Generates bitmap of a spiral

spiral.py

import math

from PIL import Image


def spiral(r=20):
    im = Image.new("RGB", (r * 2, r * 2), (255, 255, 255))
    inc = 10
    inside = True
    angle = 0
    rad = 0

    while inside:
        angle += math.radians(inc)
        rad += 0.005
        x = int(r + rad * math.cos(math.radians(angle)))
        y = int(r + rad * math.sin(math.radians(angle)))

        inside = r * 2 > x >= 0 and r * 2 > y >= 0
        for direction in [(0, 0), (0, 1), (1, 0), (1, 1)]:
            xn = x + direction[0]
            yn = y + direction[1]
            inside2 = r * 2 > xn >= 0 and r * 2 > yn >= 0
            if inside2:
                rc = round((255 / (r * 2)) * x)
                gc = round((255 / (r * 2)) * y)
                bc = abs(255 - rc - gc)
                im.putpixel((xn, yn), (rc, gc, bc))

    im.save("spiral_" + str(r) + ".png")


spiral(500)