dist/impetus.js
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