Perpendicular pt by his closest pt

Hi,

I need found a perpendicular point on a curve by his closest point.

How can I do that??

Attachments:

asd.jpg, 271 KB

Replies to This Discussion

Permalink Reply by Matthew Owens on June 23, 2012 at 5:26am

Pull Point Component? Double left-click on canvas, type 'pull point'.

Permalink Reply by David Rutten on June 23, 2012 at 5:53am

There is no way in Rhino4 to find perp-perp points between two curves. This requires the Rhino5 SDK. But note that even there, the actual points found are the closest ones, not necessarily perpendicular ones.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Sen on June 23, 2012 at 6:30am

I'm sorry but I'm not sure to understand.. so I can't find a point on the curve by his closest pt on the other curve? "The closest point reverse"..I don't know how to call it :D

Permalink Reply by Sen on June 25, 2012 at 6:53am

someone can help me? :(

Permalink Reply by David Rutten on June 25, 2012 at 7:26am

The attached file calls the Rhino5 function that computes the closest point pair between two curves. It will not work in Rhino4.

David Rutten

david@mcneel.com

Poprad, Slovakia

Attachments:

CurveClosestPointPair.gh, 2 KB

Permalink Reply by Mateusz Zwierzycki on June 25, 2012 at 12:19pm

Is it approximated or exact closest point pair ? (Exact as much as rhino document precision). Can I know what method is used to find this pair ?

Permalink Reply by David Rutten on June 25, 2012 at 1:23pm

It's probably approximated to within whatever accuracy is possible. Very, very few things are exact in nurbs programming. I have no idea what algorithm is used, I think Greg Arden wrote one from scratch.

If you use the TestCPCP command in Rhino you get to pick between two algorithms called DBrent and GSLib. Though I doubt that gets you much closer to an answer.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Mateusz Zwierzycki on June 25, 2012 at 7:13pm

Its just my curiosity, thank you very much for an answer.

Each time I find something related to "simple" geometry, I try to imagine how to do it myself - so it is this time.

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