Hi ycarry,

> because use of Catmull–Clark subdivision surface generate
> QUADrilaterals
> (from triangles or NGons or... quads)

That's true, but that doesn't mean it magically forms nice quads out of any kind of n-gon.

Part of the Catmull-Clark subdivision process involves connecting pieces to the centroid of the polygon. If you have a complex n-gon that is non-convex like the top face of the example I posted above, it will make for a messy folded-over-itself result.

That's basically why you can't use the kind of n-gon mesh that MoI generates as the input to sub-d smoothing - sub-d smoothing requires a particular kind of topology to the inputs to it in order to produce good results, and that topology is best built by hand.

But you don't need to apply sub-d smoothing to MoI generated meshes anyway - MoI exports vertex normals to make the shaded result already look nice and smooth, you just directly render the mesh that MoI exports and you shouldn't try to apply sub-d smoothing to it.

- Michael