除非我先射击,否则我不能移动我的精灵?

I cant move my sprite unless I shoot first?

我正在开发一款基本游戏,您可以在其中四处移动并发射射弹来杀死随机生成的敌人,但如果我启动游戏并在执行任何其他操作之前尝试移动,游戏就会崩溃。但是,如果我先发射弹丸,游戏运行完美,我可以毫无问题地四处走动,但我似乎无法弄清楚这是为什么。

import pygame
import random


BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)

#Classes

class Player(pygame.sprite.Sprite):

    def __init__(self, filename, x, y):

        super().__init__()

        self.image = pygame.image.load(filename).convert()
        self.image.set_colorkey(BLACK)

        self.rect = self.image.get_rect()
        self.rect.y = y
        self.rect.x = x

        self.change_x = 0
        self.change_y = 0
        self.walls = None        


    def changespeed(self, x, y):
        self.change_x += x
        self.change_y += y

    def update(self):
        self.rect.x += self.change_x

        block_hit_list = pygame.sprite.spritecollide(self, self.walls, False)
        for block in block_hit_list:
            if self.change_x > 0:
                self.rect.right = block.rect.left
            else:
                self.rect.left = block.rect.right

        self.rect.y += self.change_y

        block_hit_list = pygame.sprite.spritecollide(self, self.walls, False)
        for block in block_hit_list:
            if self.change_y > 0:
                self.rect.bottom = block.rect.top
            else:
                self.rect.top = block.rect.bottom


class Wall(pygame.sprite.Sprite):

    def __init__(self, x, y, width, height):

        super().__init__()

        self.image = pygame.Surface([width, height])
        self.image.fill(BLACK)

        self.rect = self.image.get_rect()
        self.rect.y = y
        self.rect.x = x 



class Enemy(pygame.sprite.Sprite):

    def __init__(self, filename):

        super().__init__()    

        self.image = pygame.image.load(filename).convert()
        self.image.set_colorkey(BLACK)
        self.rect = self.image.get_rect()

class ProjectileUp(pygame.sprite.Sprite):

    def __init__(self, filename):

        super().__init__()

        self.image = pygame.image.load(filename).convert()
        self.image.set_colorkey(BLACK)

        self.rect = self.image.get_rect()


    def update(self):
        self.rect.y -= 5


class ProjectileDown(pygame.sprite.Sprite):

    def __init__(self, filename):

        super().__init__()

        self.image = pygame.image.load(filename).convert()
        self.image.set_colorkey(BLACK)

        self.rect = self.image.get_rect()


    def update(self):
        self.rect.y += 5

class ProjectileLeft(pygame.sprite.Sprite):

    def __init__(self, filename):

        super().__init__()

        self.image = pygame.image.load(filename).convert()
        self.image.set_colorkey(BLACK)

        self.rect = self.image.get_rect()


    def update(self):
        self.rect.x -= 5


class ProjectileRight(pygame.sprite.Sprite):

    def __init__(self, filename):

        super().__init__()

        self.image = pygame.image.load(filename).convert()
        self.image.set_colorkey(BLACK)

        self.rect = self.image.get_rect()


    def update(self):
        self.rect.x += 5


# --- Create the window

#Initialise pygame
pygame.init()

#Window dimensions
screen_width = 1080
screen_height = 607
screen = pygame.display.set_mode([screen_width, screen_height])

#Window display name
pygame.display.set_caption('Labyrinth')


#Sprite Lists
all_sprite_list = pygame.sprite.Group()
block_list = pygame.sprite.Group()
wall_list = pygame.sprite.Group()
projectile_list = pygame.sprite.Group()


#Define game borders
wall = Wall(-32, 0, 10, 607)
wall_list.add(wall)
all_sprite_list.add(wall)

wall = Wall(0 , -64, 1080, 10)
wall_list.add(wall)
all_sprite_list.add(wall)

wall = Wall(1100, 0, 10, 607)
wall_list.add(wall)
all_sprite_list.add(wall)

wall = Wall(0 , 600, 1080, 10)
wall_list.add(wall)
all_sprite_list.add(wall)


#Create player sprite
player = Player("Isaac.png", 420, 150)
all_sprite_list = pygame.sprite.Group()
all_sprite_list.add(player)
player.walls = wall_list


#Create enemies
for i in range(7):
    block = Enemy("Judas.png")
    block.rect.x = random.randrange(50, 950)
    block.rect.y = random.randrange(50, 450)
    block_list.add(block)
    all_sprite_list.add(block)





