Timers in Games

I've been trying to figure out the best way to set up timers in games.   Timers are used all the time, for example, the firing rate of a gun, the delay in a joystick button press to check to see how many times the button was pressed, or the speed of an animation.

The overall speed of the game is controlled by a clock that is usually used to control the frame rate.  For  example,

clock = pygame.time.Clock()
framerate = 60

 In the main game loop, the clock is ticked.

clock.tick(framerate)

 To control time for individual objects, I usually use the standard python time module.

## using the standard python time library, not a pygame module.  

start_time = time.time()
## some action
elapsed_time = time.time() - start_time

## 10 millisecond delay
if elapsed_time > 10:
     ## do the action we've been waiting for.
 

I notice that many people using the pygame.time module in their games.  I've tried to figure out the advantage of this and I can't understand it out.  The people using this module are usually better programmers than I am.

## using the pygame.time module, not the standard python time library.
current_time = pygame.time.get_ticks()
## example 10 millsecond delayif next_update_time < current_time:    # do stuff    next_update_time = current_time + 10

Finally, I notice that other people are using the main game clock, the one that is usually set to 50 fps or 60 fps.  Here's a code snippet that blits the image once every 10 frames.  If the game is running at 60 frames a second, the image is blitted 6 times a second, effectively setting up a delay of over 100 ms.


class walker:
    def __init__(self):
        self.ani_speed_init = 10
        self.ani_speed = self.ani_speed_init
        self.ani = glob.glob("walk/walk*.png")
        self.ani.sort()
        self.ani_pos = 0
        self.ani_max = len(self.ani) - 1
        self.img = pygame.image.load(self.ani[0])
        self.direction = "right"
        self.movement = False
        self.update(0)
        
    def update(self, pos):
        self.ani_speed -= 1
        self.x += pos
        if self.ani_speed == 0:
            self.img = pygame.image.load(self.ani[self.ani_pos])
            self.ani_speed = self.ani_speed_init
            if self.ani_pos == self.ani_max:
                self.ani_pos = 0
            elif self.movement:
                self.ani_pos += 1
        if self.direction == "right":
            windowSurface.blit(self.img, (self.x, self.y))

Random Triggers for Falling Objects

I spent an hour tonight working with

time.time()

from the time module to create a timer for the game.  I'm using the elapsed time and a random number as the trigger to get the fish to drop a bomb.

The random number is generated with

random.randint(1, 8)


This was a bit more involved than I had anticipated.  I got the clock to work by creating a clock object and a gameClock function.  I then passed the clock object to the gameClock for updating.  The program is getting increasingly difficult to manage.  However, the playability is getting better.

In the original version, I used a random number that I stored in bomb.trigger and the bomb.rect.centerx value.  The end result is the same so far.  However, it's easier to change the frequency of the bomb drops using time.  I can simply shorten the time delay to cause the bombs to drop more frequently.