Call It Many Times

Part of the Python in a Game Window section of Coddy's Pygame journey. Lesson 23 of 32.

Call a function in a loop and it draws a pattern. The loop works out the arguments, the function does the drawing:

for i in range(8):
    draw_star(60 + i * 70, 60 + i * 45)

Each pass is 70 pixels right of the last and 45 pixels lower, so the stars run in a line from (60, 60) to (550, 375). Change 70 or 45 and every star follows.

This is why functions are worth writing. The lines that draw a star exist once. To change how every star looks, longer rays or another colour, you change the function's body, and every call draws the new star.

Name a function after what it does, often with a verb: draw_star, move_comet, reset_game. Then a line that calls it reads like a sentence.

Challenge

Easy

Draw a line of stars: replace the single call with for i in range(8): calling draw_star(60 + i * 70, 60 + i * 45). The 8 stars run from (60, 60) to (550, 375).

Try it yourself

import pygame

pygame.init()
screen = pygame.display.set_mode((640, 480))
pygame.display.set_caption("Night Sky")
clock = pygame.time.Clock()

# Set things up here, before the game loop.
def draw_star(x, y):
    pygame.draw.line(screen, (255, 240, 200), (x - 10, y), (x + 10, y), 2)
    pygame.draw.line(screen, (255, 240, 200), (x, y - 10), (x, y + 10), 2)
    pygame.draw.circle(screen, (255, 240, 200), (x, y), 4)

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

    # Change things here, once a frame.

    screen.fill((20, 24, 48))
    # Draw here, after the fill.
    draw_star(60, 60)

    pygame.display.flip()
    clock.tick(60)

pygame.quit()