Python编程：《外星人入侵》（二）

接上文 Python编程：《外星人入侵》（一）https://developer.aliyun.com/article/1618623

1.2.4 创建game_functions.py
实现功能如下：

游戏事件管理
程序源码如下：

from asyncio import events
# from fcntl import F_SEAL_SEAL
import imp
from re import A
import sys
from zoneinfo import available_timezones

from time import sleep

import pygame

from settings import Settings

from ship import Ship 

from bullet import Bullet

from alien import Alien




def check_events(ai_settings, screen,  ship, bullets):
    """响应按键和鼠标事件"""
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

        elif event.type == pygame.KEYDOWN:
            check_keydown_events(event, ai_settings, screen, ship, bullets)


        elif event.type == pygame.KEYUP:
            check_keydown_events(event, ai_settings, screen, ship, bullets)


        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x, mouse_y = pygame.mouse.get_pos()
            check_play_button(ai_settings, screen, stats, sb, play_button, ship, aliens, bullets, mouse_x, mouse_y)


def check_keydown_events(event, ai_settings, screen, ship, bullets):
    """响应按键"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        fire_bullet(ai_settings, screen, ship, bullets)

        # 创建一颗子弹，并将其加入到编组bullets中

        if len(bullets) < ai_settings.bullets_allowed:
            new_bullet = Bullet(ai_settings, screen, ship)
            bullets.add(new_bullet)
    # 如果按q键，退出
    elif event.key == pygame.K_q:
        sys.exit()


def check_keyup_events(event, ai_settings, screen, ship, bullets):
    """响应松开"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        ship.moving_left = False


def check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets):
    """检查是否有外星人抵达屏幕底端"""
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            # 像飞船被撞到一样进行处理
            ship_hit(ai_settings, stats, screen, ship, aliens, bullets)
            break

# 检测子弹和外星人之间的碰撞
def check_bullet_alien_collisions(ai_settings, screen, ship, aliens, bullets):
    """响应子弹和外星人发生碰撞"""
    # 删除发生碰撞的子弹和外星人
    collisions = pygame.sprite.groupcollide(bullets, aliens, True, True)

    if len(aliens) == 0:
        # 删除现有的所有子弹， 并创建一个新的外星人群
        bullets.empty()
        create_fleet(ai_settings, screen, ship, aliens)

    if len(aliens) == 0:
        # 如果整群外星人都被消灭，就提高一个等级
        bullets.empty()
        ai_settings.increase_speed()

        # 提高等级
        stats.level += 1
        sb.prep_level()

        create_fleet(ai_settings, screen, ship, aliens)


def check_play_button(ai_settings, screen, stats, sb, play_button, ship, aliens, bullets, mouse_x, mouse_y):
    """在玩家单击Play按钮时开始游戏"""
    button_clicked = play_button.rect.collidepoint(mouse_x, mouse_y)
    if button_clicked and not stats.game_active:
        # 重置游戏设置
        ai_settings.initialize_dynamic_settings()

        # 隐藏光标
        pygame.mouse.set_visible(False)

        # 重置游戏统计信息
        stats.reset_stats()
        stats.game_active = True

        # 重置记分牌图像
        sb.prep_score()
        sb.prep_high_score()
        sb.prep_level()
        sb.prep_ships()

        # 清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()


def check_high_score(stats, sb):
    """检查是否诞生了新的最高分"""
    if stats.score > stats.high_score:
        stats.high_score = stats.score  
        sb.prep_high_score()


def check_fleet_edges(ai_settings, aliens):
    """有外星人到达边缘时采取相应的措施"""
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings, aliens)
            break


def change_fleet_direction(ai_settings, aliens):
    """将整群外星人下移， 并改变它们的方向"""
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1


def update_aliens(ai_settings, stats, screen, ship, aliens, bullets):
    """检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""
    check_fleet_edges(ai_settings, aliens)
    aliens.update()

    # 检测外星人和飞船之间的碰撞
    if pygame.sprite.spritecollideany(ship, aliens):
        ship_hit(ai_settings, stats, screen, ship, aliens, bullets)
        print("Ship hit!!!")

