Point3f getFaceCenter(byte face) {
		if (faceCenter == null)
			faceCenter = new Point3f();
		switch (face) {
		case FRONT:
			faceCenter.set(center.x, center.y, getMaxZ());
			return faceCenter;
		case REAR:
			faceCenter.set(center.x, center.y, getMinZ());
			return faceCenter;
		case TOP:
			faceCenter.set(center.x, getMaxY(), center.z);
			return faceCenter;
		case BOTTOM:
			faceCenter.set(center.x, getMinY(), center.z);
			return faceCenter;
		case RIGHT:
			faceCenter.set(getMaxX(), center.y, center.z);
			return faceCenter;
		case LEFT:
			faceCenter.set(getMinX(), center.y, center.z);
			return faceCenter;
		}
		return null;
	}