这艘船不会发射子弹 python 速成课程第 2 版

如何解决这艘船不会发射子弹 python 速成课程第 2 版

您好，如果您能帮助我解释为什么子弹没有被发射，我将不胜感激，我按照书中的所有步骤操作，但它不起作用。

bullet.py 文件是新写的，settings.py 中的“#bullet settings”也是新写的，alien_invasion.py 中添加了一些部分。并在 Alien_invasion.py 中的“self.bullets.sprites() 中的子弹：bullet.draw_bullet”。不画任何子弹？

alien_invasion.py

​​>

import sys

import pygame
from settings import Settings
from ship import Ship
from bullet import Bullet



class AlienInvasion:

    def __init__(self):
        pygame.init()
        self.settings = Settings()

        self.screen = pygame.display.set_mode((0,0),pygame.FULLSCREEN)
        self.settings.screen_width = self.screen.get_rect().width
        self.settings.screen_height = self.screen.get_rect().height
        #self.screen = pygame.display.set_mode((self.settings.screen_width,self.settings.screen_height))
        pygame.display.set_caption("Alien Invasion")

        self.bg_color = (0,50)
        self.ship = Ship(self)
        self.bullets = pygame.sprite.Group()


    def _check_keyup_events(self,event):
        if event.key == pygame.K_RIGHT:
            self.ship.moving_right = False
        elif event.key == pygame.K_LEFT:
            self.ship.moving_left = False


    def _fire_bullet(self):
        """ Create a new bullet and add it to the bullets group."""
        new_bullet = Bullet(self)
        self.bullets.add(new_bullet)


    def _check_keydown_events(self,event):
        if event.key == pygame.K_RIGHT:
            self.ship.rect2.x += 10
            self.ship.moving_right = True
        elif event.key == pygame.K_LEFT:
            self.ship.moving_left = True
        elif event.key == pygame.K_q:
            sys.exit()
        elif event.key == pygame.K_ESCAPE:
            sys.exit()
        elif event.key == pygame.K_SPACE:
            self._fire_bullet()




     def _update_screen(self):
         """update images on the screen,and flip to the new screen"""

     def _check_events(self):
         for event in pygame.event.get():
             if event.type == pygame.QUIT:
                 sys.exit()


             if event.type == pygame.KEYDOWN:
                 self._check_keydown_events(event)


             if event.type == pygame.KEYUP:
                 self._check_keyup_events(event)
            
             for bullet in self.bullets.sprites():
                 bullet.draw_bullet()




     def run_game(self):
         while True:

             self._check_events()
             self.ship.update()
             self.bullets.update()

             self._update_screen()
             for bullet in self.bullets.sprites():
                 bullet.draw_bullet()
             pygame.display.flip()

             self.screen.fill(self.bg_color)
             self.ship.blitme()
             self.ship.blitme2()








                    

            
        
            
    
    
        






if __name__ == '__main__':
     ai = AlienInvasion()
     ai.run_game()

---

settings.py

​​>

class Settings:
    """A class to store all settings for Alien Invasion."""

    def __init__(self):
        """Initialize the game's settings."""
        # Screen settings
        self.screen_width = 1200
        self.screen_height = 800
        self.bg_color = (230,230,230)

        #Ship settings
        self.ship_speed = 15

        #Bullet settings
        self.bullet_speed = 1.0
        self.bullet_width = 3
        self.bullet_height = 15
        self.bullet_color = (60,60,60)
    
        

---

bullet.py

​​>

import pygame 
from pygame.sprite import Sprite

class Bullet(Sprite):
    """A class to manage blullets fired from the ship"""

    def __init__(self,ai_game):
        """Create a bullet object at the ships current position."""
        super().__init__()
        self.screen = ai_game.screen
        self.settings = ai_game.settings
        self.color = self.settings.bullet_color



        # Create a bullet rect at (0,0) and then the correct position.

        self.rect = pygame.Rect(0,self.settings.bullet_width,self.settings.bullet_height)
        self.rect.midtop = ai_game.ship.rect.midtop

        # Store the bullets position as a decimal value.

        self.y = float(self.rect.y)

    def update(self):
        """ Move the bullet up the screen."""
        # Update the decimal position of the bullet.
        self.y -= self.settings.bullet_speed
        #Update the rect position.
        self.rect.y = self.y 

    def draw_bullet(self):
        """ Draw the bullet to the screen"""
        pygame.draw.rect(self.screen,self.color,self.rect)

---

ship.py

---

import pygame


class Ship:
    def __init__(self,ai_game):
        self.screen = ai_game.screen
        self.screen_rect = ai_game.screen.get_rect()
        self.settings = ai_game.settings

        self.image = pygame.image.load('C:/Users/Documents/Python Learning/python crash course lessons/Alien Invasion/ship.bmp')
        self.image2 = pygame.image.load('C:/Users/Documents/Python Learning/python crash course lessons/Alien Invasion/ship1.bmp')
        self.rect = self.image.get_rect()
        self.rect2 = self.image2.get_rect()
        self.rect.midbottom = self.screen_rect.midbottom
        self.moving_right = False
        self.moving_left = False
        self.x = float(self.rect.x)
        self.x2 = float(self.rect2.x)

    def update(self):
        """Update the ships position based on the movement flagg."""
        if self.moving_right == True:
            self.rect2.x += 5
            self.rect.x +=2
        if self.moving_right and self.rect2.right < self.screen_rect.right:
            self.x += self.settings.ship_speed
        if self.moving_left == True:
            self.rect2.x -= 5
            self.rect.x -= 2
        if self.moving_left and self.rect2.left > 0:
            self.x -= self.settings.ship_speed


        #Update rect object from self.x
        self.rect2.x = self.x
        #self.rect.x = self.x


    def blitme(self):
        self.screen.blit(self.image,self.rect)

    def blitme2(self):
        self.screen.blit(self.image2,self.rect2.move(0,670))

解决方法

您必须在 _update_screen 方法中绘制项目符号：

class AlienInvasion:
    # [...]

    def _update_screen(self):
        for bullet in self.bullets.sprites():
            bullet.draw_bullet()

您必须在清除屏幕之后和更新屏幕之前调用 _update_screen：

class AlienInvasion:
    # [...]

    def run_game(self):
         while True:

             self._check_events()
             self.ship.update()
             self.bullets.update()
  
             self.screen.fill(self.bg_color)
             self.ship.blitme()
             self.ship.blitme2()
             self._update_screen()
             pygame.display.flip()

子弹的起始位置错误。更改 Bullet.__init__ 中的位置：

self.rect.midtop = ai_game.ship.rect.midtop

class Bullet(Sprite):
    def __init__(self,ai_game):
        # [...]

        self.rect = pygame.Rect(0,self.settings.bullet_width,self.settings.bullet_height)
        self.rect.midtop = ai_game.ship.rect2.move(0,670).midtop