tilck VS assimp

A Linux-compatible kernel written in C with tests written in C, C++ and Python: https://github.com/vvaltchev/tilck

If you use something like libassimp https://github.com/assimp/assimp it will allow you to import these and access the data to generate your Vertex Array Objects then render to a frame buffer object.

If you just want to load other data in a relatively simple fashion, assimp https://www.assimp.org supports loading a bunch of different formats and is pretty easy to use.

The emscripten interface for the assimp library. It runs entirely in the browser, and allows you to import 40+ 3D file formats and access the result in JSON or glTF format. This is not a full port of assimp, but an easy to use interface to access it's functionality.

I ran into what sounds like a similar problem a few months ago. It turns out this was an assimp bug: https://github.com/assimp/assimp/issues/1974

You could give assimp a go (there is a python version) i've used it for 3DS before then you can export to something else. https://github.com/assimp/assimp/blob/master/port/PyAssimp/README.md

I have checked the source code for GLTF for this and it is not handled by Assimp. I created an issue as in their Github.

Assimp is your friend

Have you read the license? It's quite permissive. https://github.com/assimp/assimp/blob/master/LICENSE

There is probably some library more specific to your use case, but you can use assimp to load 3d models in C++.