function isIntersecting(p1, p2, p3, p4) { function CCW(p1, p2, p3) { return (p3.y - p1.y) * (p2.x - p1.x) > (p2.y - p1.y) * (p3.x - p1.x); } return (CCW(p1, p3, p4) != CCW(p2, p3, p4)) && (CCW(p1, p2, p3) != CCW(p1, p2, p4)); }