Why is does my game code appear as a black screen on pygame?

Question

I am new at coding and on stack exchange. I have been trying to get this code to run a game based off a tutorial and it keeps appearing as a black screen. I think it probably has something to do with spacing? Can anyone help me? I am sure this code can also be simplified, so any advice on that would be appreciated as well.

import pygame
import random
    from pygame.locals import (
        RLEACCEL,
        K_UP,
        K_DOWN,
        K_LEFT,
        K_RIGHT,
        K_ESCAPE,
        KEYDOWN,
        QUIT,
    )
    
    pygame.init()
    
    SCREEN_WIDTH = 800
    SCREEN_HEIGHT = 600
    
    screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))
    
    running = True
    
    while running:
        for event in pygame.event.get():
            if event.type == KEYDOWN:
                if event.key == K_ESCAPE:
                    running = False
    
            elif event.type == QUIT:
                running = False
    
    screen.fill((255, 255, 255))
    
    surf = pygame.Surface((50, 50))
    
    surf.fill((0, 0, 0))
    rect = surf.get_rect()
    
    screen.blit(surf, (SCREEN_WIDTH/2, SCREEN_HEIGHT/2))
    pygame.display.flip()
    
    surf_center = (
        (SCREEN_WIDTH-surf.get_width())/2,
        (SCREEN_HEIGHT-surf.get_height())/2
    )
    
    screen.blit(surf, surf_center)
    pygame.display.flip()
    
    class Player(pygame.sprite.Sprite):
        def __init__(self):
            super(Player, self).__init__()
            self.surf = pygame.image.load("Jake.anime.png").convert()
            self.surf.set_colorkey((255, 255, 255), RLEACCEL)
            self.rect = self.surf.get_rect()
    
    player = Player()
    
    screen.fill((0, 0, 0))
    screen.blit(player.surf, player.rect)
    
    pygame.display.flip()
    
    pressed_keys = pygame.key.get_pressed()
    
    def update(self, pressed_keys):
        if presed_keys[K_UP]:
            self.rect.move_ip(0, -5)
        if pressed_keys[K_DOWN]:
            self.rect.move_ip(0, 5)
        if pressed_keys[K_LEFT]:
            self.rect.move_ip(-5, 0)
        if pressed_keys[K_RIGHT]:
            self.rect.move_ip(5,0)
    
        if self.rect.left < 0:
            self.rect.left = 0
        if self.rect.right > SCREEN_WIDTH:
            self.rect.right = SCREEN_WIDTH
        if self.rect.top <= 0:
            self.rect.top = 0
        if self.rect.bottom >= SCREEN_HEIGHT:
            self.rect.bottom = SCREEN_HEIGHT
    
    while running:
        for event in pygame.event.get():
            if event.type == KEYDOWN:
                running = False
            elif event.type == QUIT:
                running = False
    
        pressed_keys = pygame.key.get_pressed()
        player.update(pressed_keys)
        screen.fill((0,0,0))
    
    class Enemy(pygame.sprite.Sprite):
        def __init__(self):
            super(Enemy, self).__init__()
            self.surf = pygame.image.load("graham.enemy.png").convert()
            self.surf.set_colorkey((255, 255, 255), RLEACCEL)
            self.rect = self.surf.get_rect(
                center=(
                    random.randint(SCREEN_WIDTH + 20, SCREEN_WIDTH + 100),
                    random.randint(0, SCREEN_HEIGHT),
                )
            )
            self.speed = random.randint(5, 20)
    
        def update(self):
            self.rect.move_ip(-self.speed, 0)
            if self.rect.right < 0:
                self.kill()
    
    class Cloud(pygame.sprite.Sprite):
        def __init__(self):
            super(Cloud, self).__init__()
            self.surf = pygame.image.load("cloud for game.png").convert()
            self.surf.set_colorkey((0, 0, 0), RLEACCEL)
            self.rect = self.surf.get_rect(
                center=(
                    random.randint(SCREEN_WIDTH + 20, SCREEN_WIDTH + 100),
                    random.randint(0, SCREEN_HEIGHT),
                )
            )
    
        def update(self):
            self.rect.move_ip(-5, 0)
            if self.rect.right < 0:
                self.kill()
                
    
    player = Player()
    enemies = pygame.sprite.Group()
    clouds = pygame.sprite.Group()
    all_sprites = pygame.sprite.Group()
    all_sprites.add(player)
    
    running = True
    
    screen.fill((0, 0, 0))
    
    for entity in all_sprites:
        screen.blit(entity.surf, entity.rect)
    
    pygame.display.flip()
    
    screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))
    
    ADDENEMY = pygame.USEREVENT + 1
    pygame.time.set_timer(ADDENEMY, 250)
    ADDCLOUD = pygame.USEREVENT +2
    pygame.time.set_timer(ADDCLOUD, 1000)
    
    player = Player()
    
    while running:
        for event in pygame.event.get():
            if event.type == KEYDOWN:
                if event.key == K_ESCAPE:
                    running = False
                elif event.type == QUIT:
                    running = False
                elif event.type == ADDENEMY:
                    new_enemy = Enemy()
                    enemies.add(new_enemy)
                    all_sprites.add(new_enemy)
                elif event.type ==ADDCLOUD:
                    new_cloud = Cloud()
                    clouds.add(new_cloud)
                    all_sprites.add(new_cloud)
    
        pressed_keys = pygame.key.get_pressed()
        player.update(pressed_keys)
        enemies.update()
        clouds.update()
    
    screen.fill((135, 206, 250))
    
    for entity in all_sprites:
        screen.blit(entity.surf, entity.rect)
    if pygame.sprite.spritecollideany(player, enemies):
        player.kill()
        running = False
    

