public boolean hasNext() {
			while (bsptIter == null || !bsptIter.hasMoreElements()) {
				if (--bsptIndex < 0) {
					bsptIter = null;
					return false;
				}
				bsptIter = bspf.getSphereIterator(bsptIndex);
				bsptIter.initialize(center, radius);
			}
			return true;
		}