# Edit cross-section of Fattener component

Hi all,

I have been working out a workflow that makes use of Fattener component and SubD.
To note I always begin with a linear skeleton of lines, no prior mesh.

But I have stumbled upon a limitation which I understand might be able to be solved in native GH or as a last resource with code.

Basically Fattener and also SubD Multi-Pipe make circular cross sections. I would like to be able to have elliptical ones to have control on both radii.

Here I scaled in Z but as you can see the slope changes, which is not what I want.

ellipitcal section.gh (18.0 KB)

I know I can get the polygon/mesh from a SubD objcet, I think the key might be there and working with it as a mesh and then converting back to SubD…

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In my head, this should work. Since your lines are “2D”. I projected and evaluate the middle vertices, but apparently, the mesh structure of the multipipe depends on the angles, so, in this case, is not the same.

@DanielPiker Does Multipipe and Fattencould include more data such as the half-edge mesh structure used?

ellipitcal section.gh (29.7 KB)

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Hi @ThomasE

Here’s an example of using the half-edge graph which MultiPipe builds the mesh around.

However, I think not enough of the methods are exposed yet to be much use for the above.

For this though I think this approach of projecting to the plane, building and scaling the pipes then moving vertices can work, but using proximity like this instead.

elliptical_MultiPipe_scale.gh (18.0 KB)

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Thank you Daniel, this is very useful!

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I gave a chance to my previous approach and work pretty well with a high EndOffset.

elliptical_MultiPipe.gh (15.7 KB)

@DanielPiker any suggestion for this 2d Mesh offsetting the network lines?

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@ThomasE This looks really good too!

Why do you say with a high EndOffset? I works fine with a low value too.

Something like this?
flatfatten.gh (9.3 KB)

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Compared to Daniel approach EndOffset causes extra bends but clean caps.
Since I worked with normals, there are some ugly meshes on caps, but SubD apparently hides them. but If you are picky those are ugly ellipses on SubD.

@DanielPiker nice! using multipipe. For the 2D fatten I thought this method are exposed.
Anyway with this take all the features of this tool, thank you!

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