When converting mesh to grease pencil, different face materials should
also be converted to grease pencil ones. This now works by converting
viewport display color diffuse_color from the mesh material to grease
pencil material fill color. Notes:
- If there are empty material slots in the mesh, faces assgined to these
material slots will be assgined to a new fallback white material in
the converted grease pencil fills.
- If original mesh does not have any material slots, a white material
will be created in the grease pencil object for the fills.
- If original mesh has multiple material slots of the same material,
they would be reduced to one material slot in the converted fills.
Pull Request: https://projects.blender.org/blender/blender/pulls/133087
43492a8278