add WallParticles with a boolean mask

Hi all,
I am simulating the particle moving inside a lattice domain definited with a boolean mask (as in the permeability example with variable “geometry”).

Now, I would add WallParticles in the cells definited by the boolean mask, but I don’t understand how. I saw the function “addWallParticles”, that operates on a TriangleBoundary3D.

How can I do it?

Thanks in advance