/* Une classe stockage de segment de droite             */
/*                                                      */
/* Auteur: Nicolas JANEY                                */
/* nicolas.janey@univ-fcomte.fr                         */
/* Novembre 2009                                        */

public class Segment {
  public Position2D pi;
  public Position2D pf;

  public Segment() {
    pi = new Position2D();
    pf = new Position2D();
  }

  public Segment(float xi,float yi,float xf,float yf) {
    pi = new Position2D(xi,yi);
    pf = new Position2D(xf,yf);
  }

  public Segment(Position2D pi,Position2D pf) {
    this.pi = new Position2D(pi);
    this.pf = new Position2D(pf);
  }

  public Segment(Segment s) {
    pi = new Position2D(s.pi);
    pf = new Position2D(s.pf);
  }
  
  public float abscisse(float y) {
    if ( pf.x != pi.x ) {
      float a = (pf.y-pi.y) / (pf.x-pi.x);
      float b = pi.y - a*pi.x;
      return((y-b)/a); }
      else
      return(pf.x);
  }
  
  public float ordonnee(float x) {
    float a = (pf.y-pi.y) / (pf.x-pi.x);
    float b = pi.y - a*pi.x;
    return(a*x+b);
  }
  
  public String toString() {
    return("["+pi+","+pf+"]");
  }
}