Start, Stop and Step

Part of the Python in a Game Window section of Coddy's Pygame journey. Lesson 16 of 32.

range takes up to three numbers: range(start, stop, step).

range(5): 0, 1, 2, 3, 4
range(2, 6): 2, 3, 4, 5
range(60, 200, 40): 60, 100, 140, 180

It starts at the start, adds the step each time, and stops before it reaches the stop. The stop value itself is never in the range.

With a start and a step, the loop variable can be the position itself, with no sum needed:

for x in range(60, 600, 40):
    pygame.draw.circle(screen, (255, 160, 60), (x, 420), 8)

To end a row at 580, the stop must be past it: range(60, 580, 40) ends at 540. A step can be negative to count down: range(10, 0, -2) is 10, 8, 6, 4, 2.

Challenge

Easy

Under the stars, draw a row of lanterns with one for loop:

Orange (255, 160, 60) circles of radius 8 at y 420.
x from 60 to 580, every 40 pixels: 14 lanterns.
Use range with a start, a stop and a step, and replace the single lantern.

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.

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.
    for i in range(8):
        pygame.draw.circle(screen, (255, 255, 255), (40 + i * 80, 80), 5)
    pygame.draw.circle(screen, (255, 160, 60), (60, 420), 8)

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

pygame.quit()