#https://www.shadertoy.com/view/Md3GzM

pixels = W:1024 H:1024

x = from -12 to 12 W
y = from -12 to 12 H

d = length2(x, y)
a = atan2(y, x)

x = a/2/PI
y = d + x
x = ceil(y) - x
x = x*x*8

k = length2(fract(x) - 0.5, fract(y) - 0.5)

r = 1 - smoothstep(0.4, 0.5, k)
g = r
b = r
