重写游戏教程代码时的TypeError

Question

YT教程中的代码，我正在使用它作为游戏的基础，附加的元素不包括在教程中：

# Import
import os
import time
import pygame
import random

# Get font for text
pygame.font.init()

# Set directory
os.chdir(r'E:\Data\python_data\game\Space Invaders')

WIDTH, HEIGHT = 850, 850
WIN = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("Invasion from Space")


# LOADING IMAGES

# Enemy ships
RED_SHIP = pygame.image.load(os.path.join('assets', 'pixel_ship_red_small.png'))
GREEN_SHIP = pygame.image.load(os.path.join('assets', 'pixel_ship_green_small.png'))
BLUE_SHIP = pygame.image.load(os.path.join('assets', 'pixel_ship_blue_small.png'))

# Player ship
YELLOW_SHIP = pygame.image.load(os.path.join('assets', 'pixel_ship_yellow.png'))

# Background image 
SPACE = pygame.transform.scale(pygame.image.load(os.path.join('assets', 'background-black.png')), 
                               ((WIDTH, HEIGHT)))

# Lasers
RED_LASER = pygame.image.load(os.path.join('assets', 'pixel_laser_red.png'))
GREEN_LASER = pygame.image.load(os.path.join('assets', 'pixel_laser_green.png'))
BLUE_LASER = pygame.image.load(os.path.join('assets', 'pixel_laser_blue.png'))
YELLOW_LASER = pygame.image.load(os.path.join('assets', 'pixel_laser_yellow.png'))



# Setting ship class

class Ship:
    def __init__(self, x, y, health=100):
        
        self.x = x
        self.y = y
        self.health = health
        self.ship_img = None
        self.laser_img = None
        self.lasers = []
        self.cool_down_counter = 0
        
    def draw(self, window):
        #pygame.draw.rect(window, (255, 0, 0), (self.x, self.y, 50, 50))
        window.blit(self.ship_img, (self.x, self.y))
        
class Player(Ship):
    def __init__(self, x, y, health=100):
        super().__init__(x, y, health)
        self.ship_img = YELLOW_SHIP
        self.laser_img = YELLOW_LASER
        
        self.mask = pygame.mask.from_surface(self.ship_img)
        self.max_health = health
        
# Define function
    # check other FPS values (30, 60, 120)

def main():
    run = True
    FPS = 60
    level = 1
    lives = 3
    main_font = pygame.font.Font("PokemonGb-RAeo.ttf", 12)
    
    player_vel = 7.5
    ship = Ship(425, 700)
    
    clock = pygame.time.Clock()
    
    def redraw_window():
        WIN.blit(SPACE, (0, 0))
        
        # draw text
        levels_label = main_font.render(f"Level: {level}", 1, (255, 255, 255))
        lives_label = main_font.render(f"Lives: {lives}", 1, (255, 255, 255))
        
        WIN.blit(lives_label, (10, 10))
        WIN.blit(levels_label, (WIDTH - levels_label.get_width() - 10, 10))
        
        ship.draw(WIN)
        
        pygame.display.update()
    
    while run:
        clock.tick(FPS)
        redraw_window()
        
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                run = False
        
        # Define keys        
        keys = pygame.key.get_pressed()
        if keys[pygame.K_a] and ship.x - player_vel > 0: # turn left
            ship.x -= player_vel
            
        if keys[pygame.K_d] and ship.x + player_vel + 50 < WIDTH: # turn right
            ship.x += player_vel
            
        if keys[pygame.K_w] and ship.y - player_vel > 0: # turn up
            ship.y -= player_vel
            
        if keys[pygame.K_s] and ship.y + player_vel + 45 < HEIGHT: # turn down
            ship.y += player_vel

main()

我遇到的问题是TypeError：

File "E:\Data\python_data\game\Space Invaders\main.py", line 65, in draw
window.blit(self.ship_img, (self.x, self.y))

TypeError: argument 1 must be pygame.Surface, not None

我很困惑为什么TypeError会发生，因为我做的和视频中的人一样。

链接到YT教程视频：https://www.youtube.com/watch?v=Q-__8Xw9KTM&t=159s

Answer 1

在Ship类的__init__函数中，self.ship_img设置为None。这可能是为了以后把它设置成一个真实的图像，但这从来没有发生过。

在本教程中，这是在Player和Enemy子类中完成的。由于您正在直接使用` `Ship类，您必须自己设置它。

由于有三个船舶映像和random模块是无用的导入，我认为意图是随机选择船舶的形象。这可以通过在创建ship之后添加以下代码行来完成：

ship.ship_img = random.choice([RED_SHIP, GREEN_SHIP, BLUE_SHIP])