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

pixels = W:1024 H:1024

x = from -1 to 1 W
y = from -1 to 1 H

t = 5.25
a = atan2(y, x)
d = length2(x, y)

x = fract(a/2/PI)
y = d

k = step(0.5, fract(exp2(ceil(y * 5)) * x + t))
k = if(y < 1, k, 0)

r = k
g = k
b = k
