align circle cnr to corresponding curve

Hi guys, I'd like to create a small gap on my distorted octagon.. What I did was to find the mid point of one of the sides, then create circle CNR, and trim with region after that. However, I'm having a problem aligning the circle to the direction of the curve. It won't trim if the circle is not aligned with it. I've tried to input the normal vector with the corresponding curve, but it goes perpendicular to what I want. Is there maybe an expression editor that I could input to undo the perpendicular alignment? Thank you!

I've attached my files..

Attachments:

align cnr.3dm, 102 KB
align cnr.ghx, 223 KB

Replies to This Discussion

Permalink Reply by Chris Tietjen on April 25, 2011 at 6:11am

I don't have time to look at your definition right now but you can probably extrude the circle a little bit (both ways) and get the intersection points.

Chris

Permalink Reply by Yoann Mescam (Systemiq) on April 25, 2011 at 7:18am

Use the Extend component, but with L0 and L1 being < 0.

This will create a gap at the start/end point of your curve.

To change this point, type :

x.ChangeClosedCurveSeam(y)

A = x

in a vb script, the y is the parameter on curve x which will be the new start/end point.

Attachments:

CutCrv.ghx, 57 KB

Permalink Reply by Ruby on April 25, 2011 at 9:58am

Thank you, but sorry that I can't understand your solution.. Is there any simpler way of doing it without vb script? I just need a tiny gap in the middle of the line to determine the unrolling split point.

Permalink Reply by Dimitri Nikitin on April 25, 2011 at 10:54am

Hi, Ruby..

me again..

just use sphere instead of circle..

..here is the file..

Attachments:

aligncnr_2.ghx, 218 KB

Permalink Reply by Ruby on April 26, 2011 at 1:23am

Thanks again, Dimitri!

Permalink Reply by Yoann Mescam (Systemiq) on April 25, 2011 at 11:47am

You could also get a subdomain of your curve with the SubCurve component, but it would also involve changing the start/end point.

The sphere cutting method from Dimitri is simpler.

Permalink Reply by Ruby on April 28, 2011 at 7:18am

Hello everybody, sorry for bringing up this question again. Once I changed my surface in rhino, both circle and sphere do not intersect my curves to create a gap at every tube. I have also tried to divide the line to get two points in the middle for intersection, but not sure what's the next step.. Could anybody PLEASE suggest something asap? Thank you much..

Ruby

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