I am using the new simulation nodes to have an object rotate randomly, when the object leaves the simulation node block: all it's materials are gone. I can't seem to find a way to reapply them. There are 2 differrent materials and I have tried using vertex groups to select only the correct faces, but that hasn't worked.

I'm verry new to geo/sim nodes so please bear with me.

the selection input is the material index, I have also tried it as a vertex group. A blender geo nodes tree

This is what it should look like: enter image description here

This is setting the jewel material enter image description here

but trying to add the metal before that stops it from working enter image description here

  • $\begingroup$ pls show at least your node tree so we see what you did ...or provide your blend file so we can check it out. thx $\endgroup$
    – Chris
    Aug 15, 2023 at 12:01

1 Answer 1


Issue #108410: Geometry Nodes: Support materials in simulation state.

Currently, the simulation state in geometry nodes cannot contain materials.

What you want to do, is to capture an integer attribute, and then - after the simulation - assign materials based on this attribute.

Here's an example:

How can I control the density or probability of an object based on material using geometry nodes?

Specifically the very end of my answer:

If I remember well, I Set Material to nothing, in order to have just one material index $0$ on "Geometry", and join the "Materials Collection" afterwards, to have 1-based indexing, because it was fitting my setup. Otherwise you could swap the join order, and resign from "Set Material" node.

  • $\begingroup$ Would it be possible to get a more detailed explanation, please? I have no idea how capturing an integer attribute translates into assigning materials where they belong. $\endgroup$
    – Macciavelo
    Dec 19, 2023 at 3:59
  • $\begingroup$ @Macciavelo see edit. $\endgroup$ Dec 19, 2023 at 9:29

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