Dissolve edges in geometry nodes

In geonodes I have created a grid and from that I have randomly selected some neighbouring faces. I want to effectively dissolve the edges in these selections - so that these are a single face. I have done a lot of searches and on here and on the wider world web and the only solution that comes up is (https://blender.stackexchange.com/questions/270982/how-to-dissolve-faces-using-geo-nodes) beyond me (and a couple of years old… and I couldn’t make it work when I downloaded the file - ie, it seemed to work with a vertex group but when using different ways of selecting it messed up. My limited understanding of geonodes (other than for scattering) not helping at all). I wondered whether there have been some advances in geonodes since then or any other solution comes to mind for geonode experts out there (I am certainly not one of those).

The intention is to re-join these ‘larger’ joined faces back into the grid, so when I extrude them later there is some randomness to the size of some of the blocks.

Any help would be appreciated. I hope its something blindingly obvious that I’ve overlooked! Also, if there is some information missing that I should have provided, then please let me know.

Many thanks.


Dissolve grid edges - Geometry Nodes - 4.4 - 2024-12-07.blend (142.9 KB)
You can split the geometry (based on your selections) to instances, then convert the boundary of each selection to a curve, and then fill the curve with an N-gon.

This is pretty delicate, though - it should work in your case, as you’re working with a grid (in the XZ plane? Rotate to the XY plane and then rotate back.) But with non-planar geometry, this can get more complicated.

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Many thanks - that works a treat! Very much appreciated.
Cheers
Laz

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