# 02 Events

An **Event** is a callback that fires when an AI interacts with a node or path. Use them to trigger gameplay (sound, dialog, spawn, quest update).

## Timing options

| Timing         | Fires when                                |
| -------------- | ----------------------------------------- |
| **OnEnter**    | AI enters a node radius / starts a path.  |
| **OnExit**     | AI exits a node radius / finishes a path. |
| **OnTraverse** | AI fully traverses a path (start to end). |
| **OnMidpoint** | AI reaches the midpoint of a path.        |

## Adding an event

1. Select an OWP Node or Path.
2. In the **Details** panel, expand **OWP > Gameplay > Events**.
3. Click **+** and pick an event class (or your own custom subclass).
4. Set **Timing** and any class-specific properties.

## Properties

| Property         | What it does                                             |
| ---------------- | -------------------------------------------------------- |
| **Display Name** | Label in the editor.                                     |
| **Timing**       | When to fire (see above).                                |
| **Repeatable**   | If off, the event fires at most once per actor lifetime. |

## Custom event (Blueprint)

1. Content Browser → Add → Blueprint Class → Parent: **OWP Event**.
2. Override **Execute** in the event graph.
   * Inputs: **Traveler** (struct with the AI's actor, tags, etc.) and **OWP Element** (the node or path).
   * Add your gameplay logic.
3. Optionally override **Should Trigger** for runtime gates.
4. Add your event to a node or path.

## Examples

| Goal                       | Setup                                                              |
| -------------------------- | ------------------------------------------------------------------ |
| Play sound at intersection | OnEnter on the node, custom event plays sound at element location. |
| Spawn ambush at bridge     | OnMidpoint on the bridge path, custom event spawns enemies.        |
| Award XP after a path      | OnTraverse on the path, custom event awards XP to Traveler.Actor.  |
| One-shot tutorial step     | OnEnter, **Repeatable = false**, custom event advances tutorial.   |

## Tips

{% hint style="warning" %}
Don't modify the network from inside Execute. Spawning/deleting nodes mid-traversal can break the AI's current path. Defer with a timer if you must.
{% endhint %}

{% hint style="info" %}
Keep Execute cheap. It runs during the AI's move tick.
{% endhint %}

{% hint style="info" %}
Same event instance fires for every traveler. Don't store per-traveler state on the event — read it from the Traveler input.
{% endhint %}


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