tinyobjloader | Tiny but powerful single file wavefront obj loader | Graphics library

E: When I wrote this answer originally I had only worked with vertices and normals. I've figured out how to get materials and textures working, but don't have time to write that out at the moment. I will add that in when I have some time, but it's largely the same logic if you wanna poke around the tinyobj header yourselves in the meantime. :-)

I've learned a lot about TinyOBJLoader in the last day so I hope this helps someone in the future. Credit goes to this GitHub repository which uses TinyOBJLoader very clearly and cleanly in fileloader.cpp.

To summarise what I learned studying that code:

Shapes are of type shape_t. For a single model OBJ, the size of shapes is 1. I'm assuming OBJ files can contain multiple objects but I haven't used the file format much to know.

shape_t's have a member mesh of type mesh_t. This member stores the information parsed from the face rows of the OBJ. You can figure out the number of faces your object has by checking the size of the material_ids member.

The vertex, texture coordinate and normal indices of each face are stored in the indices member of the mesh. This is of type std::vector. This is a flattened vector of indices. So for a model with triangulated faces f1, f2 ... fi, it stores v1, t1, n1, v2, t2, n2 ... vi, ti, ni. Remember that these indices correspond to the whole vertex, texture coordinate or normal. Personally I triangulated my model by importing into Blender and exporting it with triangulation turned on. TinyOBJ has its own triangulation algorithm you can turn on by setting the reader_config.triangulate flag.

I've only worked with the vertices and normals so far. Here's how I access and store them to be used in OpenGL:

1. Convert the flat vertices and normal arrays into groups of 3, i.e. 3D vectors