
  // MOUSE DOWN HANDLER
  //

  elem.addEventListener('mousedown', function(e) {
    var wave = createWave(e.target);
    var elem = scope.element;

    wave.isMouseDown = true;
    wave.tDown = 0.0;
    wave.tUp = 0.0;
    wave.mouseUpStart = 0.0;
    wave.mouseDownStart = now();

    var width = e.target.width / 2; // Retina canvas
    var height = e.target.height / 2;
    var touchX = e.clientX - e.target.offsetLeft - e.target.offsetParent.offsetLeft;
    var touchY = e.clientY - e.target.offsetTop - e.