Pygame Timers: set_timer() and get_ticks()

Games are full of things that happen on a schedule: an enemy every two seconds, a power-up that lasts five, a 30 second round. Pygame has two tools for this:

• pygame.time.set_timer(event, ms) posts an event every ms milliseconds. Good for repeating things.
• pygame.time.get_ticks() returns the milliseconds since pygame.init(). Compare two values for cooldowns and countdowns.

Repeating events: set_timer

import random
import pygame

pygame.init()
screen = pygame.display.set_mode((480, 320))
clock = pygame.time.Clock()

SPAWN = pygame.event.custom_type()
pygame.time.set_timer(SPAWN, 500)
stars = []
running = True

while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == SPAWN:
            stars.append([random.randint(10, 470), 0])

    for star in stars:
        star[1] += 3
    stars = [s for s in stars if s[1] < 330]

    screen.fill((10, 10, 30))
    for x, y in stars:
        pygame.draw.circle(screen, (255, 240, 150), (x, y), 4)
    pygame.display.flip()
    clock.tick(60)

pygame.quit()

A new star appears every half second. The timer keeps running until you stop it:

pygame.time.set_timer(SPAWN, 0)              # stop
pygame.time.set_timer(SPAWN, 2000, loops=1)  # fire once, in two seconds
pygame.time.set_timer(SPAWN, 250)            # restart faster (replaces the old timer)

Each event type has one timer; calling set_timer again with the same type replaces it. pygame.event.custom_type() gives you a new type for each timer, so a game can have one for spawning, one for the clock, one for flashing text.

Cooldowns with get_ticks

A cooldown stops the player from firing too fast. Remember when they last fired and only allow it again after enough milliseconds:

import pygame

pygame.init()
screen = pygame.display.set_mode((480, 320))
clock = pygame.time.Clock()

COOLDOWN = 400
last_shot = -COOLDOWN
bullets = []
running = True

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

    now = pygame.time.get_ticks()
    keys = pygame.key.get_pressed()
    if keys[pygame.K_SPACE] and now - last_shot >= COOLDOWN:
        bullets.append(pygame.Rect(236, 280, 8, 16))
        last_shot = now

    for b in bullets:
        b.y -= 8
    bullets = [b for b in bullets if b.bottom > 0]

    ready = now - last_shot >= COOLDOWN
    screen.fill((20, 22, 40))
    pygame.draw.rect(screen, (90, 220, 120) if ready else (120, 120, 140), (220, 296, 40, 16))
    for b in bullets:
        pygame.draw.rect(screen, (255, 200, 80), b)
    pygame.display.flip()
    clock.tick(60)

pygame.quit()

Press Play, click the game and hold Space: shots come out at most every 0.4 seconds, and the cannon turns gray while it reloads.

A countdown

Store when the round ends, and work out what is left each frame:

import pygame

pygame.init()
screen = pygame.display.set_mode((480, 240))
clock = pygame.time.Clock()
font = pygame.font.Font(None, 80)

end_time = pygame.time.get_ticks() + 10_000
running = True

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

    left_ms = max(0, end_time - pygame.time.get_ticks())
    seconds = (left_ms + 999) // 1000
    text = "Time's up!" if left_ms == 0 else f"{seconds}"

    screen.fill((40, 20, 30) if left_ms == 0 else (20, 30, 50))
    label = font.render(text, True, (255, 255, 255))
    screen.blit(label, label.get_rect(center=(240, 120)))
    pygame.display.flip()
    clock.tick(60)

pygame.quit()

(left_ms + 999) // 1000 rounds up, so the display shows 10 for the whole first second and reaches 0 only when the time is really up.

Do not sleep

time.sleep(1) or pygame.time.wait(1000) inside the loop pauses everything: no drawing, no input, and after a few seconds the window is reported as not responding. A game waits by checking the time each frame and doing nothing until it has passed. pygame.time.delay() and wait() are for small scripts, not game loops.