If you make a cube in 3DS Max, then check the UV mapping, it's mapped with the whole texture on each face - so the vertices have UV mapping by default when you create them. Other modelling packages might be different, but it makes sense that you make a cube and can texture straight onto it without UV mapping first. So, if you imagine the UV data at each corner of a cube, you'd have the verts at the corner (number of verts depends on the orientation of the poly split), but the UV data would never match because each takes a different corner of the texture. The only truly identical verts are those at the poly split line, because they're simply being used to make a 2 poly plain, each plain is identical, but the edges and corners never match.
It's not a import or an export problem, there's nothing we can do about it - because without it UV mapping would be a nightmare on anything but a tileable texture.
In VANmesh, I'll give the option to ignore the UV mapping when importing, so the model could be created as a completely sealed unit, until your happy with it - but even then you'd have to split a line of verts so you could unwrap the texture onto 2D.
It's pretty hard to picture without the data laid out in front of you, I used to think the texturing and normals data was part of the poly, not the vert - every UV mapper has given me this impression. That's why texturing in VANmesh will be tackled differently - it makes sense to me that if you have verts with there own UV data, show the vert, show the poly using the vert, and let the user edit it in it's purest form if they like. It might not please everyone, but it'll let people see exactly how UV mapping works for a change.
I'm gonna see about ways to keep the smoothing groups - experiment with verts etc. I think the problem is not us, but modelling software having problems calculating normals when the verts have less connected verts to work with. I'm thinking vert linking as an alternative to welding, so there's 2 verts - but they'll act as if they'd been welded into 1.
This has been a very informative thread - cheers!, next time I'll stay on topic I promise.
Van-B
My cats breath smells of cat food.
