tangent line between two pseudo ellipses

Replies to This Discussion

Permalink Reply by Wiet Mazairac on July 14, 2010 at 9:27am

Could you show us the method you developed and a simple drawing of what you wish to achieve?

Permalink Reply by Miguel on May 10, 2014 at 2:37am

Hi Phil, I am facing the same issue at the moment, how did you solve your problem? thanks!

Permalink Reply by Fred Becquelin on May 10, 2014 at 3:24am

Salut Philippe! Long time! Comment vas-tu?

I guess you went there already http://www.grasshopper3d.com/forum/topics/tangent-to-ellipse

What's your approximation method? is it similar to mine?

I think all I could do more on the subject would be a binary search script, but it would still be an approximation of course to a threshold...

Tiens moi au courant quand tu passes à Paris! A+

Fred

Oh my! I didn't see the dates!

Permalink Reply by Miguel on May 10, 2014 at 5:59am

Hey Fred

That was funny, but it does not hurt to try some post of 4 years ago haha..

I saw your strategy. So let me see if I understand, as we can only get tangents from a circle, you used a circle and then stretched into an ellipse? Yesterday I noticed that there are tangents between circles, but the component did not work with ellipses...

The question here will be, as I already have an ellipse, I cant obtain it from a circle, I wonder if there could be some reverse engineering process to that.... hummm 

By the way, I am a beginner at GH getting into very challenging problems...

Thanks!

Attachments:

• Canvasat214817.png, 89 KB

Permalink Reply by Fred Becquelin on May 10, 2014 at 6:08am

post a file if you want an answer. I'll look into it.

http://www.grasshopper3d.com/forum/topics/how-to-get-help-when-you-...

Permalink Reply by Miguel on May 10, 2014 at 6:41am

ok, let me clean it, its a bit of a big file...

Permalink Reply by Miguel on May 10, 2014 at 6:56am

Hi, here it is, the file is large, but I cant take the part concerning this issue as the rest will be affected. Please find the files here.

https://www.dropbox.com/sh/65k2j5kcqbv3fgk/AAB86ADPL3bzGcM-yLqxKbura

Thanks a lot

Mig.

Permalink Reply by David Rutten on May 10, 2014 at 7:40am

I used Convex Hull to get the wrapping curve. It's an approximation, but if you sample the ellipsesish curves densely you should get an answer close to the real one.

If you only want the tangents, explode the polyline and find the two longest segment.

--

David Rutten

david@mcneel.com

Attachments:

• tangents.gh, 21 KB

Permalink Reply by Miguel on May 10, 2014 at 7:45am

thanks David, I will take a look at it now.

Permalink Reply by Miguel on May 10, 2014 at 8:10am

Hull solves the need for tangents of top of ellipse with top of ellipse, but I cant make crossed tangents  between the top of one ellipse and the bottom of the other one, any clues? this is driving me crazy, interesting, seems so simple yet so hard...