/**
* Calculates the minimum bounding sphere of 4 points. Used in welzl's algorithm.
*
* @param O The 1st point inside the sphere.
* @param A The 2nd point inside the sphere.
* @param B The 3rd point inside the sphere.
* @param C The 4th point inside the sphere.
* @see #calcWelzl(java.nio.FloatBuffer)
*/
private void setSphere(final Vector3 O, final Vector3 A, final Vector3 B, final Vector3 C) {
final Vector3 a = A.subtract(O, null);
final Vector3 b = B.subtract(O, null);
final Vector3 c = C.subtract(O, null);
final double Denominator =
2.0
* (a.getX() * (b.getY() * c.getZ() - c.getY() * b.getZ())
- b.getX() * (a.getY() * c.getZ() - c.getY() * a.getZ())
+ c.getX() * (a.getY() * b.getZ() - b.getY() * a.getZ()));
if (Denominator == 0) {
_center.set(0, 0, 0);
setRadius(0);
} else {
final Vector3 o =
a.cross(b, null)
.multiplyLocal(c.lengthSquared())
.addLocal(c.cross(a, null).multiplyLocal(b.lengthSquared()))
.addLocal(b.cross(c, null).multiplyLocal(a.lengthSquared()))
.divideLocal(Denominator);
setRadius(o.length() * radiusEpsilon);
O.add(o, _center);
}
}
/**
* Calculates the minimum bounding sphere of 3 points. Used in welzl's algorithm.
*
* @param O The 1st point inside the sphere.
* @param A The 2nd point inside the sphere.
* @param B The 3rd point inside the sphere.
* @see #calcWelzl(java.nio.FloatBuffer)
*/
private void setSphere(final Vector3 O, final Vector3 A, final Vector3 B) {
final Vector3 a = A.subtract(O, null);
final Vector3 b = B.subtract(O, null);
final Vector3 acrossB = a.cross(b, null);
final double Denominator = 2.0 * acrossB.dot(acrossB);
if (Denominator == 0) {
_center.set(0, 0, 0);
setRadius(0);
} else {
final Vector3 o =
acrossB
.cross(a, null)
.multiplyLocal(b.lengthSquared())
.addLocal(b.cross(acrossB, null).multiplyLocal(a.lengthSquared()))
.divideLocal(Denominator);
setRadius(o.length() * radiusEpsilon);
O.add(o, _center);
}
}
