UBlackboardComponent

class AIModule Blueprint Since 4.0

Inherits: UObjectBase › UObjectBaseUtility › UObject › UActorComponent › UBlackboardComponent

#include "BehaviorTree/BlackboardComponent.h"

Description

A component that stores key-value pairs for AI decision-making. Acts as shared memory between the behavior tree, decorators, services, and C++ game code.

Caveats & Gotchas

• Keys must be defined in the UBlackboardData asset in the editor — you cannot add keys at runtime.
• Get the component via AAIController::GetBlackboardComponent(). It is null until UseBlackboard() or RunBehaviorTree() has been called.
• Key names are FName lookups — typos silently fail and return default values. Prefer caching key IDs with GetKeyID() in production code.

Example

Write and read a blackboard value from C++ C++

UBlackboardComponent* BB = AIController->GetBlackboardComponent();
BB->SetValueAsObject(FName("TargetActor"), EnemyActor);

UObject* Target = BB->GetValueAsObject(FName("TargetActor"));

Functions (52)

Lifecycle 2 Blackboard 50

Lifecycle

2 ▼

Access	Type	Name	Description
public	function	UBlackboardComponent::InitializeComponent	Overrides UActorComponent::InitializeComponent to set up the blackboard's default asset (DefaultBlackboardAsset) if one hasn't already been assigned via InitializeBlackboard.
public	function	UBlackboardComponent::UninitializeComponent	Overrides UActorComponent::UninitializeComponent to tear down the blackboard's allocated key values and release observers when the component is uninitialized.

