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  3. UBehaviorTreeComponent

UBehaviorTreeComponent

API > API/Runtime > API/Runtime/AIModule > API/Runtime/AIModule/BehaviorTree

Inheritance Hierarchy

References

   
Module AIModule
Header /Engine/Source/Runtime/AIModule/Classes/BehaviorTree/BehaviorTreeComponent.h
Include #include "BehaviorTree/BehaviorTreeComponent.h"

Syntax

class UBehaviorTreeComponent : public UBrainComponent

Variables

  Type Name Description
Protected variable float AccumulatedTickDeltaTime Accumulated DeltaTime if ticked more than predicted next delta time
Protected variable uint16 ActiveInstanceIdx Index of last active instance on stack
Protected variable uint8: 1 bIsPaused If set, execution requests will be postponed
Protected variable uint8: 1 bIsRunning If set, tree execution is allowed
Protected variable uint8: 1 bLoopExecution Loops tree execution
Protected variable uint8: 1 bRequestedFlowUpdate Set when execution update is scheduled for next tick
Protected variable uint8: 1 bRequestedStop Set when tree stop was called
Protected variable bool bTickedOnce Used to tell tickmanager that we want interval ticking
Protected variable uint8: 1 bWaitingForLatentAborts Set when execution is waiting for tasks to finish their latent abort (current or parallel's main)
Protected variable TMap< FGameplayTag, double > CooldownTagsMap Behavior cooldowns mapped by tag to last time it was set
Protected variable TArray< TArray< FBehaviorTreeDebuggerInstance::FNodeFlowData > > CurrentRestarts  
Protected variable TArray< TArray< FBehaviorTreeDebuggerInstance::FNodeFlowData > > CurrentSearchFlow Search flow for debugger
Protected variable TArray< FBehaviorTreeExecutionStep > DebuggerSteps Debugger's recorded data
Protected variable TObjectPtr< UBehaviorTree > DefaultBehaviorTreeAsset Data asset defining the tree
Protected variable FBTNodeExecutionInfo ExecutionRequest Execution request, search will be performed when current task finish execution/aborting
Protected variable friend FBehaviorTreeDebugger  
Protected variable friend FBehaviorTreeInstance  
Protected variable TArray< FBehaviorTreeInstance > InstanceStack Stack of behavior tree instances
Protected variable TArray< FBehaviorTreeInstanceId > KnownInstances List of known subtree instances
Protected variable double LastRequestedDeltaTimeGameTime GameTime of the last DeltaTime request, used for debugging to output warnings about ticking
Protected variable float NextTickDeltaTime Predicted next DeltaTime
Protected variable TArray< TObjectPtr< UBTNode > > NodeInstances Instanced nodes
Protected variable TArray< FBranchActionInfo > PendingBranchActionRequests List of all pending branch action requests
Protected variable FBTPendingExecutionInfo PendingExecution Result of ExecutionRequest, will be applied when current task finish aborting
Protected variable TArray< FBehaviorTreeDebuggerInstance > RemovedInstances  
Protected variable FBehaviorTreeSearchData SearchData Search data being currently used
Protected variable TMap< FName, FString > SearchStartBlackboard  
Protected variable EBTBranchAction SuspendedBranchActions Type of suspended branch action
Protected variable TMultiMap< FBTNodeIndex, FAIMessageObserverHandle > TaskMessageObservers Message observers mapped by instance & execution index
Protected variable FBTTreeStartInfo TreeStartInfo Stored data for starting new tree, waits until previously running finishes aborting
Protected variable friend UBTCompositeNode  
Protected variable friend UBTNode  
Protected variable friend UBTTask_RunBehavior  
Protected variable friend UBTTask_RunBehaviorDynamic  
Protected variable friend UBTTaskNode  

Constructors

  Type Name Description
Public function  

UBehaviorTreeComponent ( const FObjectInitializer& ObjectInitializer
)

  
Public function   DO NOT USE. This constructor is for internal usage only for hot-reload purposes.

Functions

  Type Name Description
Protected function void Abort currently executed task
Protected function void

ActivateBranch ( const UBTDecorator& RequestedBy,
bool bRequestEvenIfNotExecuting
)

 Activate a branch as the decorator conditions are now passing
Public function void

AddCooldownTagDuration ( FGameplayTag CooldownTag,
float CooldownDuration,
bool bAddToExistingDuration
)

 Add to the cooldown tag's duration
Protected function void Apply pending node updates required for discarded search
Protected function void

ApplySearchData ( UBTNode* NewActiveNode
)

 Apply pending node updates from SearchData
Protected function void

ApplySearchUpdates ( const TArray< FBehaviorTreeSearchUpdate >& UpdateList,
int32 NewNodeExecutionIndex,
bool bPostUpdate
)

 Apply updates from specific list
Protected function Const EBTNodeRelativePriority

CalculateRelativePriority ( const UBTNode* NodeA,
const UBTNode* NodeB
)

