How to set waits for object in pygame without freezing other objects

Question

Lets say I have class Truck. There are many instances of this class, on arrival to specific point instance should "unload" it's cargo - simply not move for N seconds, while other trucks should keep moving, unless they arrived to their unloading points.

I do the stop part by setting movement vector to (0,0) and then resetting it back to original.

But how to wait N seconds without freezing other cars? From what I've found so far I think I need to somehow apply pygame.time.set_timer, but it is really confusing for me.

It really depends on how your code is. Usually in pygame you have a sprite class with a update method that takes in the time between frames to update properly. If each Truck instance have a timer then you should be able to just use each instance timer to control how long it waits, without affecting other trucks. Maybe you should include your Truck class and how you update them currently? — Ted Klein Bergman, Oct 12 '17 at 15:18
You can also use `pygame.time.get_ticks` or the delta time that clock.tick returns (`dt = clock.tick(fps)`) to [implement a timer](https://stackoverflow.com/questions/30720665/countdown-timer-in-pygame). I'd like to see your code (an [mcve](https://stackoverflow.com/help/mcve)) as well, and please describe more precisely what you want to achieve. — skrx, Oct 12 '17 at 23:28
@skrx Actually, solved with `get_ticks()`. If you want - post your comment as answer, so I can accept it — wasd, Oct 17 '17 at 16:17

score 0 · Accepted Answer · answered Oct 18 '17 at 01:05

Something along these lines should work: Stop the truck when the target is reached (truck.vel = Vector2(0, 0)) and then set its waiting_time and start_time attributes (I just do it in the __init__ method here).

import pygame as pg
from pygame.math import Vector2


class Truck(pg.sprite.Sprite):

    def __init__(self, pos, waiting_time, *groups):
        super().__init__(*groups)
        self.image = pg.Surface((50, 30))
        self.image.fill(pg.Color('steelblue2'))
        self.rect = self.image.get_rect(center=pos)
        self.vel = Vector2(0, 0)
        self.pos = Vector2(pos)
        self.waiting_time = waiting_time  # In seconds.
        self.start_time = pg.time.get_ticks()

    def update(self):
        current_time = pg.time.get_ticks()
        # * 1000 to convert to milliseconds.
        if current_time - self.start_time >= self.waiting_time*1000:
            # If the time is up, start moving again.
            self.vel = Vector2(1, 0)

        self.pos += self.vel
        self.rect.center = self.pos


def main():
    screen = pg.display.set_mode((640, 480))
    clock = pg.time.Clock()
    all_sprites = pg.sprite.Group()
    truck = Truck((70, 70), 4, all_sprites)
    truck2 = Truck((70, 300), 2, all_sprites)

    done = False

    while not done:
        for event in pg.event.get():
            if event.type == pg.QUIT:
                done = True

        all_sprites.update()
        screen.fill((30, 30, 30))
        all_sprites.draw(screen)

        pg.display.flip()
        clock.tick(30)


if __name__ == '__main__':
    pg.init()
    main()
    pg.quit()

Here's the dt version:

import pygame as pg
from pygame.math import Vector2


class Truck(pg.sprite.Sprite):

    def __init__(self, pos, waiting_time, *groups):
        super().__init__(*groups)
        self.image = pg.Surface((50, 30))
        self.image.fill(pg.Color('steelblue2'))
        self.rect = self.image.get_rect(center=pos)
        self.vel = Vector2(0, 0)
        self.pos = Vector2(pos)
        self.waiting_time = waiting_time

    def update(self, dt):
        self.waiting_time -= dt
        if self.waiting_time <= 0:
            self.vel = Vector2(1, 0)

        self.pos += self.vel
        self.rect.center = self.pos


def main():
    screen = pg.display.set_mode((640, 480))
    clock = pg.time.Clock()
    all_sprites = pg.sprite.Group()
    truck = Truck((70, 70), 4, all_sprites)
    truck2 = Truck((70, 300), 2, all_sprites)

    done = False

    while not done:
        dt = clock.tick(30) / 1000

        for event in pg.event.get():
            if event.type == pg.QUIT:
                done = True

        all_sprites.update(dt)
        screen.fill((30, 30, 30))
        all_sprites.draw(screen)

        pg.display.flip()


if __name__ == '__main__':
    pg.init()
    main()
    pg.quit()

How to set waits for object in pygame without freezing other objects

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