How do I continuously trigger an action at certain time intervals? Enemy shoots constant beam instead of bullets in pygame

Question

Trying to make an enemy in pygame that shoots bullets in a straight line in pygame. I\'ve managed to make the enemy shoot, but it shoots a constant beam of bullets instead o

Answer 1

I recommend to use a timer event. Use pygame.time.set_timer() to repeatedly create an USEREVENT. e.g.:

milliseconds_delay = 500 # 0.5 seconds
bullet_event = pygame.USEREVENT + 1
pygame.time.set_timer(bullet_event, milliseconds_delay)

Note, in pygame customer events can be defined. Each event needs a unique id. The ids for the user events have to start at pygame.USEREVENT. In this case pygame.USEREVENT+1 is the event id for the timer event, which spawns the bullets.

Create a new bullet when the event occurs in the event loop:

running = True
while running:

    clock.tick(FPS)

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

         elif event.type == bullet_event:
             if boss.rect.y >= 30:
                 boss.shoot()

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is there any way to make it so the enemy pauses for a while after..let's say 5 shots, then starts shooting again after the pause

The timer event can be stopped by passing 0 to the time parameter. e.g.:

delay_time = 500  # 0.5 seconds
pause_time = 3000 # 3 seconds
bullet_event = pygame.USEREVENT + 1
pygame.time.set_timer(bullet_event, delay_time)

no_shots = 0

running = True
while running:

    clock.tick(FPS)

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

         elif event.type == bullet_event:
             if boss.rect.y >= 30:
                 boss.shoot()

                 # change the timer event time
                 if no_shots == 0:
                     pygame.time.set_timer(bullet_event, delay_time)
                 no_shots += 1
                 if no_shots == 5:
                     pygame.time.set_timer(bullet_event, pause_time)
                     no_shots = 0

    killed = # [...] set state when killed

    # stop timer
    if killed:
        pygame.time.set_timer(bullet_event, 0)