StateTree Tools

Ready-made StateTree tools for Unreal Engine 5

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GAS Event Forwarder

Plugin: StateTreeToolsGameplayAbilitySystem Class: UGASEventForwarder

This component is only available when Unreal’s built-in Gameplay Abilities plugin is enabled.

Bridges the Gameplay Ability System and the StateTree event system. Add this component to any actor that has an UAbilitySystemComponent. It handles two kinds of forwarding:

• GAS gameplay events — maps each incoming FGameplayEventData to a chosen StateTree event tag.
• Gameplay tag changes — watches specific tags and fires a StateTree event whenever one is added or removed.

Both mechanisms run automatically at BeginPlay with no C++ required.

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Configuration

Forward GAS Events to StateTree Events

A map from a GAS gameplay event tag to a StateTree event configuration. Each entry has:

Field	Description
Key (FGameplayTag)	The GAS gameplay event tag to listen for
StateTree Tag	The tag to use when forwarding the event into the StateTree

When the GAS event fires, the full FGameplayEventData payload is wrapped in an FInstancedStruct and sent to all UStateTreeComponents on the actor under the mapped StateTree tag. Bind Payload.EventTag, Payload.Instigator, Payload.Target, Payload.EventMagnitude, or other fields in your StateTree transitions.

Tags to Watch for Added

A list of gameplay tags. Whenever one of these tags is added to the actor’s ASC, a StateTree event is fired with the tag StateTreeTools.Events.TagAdded. The payload is FTagChangedPayload:

Field	Type	Description
ChangedTag	FGameplayTag	The tag that was added

If the tag is already present when BeginPlay runs, the event fires immediately.

Tags to Watch for Removed

A list of gameplay tags. Whenever one of these tags is removed from the actor’s ASC, a StateTree event is fired with the tag StateTreeTools.Events.TagRemoved. The payload is also FTagChangedPayload with the tag that was removed.

If the tag is already absent when BeginPlay runs, the event fires immediately.

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Setup

1. Enable Unreal’s built-in Gameplay Abilities plugin.
2. Add UGASEventForwarder to any actor that has an UAbilitySystemComponent.
3. To forward GAS gameplay events: add entries to Forward GAS Events to StateTree Events, setting the GAS tag and the StateTree tag you want to raise.
4. To react to tag changes: add tags to Tags to Watch for Added or Tags to Watch for Removed.
5. In your StateTree, add transitions with On Event set to the appropriate tag (StateTreeTools.Events.TagAdded, StateTreeTools.Events.TagRemoved, or your custom mapped tag).

The component logs an error if no UAbilitySystemComponent is found on the owner when tag watching is configured.

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