Hi, newbie question here but I couldn't find an answer by searching. In the attached image you will see a simple object that was revolved from the curve next to it. My question is how to make it longer without distorting the "ball" shape at the top. I can't get the scale command to work this way. In my polygon modeler, I would simply grab the polygon on the bottom and move it down but that does not work in Moi. I realize I can turn on points for the curve, grab the bottom points, move them down and then revolve again but I would like to make this sort of change after the object has been rotated, moved, etc. away from the original curve. Sometimes this occurs several hours later after lots of other things have been built around the shape and I am trying to fit it in... Hope I'm making myself clear and any help much appreciated.

the revolve command has got the history update enabled, so it will update the revolved surface if you edit the original curve..but as soon as you move/rotate/copy that object, the history update will break, as far as i know..

Hi mharr, typically to make a shape like that longer later on if you don't have the original curves around you would probably duplicate the existing edge curves on the object using copy and paste, and then just delete the shape and use those duplicated curves for editing and reconstructing. If you just stretch out the bottom like you are asking about it will change the angle which the bottom piece connects to the top piece, and that can then make that connection to be a sharp connection rather than a tangent connection.

In order to maintain a tangent connection with the same radius ball on top, you can't just drag out the bottom the location for where the bottom segment touches the top ball has to be redone as well, you would do something like that by starting a new line at the bottom and using tangent snap to snap it on to the upper part's curve and that will give you an exact tangent meeting point and then you can trim the upper curve with that new line.

If you don't care about maintaining tangency then it is possible to just yank down the bottom surface in your particular situation there, you can do that by turning on surface control points. In order to turn on surface control points you'll need to use Edit > Separate on your object first to break it into individual surfaces, then you can select the bottom surface, use Edit > Show pts to turn on its control points, select the bottom ring of control points and pull them down, and then rejoin the edited surface with the upper one. But as I mention above if you do it that way you will not have a tangent connection there anymore.

Surface control point editing is possible to do in MoI but it's not a major focus for how to generally do things because you can only edit control points of an "underlying surface". In your particular case here the underlying surface is aligned with the bottom edge of the thing you want to manipulate so it would work ok here but if the edge had been created by a cutting operation it will probably be a "trim edge" which is not necessarily aligned with the surface control points. See here for some more info about how "underlying surfaces" and trimming edges work:
http://moi3d.com/wiki/FAQ#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F

The general method that MoI is more focused on is constructing things from curves and in generating your surfaces from those curves. If you need to edit a surface there are various ways that you can extract curves from it if you do not have the original curves handy anymore, often times just using Copy and Paste to duplicate existing edges is the easiest.

- Michael

Thanks, Michael. I didn't realize you could copy and paste edges from existing objects like that. I tried it out and it worked perfectly. That will take care of exactly what I need. It is so great to have a developer that is active on the forum and can explain concepts so simply and effectively. Appreciate it! And thank you too, Marco!