Exclude naked edges of a mesh

GridDiagonals.gh (8.3 KB)
GridRhino.3dm (32.7 KB)

Hi all,

I have a mesh that I created from a manually drawn surface in Rhino. Then I used “DiagonalizeMesh” component to convert the rectangular grid to diagonal. I would like to select all the grid edges (in this case all the diagonal) except of the outer perimeter ones (parallel to X and Y coordinates).

I am still new to Grasshopper environment and would highly appreciate if someone can suggest a way of doing this.

All the best,

GridDiagonals_2021Sep24a.gh (20.0 KB)

This works with or without the Weaverbird’ components. Surface is internalized, no need for .3dm file.

1 Like

Use NGon DiagonalMesh is better


If your diagonalized mesh’s vertices were properly welded, you could use Mesh Edgesto get the interior edges(E2)which is what you want…

GridDiagonals_re.gh (8.3 KB)


Hi Joseph,

That is great. Thank you for the solution presented.

Hi Seghier,

Thank you for the reply. By far this solution works best for my case.

Hi HS_Kim,

Thank you for the unique methodology. It also works.

If you zoom in you can see why the edges appear to be naked.:

It seems to use slightly different vertices for the mesh creation. I would call this a bug. Maybe @DanielPiker knows(and cares :)) why this is happening.
Also Petras’ version seems to suffer from this but less(you can see by zooming in) So probably all this is also a tolerance issue.
Here my clumsy C# attempt(if someone cares):

File:20210925_DiagonalizeMesh.gh (8.2 KB)


Thanks for pointing this out,
Yes , this looks an easy fix. I’ll get the component updated.