Java had a cute wireframe modeller, which modelled a cube, dino, ship and chopper. Any one have any idea what ‘f’ and ‘fo’ mean in those obj files. They are driving me nuts. I thought f stood for a face and tried GL_LINE_LOOP on a trio of vertices. It doesn’t work. 
Any help will be appreciated.
a link to those files please ?
http://www-lsi.ugr.es/~rosana/software/wannabe/escenas/samples/obj/dinosaur.obj
Any help will be appreciated.
Regarding to the structure of the file, the first float values are all the vertex data marked by a ‘v’ marker prefix. Each of them is at an incremented index (first v group is index 1, next is index 2 and so on). Next, after each ‘fo’ marker, you have the 3 indices of each face.
If you draw triangles with following the indices in order, you’ll have your dinosaur 
Finally, I could easily found some doc about that format: http://www.javaview.de/guide/formats/Format_Obj.html
It says that the marker ‘f’ is for indices, but your file seems to use ‘fo’. So you’ll have to take care of that difference on other files.
That must help