Jan Marsch

From what I see code did not get properly transpiled into ES6. Ideally you could fine tune this process. Resulting tasks would be refactoring to a modern code base +...

You could check whether your OBJ file is triangulated. Otherwise, without sample files and/or a test application there is very little chance of help.

What I thought, faces are not triangulated. You need to do that first. Usually when saving an OBJ file.

This time it's hard to tell. Perhaps it is about size, in terms of number of vertices and also extent of contained meshes. Could you try to split this into...