cardioid.py

from numpy import pi, sin, cos
import pygame
from time import sleep


# colors
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)

pygame.init()
canvas = pygame.display.set_mode((800, 800))
canvas.fill(BLACK)
pygame.display.set_caption("trygonometry test")
exit = False

center = x, y = [400, 400]
iterations = 360
radius = 400

points = []



for j in range(iterations):
    step_x = sin(2*pi/iterations * j) * radius + x
    step_y = cos(2*pi/iterations * j) * radius + y
    points.append([step_x, step_y])

i = 0

step = 2

while not exit:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            exit = True
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_r:
                canvas.fill(BLACK)
                step=3
            if event.unicode == "+":
                canvas.fill(BLACK)
                step += 1
            if event.unicode == "-":
                canvas.fill(BLACK)
                step -= 1

    pygame.draw.circle(canvas, WHITE, center, radius, 1)

    pygame.draw.line(canvas, BLUE, points[i], points[i*step % iterations])

    for j, point in enumerate(points):
        pygame.draw.circle(canvas, GREEN, point, 2)
    #     pygame.draw.line(canvas, BLUE, point, points[j*6 % iterations])

    i += 1
    i = 0 if i == iterations else i
    pygame.display.update()