pointToLinePerpendicular static method

double pointToLinePerpendicular(Coordinate p, Coordinate A, Coordinate B)

Computes the perpendicular distance from a point p to the (infinite) line containing the points AB

@param p the point to compute the distance for @param A one point of the line @param B another point of the line (must be different to A) @return the distance from p to line AB

Implementation

static double pointToLinePerpendicular(
    Coordinate p, Coordinate A, Coordinate B) {
  // use comp.graphics.algorithms Frequently Asked Questions method
  /*
   * (2) s = (Ay-Cy)(Bx-Ax)-(Ax-Cx)(By-Ay)
   *         -----------------------------
   *                    L^2
   *
   * Then the distance from C to P = |s|*L.
   */
  double len2 = (B.x - A.x) * (B.x - A.x) + (B.y - A.y) * (B.y - A.y);
  double s = ((A.y - p.y) * (B.x - A.x) - (A.x - p.x) * (B.y - A.y)) / len2;

  return s.abs() * math.sqrt(len2);
}