public Point2DDouble[] intersect(Circle2DDouble c, DoubleComparator dblComp) {
double d = p.distance(c.p);
if (dblComp.compare(d, radius + c.radius) > 0
|| dblComp.compare(d + Math.min(radius, c.radius), Math.max(radius, c.radius)) < 0) {
return new Point2DDouble[0];
}
if (dblComp.compare(d, 0) == 0) {
return null;
}
double diff = (radius * radius - c.radius * c.radius) / d;
double d1 = (d + diff) * .5;
Point2DDouble v = c.p.subtract(p);
Point2DDouble v1 = v.multiply(d1 / v.length());
double z = radius * radius - d1 * d1;
Point2DDouble p0 = p.add(v1);
// if (dblComp.compare(z, 0) < 0) {
// System.out.println(this + " " + c);
// System.out.println(d + " " + (radius + c.radius));
// throw new AssertionError();
// }
if (dblComp.compare(z, 0) <= 0) {
return new Point2DDouble[] {p0};
}
z = Math.sqrt(z);
Point2DDouble v2 = new Point2DDouble(-v.y, v.x).multiply(z / v.length());
return new Point2DDouble[] {p0.add(v2), p0.subtract(v2)};
}
public Point2DDouble[] getTangents(Point2DDouble q, DoubleComparator comp) {
double d = p.distance(q);
if (comp.compare(d, radius) < 0) {
return null;
}
if (comp.compare(d, radius) == 0) {
return new Point2DDouble[] {p};
}
double d1 = radius * radius / d;
Point2DDouble v = q.subtract(p);
Point2DDouble vn = new Point2DDouble(-v.y, v.x);
v = v.multiply(d1 / v.length());
Point2DDouble c = p.add(v);
double d2 = radius * radius - d1 * d1;
if (d2 < 0) d2 = 0;
d2 = Math.sqrt(d2);
vn = vn.multiply(d2 / vn.length());
return new Point2DDouble[] {c.add(vn), c.subtract(vn)};
}
