How to get and set face set values?

Coding Python Support
1

I’d like to write a script that can iterate over the a mesh that has had face set values set on it and be able to read and update the face set values. Is there a way to do this?

2

To get polygons, you can use bpy.types.Mesh.polygons.

import bpy
o = bpy.data.objects["Cube"]

# Get Polygons
for p in o.data.polygons:
    print("Vertex:" + str(p))

If you’re hoping to transform some polygons in edit-mode, you’re going to need to use the BMesh module as well in order for changes to be reflected in real-time. I made a demo of the module recently here.

3

It’s really hard to find API documentation about face sets because the keywords are so common but the information doesn’t seem to be stored in the mesh polygons.

https://docs.blender.org/api/current/bpy.types.MeshPolygon.html

It might be that the information is not available to the python API at all, only to the underlying C code. All I could find were operators, not direct data access.

4

Looks like this is still in development: https://devtalk.blender.org/t/accessing-face-sets-with-python/25685