How to split closed curve at seam

I'm trying to split a closed curve at its seam (to get an open curve). I tried using Shatter but if I only pass in one parameter, the curve remains closed. Should it?

If this is not a bug in Shatter, then how would I split my closed curve?

Replies to This Discussion

Permalink Reply by David Rutten on July 24, 2012 at 12:08pm

A closed curve is already split at the seam. That what the seam means. It's where the two ends just happen to meet up to provide a closed rather than an open curve. But even assuming this wasn't the case, what two segments do you expect to get if you split a closed curve at a single point?

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Dave Johnson on July 24, 2012 at 12:37pm

Really I just want to convert my closed curve to an open one where the start and end points just happen to be coincident. But from what you said it sounds like that's the very definition of a closed curve.

The bigger picture here is that I'm writing a definition that will divide curves by length with adjustable "start" point, and I'd like it to work with either open or closed curves. It's working well with open curves, so my thought was simply to test the input curve for closed-ness, and if closed then make it an open curve before passing it along. Of course, I can make separate paths for closed and open curves, I was just hoping to collapse as much of the definition as I can.

I am, as always, open to suggestions!

Permalink Reply by David Rutten on July 24, 2012 at 12:49pm

Rhino has two kinds of closed curve. A regular curve where the distance between the start and end-points is less than some very small tolerance and periodic nurbs curves.

It is not possible to have an 'open' curve which has end-points that meet to within that tolerance.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by David Rutten on July 24, 2012 at 12:51pm

You can adjust the seam of a closed curve btw. There's a component that does just that.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Dave Johnson on July 24, 2012 at 1:01pm

Thanks for the explanation, David. Somehow I envisioned a boolean in the data structure that declared 'closed' or 'open', independent of end point positions. I'll just keep the 2 paths (closed and open) separate a little further into the definition.

(FWIW, I had a working definition already for closed curves, where a seam adjustment via slider was followed by DivLength. But for the current project I need to add open curves to the mix, which is a bit trickier.)

Thanks again

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