Hi Micha,

> The object I used is a Rhino object (copy&paste to MOI) and I
> attach it now. Could be nice, if the mesh could be same, dosn't
> matter it is a STEP import, a Rhino copy&paste or a MOI3D
> creation. ;)

That would be cool, I agree! But a rounded box can be defined in many different ways, and in order to get one to mesh with all quads the "underlying" surface of the rounded part must be aligned with the other pieces.

The model that you have posted here is not configured in that way at all, if you use Edit/Separate on it to break it into surfaces and then turn on control points for a corner, you can see the surface for it is actually set up like this:



Notice how the surface control points of that corner piece are not aligned with the trim edges?

That corner is defined as a kind of rotated sub-region trimmed out from a larger sphere portion, the sphere is oriented like this:


The problem here is that the UV layout of that sphere (for instance if you were to look at its isoparm grid) does not have any kind of alignment with those edges. Here is dense mesh of just the sphere where you can see how the trim edges collide with the natural surface UV grid at an odd angle:



Because of this lack of alignment, you won't get simple quads from that kind of corner patch.

If you do a similar examination of the rounded box built in MoI, you will see this kind of structure instead:






Notice how the corner pieces there have a natural alignment between the surface and its trim edges? That kind of more simple structure provides the alignment between the surfaces that is necessary to get simple pure quad mesh generation.


So again, don't just assume that every rounded box is constructed in the same way! :) It is possible for some to have a construction method where surfaces do not share natural edges and that will prevent simple mesh output from that kind of stuff.

- Michael