Slowdown a pygame function without slowing the whole game

Question

I'm trying to make my first game in pygame.

I want the game to have this animation in the background

I'm using python 3.9.2

import pygame, math, random, sys
from pygame.locals import *

screen = pygame.display.set_mode((400, 400))
fps = 60

pygame.init()
mainClock = pygame.time.Clock()

# Colors 
black = (0, 0, 0)
white = (255, 255, 255)

# Function for close the game ------------------------------------------------------------------------------------------------------------

def close_game():
    pygame.quit()
    sys.exit()

# Functions for drawing ------------------------------------------------------------------------------------------------------------------

def background():
    screen.fill(black)

def canvas():
    margin = pygame.draw.rect(screen, white, (50, 50, 300, 300), 1)

def bar_animation():
    bar_width = 15
    for b in range(0, 20):
        bar_b_height = random.randint(10, 100)
        bar_b = pygame.draw.rect(screen, white, (50 + (bar_width * b), 350 - bar_b_height,    bar_width, bar_b_height), 0)


# Main game loop --------------------------------------------------------------------------------------------------------------------------

def main_loop():
    running = True
    while running:

        background()
        bar_animation()
        canvas()

        for event in pygame.event.get():
            if event.type == QUIT:
                close_game()

            pass

        pygame.display.update()
        mainClock.tick(fps)


# Run game --

main_loop()

On that code, I recreated what I want for the background of my game. I want to have the bar_animation() function running slower without making the whole game or other functions run slower...

That code produce something like this:

i recommend you to execute the code to understand what im doing

user_2255764 · Answer

You can slow down your function by updating it once per several ticks:

import pygame
import random

pygame.init()
screen = pygame.display.set_mode((400, 400))
mainClock = pygame.time.Clock()

running = True
bar_b_heights = []
while running:
    screen.fill((0, 0, 0))
    pygame.draw.rect(screen, (255, 255, 255), (50, 50, 300, 300), 1)

    if pygame.time.get_ticks() % 10 == 0 or not bar_b_heights:
        bar_b_heights = [random.randint(10, 100) for b in range(0, 20)]
    for i, bar_b_height in enumerate(bar_b_heights):
        pygame.draw.rect(screen, (255, 255, 255), (50 + (15 * i), 350 - bar_b_height, 15, bar_b_height), 0)

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    pygame.display.update()
    mainClock.tick(60)

pygame.display.quit()
pygame.quit()

Output:

Slowdown a pygame function without slowing the whole game

1 Answers