[This is a mess. TODO: Turn it into a
def cyclic_noise function.]
This generates cyclic/repeating/perfect loop noise by low-pass filtering white noise in a cyclic way. Useful for "random" but looping animations, etc.:
This one loops in both space and time, for instance:
Simplex noise typically has a more trapezoidal value distribution:
which could be emulated by stretching the sample values.