function onDown(ev) {
            var event = normalizeEvent(ev);
            if (!pointerActive && !paused) {
                pointerActive = true;
                decelerating = false;
                pointerId = event.id;

                pointerLastX = pointerCurrentX = event.x;
                pointerLastY = pointerCurrentY = event.y;
                trackingPoints = [];
                addTrackingPoint(pointerLastX, pointerLastY);

                addRuntimeEvents();
            }
        }
function onDown(ev) {
            var event = normalizeEvent(ev);
            if (!pointerActive && !paused) {
                pointerActive = true;
                decelerating = false;
                pointerId = event.id;

                pointerLastX = pointerCurrentX = event.x;
                pointerLastY = pointerCurrentY = event.y;
                trackingPoints = [];
                addTrackingPoint(pointerLastX, pointerLastY);

                addRuntimeEvents();
            }
        }
function onDown ( ev ) { var event = normalizeEvent ( ev ) ; if ( ! pointerActive && ! paused ) { pointerActive = true ; decelerating = false ; pointerId = event . id ; pointerLastX = pointerCurrentX = event . x ; pointerLastY = pointerCurrentY = event . y ; trackingPoints = [ ] ; addTrackingPoint ( pointerLastX , pointerLastY ) ; addRuntimeEvents ( ) ; } }
Initializes movement tracking
@param  {Object} ev Normalized event
Initializes movement tracking