mtllib cubes.mtl

# cube 01: pair of group and material per side/quad
o cube 01

v -10.00000 10.00000 10.00000
v -10.00000 -10.00000 10.00000
v 10.00000 -10.00000 10.00000
v 10.00000 10.00000 10.00000
v -10.00000 10.00000 -10.00000
v -10.00000 -10.00000 -10.00000
v 10.00000 -10.00000 -10.00000
v 10.00000 10.00000 -10.00000

g front
usemtl red
f 1 2 3 4
g back
usemtl blue
f 8 7 6 5
g right
usemtl green
f 4 3 7 8
g top
usemtl lightblue
f 5 1 4 8
g left
usemtl orange
f 5 6 2 1
g bottom
usemtl purple
f 2 6 7 3

# cube 02: one pair of group and material with different smoothing groups
o cube 02

v 20.00000 10.00000 10.00000
v 20.00000 -10.00000 10.00000
v 40.00000 -10.00000 10.00000
v 40.00000 10.00000 10.00000
v 20.00000 10.00000 -10.00000
v 20.00000 -10.00000 -10.00000
v 40.00000 -10.00000 -10.00000
v 40.00000 10.00000 -10.00000

g cube 02 one group
usemtl blue
s 0
f 9 10 11 12
f 16 15 14 13
s 1
f 12 11 15 16
f 13 9 12 16
s 2
f 13 14 10 9
s off
f 10 14 15 11