Unreal Engine 4.26 Documentation

Unreal Engine 4.27 Documentation

Unreal Engine 5.0 Documentation

> Unreal Engine API Reference > Runtime > Engine > Engine > UBlueprint

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UBlueprint

Blueprints are special assets that provide an intuitive, node-based interface that can be used to create new types of Actors and script level events; giving designers and gameplay programmers the tools to quickly create and iterate gameplay from within Unreal Editor without ever needing to write a line of code.

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Inheritance Hierarchy

UObjectBase

UObjectBaseUtility

UObject

UBlueprintCore

UBlueprint

UAnimBlueprint

UControlRigBlueprint

UDisplayClusterBlueprint

UEditorUtilityBlueprint

UGameplayAbilityBlueprint

ULegacyLevelSequenceDirectorBlueprint

ULevelScriptBlueprint

UUserWidgetBlueprint

UBaseWidgetBlueprint

UWidgetBlueprint

UEditorUtilityWidgetBlueprint

References

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

Syntax

class UBlueprint : public UBlueprintCore

Remarks

Blueprints are special assets that provide an intuitive, node-based interface that can be used to create new types of Actors and script level events; giving designers and gameplay programmers the tools to quickly create and iterate gameplay from within Unreal Editor without ever needing to write a line of code.

Variables

	Name	Description
uint8: 1	bBeingCompiled	The blueprint is currently compiled
bool	bCachedDependenciesUpToDate
uint8: 1	bDeprecate	Deprecates the Blueprint, marking the generated class with the CLASS_Deprecated flag
uint8: 1	bDisplayCompilePIEWarning	TRUE to show a warning when attempting to start in PIE and there is a compiler error on this Blueprint
uint8: 1	bDuplicatingReadOnly	Flag indicating that a read only duplicate of this blueprint is being created, used to disable logic in ::PostDuplicate,
uint8: 1	bForceFullEditor	Whether to force opening the full (non data-only) editor for this blueprint.
uint8: 1	bGenerateAbstractClass	Whether or not this blueprint's class is a abstract class or not.
uint8: 1	bGenerateConstClass	Whether or not this blueprint's class is a const class or not.
EIsBPNonReducib...	bHasAnyNonReducibleFunction	Cached information if the BP contains any non-reducible functions (that can benefit from nativization).
uint8: 1	bHasBeenRegenerated	When the class generated by this blueprint is loaded, it will be recompiled the first time.
uint8: 1	bIsNewlyCreated	Whether or not this blueprint is newly created, and hasn't been opened in an editor yet
uint8: 1	bIsRegeneratingOnLoad	State flag to indicate whether or not the Blueprint is currently being regenerated on load
FString	BlueprintCategory	The category of the Blueprint, used to organize this Blueprint class when displayed in palette windows
FString	BlueprintDescription	Shows up in the content browser tooltip when the blueprint is hovered
FString	BlueprintDisplayName	Overrides the BP's display name in the editor UI
FString	BlueprintNamespace	The namespace of this blueprint (if set, the Blueprint will be treated differently for the context menu)
int32	BlueprintSystemVersion	The version of the blueprint system that was used to create this blueprint
TEnumAsByte< en...	BlueprintType	The type of this blueprint
TArray< FBPEdit...	BookmarkNodes	Bookmark nodes (for display)
TMap< FGuid, st...	Bookmarks	Bookmark data
uint8: 1	bQueuedForCompilation
uint8: 1	bRecompileOnLoad	Whether or not this blueprint should recompile itself on load
uint8: 1	bRunConstructionScriptInSequencer	Whether or not you want to continuously rerun the construction script for an actor in sequencer
uint8: 1	bRunConstructionScriptOnDrag	Whether or not you want to continuously rerun the construction script for an actor as you drag it in the editor, or only when the drag operation is complete
TSet< TWeakObje...	CachedDependencies	Set of blueprints that we reference - i.e. blueprints that we have some kind of reference to (variable of that blueprints type or function call
TSet< TWeakObje...	CachedDependents	Transient cache of dependent blueprints - i.e. blueprints that call functions declared in this blueprint.
TSet< TWeakObje...	CachedUDSDependencies	User Defined Structures, the blueprint depends on.
TArray< FName >	CategorySorting	Array of user sorted categories
EBlueprintCompi...	CompileMode	The mode that will be used when compiling this class.
TArray< FBPComp...	ComponentClassOverrides	Array of blueprint overrides of component classes in parent classes
TMap< FName, in...	ComponentTemplateNameIndex	Index map for component template names
TArray< TObject...	ComponentTemplates	Array of component template objects, used by AddComponent function
uint32	CrcLastCompiledCDO	CRC for CDO calculated right after the latest compilation used by Reinstancer to check if default values were changed
uint32	CrcLastCompiledSignature
FCompilerResult...	CurrentMessageLog	If this blueprint is currently being compiled, the CurrentMessageLog will be the log currently being used to send logs to.
TWeakObjectPtr<...	CurrentObjectBeingDebugged	Current object being debugged for this blueprint
TWeakObjectPtr<...	CurrentWorldBeingDebugged	Current world being debugged for this blueprint
TArray< TObject...	DelegateSignatureGraphs	Graphs of signatures for delegates
TArray< TObject...	DeprecatedPinWatches
TArray< TObject...	EventGraphs	Set of functions actually compiled for this class
TArray< TObject...	Extensions	Array of extensions for this blueprint
TArray< TObject...	FunctionGraphs	Set of functions implemented for this class graphically
TArray< FString...	HideCategories	Additional HideCategories. These are added to HideCategories from parent.
TArray< struct ...	ImplementedInterfaces	Array of info about the interfaces we implement in this blueprint
TSet< FString >	ImportedNamespaces	Namespaces imported by this blueprint
TObjectPtr< cla...	InheritableComponentHandler	Stores data to override (in children classes) components (created by SCS) from parent classes
TArray< TObject...	IntermediateGeneratedGraphs	Set of functions actually compiled for this class
TArray< struct ...	LastEditedDocuments	Set of documents that were being edited in this blueprint, so we can open them right away
TArray< TObject...	MacroGraphs	Set of macros implemented for this class
TArray< struct ...	NewVariables	Array of new variables to be added to generated class
FString	ObjectPathToDebug	Raw path of object to be debugged, this might have been spawned inside a specific PIE level so is not stored as an object path type
TMap< FName, FN...	OldToNewComponentTemplateNames	Maps old to new component template names
FOnSetObjectBei...	OnSetObjectBeingDebuggedDelegate	Delegate called when the debug object is set
TObjectPtr< UCl...	OriginalClass	If this BP is just a duplicate created for a specific compilation, the reference to original GeneratedClass is needed.
TSubclassOf< UO...	ParentClass	Pointer to the parent class that the generated class should derive from.
TSharedPtr< cla...	PreCompileLog	Message log for storing pre-compile errors/notes/warnings that will only last until the next Blueprint compile
TMap< TObjectPt...	PRIVATE_CachedMacroInfo	Cached cosmetic information about macro graphs, use GetCosmeticInfoForMacro() to access
TObjectPtr< cla...	SimpleConstructionScript	'Simple' construction script - graph of components to instance
TEnumAsByte< en...	Status	The current status of this blueprint
TObjectPtr< cla...	ThumbnailInfo	Information for thumbnail rendering
TArray< TObject...	Timelines	Array of templates for timelines that should be created
TArray< TObject...	UbergraphPages	Set of pages that combine into a single uber-graph
TSharedPtr< cla...	UpgradeNotesLog	Message log for storing upgrade notes that were generated within the Blueprint, will be displayed to the compiler results each compiler and will remain until saving

