Hi Mr_L,
that was a problem in the last version actually,did some tests yesterday after
reading your post and in TG2.2 everything was working like it should (with a
non UV object).
A work around i had success with in 21181 was to use surface layers with a
PF as mask (1 PF per layer) before or after the parts shader,iirc.
Hope you'll find a solution,good luck!