> Michael, I am very interested to hear your opinion about the curve-solid connection.

It's an interesting idea, but it is pretty different than how every other history-based modeler that I know of works - you're talking about a sort of history reversal there where modifying the output of a command would backtrack and change the input to it. That's reversed from the normal flow of modifying inputs and reapplying commands to generate new outputs.

Is this something that you are imagining only applies to just moving the output? Or would you imagine that other operations should backtrack to the original object as well - like if you have a rectangle and extrude it, then fillet an edge of the extruded box, would you expect a fillet operation to backtrack to the original rectangle as well? That would be extremely difficult to achieve.

The complication that Jonah mentions is definitely a concern too - going back and modifying the original curve could then have a ripple effect that causes modifications to any other objects that are also constructed using that curve.

Here's a scenario where a curve-solid connection would cause a problem - let's say you draw a rectangle and you then extrude it into a box. Now you want to keep this box but edit the rectangle slightly and produce a new box. So you grab the box and move it away off to the side so you can get back to your curve to edit it to produce a new second box. But if the curve moved with the box as you describe, this wouldn't work. This is kind of a general problem with embedding too much history connections into things by default - suddenly what should be simple actions (move the box to uncover your original curve) end up behaving in unexpected ways. That's why many operations in MoI have history updates turned off by default (like copy for instance), because the history can sometimes get in the way of just doing simple things.


> Also, the ability to undo some changes and control the modification history (No 6)
> because -at least I work like that- i often need last minute changes and I can't
> reproduce the solid from the start just to correct the fillet I did some days before.
> Also, there is no way to remember the dimensions and the values for each one of
> them (fillet radius, cirle radius, extrude height etc).

I want to try and add this in eventually, but it will be quite a bit of work, it means that there has to be a lot more information stored than MoI currently keeps track of, and there will be quite a bit of user interface work to provide a way to manage that information.

But what you're describing here is exactly how a "parametric solid modeling" type of CAD program works, such as SolidWorks, Pro/E, Alibre, or Inventor. You may want to look into using one of these types of programs for doing this type of solid modeling - they can handle frequently changing fillets or connectors or holes a lot easier than MoI can right now.

This hasn't been a top priority for MoI partly because this type of thing is already handled very well by those other types of programs.

- Michael