Tangent to curve starting at a point

Hi, im trying to figure out how to make a tangent line to a curve, starting at a point

Thank you in advance

Replies to This Discussion

Permalink Reply by Brian Harms on March 17, 2017 at 11:50am

Here's one way

Permalink Reply by Victor Perez on March 17, 2017 at 11:58am

Thank you,

as shown in the image, the tangent must start in the point (EXTERIOR, PLANAR)

Permalink Reply by Victor Perez on March 17, 2017 at 12:01pm

Start at a specific point, and end at the tangent point, thank you in advance

Permalink Reply by Marios Tsiliakos on March 17, 2017 at 12:30pm

this is a crude way (if you don't mind error factors) . I am sure there is a more scientific (mathematical) way to resolve this.

cheers

Permalink Reply by Victor Perez on March 17, 2017 at 12:32pm

thank you, that error factor is ok, can you attach, please gh file?

Permalink Reply by Joseph Oster on March 17, 2017 at 12:37pm

When you didn't post any file in the first place? Your screen shot appears to show a polyline (straight segments) so the concept of tangent doesn't make much sense anyway.

Permalink Reply by Victor Perez on March 17, 2017 at 12:39pm

I should have attacked a file, but since the elements used in rhino are so easy to create I thought it would save time drawing them instead of downloading a file

Permalink Reply by Marios Tsiliakos on March 18, 2017 at 7:28am

apologies I didn't even save the previous one. refer to my new reply

Permalink Reply by Brian Harms on March 17, 2017 at 2:17pm

Gotcha, I didn't see that little point in the corner of the pic.

Marios' solution will work. He's effectively dividing the curve up into lots of points, measuring the angle between the vector from your starting point to each of the division points, with the tangent vector at that point on the curve. He's then finding the smallest angle, and using the point on the curve that is associated with that small angle.

Permalink Reply by Joseph Oster on March 17, 2017 at 2:31pm

Without a file from him, we don't know if the curve and point are in the same plane? Or if the curve is a polyline?

This yellow line is an approximation, depending on the number of 'Divide' points - likely not the best way at all:

Permalink Reply by Brian Harms on March 17, 2017 at 2:55pm

The other issue (assuming everything is in the same plane) is that depending on the curve, there could be multiple lines tangent to different points on the curve.

But it sounds like both of these solutions are fine with him.

Permalink Reply by Joseph Oster on March 17, 2017 at 12:42pm

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

3. Attach minimal versions of all the relevant files

If you have a GH/GHX file you have a question about, attach it to the post. Don't expect that people will recreate a file based on a screen-shot because that's a lot of pointless work. It's also a good idea to remove everything non-essential from a GH file. You can use the 'Internalise Data' menu option to cut everything to the left of a parameter:

If you're importing curves or Breps or meshes from Rhino, you can also internalise them so you won't have to post a 3DM file as well as a GH file. If you do attach large files, consider zipping them first. Do not use RAR, Ning doesn't handle it.

It is especially a good idea to post files that don't require any non-standard components if at all possible. Not everyone has Kangaroo or Hoopsnake or Geco installed so if your file relies on those components, it might not open correctly elsewhere.