Audio

DownDraft provides a pluggable audio system with a Kira backend via Rust FFI.

AudioEngine

import { startGame } from "@downdraft/engine/app/renderer";
import { AudioKiraLib, AudioEngineTok } from "@downdraft/engine/libraries/audio-kira";

startGame({
  libraries: [AudioKiraLib],
  // inject the backend via the typed token in onReady:
  onReady: (ctx) => {
    const audio = ctx.inject(AudioEngineTok);
  },
});

Spatial Audio

Audio sources have 3D positions. An audio listener follows the camera, enabling distance-based attenuation and spatial panning.

Audio Source Component

import { createAudioSource } from "@downdraft/engine";

const source = createAudioSource({
  buffer: "explosion.wav",
  volume: 0.8,
  loop: false,
  spatial: true,
});

Audio Listener

The audio listener tracks the camera position and orientation. Spatial audio is calculated relative to the listener.

Mixer

The audio mixer supports:

Multiple channels (master, music, sfx, voice)
Per-channel volume control
Effects (reverb, low-pass filter, etc.)

Backend Interface

The AudioBackend interface defines the contract for audio implementations; AudioEngine takes any backend at construction. The Kira backend (KiraAudioBackend, wired declaratively via AudioKiraLib) is a Rust cdylib (libdowndraft_audio, crate downdraft-audio under libraries/audio-kira/native) loaded over FFI when present. Alternative backends can be implemented by implementing the interface.