How to simplify mesh with texture?

[ShangXiaoYun]

First, thanks for your pleasant work!
The format of input obj file for me is as follow,

v x1 y1 z1
v x2 y2 z2
...
vt x1 y1 z1
vt x2 y2 z2
...

f f1/f1'/ f2/f2'/ f3/f3'/
...
In the vt flag for every line, there is texture coordinate (x1, y1, z1). I run your code, even if I don't process 'vt' flag, and just write .obj with 'v x1 y1 z1' and 'f f1 f2 f3', the output file don't display anything. There must be something wrong with what I've done.
How should I process 'vt' value?
Your reply will be much appreciated!