void setSurfaceAtoms(BitSet bsSurface, BitSet bsEnclosed) {
		bsSurfaceSet = (BitSet) bsEnclosed.clone();
		surfaceDistances = null;
		int n = viewer.cardinalityOf(bsSurface);
		if (n == 0) {
			surfaceAtoms = null;
			return;
		}
		surfaceAtoms = new int[n];
		for (int i = atomCount, pt = 0; --i >= 0;)
			if (bsSurface.get(i))
				surfaceAtoms[pt++] = i;
	}