/** Point label with cartesian coordinates (x,y) */
private final GeoPoint Point(String label, double x, double y) {
GeoPoint p = new GeoPoint(cons);
p.setCoords(x, y, 1.0);
p.setMode(Kernel.COORD_CARTESIAN);
p.setLabel(label); // invokes add()
return p;
}
public AlgoPointOnPath(Construction cons, Path path, double x, double y) {
super(cons);
this.path = path;
// create point on path and compute current location
P = new GeoPoint(cons);
P.setPath(path);
P.setCoords(x, y, 1.0);
setInputOutput(); // for AlgoElement
addIncidence();
}
// calc axes
@Override
public final void compute() {
// only parabola has directrix
if (c.type == GeoConicNDConstants.CONIC_PARABOLA) {
// directrix has direction of second eigenvector
// through point (b - p/2* eigenvec1)
directrix.x = -eigenvec[1].getY();
directrix.y = eigenvec[1].getX();
double px = b.getX() - c.p / 2.0 * eigenvec[0].getX();
double py = b.getY() - c.p / 2.0 * eigenvec[0].getY();
directrix.z = -(directrix.x * px + directrix.y * py);
P.setCoords(px, py, 1.0);
} else directrix.setUndefined();
}
@Override
public final void compute() {
// bugfix Michael Borcherds
// undefined unless A is a point on f
if (!f.isOnPath(A, Kernel.MIN_PRECISION)) {
circle.setUndefined();
return;
}
double radius = 1 / Math.abs(curv.getValue());
double r2 = radius * radius;
double x = r2 * v.x;
double y = r2 * v.y;
R.setCoords(A.inhomX + x, A.inhomY + y, 1.0);
circle.setCircle(R, A);
}
