Extends this bounding box with the given bounding box.
Source
void extendBB(BoundingBox bbox) {
Vector3 newMin = new Vector3.zero(), newMax = new Vector3.zero();
Vector3.min(minCorner, bbox.minCorner, newMin);
Vector3.max(maxCorner, bbox.maxCorner, newMax);
minCorner = new Point3.vec(newMin);
maxCorner = new Point3.vec(newMax);
}