Hi Christopher, you can usually only show points on individual surfaces, not on faces that are joined up with other faces in a solid.

You can extract the face you want to edit by selecting it and running Edit > Separate on it to break it away. Then once you have it as a single surface you can then turn on control points for the individual surface. There is some info on that here:
http://moi3d.com/wiki/FAQ#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F

But what kind of editing are you trying to do on the face directly? One thing to note is that on a flat planar face, the surface that is underneath everything is usually a very simple plane surface just made up of 4 corner points, then there can be numerous "trim edges" that live on that plane to form its trimming boundary.

When you edit surface control points you will not be editing the trim curves, you will be editing the "underlying surface", the thing that the trim curves are living on...

Usually for editing an extruded solid you would have the extrusion come from a closed planar curve rather than a face and you would edit the curve and re-extrude it (or if you have not done other operations on it you can edit the curve and let history update apply the extrusion again).

You can't really directly edit trim curves by pushing and pulling the face's edge curves themselves around, you usually edit regular non-edge curves in that way. If you have edge trim curves and you want to get regular curves from those you can select the edges and do a Copy/Paste to duplicate them as curve objects.

- Michael

"But what kind of editing are you trying to do on the face directly?"

I'm trying to edit the curve that was extruded into a solid. And I'd like to do this without
Edit > Separate
move the curve somewhere
edit the curve
re-extrude the curve
delete the old extrusion
move the re-extrusion into place

It's similar to the typical "edit group" functionality: If you double-click on an extruded solid, the solid is grayed-out and you see the curve, with control points which you can edit. When you click "Done", the solid is re-generated.

I got used to this in VectorWorks, very convenient and quick! :-)

Thanks for asking.
Christopher

Hi Christopher, you may be wanting to use a different kind of CAD program for that type of editing - one that's called a "feature based parametric" CAD program. Those are the ones like SolidWorks or Solid Edge where they keep a list of "features" that went into constructing the object and allow you to edit the features and have the model update.

Those systems can work really well for the types of edits that you are describing. MoI does not currently have the full set of that same functionality, the focus in MoI is much more on just drawing things quickly the first time and not so much on editing built things later on. So in MoI you'd mostly do the workflow that you are describing like edit the curve, re-extrude it, etc... The exception is that MoI does have some limited amount of history in it, if you generate an extrusion from a curve in MoI it is then possible to edit the curve and the extrusion that was created from it will update but not if you have done other operations on the extrusion like additional booleans after the extrusion was finished.

I do want to implement a deeper history function in the future but if that's something you really need a lot right now you would want to look into those parametric CAD programs which are focused on that type of thing right now.

- Michael

"The exception is that MoI does have some limited amount of history in it, if you generate an extrusion from a curve in MoI it is then possible to edit the curve and the extrusion that was created from it will update but not if you have done other operations on the extrusion like additional booleans after the extrusion was finished."

This is exactly what I want to do! How do I do this, please? :-) I've noticed that when you create a solid via extrusion, the curve you use is left behind. I normally delete this because it gets in the way of easy selection of the solid. Are you saying that if you edit THIS curve, the solid will automatically re-extrude?

I'm familiar with the parametric-type CAD programs you're describing. I've used VectorWorks for many years. I find myself liking the MOI way, where the solid is just the solid as you operate on it and it has no notion of where it's from, sometimes. Sometimes I miss the ability to go back and edit the two cylinders (for example) that the soild is made from. On the whole, I VASTLY prefer MOI, so I'm sticking with it for now. Thanks!

Christopher

>> Are you saying that if you edit THIS curve, the solid will automatically re-extrude?

Yes! When you edit a generator curve this one remakes the Curve/surface/Volume of any function of the object! :)
Careful : as soon as the object moves or is modified by another thing this link will be dead!

here after an extrude