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[][] getExternalTangents(Circle2DDouble c, DoubleComparator comp) {
if (comp.compare(radius, c.radius) < 0) {
Point2DDouble[][] ret = c.getExternalTangents(this, comp);
for (Point2DDouble[] e : ret) {
Point2DDouble t = e[0];
e[0] = e[1];
e[1] = t;
}
if (comp.compare(ret[0][0].distance(p), radius) != 0) throw new AssertionError();
if (comp.compare(ret[1][0].distance(p), radius) != 0) throw new AssertionError();
if (comp.compare(ret[0][1].distance(c.p), c.radius) != 0) throw new AssertionError();
if (comp.compare(ret[1][1].distance(c.p), c.radius) != 0) throw new AssertionError();
if (comp.compare(GeometryAlgorithms.distanceToLine(ret[0][0], ret[0][1], p), radius) != 0)
throw new AssertionError();
if (comp.compare(GeometryAlgorithms.distanceToLine(ret[0][0], ret[0][1], c.p), c.radius) != 0)
throw new AssertionError();
if (comp.compare(GeometryAlgorithms.distanceToLine(ret[1][0], ret[1][1], p), radius) != 0)
throw new AssertionError();
if (comp.compare(GeometryAlgorithms.distanceToLine(ret[1][0], ret[1][1], c.p), c.radius) != 0)
throw new AssertionError();
return ret;
}
double d = p.distance(c.p);
if (comp.compare(d + Math.min(radius, c.radius), Math.max(radius, c.radius)) < 0) {
return new Point2DDouble[0][];
}
if (comp.compare(d + Math.min(radius, c.radius), Math.max(radius, c.radius)) == 0) {
Point2DDouble v = c.p.subtract(p);
v = v.multiply(radius / v.length());
v = v.add(p);
return new Point2DDouble[][] {{v, v}};
}
Point2DDouble[] tangentsFromPoint =
new Circle2DDouble(p, radius - c.radius).getTangents(c.p, comp);
Point2DDouble vn1 = tangentsFromPoint[0].subtract(c.p);
vn1 = new Point2DDouble(vn1.y, -vn1.x);
vn1 = vn1.multiply(c.radius / vn1.length());
Point2DDouble vn2 = tangentsFromPoint[1].subtract(c.p);
vn2 = new Point2DDouble(-vn2.y, vn2.x);
vn2 = vn2.multiply(c.radius / vn2.length());
Point2DDouble[][] ret =
new Point2DDouble[][] {
{tangentsFromPoint[0].add(vn1), c.p.add(vn1)},
{tangentsFromPoint[1].add(vn2), c.p.add(vn2)}
};
if (comp.compare(ret[0][0].distance(p), radius) != 0) throw new AssertionError();
if (comp.compare(ret[1][0].distance(p), radius) != 0) throw new AssertionError();
if (comp.compare(ret[0][1].distance(c.p), c.radius) != 0) throw new AssertionError();
if (comp.compare(ret[1][1].distance(c.p), c.radius) != 0) throw new AssertionError();
if (comp.compare(GeometryAlgorithms.distanceToLine(ret[0][0], ret[0][1], p), radius) != 0)
throw new AssertionError();
if (comp.compare(GeometryAlgorithms.distanceToLine(ret[0][0], ret[0][1], c.p), c.radius) != 0)
throw new AssertionError();
if (comp.compare(GeometryAlgorithms.distanceToLine(ret[1][0], ret[1][1], p), radius) != 0)
throw new AssertionError();
if (comp.compare(GeometryAlgorithms.distanceToLine(ret[1][0], ret[1][1], c.p), c.radius) != 0)
throw new AssertionError();
return ret;
}
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)};
}
public boolean containsOn(Point2DDouble p, DoubleComparator comp) {
return comp.compare(p.distanceSquared(this.p), radius * radius) == 0;
}
@Override
public String toString() {
return p.toString() + " " + radius;
}
public Point2DDouble[][] getInternalTangents(Circle2DDouble c, DoubleComparator comp) {
double d = p.distance(c.p);
if (comp.compare(d, radius + c.radius) < 0) return new Point2DDouble[0][];
if (comp.compare(d, radius + c.radius) == 0) {
Point2DDouble v = c.p.subtract(p);
v = v.multiply(radius / v.length());
v = v.add(p);
return new Point2DDouble[][] {{v, v}};
}
double nRadius = radius + c.radius;
Point2DDouble[] tangentsFromPoint = new Circle2DDouble(p, nRadius).getTangents(c.p, comp);
Point2DDouble vn1 = tangentsFromPoint[0].subtract(c.p);
vn1 = new Point2DDouble(-vn1.y, vn1.x);
vn1 = vn1.multiply(c.radius / vn1.length());
Point2DDouble vn2 = tangentsFromPoint[1].subtract(c.p);
vn2 = new Point2DDouble(vn2.y, -vn2.x);
vn2 = vn2.multiply(c.radius / vn2.length());
Point2DDouble[][] ret =
new Point2DDouble[][] {
{tangentsFromPoint[0].add(vn1), c.p.add(vn1)},
{tangentsFromPoint[1].add(vn2), c.p.add(vn2)}
};
if (comp.compare(ret[0][0].distance(p), radius) != 0) throw new AssertionError();
if (comp.compare(ret[1][0].distance(p), radius) != 0) throw new AssertionError();
if (comp.compare(ret[0][1].distance(c.p), c.radius) != 0) throw new AssertionError();
if (comp.compare(ret[1][1].distance(c.p), c.radius) != 0) throw new AssertionError();
return ret;
}
