Personally, I use:
Object3D.invertCulling(true);
See: https://www.jpct.net/jpct-ae/doc/com/threed/jpct/Object3D.html#invertCulling-boolean-

Alternatively, it is possible to use: https://www.jpct.net/jpct-ae/doc/com/threed/jpct/Object3D.html#invert--
I don't think there is much of a difference...

My approach is highly simplified as well. It only has to work for this kind of retro-styled arcade racer. Generating an actual landscape with free roaming would have been a completely different and much more complex story.

Great!
i also wished for a game that has auto-generated roads, preferably a rally game, so i would have unlimited stages to drive on. but that project would be too difficult for me.

Long time no new project here...so I thought that I might as well contribute something.

It's not really a "project", but something that I'm working on from time to time. It started out as an experiment to see, how feasible it is to generate a road based on the random number generator alone. Over the months, it turned into something that you can actually "play" albeit it's far from being a game of some sort.

The road and the AI vehicles are all generated, nothing has been placed by hand. It has basic sounds, arcade like vehicle controls, traffic and a very crude collision "model".

Here's a video: https://youtu.be/o3MthgPRDsE?si=GEl1AJA2DRFxJCaJ

And this is how it looks:

I see. If you call refreshMeshData() on the controller, the newly calculated normals should be updated in the controller and you can obtain them from there.

Thank you, works perfectly!

Also, this might be a minor bug: I think the 'shininess' value is not seem to be passed to the fragment shader (while the other uniform variables from the default vertex shader seem accessible though in the fragment shader). I don't need this as I can put custom shader code anyway... But I thought it would be nice to know.