Spiral Ramp on a Surface of a Dome


I am trying to model a ramp on a dome surface.
I want to 1. create a dome 2. set a platform on upper platform 3. create many iso curves and divide them 4. sift the points for the spiral path and interpolate them 5. Offset the curve to get the width of the ramp

However, I got blocked on two things.

  1. I can’t make the ramp goes up more slowly so that it isn’t too steep.
  2. I can’t sift the points that I required. It can only spin for 1 turn then straight goes up.

    Appreciate any kind of tips and helps. Thanks!
    Spiral ramp on a dome surface.gh (15.1 KB)

I adapted code I posted here:

By replacing the purple group (base shape) with the cyan group. Turning these steps into a ramp is easy.

Spiral_Stair_Cone_2021Dec19a.gh (31.2 KB)

P.S. It was only after I implemented a ramp that I realized there is a ramp in the old code with preview disabled. The ‘riser’ and ‘tread’ sliders affect the steepness of the ramp, just as if there were stairs.

Spiral_Stair_Cone_2021Dec19b.gh (31.3 KB) (UPDATED)


In this example you need these components from Fennec Addon.



The last looks very promising!!
Could you please send the code of the third one again?
It appears that it is the same as the second one.
I try to replicate it myself but didn’t go well.


The result is very impressive! I will try this in my model to see if this works.
Thanks for the tips! :slight_smile:

Oops! Sorry, I have updated the previous post.

Would the original code be available?
I try to duplicate the code myself but encounter some errors.

What do you mean by the original code?

Oh, I mean, if there is a GH file of the image that you shared available.

Because I downloaded the addon and try to make the ramp, but some errors occurred.
And I went to download the example file, but couldn’t find the solution there.

Therefore, I am thinking that a GH file of the image might be really helpful.

Sorry i thought i posted it

Spiral ramp on a dome surface.gh (28.3 KB)


Appreciate the help, thanks!