I have a character where the hair particles of the back of the head penetrate the head surface and can be seen from the mouth. The picture shows a very simplified model of my issue.
I would like to keep the part of the hair that exists out of the head and delete the rest of it or at least delete the part that appears when you look inside the mouth (if it's open).
I tried the Boolean modifier but they don't work (I think because the head is a plan and has no volume). What else can I try?