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Blender 3.3, still new to Geo nodes. I'm trying to replace some of my array modifier workflows and I've gone down a wrong path here. The idea is to have a an instance scattered across faces, and then to have a duplicate of the arrangement translated along the face normals, but flipped.

Imagine two nested rainbow shapes with little pyramids scattered along them. On the upper arch, the pyramids point up, and on the lower arch, the pyramids point down. In other words, the pyramid shapes would be mirrored about the gap between the two arches.

In this image, I've gotten the pair of scattered pyramids translated along the normals, but I've run into a lack of knowledge with getting the rotation working. Pyramids scattered along faces

The geometry node setup I'm using so far is shown below. Distribute Points on faces and create a new Join geometry using the points and a copy of the points that is passed through a Set Position node scaling the normal vector as an offset.

The reason I haven't got mirrored pyramids is clear: I've plugged the rotation from the Distribute node straight into the rotation of the Instance on Paths node.

What I was hoping to do: Split out two sets of points, translate and flip one of them, join the sets back into one Geometry, and place instances on the points using the joined geometry's rotation to drive the Instance on Paths node.

I worry I'm down a wrong path because I cannot find a way to flip the normals for the point geometry and I do not see a way to get the "Rotation" out of my joined geometry.

Are there ways to do this? Is there an alternate method? (I could certainly set up my initial pyramid as 2 pyramids within the same object, but I'm searching for a way within nodes.

My starter file: https://www.dropbox.com/s/39xkyvsabhkj9ir/Geo%20node%20bilayer.blend?dl=0

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  • $\begingroup$ Would you mind sharing your .blend file (upload to DropBox or similar and share a link)? I think I understand what you're asking and I think I've been working on something similar recently. I may be able to help (no promises!) $\endgroup$
    – SlickRed
    Sep 21, 2022 at 22:42
  • $\begingroup$ @SlickRed: Good idea, done! I've updated the OP with a link to the blend file used to try to set this all up. $\endgroup$
    – Journeyman
    Sep 22, 2022 at 15:37

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It looks as if you want instances scattered on, and oriented to a surface. The instances duplicated and reflected in their local Z, and then offset in that direction.

If you want the surface doubled up too, then its geometry would be duplicated and offset along its normal.

This is one way, with the surface as the input:

enter image description here

With this sort of result:

enter image description here

enter image description here

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  • $\begingroup$ Took me a few but I see it--Scaling instance -1 on the local space, rather than the skullduggery of trying to get the points to flip pre-instance; that's wonderful! Does exactly what I am looking for, and in the hoped-for way (only needing to plug the instance in once, only needing one scatter). $\endgroup$
    – Journeyman
    Sep 22, 2022 at 20:19
  • $\begingroup$ @Journeyman Great! Glad I interpreted your question OK $\endgroup$
    – Robin Betts ♦
    Sep 22, 2022 at 22:01

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