This function generates 3 dimensional periodic noise.
The return value will be float, point, vector, normal or color 
depending on the cast, whose component(s) lie in the range [0,1].

This must be a varying point, vector or normal.
The default is the surface point, P.
This is the seed for the pnoise function.

This must be a point, vector or normal which lies on the 
integer lattice. (i.e. all components must be integers)
This is the period for the function. The default is point(1,1,1).

This function generates 3 dimensional periodic noise.
The return value will be float, point, vector, normal or color 
depending on the cast, whose component(s) lie in the range [0,1].