@Override
public boolean intersectsSphere(final BoundingSphere bs) {
if (!Vector3.isValid(_center) || !Vector3.isValid(bs._center)) {
return false;
}
final Vector3 diff = _compVect1.set(getCenter()).subtractLocal(bs.getCenter());
final double rsum = getRadius() + bs.getRadius();
return (diff.dot(diff) <= rsum * rsum);
}
@Override
public boolean intersects(final ReadOnlyRay3 ray) {
if (!Vector3.isValid(_center)) {
return false;
}
final Vector3 diff = ray.getOrigin().subtract(getCenter(), _compVect1);
final double radiusSquared = getRadius() * getRadius();
final double a = diff.dot(diff) - radiusSquared;
if (a <= 0.0) {
// in sphere
return true;
}
// outside sphere
final Vector3 dir = _compVect2.set(ray.getDirection());
final double b = dir.dot(diff);
if (b >= 0.0) {
return false;
}
return b * b >= a;
}
@Override
public IntersectionRecord intersectsWhere(final ReadOnlyRay3 ray) {
final Vector3 diff = ray.getOrigin().subtract(getCenter(), _compVect1);
final double a = diff.dot(diff) - (getRadius() * getRadius());
double a1, discr, root;
if (a <= 0.0) {
// inside sphere
a1 = ray.getDirection().dot(diff);
discr = (a1 * a1) - a;
root = Math.sqrt(discr);
final double[] distances = new double[] {root - a1};
final Vector3[] points =
new Vector3[] {
ray.getDirection().multiply(distances[0], new Vector3()).addLocal(ray.getOrigin())
};
return new IntersectionRecord(distances, points);
}
a1 = ray.getDirection().dot(diff);
if (a1 >= 0.0) {
// No intersection
return null;
}
discr = a1 * a1 - a;
if (discr < 0.0) {
return null;
} else if (discr >= MathUtils.ZERO_TOLERANCE) {
root = Math.sqrt(discr);
final double[] distances = new double[] {-a1 - root, -a1 + root};
final Vector3[] points =
new Vector3[] {
ray.getDirection().multiply(distances[0], new Vector3()).addLocal(ray.getOrigin()),
ray.getDirection().multiply(distances[1], new Vector3()).addLocal(ray.getOrigin())
};
final IntersectionRecord record = new IntersectionRecord(distances, points);
return record;
}
final double[] distances = new double[] {-a1};
final Vector3[] points =
new Vector3[] {
ray.getDirection().multiply(distances[0], new Vector3()).addLocal(ray.getOrigin())
};
return new IntersectionRecord(distances, points);
}
/**
* 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);
}
}