NormalsMaterial / UvsMaterial not working

[RaduBerinde]

I tried switching to NormalsMaterial or UvsMaterial and neither seems to be working (the shapes I apply the material to don't show up). I tried comparing the code to ObjectsMaterial and couldn't find anything materially different in the use of underlying APIs, so I don't know what's not working. Tried messing around with the shaders (eg to always show white) but still nothing shows up. I can create my own material (starting from ObjectsMaterial) and I can make it show normals or UVs and that works fine.

In any case, I think it would be worth it to have an example with all materials just so the code doesn't rot.