flame_flutter3d_audio

Sound for a Flame game bridged to flutter3d with flame_flutter3d, over flutter3d_audio.

class MyGame extends FlameGame with HasFlutter3d {
  late final sound = AudioSceneComponent(bank: Sounds.all);
  final engine = SoundEmitterComponent(Sounds.engine, playing: false);

  @override
  Future<void> onLoad() async {
    await super.onLoad();
    await addAll([sound, engine]);
  }

  // From the player's first key, touch or button:
  void takeOff() => sound.open();

  @override
  void update(double dt) {
    engine
      ..playing = flying
      ..rate = 0.8 + 0.5 * throttle;
    super.update(dt);
  }
}

The game's sound

AudioSceneComponent holds one AudioScene. Until open() it plays into a silent backend, so the game makes the same calls either way and nothing is heard; a browser allows sound only after the user has touched the page, so open() belongs to the first input. When the game has HasFlutter3d, the listener rides on its 3D camera. The mix is worked out after everything else has moved in the frame.

Loops held by state

SoundEmitterComponent asks every frame whether it should be sounding: it plays while it is in the game and playing is true, and stops when either changes. Under a bridged component it sounds from that component's place in the scene. Set playing before the game's children update (before super.update in the game's own update) and the loop is mixed in the same frame.

Positional and flat sounds together

Each SoundDef says how it carries. NoAttenuation() is heard the same everywhere, like music or an interface click. InverseRolloff, the default, LinearRolloff and ExponentialRolloff fade with distance from the listener up to their maximum, and every sound that carries is panned by which side of the listener it is on. Both play in the same scene: play(boom, at: craft.scenePosition) for a blast out on the river, play(click) for a sound at the listener.

Why a separate package

flutter3d_audio plays through SoLoud, which brings a native library and, on the web, a script. A bridged game with no sound should carry neither, so the bridge does not depend on this package.