNetworking means an object can be referred to its path name (relative to outer) over the network
bool	IsReadyForFinishDestroy()	Called to check if the object is ready for FinishDestroy.
void	PostEditChangeProperty ( FPropertyChangedEvent& PropertyCha... )	Called when a property on this object has been modified externally
void	PostEditUndo()	Called after applying a transaction to the object.
void	PostInitProperties()	Called after the C++ constructor and after the properties have been initialized, including those loaded from config.
void	PostLoad()	Do any object-specific cleanup required immediately after loading an object.
void	PreDuplicate ( FObjectDuplicationParameters& DupP... )	Called before duplication.
void	PreEditUndo()	Called before applying a transaction to the object.
void	PreSave ( FObjectPreSaveContext SaveContext )	Presave function.
bool	ResolveSubobject ( const TCHAR* SubObjectPath, UObject*& OutObject, bool bLoadIfExists )	Called to defer loading a subobject to its top-level container object.
void	Serialize ( FArchive& Ar )	Handles reading, writing, and reference collecting using FArchive.

Overridden from UObjectBaseUtility

		Name	Description
	bool	CanBeClusterRoot()	Called after load to determine if the object can be a cluster root
	void	CreateCluster()	Called after PostLoad to create UObject cluster

Overridden from IInterface_AssetUserData

		Name	Description
	void	AddAssetUserData ( UAssetUserData* InUserData )
	UAssetUserDa...	GetAssetUserDataOfClass ( TSubclassOf< UAssetUserData > InUse... )
	void	RemoveUserDataOfClass ( TSubclassOf< UAssetUserData > InUse... )

Overridden from ITextureStreamingContainer

		Name	Description
	void	InitializeTextureStreamingContainer ( uint32 InPackedTextureStreamingQual... )
	uint16	RegisterStreamableTexture ( UTexture* InTexture )

Classes

	Name	Description
	FLevelBoundsActorUpdatedEvent	Called when Level bounds actor has been updated
	FLoadedActorAddedToLevelEvent	Called when dynamically loaded actor is added to this level
	FLoadedActorRemovedFromLevelEvent	Called when dynamically loaded actor is removed from this level

Enums

	Name	Description
	EIncrementalComponentState
	ERouteActorInitializationState

Typedefs

Name	Description
FLevelCleanupEvent
FLevelTransformEvent	Event on level transform changes.

Constants

Name	Description
DontLoadExternalObjectsTag
LevelDirtiedEvent	Called when a level package has been dirtied.
LoadAllExternalObjectsTag
StreamedLevelsOwningWorld	Set before calling LoadPackage for a streaming level to ensure that OwningWorld is correct on the Level

Deprecated Functions

		Name	Description
	TArray< clas...	GetLevelBlueprints()	This function is deprecated, we only support having a single level script blueprint. Use GetLevelScriptBlueprint instead.
	PRAGMA_DISAB...	PreSave ( const ITargetPlatform* TargetP... )	Use version that takes FObjectPreSaveContext instead.