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?
It's possible and really really easy to do. You just need two nodes to make it happen
(I am using blender 2.93)
P.s. For it to work, U have to select the target faces(editmode)-> right click-> shade smooth them
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.
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.