bool Edge::intersects(Edge* other) {
Point2 p = first;
Point2 q = other->getFirst();
Point2 r = second.minus(first);
Point2 s = other->getSecond().minus(other->getFirst());
Point2 sub = q.minus(p);
real rcs = r.wedgeProduct(s);
real tnum = sub.wedgeProduct(s);
real unum = sub.wedgeProduct(r);
// first case
if(rcs == 0.0 && unum == 0.0) {
// colinier case .. don't need to worry about I think
return false;
}
// second case
if(rcs == 0.0 && unum != 0.0) {
// parallel and non-intersecting
return false;
}
// third case
real t = tnum / rcs;
real u = unum / rcs;
if(rcs != 0.0 && t < 1.0 && t > 0.0 && u < 1.0 && u > 0.0) {
// points meet at ::
// p + t*r
// q + u*s
return true;
}
// fourth case
// not parallel and do not intersect
return false;
}
