Access to geometry data

This offer:
https://developer.blender.org/D15117
is the beginning of the implementation of this feature request:

Now that we have the first working prototype, there is a design challenge.

The purpose of this topic:
Suggestions, designs, use cases
You can also use these Build path or Node Groups version for experiments (but they don’t have Face corner)

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In the course of experiments, I realized that this node should be implemented as an attribute transfer node, and not just as an attribute by index

Also, for experiments, I requested a build

After the creation of the first prototype, plans changed. At the moment they look like this:

Mesh.Face[Index].Loop[Number] // Face Corner

Mesh.Loop[Index].V // First - simple
Mesh.Loop[Index].SortedV
// In loops of single face vertices can repeat, need sorting by loops edges
Mesh.Loop[Index].E

Mesh.Edge[Index].Connection_Faces[Number]
Mesh.Edge[Index].Connection_Edges[Left/Right] [Number]
Mesh.Edge[Index].Connection_Points[Left/Right] [Number]

Mesh.Point[Index].Connection_Faces[Number]
Mesh.Point[Index].Connection_Edges[Number]
Mesh.Point[Index].Connection_Points[Number]

The essence of the difference is that now there is a receipt of the loop number, and data on the connection of the polygon is already obtained from it.
Since this may be redundant, a design problem has arisen.
Without it, this possibility will be ignored.

Usage example:
You want to connect 2 boards with a hinge.
You can create these boards on polygons.
Now you want a hinge.
You create it on the edges, and rotate it to the polygon
And in order to know the polygon, this node is needed.

Or another example: You create an effect like this:


You want to know about each vertex its neighbors.
You can convert this to a curve and do index +/-
But it’s long and redundant in some cases.
And with a node, you can know the indices of the neighbors for the vertex.


A fresh example of using these vertices.
In this example, I’ve used a new version of the node where you can enter a data source.
This is a generator of fasteners at the corners of polygons

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Some examples of the new design:
Neighbor polygon data for a polygon

And neighboring polygons for the edge

I think the last example is the most understandable in a practical sense.

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