StateTree Tools

Ready-made StateTree tools for Unreal Engine 5

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Project maintained by StateTreeTools Hosted on GitHub Pages — Theme by mattgraham

Perception Event Forwarder

Plugin: StateTreeToolsCore Class: UPerceptionEventForwarder

Bridges the AI perception system and the StateTree event system. Add this component alongside a UAIPerceptionComponent on an AI controller or character. At runtime it listens to the perception component’s delegates and fires StateTree events whenever a target is detected or forgotten, so your StateTree can react to perception without any custom C++.

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Events Fired

Both events are sent to all UStateTreeComponents on the same actor (or filtered to one by name — see State Tree Component Name below).

StateTreeTools.Events.Perception.TargetUpdated

Fired by OnTargetPerceptionUpdated. The event payload is FTargetPerceptionUpdatedPayload:

Field	Type	Description
Actor	AActor*	The perceived actor
Stimulus	FAIStimulus	Full stimulus data — sense class, strength, age, success flag
Attitude	ETeamAttitude	Relationship between owner and perceived actor (Friendly, Neutral, Hostile)

StateTreeTools.Events.Perception.TargetForgotten

Fired by OnTargetPerceptionForgotten. The event payload is FTargetPerceptionForgottenPayload.

Requires UE 5.2 or later. The OnTargetPerceptionForgotten delegate was added to UAIPerceptionComponent in UE 5.2. On UE 5.1 only TargetUpdated events are fired.

Field	Type	Description
Actor	AActor*	The forgotten actor
Attitude	ETeamAttitude	Relationship between owner and forgotten actor

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Configuration

State Tree Component Name

The name of the UStateTreeComponent on the owner to send events to. Leave as None (default) to broadcast to every StateTree component on the actor. Set this if the actor has multiple StateTree components and you want to target only one.

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Setup

1. Add a UAIPerceptionComponent to your AI character or controller and configure the senses you need (e.g. Sight, Hearing).
2. Add UPerceptionEventForwarder to the same actor.
3. In your StateTree, add a transition with On Event set to StateTreeTools.Events.Perception.TargetUpdated or StateTreeTools.Events.Perception.TargetForgotten.
4. In the transition’s Payload Struct field, select the matching payload type — TargetPerceptionUpdatedPayload or TargetPerceptionForgottenPayload. If the payload type is wrong or left unset, the event will not match and the transition will never fire.
5. Bind the event payload fields (e.g. Payload.Actor, Payload.Stimulus.bWasSuccessfullySensed, Payload.Attitude) using the StateTree binding system.

The component logs a warning and becomes inactive if no UAIPerceptionComponent is found on the owner at BeginPlay.

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