error: new closed curve loops in on self. Any ideas?

I searched the site for an answer to this question and didn't find any results:

Here's what I did:

I created a closed curve,
rebuilt the curve,
increased and evened out control points,
then built a new curve through the control points.

the resulting new closed curve ends up creating a loop inside itself.

Any ideas on how to remove the loop and force the new curve to run smoothly through the CPs? Thanks.

Attachments:

closed curve error.ghx, 49 KB
curve.3dm, 26 KB

Replies to This Discussion

Permalink Reply by Chris Tietjen on February 25, 2011 at 12:58pm

I didn't look at your files but it's probably a case of duplicate points. Once they've been culled it should work.

Chris

Permalink Reply by David Rutten on February 25, 2011 at 1:24pm

A periodic curve has N overlapping points on either end, where N equals the degree of the curve. If you're accessing control points directly, be sure to ignore the N last ones on periodic curves.

Alternatively, use the Control Polygon component which already has this logic build in.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by TheChosenOne on February 25, 2011 at 3:00pm

How to open or close the curve? ...make periodic or non periodic?

Permalink Reply by David Rutten on February 25, 2011 at 3:32pm

A curve is closed if the start-point and the end-point are in the same location. A curve is periodic if it has overlapping control-points and if the knot-vector is not clamped. We hide these details from the Rhino UI because most users will never understand what a knot-vector is, but as a programmer you'll be confronted with this.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by TheChosenOne on February 25, 2011 at 3:38pm

How to implement this tool in the grasshopper?

Permalink Reply by Chris Tietjen on February 25, 2011 at 3:34pm