BitSet findAtomsInOval(Rectangle r) {
		bsFoundRectangle.and(bsEmpty);
		float dx, dy;
		Atom a;
		for (int i = atomCount; --i >= 0;) {
			a = atoms[i];
			dx = a.screenX - r.x - r.width * 0.5f;
			dy = a.screenY - r.y - r.height * 0.5f;
			dx *= 2.0f / r.width;
			dy *= 2.0f / r.height;
			if (dx * dx + dy * dy < 1) {
				bsFoundRectangle.set(i);
			}
		}
		return bsFoundRectangle;
	}