Answer 1

You need to restructure your program. Write 1 application loop only. The typical PyGame application loop has to:

• handle the events by either pygame.event.pump() or pygame.event.get().
• update the game states and positions of objects dependent on the input events and time (respectively frames)
• clear the entire display or draw the background
• draw the entire scene (blit all the objects)
• update the display by either pygame.display.update() or pygame.display.flip()
• limit frames per second to limit CPU usage

See also Python Pygame Introduction and see the following example for a minimal application loop:

import pygame
pygame.init()

window = pygame.display.set_mode((500, 500))
clock = pygame.time.Clock()

# main application loop
run = True
while run:

    # limit frames per second
    clock.tick(60)

    # event loop
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False

    # clear the display
    window.fill(0)

    # draw the scene   
    pygame.draw.circle(window, (255, 0, 0), (250, 250), 100)

    # update the display
    pygame.display.flip()

pygame.quit()
exit()

repl.it/@Rabbid76/PyGame-MinimalApplicationLoop

See also Event and application loop

---

Complete applicaition:

import pygame
import random

from pygame.locals import (
    RLEACCEL,
    K_UP,
    K_DOWN,
    K_LEFT,
    K_RIGHT,
    K_ESCAPE,
    KEYDOWN,
    QUIT,
)

pygame.init()

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600

screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))

class Player(pygame.sprite.Sprite):
    def __init__(self):
        super(Player, self).__init__()
        self.surf = pygame.image.load("Jake.anime.png").convert()
        self.surf.set_colorkey((255, 255, 255), RLEACCEL)
        self.rect = self.surf.get_rect()

    def update(self, pressed_keys):
        if pressed_keys[K_UP]:
            self.rect.move_ip(0, -5)
        if pressed_keys[K_DOWN]:
            self.rect.move_ip(0, 5)
        if pressed_keys[K_LEFT]:
            self.rect.move_ip(-5, 0)
        if pressed_keys[K_RIGHT]:
            self.rect.move_ip(5,0)

        if self.rect.left < 0:
            self.rect.left = 0
        if self.rect.right > SCREEN_WIDTH:
            self.rect.right = SCREEN_WIDTH
        if self.rect.top <= 0:
            self.rect.top = 0
        if self.rect.bottom >= SCREEN_HEIGHT:
            self.rect.bottom = SCREEN_HEIGHT

class Enemy(pygame.sprite.Sprite):
    def __init__(self):
        super(Enemy, self).__init__()
        self.surf = pygame.image.load("graham.enemy.png").convert()
        self.surf.set_colorkey((255, 255, 255), RLEACCEL)
        self.rect = self.surf.get_rect(
            center=(
                random.randint(SCREEN_WIDTH + 20, SCREEN_WIDTH + 100),
                random.randint(0, SCREEN_HEIGHT),
            )
        )
        self.speed = random.randint(5, 20)

    def update(self):
        self.rect.move_ip(-self.speed, 0)
        if self.rect.right < 0:
            self.kill()

class Cloud(pygame.sprite.Sprite):
    def __init__(self):
        super(Cloud, self).__init__()
        self.surf = pygame.image.load("cloud for game.png").convert()
        self.surf.set_colorkey((0, 0, 0), RLEACCEL)
        self.rect = self.surf.get_rect(
            center=(
                random.randint(SCREEN_WIDTH + 20, SCREEN_WIDTH + 100),
                random.randint(0, SCREEN_HEIGHT),
            )
        )

    def update(self):
        self.rect.move_ip(-5, 0)
        if self.rect.right < 0:
            self.kill()
            

player = Player()
enemies = pygame.sprite.Group()
clouds = pygame.sprite.Group()
all_sprites = pygame.sprite.Group()
all_sprites.add(player)

ADDENEMY = pygame.USEREVENT + 1
pygame.time.set_timer(ADDENEMY, 250)
ADDCLOUD = pygame.USEREVENT +2
pygame.time.set_timer(ADDCLOUD, 1000)

clock = pygame.time.Clock()
running = True
while running:

    # limit frames per second
    clock.tick(60)

    # event loop
    for event in pygame.event.get():
        if event.type == QUIT:
                running = False
        if event.type == KEYDOWN:
            if event.key == K_ESCAPE:
                running = False    
        if event.type == ADDENEMY:
            new_enemy = Enemy()
            enemies.add(new_enemy)
            all_sprites.add(new_enemy)
        elif event.type ==ADDCLOUD:
            new_cloud = Cloud()
            clouds.add(new_cloud)
            all_sprites.add(new_cloud)

    # update objects
    pressed_keys = pygame.key.get_pressed()
    player.update(pressed_keys)
    enemies.update()
    clouds.update()

    # clear the display
    screen.fill((135, 206, 250))

    # draw the scene   
    for entity in all_sprites:
        screen.blit(entity.surf, entity.rect)
    if pygame.sprite.spritecollideany(player, enemies):
        player.kill()
        running = False
    screen.blit(player.surf, player.rect)

    # update the display
    pygame.display.flip()

pygame.quit()
exit()

Answer 2

You have multiple while running loops and are not calling pygame.display.update at the end to draw everything. You should have one loop which checks for events, updates everything, and draws everything.

while running:
  get_events()
  update()
  draw()

move all the code for each thing inside its own function. Collision checking would be at the end of update(). Also I am not sure why you have indented the from pygame.locals import, that should be left aligned, as should the class definitions.