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Let's say I create object primitive plane and I create a vertex group. I add one vertex of the plane into the group but leave the other 3.

Is it then possible to transform that one vertex in the group using geometry nodes?

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2 Answers 2

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It's possible and really really easy to do. You just need two nodes to make it happen

Demonstration:

enter image description here

Node Setup: enter image description here Note that test is the name of the vertex group. Also the vertex group should have weight of 1

(I am using blender 2.93)

To change material_index follow this node group: enter image description here

Demonstration: enter image description here

P.s. For it to work, U have to select the target faces(editmode)-> right click-> shade smooth them

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  • $\begingroup$ As a follow up question, would it be possible to change the material index instead of the position? $\endgroup$
    – Dalibor-P
    Commented Apr 19, 2021 at 12:03
  • $\begingroup$ !My attempt uses a vertex group (r) and checks if it's weight is 0 and puts the result into a custom c attribute. The c attribute is created as boolean within vertex domain, so I convert it to d attribute that's in the face domain and is an integer. Then I'm trying to add/subtract the d attribute to/from the material index, but the material index doesn't change. $\endgroup$
    – Dalibor-P
    Commented Apr 19, 2021 at 16:14
  • $\begingroup$ Hey, turns out I was being an idiot. You can change material_index. I have edited my answer please read it.......The key is to instead of putting material_index as result of attribute math, u have to keep a different attribute and later convert that attribute as an integer to material_index $\endgroup$ Commented Apr 20, 2021 at 11:15
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A Blender 3.0+ solution

As of Blender 3.0 the Attribute Vector Math node is legacy. And there is now a much simpler way to transform vertices by group.

The Set Position node has a Selection input socket, so you can connect that to the Group Input node to access your vertex group.

Moving the vertices of a specific node group using the Set Position node and its Selection and Offset sockets

Then in the Geometry Nodes modifier, click the icon resembling a Swedish flag and the input field will change from a boolean value of 1 to a clickable area where your vert groups will show up in a drop-down menu.

You can control the placement of vertices by Position or Offset (or both) from the modifier settings by connecting those sockets to the Group Input node too.

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    $\begingroup$ Thank you for updating the answer for the fields workflow ! It shows how more straightforward this kind of operations is now compared to the first iteration. $\endgroup$
    – Gorgious
    Commented Feb 22, 2022 at 12:24

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