(Geometry Nodes) How to delete all faces that use vertices of selected edges

Question

I don't know the best way to communicate my issue so I've added an image with the issue highlighted.

My current tree uses split edges to create random islands, subdivides those islands (To control size of gap), and then deletes the outer edges of the islands.

It almost works the way I want, but only the faces using the selected edges are deleted, so when the islands have concave corners they leave a face there.

I've been trying for an hour to figure out a way to make it delete all the faces that use the vertices of the edge selection, but I can't find anything online that helps and I can't solve it myself.

Basically trying to replicate the results of if you had selected a bunch of edges in edit mode, swapped to vertex select and pressed delete, all the faces using those selected vertices would be deleted, I need that functionality with geo nodes.

I'm not sure if this is even possible to be honest, but if somebody could help me out that'd be great, thanks

Answer 1

(Using Blender 3.6.8)

One approach is to tag split edges before subdivision, then to delete all points along these edges after subdivision.

1. The user-defined named attribute "to delete" is attached to each Edge and it is initialized to False by the first Store Named Attribute node.
2. The second Store Named Attribute node is setting the attribute "to delete" to True for some edges matching the selection mask, based on a random selection.
3. The attribute "to delete" is transferred to refined edges by the Subdivide Mesh node.
4. The attribute "to delete" is interpolated from Edge to Point domain, as required by the Delete Geometry node set in Point domain. Be aware that Boolean data type attributes have special rules for interpolation. As a consequence, a point is deleted if at least one of the edges it is connected to has the attribute "to delete" set to True.

Resources: