mtllib model.mtl
v -0.100000 -0.100000 -0.100000
v 0.100000 -0.100000 -0.100000
v -0.100000 0.100000 -0.100000
v 0.100000 0.100000 -0.100000
v -0.100000 -0.100000 0.100000
v 0.100000 -0.100000 0.100000

vn 0.000000 0.000000 -1.00000
vn 0.000000 -1.000000 0.000000
vn -0.333334 -0.333333 -0.333333
vn 0.333334 -0.333333 -0.333333

vt 0.000000 0.000000
vt 0.000000 1.000000
vt 1.000000 0.000000
vt 1.000000 1.000000

usemtl Material.001
f 1/1/3 2/2/4 4/4/1 3/3/1
usemtl Material.002
f 2/4/4 1/2/3 5/1/2 6/3/2
usemtl Material.003