ConvexHull inset_ch(ConvexHull ch, double dist) {
ConvexHull ret;
for(unsigned i = 0; i < ch.size(); i++) {
Point bisect = (rot90(ch[i+1] - ch[i]));
ret.merge(unit_vector(bisect)*dist+ch[i]);
ret.merge(unit_vector(bisect)*dist+ch[i+1]);
}
return ret;
}
ConvexHull rect2convexhull(Rect const & r) {
ConvexHull ch;
for(int i = 0; i < 4; i++)
ch.merge(r.corner(i));
return ch;
}