Unreal Engine 5 Documentation has been moved to the Epic Developer Community

Unreal Engine 4.26

Unreal Engine 4.27

Unreal Engine 5.0

Unreal Engine 5.1

Unreal Engine 5.2

Unreal Engine 5.3

> Making Interactive Experiences > Artificial Intelligence > Behavior Trees > Behavior Tree Node Reference > Behavior Tree Node Reference: Services

Light Theme

Dark Theme

Behavior Tree Node Reference: Services

Reference for the Behavior Tree Service nodes.

Choose your operating system:

Windows

macOS

Linux

On this page

Default Focus
Run EQS
Custom Services

Services attach to Composite or Task nodes and will execute at their defined frequency as long as their branch is being executed. These are often used to make checks and to update the Blackboard. These take the place of traditional Parallel nodes in other Behavior Tree systems.

Default Focus

The Default Focus creates a shortcut to accessing an Actor in your Blueprints and Code by setting the focus of the AI Controller. By setting the focus of the AI Controller to an Actor, you can directly access it from the AI Controller instead of accessing a Blackboard key.


Property	Description
Blackboard Key	This takes in an Actor Key (an Object Key with its base class set to Actor) to be quickly referenced by the AI Controller using `GetFocusActor` .
Node Name	The name the node should display in the Behavior Tree graph.

Run EQS

The Run EQS Service node can be used to regularly execute an Environmental Query System (EQS) template at assigned intervals and can update a specified Blackboard Key.

Property

Description

Query Template

The EQS asset to run.

Query Config

Optional array of additional parameters to include in the query.

EQSQuery Blackboard Key

Option to use a Blackboard Key that stores an EQS Query Template instead of a specified EQS Query Template.

Run Mode


Single Best Item	Pick the first item with the best score.
Single Random Item from Best 5%	Pick a random item with score `95%` to `100%` of max.
Single Random Item from Best 25%	Pick a random item with score `75%` to `100%` of max.
All Matching	Get all items that match conditions.

Blackboard Key

The Blackboard Key the Service will write results into - either an FVector or an Actor.

Interval

Defines the time span between subsequent ticks of the Service.

Random Deviation

Adds a random range value to the Service's Interval value.

Call Tick on Search Start

Call Tick Event when Task search enters this node ( Search Start will be called as well).

Restart Timer on Each Activation

If set, the next Tick time will be always reset to Service's Interval value when the node is activated.

Node Name

The name the node should display in the Behavior Tree graph.

Custom Services

You can create Services by clicking the New Service button from the toolbar that contains Blueprint logic and (or) parameters.

Blueprint Services are less performant than C++ Services. If optimization is a concern, you may want to use native Services.

The following properties are also available when creating a Service.


Property	Description
Show Property Details	Shows detailed information about properties when enabled.
Show Event Details	Shows detailed information about implemented Events when enabled.
Node Name	The name the node should display in the Behavior Tree graph.
Interval	Defines the time span between subsequent ticks of the Service.
Random Deviation	Adds a random range value to the Service's Interval value.
Call Tick on Search Start	Call Tick Event when Task search enters this node ( Search Start will be called as well).
Restart Timer on Each Activation	If set, the next Tick time will be always reset to Service's Interval value when the node is activated.