BUG: "Undo selected" does not work

Seems like the ! _UndoSelected command is not doing its usual thing from some time. Today I worked on a few curves, then tried to undo one of them with the ! _UndoSelected command, but instead of showing its previous state, Rhino simply deleted the curve… Then I tried this on a few more objects and got the same result.

This is not new behavior. It has occured since V4 or V5. It can be very annoying.

My guess is the cause is how the Undo commands work. They do not perform inverse operations on the new geometry to obtain the old geometry. For example if an object is scaled by a factor of 2 then Undo does not scale the new object by a factor of 0.5. Instead Undo replaces the object(s) with “saved” versions. What I think happens is in some instances when other geometry has also changed and the new geometry is incompatible with surrounding geometry then the saved old geometry is not used.

It was a deformable circle with degree 5 that I split into two halves with a line, then I wanted to undo the split operation of that particular circle. Other objects were not involved with the circle in any way. However, I had some more curves drawn in different locations, so I wanted to avoid losing them with the regular Undo. I ended up saving the scene, then doing multiple undos, copying the initial version of the circle, then going forward with multiple redos and used Paste to have the untrimmed circle and the rest curves that were made afterwards. Basically the “Undo selected” command is useless in its current implementation. I remember that it worked wonderfully years ago, but not in Rhino 7.

Hi Bobi - the disappearing act on UndoSelected has been around for ever as far as I recall. Redo gets the objects back but the undo still fails. If you can provide a repeatable example, you’ll get a medal.

-Pascal

I guess that I have to learn coding and become a Rhino developer, wow. :smiley: I don’t use that particular command often, but when I do, I see that it can mess up with the models. Hopefully it will be fixed at some point, because Undo and Redo are two commands that people rely onto for obvious reasons. Mistakes or accidental moving of objects happen all the time and it’s nice to have a way to undo them.