/*
Returns the closest distance between point pnt and the segment
that goes from point a to b
Idea by:
http://local.wasp.uwa.edu.au/~pbourke/geometry/pointline/
*/
double distance_point_to_segment(const point &a,const point &b,
const point &pnt){
double u =
((pnt.x - a.x)*(b.x - a.x) + (pnt.y - a.y)*(b.y - a.y))
/distsqr(a, b);
point intersection;
intersection.x = a.x + u*(b.x - a.x);
intersection.y = a.y + u*(b.y - a.y);
if (u < 0.0 || u > 1.0){
return min(dist(a, pnt), dist(b, pnt));
}
return dist(pnt, intersection);
}
bool graham_cmp(point a, point b) {
int t = cross(pivot, b, a);
if(t < 0) return true;
if(t == 0) return distsqr(pivot, a) < distsqr(pivot, b);
return false;
}