v   1.0 2.0 3.0   
v 2.0   3.0 1.0
v 3.0 1.0   2.0
v   1.0    2.0    3.0

vt   1.0 2.0 3.0   
vt 2.0   3.0 1.0
vt 3.0 1.0   2.0
vt   1.0    2.0    3.0

f 1  2   3