Hilbert curve

hilbert.py

#!/usr/bin/env python3

import argparse
from turtle import *


def hilbert_curve(step, parity, n):
    if n < 1:
        return

    angle = parity * 90
    parity_neg = -parity
    n_1 = n - 1

    left(angle)
    hilbert_curve(step, parity_neg, n_1)

    forward(step)
    update()
    right(angle)
    hilbert_curve(step, parity, n_1)
    
    forward(step)
    update()
    hilbert_curve(step, parity, n_1)
    
    right(angle)
    forward(step)
    update()
    hilbert_curve(step, parity_neg, n_1)
    
    left(angle)


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument(
            '--step',
            '-s',
            type=int,
            default=8,
            help='Step size',
    )
    parser.add_argument(
            '--parity',
            '-p',
            type=float,
            default=1,
            help='Parity',
    )
    parser.add_argument(
            '-n',
            type=int,
            default=4,
            help='N',
    )
    args = parser.parse_args()
    step = args.step
    parity = args.parity
    n = args.n

    tracer(0, 0)

    bgcolor('black')
    hideturtle()
    title('Hilbert curve')
    speed('fastest')
    pencolor('green')
    width(2)

    penup()
    goto(
            step * 2 - window_width() / 2,
            step * 3 - window_height() / 2,
    )
    pendown()

    hilbert_curve(step, parity, n)

    exitonclick()