Constructors

	Name	Description
	UBlueprint ( const FObjectInitializer& ObjectIn... )

Functions

	Name	Description
bool	AllowsDynamicBinding()
bool	AlwaysCompileOnLoad()	Allows derived blueprints to require compilation on load, otherwise they may get treated as data only and not compiled on load.
void	BroadcastChanged()	This should NOT be public
void	BroadcastCompiled()
bool	CanAlwaysRecompileWhilePlayingInEditor()	Some Blueprints (and classes) can recompile while we are debugging a live session (play in editor).
bool	CanImportGraphFromText ( const FString& InClipboardText )	Returns true if the blueprint can import a given InClipboardText.
bool	ChangeOwnerOfTemplates()
void	ClearEditorReferences()	Clears out any editor data regarding a blueprint class, this can be called when you want to unload a blueprint
void	ConformNativeComponents()	Updates the blueprint's OwnedComponents, such that they reflect changes made natively since the blueprint was last saved (a change in AttachParents, etc.)
bool	ExportGraphToText ( UEdGraph* InEdGraph, FString& OutText )	Copies a given graph into a text buffer. Returns true if successful.
bool	FindDiffs ( const UBlueprint* OtherBluepri..., FDiffResults& Results )	Fills in a list of differences between this blueprint and another blueprint.
UActorCompon...	FindTemplateByName ( const FName& TemplateName )	Find the object in the TemplateObjects array with the supplied name
const UTimel...	FindTimelineTemplateByVariableName ( const FName& TimelineName )	Find a timeline by name
UTimelineTem...	FindTimelineTemplateByVariableName ( const FName& TimelineName )	Find a timeline by name
bool	ForceLoad ( UObject* Obj )
void	ForceLoadMembers ( UObject* InObject )
void	ForceLoadMetaData ( UObject* InObject )
void	GatherDependencies ( TSet< TWeakObjectPtr< UBlueprint >>... )	Collect blueprints that depend on this blueprint.
void	GetAllGraphs ( TArray< UEdGraph* >& Graphs )	Get all graphs in this blueprint
void	GetBlueprintCDONames ( FName& GeneratedClassName, FName& SkeletonClassName, FName NameOverride )
UClass *	GetBlueprintClass()	Gets the class generated when this blueprint is compiled.
void	GetBlueprintClassNames ( FName& GeneratedClassName, FName& SkeletonClassName, FName NameOverride )
UBlueprint &...	GetBlueprintFromClass ( const UClass* InClass )	Get the Blueprint object that generated the supplied class
bool	GetBlueprintHierarchyFromClass ( const UClass* InClass, TArray< UBlueprint* >& OutBlu... )	Gets an array of all blueprints used to generate this class and its parents.
bool	GetBlueprintHierarchyFromClass ( const UClass* InClass, TArray< UBlueprintGeneratedClass&#... )	Gets an array of all BPGCs used to generate this class and its parents.
int32	GetCurrentBlueprintSystemVersion()	Gets the current blueprint system version.
FName	GetFieldNameFromClassByGuid ( const UClass* InClass, const FGuid FunctionGuid )
FName	GetFieldNameFromClassByGuid ( const UClass* InClass, const FGuid VarGuid )
FString	GetFriendlyName()
bool	GetFunctionGuidFromClassByFieldName ( const UClass* InClass, const FName FunctionName, FGuid& FunctionGuid )
FName	GetFunctionNameFromClassByGuid ( const UClass* InClass, const FGuid FunctionGuid )
bool	GetGuidFromClassByFieldName ( const UClass* InClass, const FName FunctionName, FGuid& FunctionGuid )
bool	GetGuidFromClassByFieldName ( const UClass* InClass, const FName VarName, FGuid& VarGuid )
UInheritable...	GetInheritableComponentHandler ( bool bCreateIfNecessary )
void	GetInstanceActions ( FBlueprintActionDatabaseRegistrar&... )	Allow each blueprint instance to add specific UBlueprintNodeSpawners pertaining to the sub-class type.
