Hi Pilou,

> In the same order of idea it's not obvious that the function "Extrude" can't extrude this ribbon face...
> just some parts if they are trimmed...

Well extrusion is something that actually happens to curves. When you extrude a surface what actually happens is all the edge curves of the surface are extruded and then the surface is copied to the end to make a cap.

Extrusion of curves works by translating the curve in a fixed direction.

What direction are you expecting to use for those curves such that they don't cross over and interfere with themselves making a "self-intersecting" result?

- Michael

There is a Joint Push Pull inside SketchUp who Extrude the curvated ribbon face above ;)

In Moi that will be the Shell...

As we can extrude these flat vertical faces ribbon (even they auto intersect during the extrusion) it's tempting to make the same with the curvating above! :)

Hi Pilou,

> There is a Joint Push Pull inside SketchUp who Extrude the curvated ribbon face above ;) <...>

SketchUp doesn't have actual curved surfaces, only flat polygons.


> As we can extrude these flat vertical faces ribbon (even they auto intersect during the extrusion)
> it's tempting to make the same with the curvating above! :)

If you divide the curved surface into flat pieces then an extrusion for each flat piece will be better defined.

Since MoI works on true curved spline surfaces there are different kinds of issues with possible self intersections.

- Michael