framerate independent movement breaking at higher fps?

Question

I am trying to understand framerate independence and wrote this test code: import pygame, sys, time

pygame.init()
screen = pygame.display.set_mode((1280,720))
clock = pygame.time.Clock()
framerate = 60

test_rect = pygame.Rect(0,340,40,40)
move_speed = 300

prev_time = time.time()

while True: 
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()

    screen.fill('white')
    
    dt = time.time() - prev_time
    prev_time = time.time()
    
    test_rect.x += move_speed * dt

    pygame.draw.rect(screen,'red',test_rect)
    pygame.display.flip()
    clock.tick(framerate)

This works but only until about a framerate of 120. Once the framerate goes higher the movement slows down or speeds up. At very high framerates (500+) it often stops as well.

I followed a few different youtube tutorials and they all limit the framerate to 60fps, which seems somewhat hacky. Is there a way to make this work at any framerate?

Answer 1

tick() already returns how many milliseconds have passed since the last call. So there is no need to use time:

clock = pygame.time.Clock()

while True: 
    dt = clock.tick(framerate) / 1000
    
    # [...]