UEdGraph ...	GetLastEditedUberGraph()	Gets the last edited uber graph.
UObject *...	GetObjectBeingDebugged ( EGetObjectOrWorldBeingDebuggedFlags... )
const FStrin...	GetObjectPathToDebug()
void	GetReparentingRules ( TSet< const UClass* >& Allowe..., TSet< const UClass* >& Disall... )
ETimelineSig...	GetTimelineSignatureForFunctionByName ( const FName& FunctionName, const FName& ObjectPropertyName )	Find a function given its name and optionally an object property name within this Blueprint
void	GetTypeActions ( FBlueprintActionDatabaseRegistrar&... )	Allow each blueprint type (AnimBlueprint or ControlRigBlueprint) to add specific UBlueprintNodeSpawners pertaining to the sub-class type.
UWorld *	GetWorldBeingDebugged ( EGetObjectOrWorldBeingDebuggedFlags... )
bool	IsBlueprintHierarchyErrorFree ( const UClass* InClass )	Returns true if the class hierarchy is error free
bool	IsPossiblyDirty()
bool	IsUpToDate()
bool	IsValidForBytecodeOnlyRecompile()	Whether or not this blueprint can be considered for a bytecode only compile
void	LoadModulesRequiredForCompilation()	Blueprint can choose to load specific modules for compilation.
void	Message_Error ( const FString& MessageToLog )
void	Message_Note ( const FString& MessageToLog )	Sends a message to the CurrentMessageLog, if there is one available.
void	Message_Warn ( const FString& MessageToLog )
void	NotifyGraphRenamed ( UEdGraph* Graph, FName OldName, FName NewName )	Notify the blueprint when a graph is renamed to allow for additional fixups.
FChangedEven...	OnChanged()
FCompiledEve...	OnCompiled()
FOnSetObject...	OnSetObjectBeingDebugged()
void	RemoveChildRedirectors()	Removes any child redirectors from the root set and marks them as transient
void	RemoveGeneratedClasses()	Consigns the GeneratedClass and the SkeletonGeneratedClass to oblivion, and nulls their references
bool	RenameGeneratedClasses ( const TCHAR* NewName, UObject* NewOuter, ERenameFlags Flags )	Renames only the generated classes. Should only be used internally or when testing for rename.
void	ReplaceDeprecatedNodes()	Checks all nodes in all graphs to see if they should be replaced by other nodes
void	SetObjectBeingDebugged ( UObject* NewObject )	Sets the current object being debugged
void	SetWorldBeingDebugged ( UWorld* NewWorld )
bool	ShouldBeMarkedDirtyUponTransaction()	Returns true if this blueprint should be marked dirty upon a transaction
bool	SupportedByDefaultBlueprintFactory()	Should the generic blueprint factory work for this blueprint?
bool	SupportsAnimLayers()	Returns true if this blueprint supports animation layers
bool	SupportsDelegates()	Returns true if this blueprint supports delegates
bool	SupportsEventGraphs()	Returns true if this blueprint supports event graphs
bool	SupportsFunctions()	Returns true if this blueprint supports functions
bool	SupportsGlobalVariables()	Returns true if this blueprint supports global variables
bool	SupportsInputEvents()
bool	SupportsLocalVariables()	Returns true if this blueprint supports global variables
bool	SupportsMacros()	Returns true if this blueprint supports macros
bool	TryImportGraphFromText ( const FString& InClipboardText, UEdGraph** OutGraphPtr )	Returns a new ed graph if the blueprint's specialization imported a graph based on a clipboard text content an nullptr if that's not successful.
void	UnregisterObjectBeingDebugged()	Clears the current object being debugged because it is gone, but do not reset the saved information
bool	ValidateGeneratedClass ( const UClass* InClass )

