slicing 3D surface via z-plane

Hi all,

Given 3D surface (x,y,z points) with origin point p (xp,yp,zp), I wish to slice the 3D surface vertically align to z-axis via origin point p. In other words, I wish to slice 3D surface using z-plane such that simply rotate the slice angle (e.g. 60 deg interval, Imagine slicing a pizza), resulting an intersection of the surface and z-plane. Thanks for any help

Regards, Bhuvendhraa