Create a circle from three tangents in GH

Hi,
I've been trying to create a custom component which takes three tangents as a vector and creates a circle from that. I didn't succeed :-(
but I know it must be possible since Rhino has this feature in the circle commands. I just don'T know how to access it via .Net

I was wondering if someone could help me?

Thanks in advance
Karl

Replies to This Discussion

Permalink Reply by David Rutten on November 20, 2009 at 2:28am

Karl,

that feature isn't exposed. In fact, this is not possible, you cannot define a circle with 3 tangents. You can define a circle through 3 points (provided they are not coincident and not colinear), and you can define a circle through two points and a single tangent. I think the command in Rhino you are referring to is the option in _Circle which creates a circle tangent to three existing curves?

I do not think that function is exposed, and I can tell you it's incredibly difficult to get that work, especially if you have no mouse-picks to guide you towards the correct solution.

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by Daniel Piker on November 20, 2009 at 5:08am

If you mean tangent to 3 lines then this is a special case of Apollonius' problem

In general there are 4 solutions - an incircle and 3 excircles. Here's a def I made a while back to solve this that you might find useful:

Attachments:

Apollonius_LLL.ghx, 395 KB

Permalink Reply by Karl Wecker on November 21, 2009 at 5:41am

Thank you both.
There really is a lot of math behind these very easy klicks in Rhino.

I guess I for now will try to use the Apollonius Problem solution and will work on that. Thanks for sharing your GHX.

Karl

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