Trimmed surface, Lunchbox

Hello , I’m an architectural student and beginner in grasshopper. So I’m trying to do diamond panels on this trimmed surface. I know that because it is trimmed it’s not working. please if anyone know how to fix it let me know ASAP. trimmed (8.6 KB)

Trimmed surfaces have their own chalk challenges. Here is a thread that might help:

Hi Welcome,

What I did was just trimming. For more and to do it in proper way follow Scott’s advice.


If you want a pattern that conforms more to the original shape, you might want to look at doing something a little more manual.

trimmed (11.9 KB)

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Another way:


Can you elaborate a bit more about it. Like how to achieve this ? I am getting something like this.

I adapted this old model to your geometry.


Maybe the only thing useful is the white group? It recreates the surface by lofting its edges so it’s no longer a trimmed surface. These diamonds consist of polylines so they are straight segments.

diamond (27.6 KB)

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You are feeding a trimmed surface in,instead of an untrimmed.
Thats the difference.

I hope the query is about trimmed surface. So I input a trimmed surface with Petras plugin.

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It is two lofted circles or revolved one:

For case 1 I am surprised that it returns a valid mesh.
Also works for donuts and spheres:

Same for hex grid:

It can be that updates for the clean seam is for the recent version, as I solved it for a student workshop half a year ago.

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Another way. These are interpolated curves instead of segmented polylines. The ‘rotate’ slider has more effect that the ‘Steps’ slider.

diamond (21.7 KB)

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I implemented a switch feature yesterday (blue group) to “round off” the rotation value so the curves always meet exactly along the inner circle. But I still don’t know why it doesn’t work as intended?

diamond (23.1 KB)

In response to a question in a necklace thread about using an ellipse as the basis, I substantially modified this model to avoid basing it on a surface:

Playfully, I added a feature to move the inner ellipse off center but didn’t realize until later that it still works when moved way off center, where I thought the tween curves would fail (but they don’t).

So now I’ve added the ability to move the inner ellipse in X, Y and Z directions and sorted the “intersection” points (actually CrvProx points). Kinda cool?

diamond (30.3 KB)

I made a mistake sorting the points by Z because it obviously fails when the Z slider is set to zero (Doh!). Easily fixed using Sort Along Curve instead (yellow group).

diamond (49.5 KB)

Then I added an optional “CLIP” toggle (light green group) that cuts away a portion of the curves and points based on the ‘clip’ slider (blue group). Sometimes it fails when the Z slider is zero…

Clipping adds some extra processing that isn’t needed when CLIP is disabled so if I were using this regularly, I would add code to disable the unused bits when CLIP is False.