Hi Simon, I just sent you a reply through e-mail with a lot of description in it.

To answer your question here though - no it is not possible to alter the exported polygon mesh topology just by the supplying some individual curves on a surface.

In order to adjust the topology the main way you would need to do that is to take the exported mesh as a starting point and then use retopology tools in a polygon modeling program to draw out the specific topology that you need.

One other option though would be to reconstruct certain zones of your object by deleting faces and building new ones in using surfacing tools like lofting or sweeping between those edges. The difference is that if you just split or cut an object using booleans or trim tools that does not alter the underlying surfaces, the base surfaces stay the same and only new trim curves are created. Since the base polygon topology follows the UV quad structure of the underlying surfaces, just splitting an object does not have a big effect on the generated topology, the quad flow still just follows along the same underlying surface as before there are just new n-gons formed where the new trim boundaries are at.

So you would need to do surface reconstruction building new base surfaces in order to have a big effect on the generated topology.

You would not normally need to be concerned so much about the topology for the regular use of just rendering mesh output though, you only really need to have a quad edge flow topology if you plan on doing sub-d smoothing to the mesh output, but that is not typically what you do to CAD mesh output since usually CAD files are already smoothed with things like fillets in places that are supposed to be smooth. You can just render the direct output from MoI and it will look smooth because of the vertex normals that are used in the render. It generally does not make sense to try and apply further sub-d smoothing to a CAD model because that would mutate things away from the current precise already smoothed model shape.

If you are looking to generate sub-d friendly mesh topology though then the standard way you should plan for getting that is to use retopology tools in your polygon mesh editing program though.

- Michael