Can you share an .obj file with smoothing? That is not currently support in the .obj loader, but I’d be keen to add it. Looks like the loader needs to use the normals when supplied for vertices and otherwise an average. Like a post-process.
There should be lines starting with “s”. Like:
s 2
s 4
s 0/off
If you can provide an expected image would be also excellent to make sure that it is working as expected? That will make it easier to work towards. 