Matthias Moulin matt77hias

Integer Hash Function

Thomas Wang, Jan 1997

last update Mar 2007

	"""Perlin noise implementation."""
	# Licensed under ISC
	from itertools import product
	import math
	import random


	def smoothstep(t):
	"""Smooth curve with a zero derivative at 0 and 1, making it useful for
	interpolating.

	ZigZag-Encoding
	---------------

	Maps negative values to positive values while going back and
	forth (0 = 0, -1 = 1, 1 = 2, -2 = 3, 2 = 4, -3 = 5, 3 = 6 ...)

	(i >> bitlength-1) ^ (i << 1)

	with "i" being the number to be encoded, "^" being
	XOR-operation and ">>" would be arithemtic shifting-operation

	# Simulator for depth comparison error (i.e. z-fighting)
	# Nathan Reed, June 2015
	# Written for Python 3.4; requires numpy

	import math
	import numpy as np
	import optparse

	# Parse command-line options
	parser = optparse.OptionParser()