Interval(update, 1000 / 60);
         
         //mouse
         
         var mouseX, mouseY, mousePVec, isMouseDown, selectedBody, mouseJoint;
         var canvasPosition = getElementPosition(document.getElementById("canvas"));
         
         document.addEventListener("mousedown", function(e) {
            isMouseDown = true;
            handleMouseMove(e);
            document.addEventListener("mousemove", handleMouseMove, true);
         }, true);
         
         document.addEventListener("mouseu