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.
void	ClearAllCachedCookedPlatformData()	Clear all cached cooked platform data
void	GetAssetRegistryTags ( TArray< FAssetRegistryTag >& OutTa... )	Gathers a list of asset registry searchable tags which are name/value pairs with some type information This only needs to be implemented for asset objects
FString	GetDesc()	Return a one line description of an object for viewing in the thumbnail view of the generic browser
void	GetPreloadDependencies ( TArray< UObject* >& OutDeps )	Called during cooking.
FPrimaryAsse...	GetPrimaryAssetId()	Returns an Type:Name pair representing the PrimaryAssetId for this object.
bool	IsCachedCookedPlatformDataLoaded ( const ITargetPlatform* TargetP... )	Have we finished loading all the cooked platform data for the target platforms requested in BeginCacheForCookedPlatformData
EDataValidat...	IsDataValid ( TArray< FText >& ValidationErrors )	Returns Valid if this object has data validation rules set up for it and the data for this object is valid.
bool	Modify ( bool bAlwaysMarkDirty )	That the object will be modified.
bool	NeedsLoadForClient()	Called during saving to determine the load flags to save with the object.
bool	NeedsLoadForEditorGame()	Called during saving to include this object in client/servers running in editor builds, even if they wouldn't normally be.
bool	NeedsLoadForServer()	Called during saving to determine the load flags to save with the object.
void	PostDuplicate ( bool bDuplicateForPIE )	Called after duplication & serialization and before PostLoad.
void	PostLoad()	Do any object-specific cleanup required immediately after loading an object.
void	PreSave ( FObjectPreSaveContext SaveContext )	Presave function.
UClass *	RegenerateClass ( UClass* ClassToRegenerate, UObject* PreviousCDO )	Called on the target when a class is loaded with ClassGeneratedBy is loaded.
bool	Rename ( const TCHAR* NewName, UObject* NewOuter, ERenameFlags Flags )	Rename this object to a unique name, or change its outer.
void	Serialize ( FArchive& Ar )	Handles reading, writing, and reference collecting using FArchive.
void	TagSubobjects ( EObjectFlags NewFlags )	Tags objects that are part of the same asset with the specified object flag, used for GC checking

Classes

	Name	Description
	FChangedEvent	Broadcasts a notification whenever the blueprint has changed.
	FCompiledEvent	Broadcasts a notification whenever the blueprint has changed.
	FOnSetObjectBeingDebugged	Delegate called when the debug object is set

Enums

	Name	Description
	EIsBPNonReducible

Deprecated Variables

	Name	Description
TArray< TObject...	Breakpoints_DEPRECATED	Moved to FPerBlueprintSettings
EBlueprintNativ...	NativizationFlag	Blueprint Nativization has been removed as a supported feature. This property will eventually be removed.
TArray< FEdGrap...	WatchedPins_DEPRECATED	Moved to FPerBlueprintSettings

Deprecated Functions

	Name	Description
bool	CanRecompileWhilePlayingInEditor()	CanRecompileWhilePlayingInEditor was renamed to CanAlwaysRecompileWhilePlayingInEditor to better explain usage.
void	PreSave ( const ITargetPlatform* TargetP... )	Use version that takes FObjectPreSaveContext instead.
bool	SupportsNativization ( FText* OutReason )	Blueprint Nativization has been removed as a supported feature. This API will eventually be removed.