Now that rhino.io is available for quite some time - is it possible to implement Sweep Nurbs exported from Cinema4D?

I want to do some pipe planning and have the main model setup in MoI.
As there are definitely some revisions to be done and MoI doesn't always behave as expected - is it possible to have the pipes setup in c4d and just the paths and diameters for the extrusions/sweep nurbs exported? if this is exported - do the splines behave as polylines including points or is everything meshed and loads of polygons imported in MoI?



My main concern in MoI is that sometimes it works: model the profile and path spline and afterwards, when adjusting the path the extruded 'pipe' is changing along. BUT this doesn't always happen, no clue why. to avoid running into this and doing the extrusion every time again I wanted to try to model it in Cinema and then just export the extrusion paths..

Hi macray - no it's not possible to export from Cinema4D into MoI, because the objects that you create in C4D are made up of polygon mesh data.

MoI does not work on polygon mesh data - MoI works on NURBS surface data.

This may be a bit confusing, because Cinema4D happens to use some tools named NURBS in some of its construction tools, but it's still generating polygons as the final result.


It's possible to export from MoI to Cinema4D, in which case MoI will break up the smooth NURBS surfaces into polygons. But once you've got a model in polygon mesh form where it is made up of a lot of little facets, it's not very easy at that point to go back to large smooth NURBS surfaces like MoI is designed to work with.

The Rhino.io plug-in for Cinema4D that you mention is not going to help you because it is only going to store polygon mesh objects in 3DM files that it generates, and MoI does not read polygon mesh objects from 3DM files, MoI only reads NURBS objects from 3DM files.


> My main concern in MoI is that sometimes it works: model
> the profile and path spline and afterwards, when adjusting
> the path the extruded 'pipe' is changing along. BUT this doesn't
> always happen, no clue why.

This will happen if you do some other operations on the sweep result, like if you boolean the sweep with another object. Currently that will break the history chain and you will lose the ability to update the sweep by editing the path after that.

But if you don't do any other operations on the sweep after you create it, then it should stay editable and update when you edit the path curve.

So if that kind of editability is important to you, avoid doing any other operations to the result of the sweep and you should then still have the history updating intact.

- Michael

test post

to keep the history intact does not always work, even when trying around with nothing else in the scene. It works most of the times but not always. I'll try to remember this the next time i run into it and send you the scene.
Here I mainly work by setting up the paths, extruding things and then hide the path and profile...

What I recognized - if I mirror the extruded model and rework the path on the original sweep it also changes the mirrored copy. If I just copy the sweep object - the copy is not changed, when changing the path spline of the original. Is this intended behaviour?
(I really like that mirrored copies are changing along, but this is not always desired, the same goes for that I'd like to have normal copies change when the original is manipulated sometimes...)


Edit:
All works fine here. I was probably referring to something else that was bugging me: When I setup a pipe roughly in outlines, use it and afterwards want to add roundings - changing the guide / path spline doesn't affect the sweeped pipe (probably because of adding points to the spline?)

and in that regard: is there a way that once setup roundings on a spline can be deleted without redrawing the spline? f.e. moving the 2 guide points to a distance of 0,0,0 merges them to 1 point that has no more bezier function? Or can I join point that share 1 coordinate? Is there a possibility to switch the two points of rounded corners to behave as corner points?

working with it lots of questions pop up that might make working with it easier... nethertheless I LOVE MoI!
(I prefer to use it here over the CAD Program I usually use - Vectorworks. The import via .sat works great btw so I model in MoI and import the final product... :) )

Hi Macray,

> to keep the history intact does not always work, even
> when trying around with nothing else in the scene. It
> works most of the times but not always. I'll try to
> remember this the next time i run into it and send
> you the scene.

Now I remember - one way that could potentially happen is if due to your edits the sweep would generate more than one output object, like 2 pieces in separate sections where a curve that bends around in 3D is coming to a kink. The history mechanism right now doesn't know how to deal with this situation of a command generating a different number of output objects than it did originally. So for now for that kind of situation you would need to re-run the Sweep command.


> What I recognized - if I mirror the extruded model and
> rework the path on the original sweep it also changes the
> mirrored copy. If I just copy the sweep object - the copy
> is not changed, when changing the path spline of the
> original. Is this intended behaviour?

Yup, that's intentional that mirroring has history updates turned on by default but some other various commands have it turned off by default.

You can change whether any particular object will update or not by using the Edit > History command. So for example to stop the mirrored object from updating you can select it, then run Edit > History and click the "Disable update" button. After that it won't get updated anymore when its source object is edited.


> the same goes for that I'd like to have normal copies
> change when the original is manipulated sometimes...)

So for this one you also use the Edit > History command but instead click the "Enable update" button. So for example if you use the Transform > Copy command to make a duplicate of an object, select the new duplicated object and then run Edit > History and click "Enable update", and then when you edit the original the copy will update after that, until you do some kind of edit that breaks the history chain.

So note that you select the object that will be updated (like the result of the copy, or the result of the mirror) when you run the Edit > History command to do this stuff, not the original source object.


> and in that regard: is there a way that once setup
> roundings on a spline can be deleted without redrawing
> the spline?

Hmm, I thought that the fillet command could be used for that, but it seems to break history updates right now. I think that should be something I can fix up for v3.


> Is there a possibility to switch the two points of rounded
> corners to behave as corner points?

Right now the way to switch a point between corner and smooth types is to insert a new point of the kind you want with Edit > Add pt and then delete the previous one. That should end up with the same result as switching the style of the single point.

In v3 I do want to make an easy way to switch a selected point between those styles though.



Note - the forum may be closed for posting for a couple of hours here as I transition to a new server.

- Michael

Thanks for the tipps. very handy for some of the things I do right now! Thank you for the support!