How Can I Spawn Multiple Game Objects Concurrently in Pygame?

Spawning Multiple Instances of the Same Object Concurrently in Python

In your game's code, you intended to create circles at random locations, expecting each circle to appear independently. However, the subsequent circles were overriding the previous ones. This behavior stems from the inherent nature of event-based applications like games.

Understanding Event-Based Applications

In pygame, the game loop continuously monitors for events (such as mouse clicks) and responds accordingly. However, time.sleep() and related functions do not truly wait or control the gameplay timing. Instead, they freeze the application while they are executed. Thus, your circles weren't appearing concurrently but rather one at a time, with sleep() freezing the program in between.

Correcting the Approach

To spawn multiple objects concurrently, two primary approaches can be taken:

1. Using Time Measurements

• Create a list to store the objects.
• Regularly check the elapsed time using pygame.time.get_ticks().
• Spawn a new object when the time interval since the last one exceeds a set duration.

2. Using Timer Events

• pygame.time.set_timer() creates a custom event that occurs at a specified time interval.
• When this event occurs, a new object is created.

Minimal Code Example Using Time Measurements

object_list = []
time_interval = 500  # milliseconds between object spawns
next_object_time = 0 

while run:
    current_time = pygame.time.get_ticks()
    if current_time > next_object_time:
        next_object_time += time_interval
        object_list.append(Object())

Minimal Code Example Using Timer Events

object_list = []
time_interval = 500  # milliseconds between object spawns
timer_event = pygame.USEREVENT+1
pygame.time.set_timer(timer_event, time_interval)

while run:
    for event in pygame.event.get():
        if event.type == timer_event:
            object_list.append(Object())

Additional Considerations

• Objects must be added to a list to track and draw them in each frame.
• Objects can be removed from the list if they exceed a certain size or age.
• Use a clock object to ensure a consistent frame rate.

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