knight path fill

#!/usr/bin/env python3

# was just curious how the patterns will appear

import ctypes
ctypes.windll.user32.SetProcessDPIAware()
import cv2
import numpy as np

def step(canvas, x, y, iter):
    h, w, _ = canvas.shape
    if x < 0 or y < 0 or x >= w or y >= h or iter < 0:
        return
    canvas[y][x] *= 0
    for i in range(8):
        di = int(i/1%2)
        xs = int((int(i/2%2))*2 - 1)
        ys = int((int(i/4%2))*2 - 1)
        step(canvas, x+int(1+di)*xs, y+int(2-di)*ys, iter-1)

canvas = np.ones((100, 100, 3))
for i in range(5):
    step(canvas, 50, 50, i)
    canvas2 = cv2.resize(canvas, dsize=(0, 0), fx=4, fy=4, interpolation=cv2.INTER_NEAREST)
    cv2.imshow('image', canvas2)
    cv2.waitKey(1000)