Purge unused materials

Hi, Thomas!
Please tell me how you do it so that when you run the command “Purge unused materials”, those that are used for proxy objects remain in the scene?
After all, some materials, such as those involved in 2-sided materials, are immediately discarded because they are not actually assigned to objects in the scene…
Is there any way, to which I have not thought of or still have to appoint them? In the preset skatter you have this problem dealt with.

You should avoid SketchUp’s “Purge unused materials” command, and use the one in V-Ray’s asset editor.

The way I do it with Skatter’s library assets, is that every material is assigned to at least an edge in the proxy geometry. These components are then added to the model’s origin, hidden and locked. This way, both the components and the materials applied to them are not purged.

If you show the hidden geometry, you will see the components at the origin after you have loaded them from the library.

Thank you very much for the explanation! I was close)