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I would like to create a general control mechanism for a vertex group. enter image description here As the image shows, I would like to be able to move vertices (they belong to a vertex group) with some control mechanism (a ColorRamp or another Mesh Line) and blend the movement between the control instances. Preferably the movement should be based on the normal of the corresponding front face or if that is too complicated than at least in separate X and Y directions. First I thought of a ColorRamp as the control instance (with external min/max values to limit the amount of movement) and somehow drive with that the position of the vertices with smooth blending for the in between vertices. I guess this is very complicated so for a start a simple line mesh with a couple of vertices as control points would also do the job. I find GN very complicated and have actually more and more problems to grasp it from Blender release to release. (Especially if the task is more than just simple scattering). I'm using Blender 3.2. If someone has the time, could you give me small examples for:

  • how do I reference Vertex Groups?
  • how can I distribute the movement of lets say 4 control points of the mesh line to lets say 100 vertices of the group and blend in between them smoothly? (A ColorRamp would give the option for different blending methods.)
  • how (and if) can I move the vertex in the direction the corresponding front surface is pointing? (The front surfaces can also be in a separate vertex group. They would have the same # as the "spikes)

Is this at all doable with geometry nodes?

Thanks for any suggestions.

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You may do something like this:

enter image description here

how do I reference Vertex Groups?

Use Named attribute node.

how (and if) can I move the vertex in the direction the corresponding front surface is pointing? (The front surfaces can also be in a separate vertex group. They would have the same # as the "spikes)

You can use Normal input node.

how can I distribute the movement of lets say 4 control points of the mesh line to lets say 100 vertices of the group and blend in between them smoothly? (A ColorRamp would give the option for different blending methods.)

In my example, I've got the polar coordinate using arctan2 (math node). These returns coordinate from -pi to pi (-180 to 180 deg) so I've mapped them to 0-1 interval before curves.

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  • $\begingroup$ Fantastic, thank you! It is much simpler as I thought. I tested it and it works but I still don't understand the "normal" part. How can I restrict the movement of the vertex to the normal direction of the corresponding front faces? The Normal Input takes the normal of the actual vertex (which I move) or am I wrong? In my example the setup works as the normal of the vertex is the same as the normal of the front face. My actual object is more complex so the normal is different than the front face. Can I somehow reference the normal of a second Named Attribute (with the front faces Vertex Group)? $\endgroup$
    – Steve
    Jun 25, 2022 at 17:29
  • $\begingroup$ Vertex group are "vertex", not "faces" group :-) how it supposed to detect face that's corresponded to vertex? $\endgroup$
    – Crantisz
    Jun 25, 2022 at 17:35
  • $\begingroup$ How true... silly me. =)) $\endgroup$
    – Steve
    Jun 25, 2022 at 18:15

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