I should be able to just run something like Split by Isocurve on an extrusion and have it work. The whole idea of making the existence of the ‘lightweight extrusions’ visible to the end user really was a mistake, it’s just bad having to “explode” simple surfaces to do basic surface stuff on them–the basic stuff that is Rhino’s rasion-d’etre! No I don’t care about the trivial ‘parametric’ editing you can do with an extrusion’s special control points, it’s just a gimmick for sales demos.
I have argued this for many, many years, to no avail. They were supposed to be completely “transparent” to the user, but they are not. And I have yet to see a real-world case presented where using extrusions vs polysurfaces made a real positive difference. Especially because as soon as one modifies them in any significant way, they must necessarily be reconverted to polysurfaces.
Yeah, explaining them to new users is just slightly embarrassing. “Uhh they’re this thing meant to reduce file size and most of the time you don’t have to think about them except when it makes you explode a “surface” just to do something with it.” WHAT IS THE POINT???
I’m aware they can be turned off…but once in a while actual Design decisions should be made and remove something that’s unnecessary, not stick in some option the normal user isn’t going to know exists.
ConvertExtrusion will convert extrusions to polysurfaces and keep the individual surfaces joined as polysurfaces.
I have never found a use for them too but it’s a one-time click and I think the OFF comes as a default.
ON is the default. Hence new users being confused. Unfortunately McNeel sometimes feels it necessary to make new “features” default so that users will know they exist.