how to move an edge or points of a volume

 From:  Michael Gibson
5265.8 In reply to 5265.3 
Hi wimverbe,

> I still don't quite grasp it. if I generate a cylinder, and highlight one of the
> circles, I cannot show points or move that circle.

You can't turn on control points for edges like you're used to with a polygon modeler - often times edges are what are called "trim curves" and are more like markers on the surface that mark which areas of the surface are active and which parts are holes. When you have an object made up of surfaces that are joined at trim curves like that, you cannot turn on control points for it, because the control points for the actual underlying surfaces are not aligned with one another.

See this FAQ entry for a lot more description of this and illustrations to help explain it:

> if I copy the 2 circles, delete the cylinder, paste the circles back and loft them, then I have full
> control over the circles and can move them, scale, rotate and move individual points. huh?

In this case you're using a different mechanism - the circles in this case are now not "edges" belonging to a solid, they are standalone circle curves, and you can always turn on control points for curve objects. And also after you have done the loft in this case you can edit the circles and the loft will update, that's the history function coming into effect there.

> I wanted to shear a cylinder, but have to go through all these steps to simply move one
> end a bit, that does not make sense...

Typically the method you would use in MoI to make a sheared cylinder would be to draw 2 circles that are in the sheared position you want and then use Loft to construct your sheared cylinder directly rather than initially drawing in a regular cylinder and then trying to modify that.

With MoI's modeling workflow you typically will put most of your effort into arranging curves how you need them and then generate surfaces from those curves, it's not so much about plopping in a different shaped object initially and then mutating it like it is with polygon modeling. Think of MoI as more like a "drawing and construction" type mechanism. You draw curves and primarily edit those curves, then construct surfaces and solids from those curves and use some additional curves as cutting objects to slice up the solids as well.

> I cannot even take one side of a cube and extend it without having to use the scale tool,
> and that is pretty restricting I find.

Actually you can for the case of a cube - not by editing an edge or face but you can turn on control points for a box object since it has all untrimmed surfaces in it (every face joins another face along a natural underlying surface edge and not at more arbitrary trim curve edges). So for a box turn on control points and select the 4 points on one side of it and then you can move those around.

But again, you're here thinking like a polygon modeling workflow again though - instead of starting with a box that is not in the shape you want in MoI you would generally instead draw 2 rectangle curves that have the shape you want and then Loft between those to generate your modified box directly from those rather than trying to start with a different solid shape and then mutate it.

- Michael