Chaos Game

import pygame

from sys import exit
from random import randint
from math import sqrt

pygame.init()

size = 1200
WINDOW_SIZE = (size, size)
screen = pygame.display.set_mode(WINDOW_SIZE)

triangle = [
    (0, size),
    (size, size),
    (size/2, 0)
]

tracer_point = triangle[0]
visited_points = [tracer_point]

def get_midpoint(point1, point2):
    x = (point1[0] + point2[0]) / 2
    y = (point1[1] + point2[1]) / 2
    return (x, y)

def draw(display):
    display.fill('white')

    pygame.draw.line(display, 'black', triangle[0], triangle[1], 5)
    pygame.draw.line(display, 'black', triangle[1], triangle[2], 5)
    pygame.draw.line(display, 'black', triangle[2], triangle[0], 5)

    for point in visited_points:
        pygame.draw.circle(display, 'black', point, 4)

    pygame.display.update()

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            exit()

    num = randint(0, 2)
    tracer_point = get_midpoint(tracer_point, triangle[num])
    visited_points.append(tracer_point)

    draw(screen)