Funky Polylines When Using Voronoi 3D on Curved Surface

Hey guys! I’m trying to create a Voronoi pattern that uses attractors to change the scale of some shapes on a curved surface. After I correctly get that, I would like to play around a bit more and offset, extrude, etc. some of the shapes, but that is not the problem at the moment, so dismiss this. The problem is that some of the polylines after creating the voronoi are doubling up, some are not joining correctly, some appear to be missing.

In the grasshopper definition 1, I used a simple flat surface and as shown, the polylines bake correctly.

In the definition 2, I’ve used the desired surface. I’ve managed to get the attractors and the Voronoi working on it, but when I go to bake the voronoi pattern:

  • A lot of the interior shapes double up.
  • Some edges are not joined.
  • Some edges are missing.

I’m trying to achieve the results that I get from definition 1 in definition 2. I want each cell to be a perfect polyline so I can proceed.

Thank you!!!

GH (7.3 KB)

storefront.3dm (271.3 KB)


I tried definition 2 on a flat surface and it has worked more or less flawlessly. So I’m guessing it has to do something with curved surfaces.

There are two alternatives for you.
The first is to resize the bounding box. The result of the BBX can vary depending on whether or how your bounding box is in contact with your surface. At the end, if there are few ramainning open curves, then you can filter them and make them closed.
The recommended method for you is the second one. After making your voronoi pattern in 2D plane, you can morph by using “surface morph” on your target surface. Fortunately, your target surface is an untrimmed surface, so there is no problem taking second alternative. Also, perhaps second method is better for your subsequent work.

GH (29.4 KB)


Thank you! Got it!

Ok now I’m struggling with a different issue. I tried checking out youtube videos but cant find a similar case and am stuck on my own. From that voronoi pattern on the 3d surface, I’d like to extrude each shape outward following a couple of rules:

  1. The farther the shape is from the attractor, the longer the extrusion.
  2. The extrusion is slanted towards the attactor.

Any help to get me started would be greatly appreciated. Thank you

grasshopper question (7.2 KB)
grasshopper question 2.3dm (66.8 KB)

The files you’ve attached has nothing different from the previous one.
Is not there anything you’ve done about the new issue?

1 Like

Next time, it’ll be better to create a new post with different issue from the original one… (19.0 KB)

1 Like

Slightly better than previous posting… (prevent overlapping) (19.9 KB)


Thank you dude! No way I’d have gotten that on my own. I’ve tried multiple ventures, but deleted them as they got me nowhere and just left what was for sure correct to avoid confusion. I’ll separate the threads next time if anybody searches for it in the future, didn’t want to spam too much. Thanks again, I’ve learned a lot from you!