Hi Nick - no history won't work with pipe as a side effect from how it works.

Behind the scenes, pipe basically creates a circle curve for you and sweeps it. But that circle generator curve does not stick around in the model.

That breaks history because currently history will only work if all the inputs that went into the command are currently present in the model so that they can be found and have that command reapplied to them.

Because the circle used for the sweep is not present in the model anymore, it is not accessible to the history functionality so that's why history does not work with Pipe.

I want to improve things in the future to keep deleted objects around somehow so that they can be accessed by the history mechanism. But this is not a very easy thing to set up because it may involve keeping a large quantity of data around and managing large quantities of data needs careful consideration.

- Michael

Thanks for the explaination. Maybe I don't understand completely what happens, but why are the circle curves deleted? Is it the boolean that deletes the circles? It would be nice to maintain some of this stuff, but I see the tradeoff... You've got some tough decisions.

Hi Nick, well the circles are deleted because they're just one stage of the scripted batch operation that the Pipe command performs.

The Pipe command is just basically a scripted set of actions that you could otherwise do manually, like drawing a circle, sweeping it along the path to make a tube, then drawing another smaller circle and sweeping it also to make a smaller tube if you have an inner radius, and then booleaning out the inner one from the outer one.

It would be kind of weird if a batch operation script like this would leave behind all of the objects from its intermediate calculations, because that would kind of clutter up your model with a lot of additional pieces that you would not really expect to see.

- Michael

Yeah, I was kind of thinking aloud that if the script could leave behind the circles (it already leaves the rail) then the problem of no history would be solved (right?). I think in this case the "the objects from its intermediate calculations" would make the tool/created objects more powerful. Or are the circles drawn in some random location?

I knew it was a script of steps to complete the object and I have actually been contemplating how to create an "Extrude Cut" script, unfortunately I am no good at coding. The best I have done is some basic LISP in AutoCAD.

Thanks for the reply.

Cheers,
Nick

Hi Nick,

> then the problem of no history would be solved (right?).

Not for the case of a hollow pipe, because that also takes 2 sweep pieces (an outer one and an inner one) and does a boolean operation to make the final result. So those 2 sweeps for that case are other intermediate pieces that would need to stick around in addition to the circles. So keeping all of that stuff would be a pile of extra stuff all stacked up on the same spot.

It basically needs a mechanism to kind of archive these intermediate objects so that history updates can find them without needing to have them immediately present in the model. Currently that archiving mechanism does not exist yet, so the history updates right now only work when all the elements in the sequence of the history are present in the model.

In the future I want to implement an archive mechanism which would then enable history to work in these kinds of cases. But because the archive may contain quite a lot of data in it, it's something that has to be designed quite carefully.


> Or are the circles drawn in some random location?

Yeah, they're actually created flat on the cplane way far off to the side so that the sweep "auto place" mode will kick in and they will get automatically moved and rotated to align with the start of the rail curve.

- Michael