#https://www.shadertoy.com/view/ll2XDV

pixels = W:1024 H:1024

x = from -4.3 to 4.3 W
y = from -4.3 to 4.3  H

u = atan2(x, y)*0.5/PI
v = length2(x, y)*0.4

n = 3.0
y = v * n
fr = fract(y)
x = u * exp2(ceil(y + 2) * step(y, n+2) ) * PI
k = cos( x + PI/2* pow(fr, 1-fr) * sign(sin(x)))

k = pow(0.5-0.5*k, (0.5+1.5*fr) * 100/length2(u, v))

r = k
g = k
b = k