Blackboard

50 ▼

Access	Type	Name	Description
public	function	UBlackboardComponent::GetBlackboardAsset	Returns the blackboard data asset currently in use by this component, defining its available keys and their types.
public	function	UBlackboardComponent::GetLocationFromEntry	Resolves a world location from the given blackboard key, whether it's a Vector key or an Object/Actor key, and writes it to ResultLocation.
public	function	UBlackboardComponent::GetValueAsBool	Returns the boolean value stored under the given blackboard key.
public	function	UBlackboardComponent::GetValueAsInt	Returns the integer value stored under the given blackboard key.
public	function	UBlackboardComponent::HasValidAsset	Returns true if the component currently has a valid, initialized blackboard data asset assigned.
public	function	UBlackboardComponent::SetValueAsBool	Sets the boolean value stored under the given blackboard key, notifying any registered observers if the value changed.
public	function	UBlackboardComponent::SetValueAsInt	Sets the integer value stored under the given blackboard key, notifying any registered observers if the value changed.
public	function	UBlackboardComponent::ClearValue	Resets the value stored under the given blackboard key to its type's default/unset state, notifying any registered observers if the value changed.
public	function	UBlackboardComponent::CopyKeyValue	Copies the raw value stored under SourceKeyID into DestinationID and returns true if the copy succeeded.
public	function	UBlackboardComponent::GetKeyID	Converts a blackboard key name into its numeric FKey ID, which is the form used by the fast RegisterObserver, GetValue, and SetValue overloads.
public	function	UBlackboardComponent::GetKeyName	Returns the name of the blackboard key with the given ID, as defined on the blackboard data asset.
public	function	UBlackboardComponent::GetKeyType	Returns the UBlackboardKeyType subclass (Bool, Int, Float, Object, Vector, and so on) used to store the value under the given key.
public	function	UBlackboardComponent::GetNumKeys	Returns the number of key entries defined on the blackboard's data asset, including keys inherited from parent blackboard assets.
public	function	UBlackboardComponent::GetRotationFromEntry	Resolves a rotation from the given blackboard key, whether it's a Rotator key or an Object/Actor key, and writes it to ResultRotation.
public	function	UBlackboardComponent::GetValueAsClass	Returns the UClass value stored under the given blackboard key.
public	function	UBlackboardComponent::GetValueAsEnum	Returns the raw enum value stored under the given blackboard key as a uint8.
public	function	UBlackboardComponent::GetValueAsFloat	Returns the float value stored under the given blackboard key.
public	function	UBlackboardComponent::GetValueAsName	Returns the FName value stored under the given blackboard key.
public	function	UBlackboardComponent::GetValueAsObject	Returns the UObject stored under the given blackboard key, or null if the key doesn't exist or holds no value.
public	function	UBlackboardComponent::GetValueAsRotator	Returns the FRotator value stored under the given blackboard key.
public	function	UBlackboardComponent::GetValueAsString	Returns the string value stored under the given blackboard key.
public	function	UBlackboardComponent::GetValueAsVector	Returns the FVector stored under the given blackboard key.
public	function	UBlackboardComponent::InitializeBlackboard	Sets up the component to use the given blackboard data asset, allocating value storage for its keys.
public	function	UBlackboardComponent::IsValidKey	Checks whether KeyID refers to a valid entry in the component's blackboard asset.
public	function	UBlackboardComponent::IsVectorValueSet	Returns true if the vector value under the given key has actually been set (rather than left at its default invalid state).
public	function	UBlackboardComponent::SetValueAsClass	Sets the UClass value stored under the given blackboard key, notifying any registered observers if the value changed.
public	function	UBlackboardComponent::SetValueAsEnum	Sets the raw enum value stored under the given blackboard key, notifying any registered observers if the value changed.
public	function	UBlackboardComponent::SetValueAsFloat	Writes a float value to a blackboard key, which can then be read by behavior tree tasks and decorators.
public	function	UBlackboardComponent::SetValueAsName	Sets the FName value stored under the given blackboard key, notifying any registered observers if the value changed.
public	function	UBlackboardComponent::SetValueAsObject	Writes a UObject reference to a blackboard key.
public	function	UBlackboardComponent::SetValueAsRotator	Sets the FRotator value stored under the given blackboard key, notifying any registered observers if the value changed.
public	function	UBlackboardComponent::SetValueAsString	Sets the string value stored under the given blackboard key, notifying any registered observers if the value changed.
public	function	UBlackboardComponent::SetValueAsVector	Writes an FVector to a blackboard key.
public	function	UBlackboardComponent::UnregisterObserversFrom	Removes every observer delegate that was registered with the given owner object, regardless of which key each one watched.
public	function	UBlackboardComponent::CacheBrainComponent	Stores a pointer to the given brain component so it can be retrieved later via GetBrainComponent, used for communication back to the tree that owns this blackboard.
public	function	UBlackboardComponent::CompareKeyValues	Compares the values stored under two keys using KeyType's comparison logic, returning Less, Equal, or Greater.
public	function	UBlackboardComponent::DescribeKeyValue	Returns a human-readable description of the value stored under KeyName, formatted according to Mode.
public	function	UBlackboardComponent::DescribeSelfToVisLog	Appends the blackboard's current key/value state to a Visual Logger snapshot, so it shows up in the Visual Logger tool alongside other AI debug data.
public	function	UBlackboardComponent::GetBrainComponent	Returns the behavior tree (or other brain) component associated with this blackboard, as previously set via CacheBrainComponent.
public	function	UBlackboardComponent::GetDebugInfoString	Builds a multi-line debug string describing every key and its current value, formatted according to Mode.
public	function	UBlackboardComponent::GetKeyRawData	Returns a raw pointer to the key's value bytes inside the blackboard's internal value buffer, for direct low-level access.
public	function	UBlackboardComponent::GetValue	Reads the value stored under the given key, decoded as the type described by the TDataClass template argument.
public	function	UBlackboardComponent::IsCompatibleWith	Returns true if the given blackboard data asset can be used with this component, meaning it matches or derives from the currently assigned asset.
public	function	UBlackboardComponent::IsKeyInstanceSynced	Returns true if the key is marked as instance-synced, meaning its value is automatically mirrored across all blackboard components sharing the same asset.
public	function	UBlackboardComponent::IsKeyOfType	Returns true if the named key's underlying value type matches the given UBlackboardKeyType subclass, specified as the template argument.
public	function	UBlackboardComponent::PauseObserverNotifications	Suspends dispatch of blackboard change notifications; any key changes made while paused are queued rather than immediately broadcast to observers.
public	function	UBlackboardComponent::RegisterObserver	Registers a delegate that fires whenever the value under the given key changes, the mechanism behind behavior tree decorator observer aborts.
public	function	UBlackboardComponent::ResumeObserverNotifications	Resumes dispatch of blackboard change notifications after a matching call to PauseObserverNotifications, optionally flushing any queued changes.
public	function	UBlackboardComponent::SetValue	Sets the value under the given key using the raw templated key-type API, notifying observers if the value actually changed.
public	function	UBlackboardComponent::UnregisterObserver	Removes a single previously registered observer delegate for the given key, identified by the handle returned from RegisterObserver.

Version History

Introduced in: 4.0

Version	Status	Notes
5.6	stable	—

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