[FIXED] bug in loading scenes with different background

Issue

I am trying to add a pause menu in my game SpaceInvaders with the last frame of the game in the background but when I load the pause scene my game does not show the game in the background

the background game looks like this

the first time I load pause it shows this

and then whenever i load pause it behaves normally like this

my game has 3 files :

1)game file

2)pause file

3)init file (that connects above two)

---

Game file

import pygame
from __init__ import __INIT__

pygame.display.set_caption("Endless")
pygame.init()
screen=pygame.display.set_mode((1920/2,1080/2),pygame.RESIZABLE)

def menu():
    running=True

    while running:
        screen.blit(pygame.image.load("docs/bg.png"),(0,0))
        
        for event in pygame.event.get():
        
            if event.type==pygame.QUIT:
                running=False
                pygame.quit()
                quit()

            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE:
                    __INIT__("pause")

        pygame.display.update()
menu()

---

Pause file

import pygame
from __init__ import __INIT__

pygame.display.set_caption("Pause")
pygame.init()
screen=pygame.display.set_mode((1920/2,1080/2),pygame.RESIZABLE) 

def PAUSE():
    running=True

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

            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE:
                    __INIT__("menu")
                if event.key == pygame.K_h:
                    from __init__ import hello
                    hello()

        screen.blit(pygame.image.load("docs/D_effect.png"),(0,0))
        pygame.display.update()
PAUSE()

---

init file

def __INIT__(a):
    if a=="pause":
        from pause import PAUSE
        PAUSE()
    if a=="menu":
        from endless import menu
        menu()

I don't know what is causing this issue because it only does it one time I am a beginner it might be a silly mistake I am sorry if that happens

in any case, if u find it difficult to understand my problem please run the endless file in Space_invaders/Space_invaders/endless.py provided here https://drive.google.com/file/d/1xkSKcptJpuY9mZhQtl6mwU1Hh3p2L5j4/view?usp=sharing

Solution

The problem is recursion. menu calls PAUSE, PAUSE calls menu:

menu
  |
   -> PAUSE
        |
         -> menu
             |
              -> PAUSE
                   |
                    ...

You don't need the extra application loop for PAUSE at all. Just add use game_state variable. e.g.:

import pygame

pygame.display.set_caption("Endless")
pygame.init()
screen=pygame.display.set_mode((1920/2,1080/2),pygame.RESIZABLE)

def menu():

    bg = pygame.image.load("docs/bg.png")
    bg_pause = pygame.image.load("docs/D_effect.png")

    game_state = 'running'
    while game_state != 'quit':

        if game_state == 'pause':
            screen.blit(bg_pause, (0,0))
        else:
            screen.blit(bg, (0,0))
        
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                game_state = 'quit'
            elif event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE:
                    if game_state == 'running':
                        game_state = 'pause'
                    else:
                        game_state = 'running' 

        if game_state == 'running':
            # draw game scene
            # [...]
            pass

        pygame.display.update()

    pygame.quit()
    quit()
    
menu()

Do not load the background images in every frame. This causes lagging. pygame.image.load is a very time consuming process, the image file has to be loaded from the volume and decoded. Load the images before the application loop and use them in the loop.

Answered By - Rabbid76