Pygame clock tick stuttering

Question

This is an issue that has been bugging me for a few weeks now. Whenever I have a pygame clock variable, so for example: clock = pygame.time.clock and I limit the fps using: clock.tick(fps) the game will occasionally stutter. I have a simple example below - a window with a cube that moves from side to side.

import pygame

screen = pygame.display.set_mode((0, 0), pygame.FULLSCREEN)
width, height = screen.get_size()

rect = pygame.Rect(0, height // 2 - 50, 100, 100)

delta_x = 5

clock = pygame.time.Clock()

running = True
while running:
    event = pygame.event.poll()
    if event.type == pygame.QUIT:
        running = False

    screen.fill((0, 0, 0))

    if rect.left < 0 or rect.right > width:
        delta_x *= -1

    pygame.draw.rect(screen, (255, 255, 255), rect)
    rect.x += delta_x

    pygame.display.flip()

    clock.tick(60)

Video: https://www.youtube.com/watch?v=6spFoKIqVQY&ab_channel=NotAHackusator
Does anyone know how to fix this? Thanks in advance.

The problem is with your system, not your code. Try to use [`tick_busy_loop()`](https://www.pygame.org/docs/ref/time.html#pygame.time.Clock.tick_busy_loop) instead of [`tick`](https://www.pygame.org/docs/ref/time.html#pygame.time.Clock.tick). — Rabbid76, Dec 04 '21 at 09:23
@Rabbid76 I tried using `tick_busy_loop()` but it's now stuttering even more. — NotAHackusator, Dec 04 '21 at 09:27
There's nothing in your code that you can change to fix the problem. Pygame is for educational purposes only, you have to accept it as it is. — Rabbid76, Dec 04 '21 at 09:38
`tick(60)` means to run not more then 60 FPS but it can run less FPS - and it retuns milliseconds between frames (sometimes called `delta time`) which you may try to use to create smoother move but it may not work in Python. It may also make other problem - it may need to keep position as floats and convert to integers only when you display. — furas, Dec 04 '21 at 10:32

score 0 · Accepted Answer · answered Dec 04 '21 at 10:37

0

Setting clock.tick to 144 from 60 makes the stutter go away from my end. I'm not not sure if you want it to be limited to 60 and why though.

answered Dec 04 '21 at 10:37

3eeaaa

49
3

score 0 · Answer 2 · answered Mar 25 '22 at 19:40

There actually is something that might help to improve performance (because the stuttering seams to come because of unstable performance. At least in my case it helped to disconnect displaying and computation meaning you cap the FPS using a custom FPS limiter.

Example:

# In your game-loop:
cur_ticks = pygame.time.get_ticks()
if cur_ticks - last_ticks > 1000//60:  # your framerate, also known as FPS, here 60
            # your draw code and display.update goes here
            last_ticks = pygame.time.get_ticks()
clock.tick(60)  # number of computation steps per second, should be greater equal to FPS-value

You need to initialze last_ticks before your game-loop to zero or to the current value of pygame.time.get_ticks().

For my game this improved the FPS from 40 to 50 FPS compared to the usual approach.

It might also help to increase the clock.tick-value to something higher like 120. This way the FPS is still limited to 60, but allows more computation steps. In my case this helped to improve the number of computation steps/second to over 60 also meaning 60 FPS (for displaying). To keep the speed of game-objects "constant" then requires you to change their speeds based on the current FPS-value. The reason why this helps seams to be that tick is very "heavy".

Pygame clock tick stuttering

2 Answers2