# AudioBusHandle

> Talos 0.7 · Since 0.6

One bus of the mixer graph, by name.

## Signature

```ts
export interface AudioBusHandle {
  /** The name this handle was created with, declared or not. */
  readonly name: string
  /**
   * Ramp this bus to `volume` over `seconds`; omitting the time is a step. Returns false
   * when the scene declares no bus by this name — which the critic reports as
   * `audio-bus-unknown` long before the scene runs.
   */
  setVolume(volume: number, seconds?: number): boolean
}
```

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

## Members

| Member | Signature | Description |
|---|---|---|
| `name` | `readonly name: string` | The name this handle was created with, declared or not. |
| `setVolume` | `setVolume(volume: number, seconds?: number): boolean` | Ramp this bus to `volume` over `seconds`; omitting the time is a step. Returns false when the scene declares no bus by this name — which the critic reports as `audio-bus-unknown` long before the scene runs. |

## Example

The tested fixture `crates/editor/templates/behaviours/empty.ts`.

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

/**
 * A behaviour with nothing in it yet.
 *
 * `update` runs every fixed tick with `dt` at 1/60 s; `init` runs once after attach and again
 * after each hot reload, with `ctx.state` preserved. Everything a behaviour can reach hangs off
 * `ctx`: `ctx.entity` is the entity this is attached to, `ctx.world` queries the scene,
 * `ctx.events` is the bus every other behaviour listens on, and `ctx.props` is a read-only copy
 * of the `props` the Details panel shows.
 *
 * Add a property in the Details panel and read it here as `ctx.props.<name>`.
 */
interface State {
  /** Whatever this behaviour needs to remember between ticks. Must stay JSON-serialisable. */
  ticks: number
}

interface Props {
  /** Every key the Details panel's Add property row introduces arrives here. */
  [key: string]: unknown
}

export default {
  init(ctx) {
    if (typeof ctx.state.ticks !== "number") ctx.state.ticks = 0
  },
  update(ctx) {
    ctx.state.ticks += 1
  },
} satisfies Behavior<State, Props>
```