group() {
	group();
	intersection() {
		surface(file = "surface.dat", center = true, invert = false);
		multmatrix([[0.70710678118, -0.70710678118, 0, 0], [0.70710678118, 0.70710678118, 0, 0], [0, 0, 1, 0], [0, 0, 0, 1]]) {
			surface(file = "surface.dat", center = true, invert = false);
		}
	}
}