Detect sound is ended in THREE.PositionalAudio?

Three.Audio is wrapper around a buffer source audio object. https://github.com/mrdoob/three.js/blob/ddab1fda4fd1e21babf65aa454fc0fe15bfabc33/src/audio/Audio.js#L12

It looks like it overrides the onended event and binds it to its own function, so we just do the same:

sound1.source.onended = function() {
    console.log('sound1 ended');
    this.isPlaying = false; /* sets Three wrapper property correctly */
};

We set isPlaying = false because this is what Three's Audio onended function does, which we just overrode.

working pen: http://codepen.io/anon/pen/GoambE