lib/Mi manual de algoritmos/version_world_finals_2009/src/geometria/distance_point_to_line.cpp

   1 /*
   2   Returns the closest distance between point pnt and the line
   3   that passes through points a and b
   4   Idea by:
   5   http://local.wasp.uwa.edu.au/~pbourke/geometry/pointline/
   6 */
   7 double distance_point_to_line(const point &a, const point &b,
   8                               const point &pnt){
   9   double u =
  10     ((pnt.x - a.x)*(b.x - a.x)+(pnt.y - a.y)*(b.y - a.y))
  11     /distsqr(a, b);
  12   point intersection;
  13   intersection.x = a.x + u*(b.x - a.x);
  14   intersection.y = a.y + u*(b.y - a.y);
  15   return dist(pnt, intersection);
  16 }