/**
* 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);
}
}
/**
* <code>merge</code> combines this sphere with a second bounding sphere. This new sphere contains
* both bounding spheres and is returned.
*
* @param volume the sphere to combine with this sphere.
* @return a new sphere
*/
@Override
public BoundingVolume merge(final BoundingVolume volume) {
if (volume == null) {
return this;
}
switch (volume.getType()) {
case Sphere:
{
final BoundingSphere sphere = (BoundingSphere) volume;
final double temp_radius = sphere.getRadius();
final ReadOnlyVector3 tempCenter = sphere.getCenter();
final BoundingSphere rVal = new BoundingSphere();
return merge(temp_radius, tempCenter, rVal);
}
case AABB:
{
final BoundingBox box = (BoundingBox) volume;
final Vector3 radVect = new Vector3(box.getXExtent(), box.getYExtent(), box.getZExtent());
final Vector3 tempCenter = box._center;
final BoundingSphere rVal = new BoundingSphere();
return merge(radVect.length(), tempCenter, rVal);
}
case OBB:
{
final OrientedBoundingBox box = (OrientedBoundingBox) volume;
final BoundingSphere rVal = (BoundingSphere) this.clone(null);
return rVal.mergeLocalOBB(box);
}
default:
return null;
}
}