An AudioSource is analogous to a speaker in the game world.

The only way to play an AudioClip is with an AudioSource.

An AudioSource can be positional or not. Positional AudioSources sound different depending on where the listener is. Non-positional AudioSources sound the same regarldess of where the listener is. The location of the listener can be controlled with an AudioManager.

NOTE: By default an AudioSource is positional.

class AudioSource {
 AudioManager _manager;
 String _name;
 GainNode _output;
 GainNode _gainNode;
 PannerNode _panNode;
 List<AudioSound> _sounds;
 num _mutedVolume;
 bool _isPaused = false;
 num _x = 0.0;
 num _y = 0.0;
 num _z = 0.0;
 bool _positional = true;

 void _setupNodes() {
   _panNode.disconnect(0);
   _gainNode.disconnect(0);
   if (_positional) {
     _gainNode.connect(_panNode, 0, 0);
     _panNode.connect(_output, 0, 0);
   } else {
     // Not positioned, we skip the panner node.
     _gainNode.connect(_output, 0, 0);
   }
 }

 AudioSource._internal(this._manager, this._name, this._output) {
   _gainNode = _manager._context.createGain();
   _panNode = _manager._context.createPanner();
   _panNode.coneOuterGain = 1.0;
   _setupNodes();
   _sounds = new List<AudioSound>();
 }

 bool get positional => _positional;

 void set positional(bool b) {
   if (b != _positional) {
     _positional = b;
     _setupNodes();
   }
 }

 /** Get the volume of the source. 0.0 <= volume <= 1.0. */
 num get volume => _gainNode.gain.value;

 /** Set the volume for the source. All sounds being played are affected. */
 void set volume(num v) {
   _gainNode.gain.value = v;
 }

 Map toJson() {
   return {
     "_name": _name,
     "volume": _gainNode.gain.value,
     "_mutedVolume": _mutedVolume,
     "_isPaused": _isPaused,
     "_x":_x,
     "_y":_y,
     "_z":_z,
   };
 }

 AudioSource fromMap(Map map) {
   _gainNode.gain.value = map["volume"];
   _mutedVolume = map["_mutedVolume"];
   _isPaused = map["_isPaused"];
   _name = map["_name"];
   _x = map["_x"];
   _y = map["_y"];
   _z = map["_z"];
   setPosition(_x, _y, _z);
   return this;
 }

 /** Is the source muted? */
 bool get mute {
   return _mutedVolume != null;
 }

 /** Mute or unmute the source. */
 void set mute(bool b) {
   if (b) {
     if (_mutedVolume != null) {
       // Double mute.
       return;
     }
     _mutedVolume = volume;
     volume = 0.0;
   } else {
     if (_mutedVolume == null) {
       // Double unmute.
       return;
     }
     volume = _mutedVolume;
     _mutedVolume = null;
   }
 }

 /** Play [clip] from the source. */
 AudioSound playOnce(AudioClip clip) {
   return playOnceIn(0.0, clip);
 }

 /** Play [clip] from the source starting in [delay] seconds. */
 AudioSound playOnceIn(num delay, AudioClip clip) {
   AudioSound sound = new AudioSound._internal(this, clip, false);
   _sounds.add(sound);
   sound.play(delay);
   sound.pause = pause;

   return sound;
 }

 /** Play [clip] from the source in a loop. */
 AudioSound playLooped(AudioClip clip) {
   return playLoopedIn(0.0, clip);
 }

 /** Play [clip] from the source in a loop starting in [delay]
  * seconds.
  */
 AudioSound playLoopedIn(num delay, AudioClip clip) {
   AudioSound sound = new AudioSound._internal(this, clip, true);
   _sounds.add(sound);
   sound.play(delay);
   sound.pause = pause;
   return sound;
 }

 bool _scanSounds() {
   for (int i = _sounds.length-1; i >= 0; i--) {
     AudioSound sound = _sounds[i];
     if (sound.isFinished) {
       int last = _sounds.length-1;
       // Copy last over
       _sounds[i] = _sounds[last];
       // Pop end
       _sounds.removeLast();
       print('removing sound.');
       sound.stop();
     }
   }
 }

 /** Is the source currently paused? */
 bool get pause => _isPaused;

 /** Pause or resume the source */
 void set pause(bool b) {
   if (b) {
     if (_isPaused == true) {
       // Double pause.
       return;
     }
     _pause();
     _isPaused = true;
   } else {
     if (_isPaused == false) {
       // Double unpause.
       return;
     }
     _resume();
     _isPaused = false;
   }
 }

 void _pause() {
   _scanSounds();
   _sounds.forEach((sound) {
     sound.pause = true;
   });
 }

 void _resume() {
   _scanSounds();
   _sounds.forEach((sound) {
     sound.pause = false;
   });
 }

 /** Stop the source. Affects all playing and scheduled sounds. */
 void stop() {
   _sounds.forEach((sound) {
     sound.stop();
   });
   _scanSounds();
 }

 /** X position of the source. */
 num get x => _x;
 /** Y position of the source. */
 num get y => _y;
 /** Z position of the source. */
 num get z => _z;

 /**
  * Set the position of the source.
  */
 void setPosition(num x, num y, num z) {
   _x = x;
   _y = y;
   _z = z;
   _panNode.setPosition(x, y, z);
 }

 /**
  * Set the linear velocity of the source.
  */
 void setVelocity(num x, num y, num z) {
   _panNode.setVelocity(x, y, z);
 }
}