how to make a spiral on a sphere?

Can I get a little help with a Grasshopper question?

Please see attached.

I am still trying to draw a spiral on a sphere.

I have now made eight arches around an axis.

I have divided the arches in 8 points

And made a list of all the points.

I want to make a line through point 0 on arch 0, point 1 on arch 1, point 2 on arch 2 and so forth up to point 8 on arch 8

Then the line will spiral its way up around the sphere of the arches.

And I can regulate the “steepness” of the spiral by changing the distance between the arches.

I am trying the command “Split list”, but I am getting lost in [()]

is this the right way to approach it?

Mikkel Johansen

Denmark

Attachments:

kogledome1.3dm, 18 KB
kogledome12.gh, 10 KB

Replies to This Discussion

Permalink Reply by Joseph Oster on September 6, 2017 at 2:15pm

I hope someone else has a better answer because I don't have a good understanding of 'RelItem' but... I wandered into the weeds anyway and discovered this, almost by accident:

from this "ball of strings":

Attachments:

kogledome12_2017Sep6a.gh, 18 KB

Permalink Reply by Mikkel Johansen on September 6, 2017 at 2:21pm

Interesting. Thanks. I'll look into it.

Permalink Reply by Chapulin Colorado on September 6, 2017 at 2:53pm

you could use this one Hyungsoo Kim showed me once:

Permalink Reply by Mikkel Johansen on September 6, 2017 at 2:59pm

Sweet! thanks

Permalink Reply by Laurent DELRIEU on September 6, 2017 at 3:03pm

There is also something near that is named loxodrome/Rhumb line, see

https://en.wikipedia.org/wiki/Rhumb_line

http://www.grasshopper3d.com/forum/topics/loxodrome

Permalink Reply by SERGEY KUZNETSOV on September 6, 2017 at 3:13pm

May be something like this?

Attachments:

Spirale on surface.gh, 8 KB

Permalink Reply by SERGEY KUZNETSOV on September 9, 2017 at 4:57am

LunchBox

Permalink Reply by Pieter Segeren on September 8, 2017 at 7:27am

Hi Mikkel,

did I understand correctly that you want to create (straight) lines between those points? If so, you can use [Relative Item] in your definition like this:
If you instead meant to draw a smooth curve through those points, you'll need another approach...