Function msSquareDistancePointToSegment

mapsearch.c:339–359

}

double msSquareDistancePointToSegment(pointObj *p, pointObj *a, pointObj *b)
{
  double l_squared; /* squared length of line ab */
  double r,s;

  l_squared = msSquareDistancePointToPoint(a,b);

  if(l_squared == 0.0) /* a = b */
    return(msSquareDistancePointToPoint(a,p));

  r = ((a->y - p->y)*(a->y - b->y) - (a->x - p->x)*(b->x - a->x))/(l_squared);

  if(r > 1) /* perpendicular projection of P is on the forward extention of AB */
    return(MS_MIN(msSquareDistancePointToPoint(p, b),msSquareDistancePointToPoint(p, a)));
  if(r < 0) /* perpendicular projection of P is on the backward extention of AB */
    return(MS_MIN(msSquareDistancePointToPoint(p, b),msSquareDistancePointToPoint(p, a)));

  s = ((a->y - p->y)*(b->x - a->x) - (a->x - p->x)*(b->y - a->y))/l_squared;

  return(fabs(s*s*l_squared));
}

#define SMALL_NUMBER 0.00000001
#define dot(u,v) ((u).x *(v).x + (u).y *(v).y) /* vector dot product */