# A concave object
# First the vertices
v 10.0 -5.0 -5.0
v 10.0 5.0 -5.0
v 6.0 5.0 -5.0
v 6.0 0.0 -5.0
v -6.0 0.0 -5.0
v -6.0 5.0 -5.0
v -10.0 5.0 -5.0
v -10.0 -5.0 -5.0
v 10.0 -5.0 5.0
v 10.0 5.0 5.0
v 6.0 5.0 5.0
v 6.0 0.0 5.0
v -6.0 0.0 5.0
v -6.0 5.0 5.0
v -10.0 5.0 5.0
v -10.0 -5.0 5.0
# Now the faces
f 4 3 2 1
f 8 5 4 1
f 8 7 6 5
f 9 10 11 12
f 9 12 13 16
f 13 14 15 16
f 1 2 10 9
f 2 3 11 10
f 3 4 12 11
f 4 5 13 12
f 5 6 14 13
f 6 7 15 14
f 7 8 16 15
f 8 1 9 16