#Manage screen updates 
clock = pygame.time.Clock()

#Load background image
background_position = [0, 0]
background_image = pygame.image.load("Floor.png").convert()

#Loop until game_exit
done = False



#---------- MAIN PROGRAM LOOP ----------#

while not done:

# --- Event processing 
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True


#Projectile spawn
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                projectile = ProjectileUp("LightningUp.png")
                projectile.rect.x = player.rect.x+65
                projectile.rect.y = player.rect.y
            elif event.key == pygame.K_DOWN:
                projectile = ProjectileDown("LightningDown.png")
                projectile.rect.x = player.rect.x+65
                projectile.rect.y = player.rect.y+100
            elif event.key == pygame.K_LEFT:
                projectile = ProjectileLeft("LightningLeft.png")
                projectile.rect.x = player.rect.x+35
                projectile.rect.y = player.rect.y+100
            elif event.key == pygame.K_RIGHT:
                projectile = ProjectileRight("LightningRight.png")
                projectile.rect.x = player.rect.x+115
                projectile.rect.y = player.rect.y+100

            all_sprite_list.add(projectile)
            projectile_list.add(projectile)


#Movement controls
        if event.type == pygame.KEYDOWN:
            if event.key == ord('a'):
                player.changespeed(-7, 0)
            elif event.key == ord('d'):
                player.changespeed(7, 0)
            elif event.key == ord('w'):
                player.changespeed(0, -7)
            elif event.key == ord('s'):
                player.changespeed(0, 7)

        elif event.type == pygame.KEYUP:
            if event.key == ord('a'):
                player.changespeed(7, 0)
            elif event.key == ord('d'):
                player.changespeed(-7, 0)
            elif event.key == ord('w'):
                player.changespeed(0, 7)
            elif event.key == ord('s'):
                player.changespeed(0, -7)



# --- Game logic

#Update sprites
    all_sprite_list.update()

#Projectile mechanics
    for projectile in projectile_list:

        block_hit_list = pygame.sprite.spritecollide(projectile, block_list, True)

        for block in block_hit_list:
            projectile_list.remove(projectile)

#Determine if player hits enemy
    blocks_hit_list = pygame.sprite.spritecollide(player, block_list, True)

#Call on background image
    screen.blit(background_image, background_position)

# --- Draw the window

    all_sprite_list.draw(screen)

    pygame.display.flip()

    clock.tick(60)

pygame.quit()

因为你的if/elif/else逻辑有点乱。 KEYDOWN 事件有两条路径。如果第一个事件恰好是一个移动命令,您的代码将首先运行弹丸代码(没有找到有效的弹丸命令),然后尝试引用一个不存在的弹丸对象。试试这个:

#---------- MAIN PROGRAM LOOP ----------#

while not done:

# --- Event processing 
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True

        elif event.type == pygame.KEYDOWN:
            projectile = None  # initialize 
            if event.key == pygame.K_UP:
                projectile = ProjectileUp("LightningUp.png")
                projectile.rect.x = player.rect.x+65
                projectile.rect.y = player.rect.y
            elif event.key == pygame.K_DOWN:
                projectile = ProjectileDown("LightningDown.png")
                projectile.rect.x = player.rect.x+65
                projectile.rect.y = player.rect.y+100
            elif event.key == pygame.K_LEFT:
                projectile = ProjectileLeft("LightningLeft.png")
                projectile.rect.x = player.rect.x+35
                projectile.rect.y = player.rect.y+100
            elif event.key == pygame.K_RIGHT:
                projectile = ProjectileRight("LightningRight.png")
                projectile.rect.x = player.rect.x+115
                projectile.rect.y = player.rect.y+100
            elif event.key == ord('a'):
                player.changespeed(-7, 0)
            elif event.key == ord('d'):
                player.changespeed(7, 0)
            elif event.key == ord('w'):
                player.changespeed(0, -7)
            elif event.key == ord('s'):
                player.changespeed(0, 7)

            if projectile: # did we create a valid projectile?
                all_sprite_list.add(projectile)
                projectile_list.add(projectile)


        elif event.type == pygame.KEYUP:
            if event.key == ord('a'):
                player.changespeed(7, 0)
            elif event.key == ord('d'):
                player.changespeed(-7, 0)
            elif event.key == ord('w'):
                player.changespeed(0, 7)
            elif event.key == ord('s'):
                player.changespeed(0, -7)