public class Intersection extends PointElement {

  PointElement A,B,C,D;

  Intersection (PointElement Aval, PointElement Bval,
	        PointElement Cval, PointElement Dval) {
    dimension = 0;
    A = Aval;  B = Bval;  C = Cval;  D = Dval;
  }

  Intersection (LineElement AB, LineElement CD) {
    dimension = 0;
    A = AB.A;  B = AB.B;  C = CD.A;  D = CD.B;
  }

  protected void update() {toIntersection(A,B,C,D);}
}