 Return NodeA's relative priority in regards to NodeB
Protected function void Copy memory block from persistent memory to running instances (rollback)
Protected function void Copy memory block from running instances to persistent memory
Protected function void

DeactivateBranch ( const UBTDecorator& RequestedBy
)

 Deactivate a branch as the decorator conditions are not passing anymore
Protected function bool

DeactivateUpTo ( const UBTCompositeNode* Node,
uint16 NodeInstanceIdx,
EBTNodeResult::Type& NodeResult,
int32& OutLastDeactivatedChildIndex
)

 Deactivate all nodes up to requested one
Public function Virtual Const FString  
Public function Virtual Const FString  
Public function Static void Code for timing BT Search for FramePro.
Protected function void

EvaluateBranch ( const UBTDecorator& RequestedBy
)

 Evaluate a branch as the decorator conditions have changed
Protected function void Evaluate a branch as current active node is finished
Protected function void

ExecuteTask ( UBTTaskNode* TaskNode
)

 Execute new task
Public function Const int32 Tries to find behavior tree instance in context
Public function Const UBTNode *

FindTemplateNode ( const UBTNode* Node
)

 Tries to find template node for given instanced node
Public function Const uint16 Get index of active instance on stack
Public function Const const UBTNode *  
Public function Const UBehaviorTree *  
Public function Const uint8 *

GetNodeMemory ( UBTNode* Node,
int32 InstanceIdx
)

  
Public function Const UBehaviorTree *  
Public function Const double  
Public function Const EBTTaskStatus::Type

GetTaskStatus ( const UBTTaskNode* TaskNode
)

  
Protected function Const bool Return true if the current or any parallel task has a latent abort in progress
Public function Const bool  
Public function Const bool

IsAuxNodeActive ( const UBTAuxiliaryNode* AuxNode
)

  
Public function Const bool

IsAuxNodeActive ( const UBTAuxiliaryNode* AuxNodeTemplate,
int32 InstanceIdx
)

  
Protected function Static bool Check if debugger is currently running and can gather data
Public function Const bool

IsExecutingBranch ( const UBTNode* Node,
int32 ChildIndex
)

  
Public function Const bool Returns true if InstanceStack contains any BT runtime instances
Public function Const bool  
Public function void

OnTaskFinished ( const UBTTaskNode* TaskNode,
EBTNodeResult::Type TaskResult
)

 Finish latent execution or abort
Protected function Virtual void Called when tree runs out of nodes to execute
Public function void Process execution flow
Protected function void Apply pending execution from last task search
Protected function void Apply pending tree initialization
Protected function bool

PushInstance ( UBehaviorTree& TreeAsset
)

 Push behavior tree instance on execution stack : should never be called out-side of BT execution, meaning only BT tasks can push another BT instance!
Public function void

RegisterMessageObserver ( const UBTTaskNode* TaskNode,
FName MessageType
)

 Setup message observer for given task
Public function void

RegisterMessageObserver ( const UBTTaskNode* TaskNode,
FName MessageType,
FAIRequestID MessageID
)

 Setup message observer for given task
Public function void

RegisterParallelTask ( const UBTTaskNode* TaskNode
)

 Add active parallel task
Protected function void Remove instanced nodes, known subtree instances and safely clears their persistent memory
Public function void

RequestBranchActivation ( const UBTDecorator& RequestedBy,
const bool bRequestEvenIfExecuting
)

 Request branch activation: helper for decorator
Public function void

RequestBranchDeactivation ( const UBTDecorator& RequestedBy
)

 Request branch deactivation: helper for decorator
Public function void

RequestBranchEvaluation ( const UBTDecorator& RequestedBy
)

 Request branch evaluation: helper for decorator
Public function void Request branch evaluation: helper for active node (ex: tasks)
Public function void

RequestExecution ( const UBTCompositeNode* RequestedOn,
const int32 InstanceIdx,
const UBTNode* RequestedBy,
const int32 RequestedByChildIndex,
const EBTNodeResult::Type ContinueWithResult,
bool bStoreForDebugger
)

 Request execution change
Public function void

RequestExecution ( EBTNodeResult::Type ContinueWithResult
)

 Replaced by RequestBranchEvaluation with EBTNodeResult
Public function void

RequestExecution ( const UBTDecorator* RequestedBy
)

 Replaced by the RequestBranchEvaluation from decorator
Public function void

RestartTree ( EBTRestartMode RestartMode
)

 Restarts execution from root
Protected function void Resume branch actions and execute all the queued up ones
Protected function void Restore state of tree to state before search
Public function void Schedule execution flow update in next tick
Public function void

ScheduleNextTick ( float NextDeltaTime
)

 END UActorComponent overrides Schedule when will be the next tick, 0.0f means next frame, FLT_MAX means never
Public function Virtual void

SetDynamicSubtree ( FGameplayTag InjectTag,
UBehaviorTree* BehaviorAsset
)

