Tips for OBJ/LWO export?

 From:  Michael Gibson
3793.14 In reply to 3793.11 
Hi Micha,

> Could you create an option that allow meshing
> like surfaces are joined?

That would be difficult to do it that way, because joining is a quite intensive process, there is a lot of searching and distance measurement that happens in joining, because you can't just join any 2 naked edges together, you only want to have edges that are close by each other to get joined. That determination involves a lot of calculation.

So that's why joining is a separate process from meshing.

But if I understand what you want, you can use the already existing weld option to do what you need.

> Maybe something like an internal join is done, but the
> created mesh is without additional "joins".

You can turn off the welding option to make the generated mesh work like that. The option is here:

When you have a joined object, if you uncheck that "Weld vertices along edges" option, it will still produce a watertight no-crack mesh but the mesh will be clustered into separate non-connected (non-connected in a topological sense, but actually physically touching in location) sets of vertices with one set for each original surface. This will then allow you to use your polygon modeler's mesh processing functions to separate the mesh into individual objects.

In Rhino v1 there was a command called ExplodeMesh which would do this job of breaking a mesh into separate objects, with one object for each connected cluster of vertices. This seems to have been removed in later Rhino versions though, and I'm not sure if there is a replacement for it. The regular Rhino Explode seems like it will do it for meshes that have sharp edges in it (but then making a group out of the pieces??) but not if the pieces are smooth where they are next to one another or something like that.

> It would be a dream. From time to time I run in the
> problem, that I mesh an object what needs different materials
> at different parts of the object.

Yes, that is a major limitation of Rhino that it does not allow you to easily select individual faces out of a joined solid and apply different materials to them.

MoI itself does not have this limitation - you can select faces within a solid in MoI and apply different styles to them, and those will become different material assignments when you export to OBJ format.

- Michael