# ActionBinding

> Talos 0.6 · Since 0.6

What one action is bound to right now, in the shape `meta.input` writes it.

## Signature

```ts
export interface ActionBinding {
  kind: "axis2" | "axis1" | "button"
  /**
   * Key names. `axis2` takes four in WASD order (+y, -x, -y, +x: up, left, down, right); `axis1`
   * two, negative then positive (`["A", "D"]` reads -1 on A, +1 on D); `button` any number, OR'd.
   * An axis takes alternate sets back to back, any of which drives it: `["A", "D", "Left",
   * "Right"]` for steering on A/D and the arrows, `["W", "A", "S", "D", "Up", "Left", "Down",
   * "Right"]` for moving on both. A count that is not a whole number of sets binds nothing.
   */
  keys: string[]
  mouse: MouseBinding | null
  gamepad: GamepadBinding | null
}
```

Import: `import type { ActionBinding } from "@argus/api"`

## Members

| Member | Signature | Description |
|---|---|---|
| `kind` | `kind: "axis2" \| "axis1" \| "button"` |  |
| `keys` | `keys: string[]` | Key names. `axis2` takes four in WASD order (+y, -x, -y, +x: up, left, down, right); `axis1` two, negative then positive (`["A", "D"]` reads -1 on A, +1 on D); `button` any number, OR'd. An axis takes alternate sets back to back, any of which drives it: `["A", "D", "Left", "Right"]` for steering on A/D and the arrows, `["W", "A", "S", "D", "Up", "Left", "Down", "Right"]` for moving on both. A count that is not a whole number of sets binds nothing. |
| `mouse` | `mouse: MouseBinding \| null` |  |
| `gamepad` | `gamepad: GamepadBinding \| null` |  |

## Example

The tested fixture `fixtures/recipes/jump-pad-and-elevator/scenes/behaviors/camera-zone.ts`.

```ts
import type { Behavior } from "@argus/api"

/**
 * A trigger volume that retunes the camera while the player is inside it.
 *
 * The engine has no camera-zone concept and needs none: a volume, a `trigger` component and this.
 * Here the player's behaviour owns the camera (it re-sends its params when the view is turned), so
 * the zone tells it what to change rather than calling `ctx.camera.set` itself. In a scene where
 * nothing else writes the camera, the zone can call `ctx.camera.set(kind, params)` directly.
 */
interface Props {
  /** `ctx.camera.set` params to merge in on the way in, and on the way out. */
  inside?: Record<string, unknown>
  outside?: Record<string, unknown>
}

export default {
  onTrigger(ctx, trigger) {
    const params = trigger.entering ? ctx.props.inside : ctx.props.outside
    if (params) ctx.events.emit("camera-zone", { target: trigger.other.id, params })
  },
} satisfies Behavior<Record<string, never>, Props>
```