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

pixels = W:1000 H:600

x = from (0) to (400) W
y = from (0) to (240) H

thickness = 3.0
width = 50.0
height = 30.0
diamondSize = 15.0

fx = mod(x, width)
fy = mod(y, height)
fax = min(fx, width - fx)
fay = min(fy, height - fy)

r = (fax + fay < diamondSize)
g = (fax + fay < diamondSize - thickness)
b = (fax < thickness / 2.0) + (fay < thickness / 2.0)


