How to define normal constraints on the inclined plane

Hello, in my model there is a constraint on a tilted plane (which is not parallel to the x,y,z coordinates) and I want to constrain its normal displacement, but i don’t know how to implemented. I noticed the ‘mpc’ maybe helpful to my question, but i can’t find the example about my question. Is there anyone can help me?

See for instance: Stokes flow with slip conditions — DOLFINx-MPC: An extension to DOLFINx for multi point constraints