Hey Laffytaffy.

Note that if you have a plane in teorms of n . (r - r0) where n is the plane normal, r is a general point on the plane and r0 is a specific point, then you can expand this to get ax + by + cz + d = 0.

Re-arranging this gives you the function z = 1/c*[-ax - by - d] = f(x,y)