pixels = W:512 H:512

x = from -8 to 8 W
z = from -8 to 8 H

fx = floor(x)
gx = x - fx
fz = floor(z)
gz = z - fz

a = xor_hash2(x, z)
b = xor_hash2(x + 1, z)
c = xor_hash2(x, z + 1)
d = xor_hash2(x + 1, z + 1)

m = xcurve_interpolate(a, b, gx)
n = xcurve_interpolate(c, d, gx)

a = 1
r = xcurve_interpolate(m, n, gz)
g = r
b = r
