Open or create a .tri file

Hi,

I was wondering if one of you would know how to create a .tri file as used in ofx facetracker ?
the tri file is looking like

n_tri: 91
{
20 21 23
21 22 23
0 1 36
15 16 45
0 17 36
16 26 45
}

and then it is interpreted by a ofMesh to be created…

if you would be able to help me to figure out how to create one or modify the other one it would be awesome !

THanks,

Cheers,

Flo