fast_obj VS libobj

The operations you're talking about with the example of loading 3d data is the realm of parsing, and there's a LOT of theory available and a LOT of code available for how to implement things -- there are TONS of options. Since you don't know where to start you should investigate parsing generally in C. I highly recommend you take a look at an existing library in C that loads 3d data, like this library https://github.com/thisistherk/fast_obj/blob/master/fast_obj.h that deals with OBJ the format.

I've replaced tinyobjloader with fast_obj which speeds up model loading process significantly. Here is a good article comparing different obj loaders.

I wanted to say try writing your own like I did, then I remember I made it in c++ with string & stringstream std lib :(. I don't know how much would it take you to write it yourself, might try it myself. After a quick search I think this one has a pure c version: https://github.com/thisistherk/fast_obj

Oh I see. I was talking about writing a program in the language of your choice that does this, it's not very difficult. If you use C or C++ you can load the file with https://github.com/thisistherk/fast_obj to make it even easier.