Hi Michael. A similar thing can be done in Rhino by using the SurfaceCreasing plugin, which allows you to output a creased single surface from commands such as Extrude, Sweep, Loft, etc. Any kinks in the curve will become a crease. Of course, it has the same toplological restraints as a single surface. But it can be point edited... It can be a very useful tool, but dangerous in the wrong hands! Many times resulting in the question "why can't i fillet this edge?". And the usual response "because there is no edge there!" :P

jonah

Good fun!
Brian

Hi jonah,

> It can be a very useful tool, but dangerous in the wrong
> hands! Many times resulting in the question "why can't i
> fillet this edge?". And the usual response "because there
> is no edge there!"

You'll probably also run into other problems in Rhino with surfaces like that, like meshing not working correctly in all cases on such a kinked single surface and also potentially problems in surface intersection and booleans as well. Also you can't use Explode on that kind of thing to break it into components anymore like you normally would be able to do with a faceted object.

The nice thing about MoI's method is that it just works directly on a polysurface, there is no need to set a special mode to create unusual geometry and so you don't need to run into all those side effects.

- Michael

Hehe... Yes the meshing is the other question which people always ask. The mesh generates just fine. But the vertices on the crease are not welded as they would be for an edge. So once you move the points, the vertex shading normal sometimes gets a bit screwy... Rhino does have a command to split it into a polysurface, called DivideAlongCreases. So you can continue adding fillets, etc...

Hi jonah,

> Rhino does have a command to split it into a polysurface,
> called DivideAlongCreases. So you can continue adding
> fillets, etc...

Yeah, but this is another good example of how Rhino has gotten so far out of hand with such an enormous pile of commands...

MoI just always splits kinked surfaces into a polysurface, but without losing the ability to point edit it.

Basically the need for the extra command has been engineered out of MoI by an improvement in a more fundamental mechanism (just regular turning points on).

- Michael