Twisted pattern on surface - customized surface

Hi there, :wave:

I created this path to create different twisted patterns on a surface based on circles:


Now I want to use this path on a custom surface created in Rhino:

But I’m doing something wrong here… Can anyone help me?
Twisted_Pattern.3dm (182.1 KB)
Twisted_Pattern.gh (35.3 KB)

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Two white groups.
Twisted_Pattern_2024Oct24a.gh (22.5 KB)

P.S. More elaborate code was needed to avoid using isocurves, which are affected by surface shape. Also, I had to check loft option ‘Align sections’ at the end (green group, not shown).


Twisted_Pattern_2024Oct24b.gh (29.5 KB)

P.P.S. Oh, rats! I tried to avoid loft option ‘Align sections’ but failed. You can uncheck it and see what it does. But I just tried using it on your original shape and it alters the result. :frowning: So it must be altering the result with the Rhino shape too… :thinking:

OK, got it. After jumping through hoops to align seams (failed!), I found the fix was just to flip curves with a circle guide (yellow groups). So loft option ‘Align sections’ is not used at all.


Twisted_Pattern_2024Oct24d.gh (32.8 KB)

LATER… Slight simplification of white group, no change to functionality.


Twisted_Pattern_2024Oct24e.gh (25.9 KB)

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That is brilliant! Thank you so much @Joseph_Oster for your help and explanations. You deserve an award!

My first reply using Iso Curve was wonderfully simple (version ‘24a’):

In addition to that white group, I needed to override the Rotate ‘P’ input because the Rhino shape was not at the origin. I was oblivious to the fact that isocurves all have the same direction so didn’t see the flip curve issue until later.

But as I said, isocurves are affected by surface shape so they weren’t evenly spaced:

Which led to versions ‘b’, ‘c’, ‘d’ and ‘e’ :bangbang: I vaguely recall now that this issue of the top edge plane intersection curve being flipped has been reported and discussed before, in relation to contours.

But I struggled with it yesterday, wasting a lot of time going through four different versions to understand and fix the problem. :man_facepalming:

Same flaw mentioned five years ago:

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Hi Joseph,

may I ask you for help again? How does it work then if you want to implement it on more complex and open surfaces like these?


Grasshopper_Surfaces.3dm (4.4 MB)

It doesn’t. It’s your code, I would think you can see why.

I added gray groups to get something reasonable using the larger surface. As you can see, rotation of the wavy curves doesn’t work well.

Twisted_Pattern_2024Oct30a2
Twisted_Pattern_2024Oct30a.gh (25.5 KB)

Easy to predict the lofted shape:

I added one more gray group to moves the seams:


Twisted_Pattern_2024Oct30b.gh (20.8 KB)

I didn’t even try with the smaller shape. Again, it’s your code (or is it?) so why ask me?

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