Hi Burr - I see what you mean now - previously when I thought you meant you didn't want a point to be edited I thought you meant one of the curve's control points to not be edited and remain in place. But it looks like you mean a particular "point on the curve" (not _control point_) to remain in place. That's a bit different.

> "Is the mechanism for manipulating a few nearby control points"
> located in the Show points command or hard coded?

It's not actually the Show points command that does the actual editing - it's the drag command that actually moves stuff around.

Show points just turns the point display itself on or off, "show points" by itself doesn't actually edit the curve.


One problem with having a mechanism that tried to do a kind of "implicit rebuild" version of the curve that was actually dragged is that it's hard to guarantee that the point that you wanted to stay fixed would actually be fixed with that method - if you dragged close enough nearby it, it would still move if the only thing that was happening during the drag was a larger number of rebuilt points automatically added in.

There could be a lot of weird side effects with that kind of "edit an automatically rebuilt version" because if you just do a rebuild by # of points, if you don't use very many points the shape of the curve will actually be changed quite significantly in the rebuilt version, so that could lead to some strange things where editing the curve morphed it into some completely different shape unless you happened to set that special auto rebuild number of points value to a high enough value...


A whole different way of doing it would be to apply multiple constraints to the edit, with one constraint producing the move and another one fixing a particular point in place - but if you try to move things nearby the fixed constraint point, that's exactly the kind of thing that introduces bulges as shown in that previous example - there will be a kind of pivoting action where things kind of pivot around the locked point - it's the pivoting that then makes for bulges.

- Michael