 Assign subtree to RunBehaviorDynamic task specified by tag
Public function void Starts execution from root
Public function void Stops execution
Protected function Const void

StoreDebuggerBlackboard ( TMap< FName, FString >& BlackboardValueDesc
)

 Describe blackboard's key values
Protected function void Make a snapshot for debugger
Protected function Const void

StoreDebuggerInstance ( FBehaviorTreeDebuggerInstance& InstanceInfo,
uint16 InstanceIdx,
EBTExecutionSnap::Type SnapType
)

 Make a snapshot for debugger from given subtree instance
Protected function Const void

StoreDebuggerRemovedInstance ( uint16 InstanceIdx
)

  
Protected function void

StoreDebuggerRestart ( const UBTNode* Node,
uint16 InstanceIdx,
bool bAllowed
)

 Store restarting node for debugger
Protected function Const void

StoreDebuggerRuntimeValues ( TArray< FString >& RuntimeDescriptions,
UBTNode* RootNode,
uint16 InstanceIdx
)

 Gather nodes runtime descriptions
Protected function Const void

StoreDebuggerSearchStep ( const UBTNode* Node,
uint16 InstanceIdx,
EBTNodeResult::Type NodeResult
)

 Store search step for debugger
Protected function Const void

StoreDebuggerSearchStep ( const UBTNode* Node,
uint16 InstanceIdx,
bool bPassed
)

 Store search step for debugger
Protected function void

SuspendBranchActions ( EBTBranchAction BranchActions
)

 Suspend any branch actions and queue them to be processed later by ResumeBranchActions()
Protected function void Tracks if there are new tasks using latent abort in progress
Protected function bool Returns true if execution was waiting on latent aborts and they are all finished;
Public function Const bool Indicates instance has been initialized to work with specific BT asset
Public function void

UnregisterAuxNodesInBranch ( const UBTCompositeNode* Node,
bool bApplyImmediately
)

 Unregister all aux nodes in branch of tree
Public function void

UnregisterAuxNodesInRange ( const FBTNodeIndex& FromIndex,
const FBTNodeIndex& ToIndex
)

 Unregister all aux nodes between given execution index range: FromIndex < AuxIndex < ToIndex
Public function void Unregister all aux nodes less important than given index
Public function void Remove message observers registered with task
Public function void Remove message observers registered with task
Public function void

UnregisterParallelTask ( const UBTTaskNode* TaskNode,
uint16 InstanceIdx
)

 Remove parallel task
Protected function Const void

UpdateDebuggerAfterExecution ( const UBTTaskNode* TaskNode,
uint16 InstanceIdx
)

 Update runtime description of given task node in latest debugger's snapshot
Protected function uint8

UpdateInstanceId ( UBehaviorTree* TreeAsset,
const UBTNode* OriginNode,
int32 OriginInstanceIdx
)

 Add unique Id of newly created subtree to KnownInstances list and return its index

Overridden from UBrainComponent

  Type Name Description
Public function Virtual void

Cleanup ()

 AI logic won't be needed anymore, stop all activity and run cleanup
Public function Virtual Const void  
Public function Virtual Const FString  
Public function Virtual void

HandleMessage ( const FAIMessage& Message
)

  
Public function Virtual Const bool  
Public function Virtual Const bool  
Public function Virtual void

PauseLogic ( const FString& Reason
)

 Pause logic and blackboard updates.
Public function Virtual void Restarts currently running or previously ran brain logic.
Public function Virtual EAILogicResuming::Type

ResumeLogic ( const FString& Reason
)

 Resumes paused brain logic. MUST be called by child implementations!
Public function Virtual void Starts brain logic. If brain is already running, will not do anything.
Public function Virtual void

StopLogic ( const FString& Reason
)

 Stops currently running brain logic.

Overridden from UActorComponent

  Type Name Description
Public function Virtual void

RegisterComponentTickFunctions ( bool bRegister
)

 Virtual call chain to register all tick functions
Public function Virtual void

SetComponentTickEnabled ( bool bEnabled
)

 Set this component's tick functions to be enabled or disabled.
Public function Virtual void

TickComponent ( float DeltaTime,
enum ELevelTick TickType,
FActorComponentTickFunction* ThisTickFunction
)

 BEGIN UActorComponent overrides
Public function Virtual void Handle this component being Uninitialized.

Classes

  Type Name Description
Protected struct FBranchActionInfo    
Protected struct FBTSuspendBranchActionsScoped    

Typedefs

Name Description
FBTSuspendBranchDeactivationScoped  

Constants

Name Description
ActiveDebuggerCounter Set when at least one debugger window is opened
bAddedEndFrameCallback Code for timing BT Search for FramePro.
FrameSearchTime  
NumSearchTimeCalls  

Deprecated Functions

  Type Name Description
Public function void This function is deprecated. Please use RequestBranchDeactivation instead.
Protected function void This function is deprecated. Please use ResumeBranchActions instead.
Protected function void This function is deprecated. Please use SuspendBranchActions instead.

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