    # 检测是否有外星人到达屏幕底端
    check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets)




def update_screen(ai_settings, screen, ship, aliens, bullets):
    """更新屏幕上的图案，并切换到新屏幕"""
    # 每次循环时都重绘屏幕
    screen.fill(ai_settings.bg_color)
    # 在飞船和外星人后面重绘所有子弹
    for bullet in bullets.sprites():
        bullet.draw_bullet()

    ship.blitme()
    # alien.blitme()
    aliens.draw(screen)
    # 让最近绘制的屏幕可见
    pygame.display.flip()


def update_bullets(ai_settings, screen, ship, aliens, bullets):
    """更新子弹的位置，并删除已消失的子弹"""
    # 更新子弹的位置
    bullets.update()

    # 删除已消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)

    check_bullet_alien_collisions(ai_settings, screen, ship, aliens, bullets)

    # 检查是否有子弹击中了外星人
    # 如果是这样，就删除相应的子弹和外星人
    collisions = pygame.sprite.groupcollide(bullets, aliens, True, True)

    if len(aliens) == 0:
        #删除现有的子弹并新建一群外星人
        bullets.empty()
        create_fleet(ai_settings, screen, ship, aliens)

def ship_hit(ai_settings, stats, screen, ship, aliens, bullets):
    """响应被外星人撞到的飞船"""
    # 将ships_left减1
    stats.ships_left -= 1

    # 清空外星人列表和子弹列表
    aliens.empty()
    bullets.empty()

    # 创建一群新的外星人，并将飞船放到屏幕底端中央
    create_fleet(ai_settings, screen, ship, aliens)
    ship.center_ship()

    # 暂停
    sleep(0.5)

    if stats.ships_left > 0:
        # 将ships_left减1
        stats.ships_left -= 1

        # 更新记分牌
        # sb.prep_ships()

    else:
        stats.game_active = False

def fire_bullet(ai_settings, screen, ship, bullets):
    """如果没有到达限制，就发射一颗子弹"""
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)

def get_number_aliens_x(ai_settings, alien_width):
    """计算每行可容纳多少个外星人"""

    # 屏幕的宽度减掉2个外星人的宽度，因为两侧各空出一个外星人
    available_space_x = ai_settings.screen_width - 2 * alien_width
    # 外星人和空格间距是相等的， 所以除以2
    number_aliens_x = int(available_space_x / (2 * alien_width))

    return number_aliens_x

def create_alien(ai_settings, screen, aliens, alien_number, row_number):
    """创建一个外星人并将其放在当前行"""
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    alien.x = alien_width + 2 * alien_width * alien_number
    alien.rect.x = alien.x
    alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_number
    aliens.add(alien)


def create_fleet(ai_settings, screen,  ship,  aliens):
    """创建外星人群"""
    # 创建一个外星人，并计算一行可容纳多少个外星人

    alien = Alien(ai_settings, screen)
    number_aliens_x = get_number_aliens_x(ai_settings, alien.rect.width)
    number_rows = get_number_rows(ai_settings, ship.rect.height, alien.rect.height)


    # 创建外星人群
    for row_number in range(number_rows):
        # 创建第一行外星人
        for alien_number in range(number_aliens_x):
            # 创建一个外星人并将其加入当前行
            create_alien(ai_settings, screen, aliens, alien_number, row_number)



def get_number_rows(ai_settings, ship_height, alien_height):
    """计算屏幕可容纳多少行外星人"""
    available_space_y = (ai_settings.screen_height - (3 * alien_height) - ship_height)
    number_rows = int(available_space_y / (2 * alien_height))
    return number_rows

1.2.5 创建bullet.py
实现功能如下：

射击功能，按空格键时发射子弹（小矩形）
源码如下：

# Sprite：小妖怪,调皮鬼
import imp


import pygame
from pygame.sprite import Sprite


class Bullet(Sprite):
    """一个对飞船发射的子弹进行管理的类"""

    def __init__(self, ai_settings, screen, ship):
        """在飞船所处的位置创建一个子弹对象"""
        super(Bullet, self).__init__()
        self.screen = screen

        # 在(0,0)处创建一个表示子弹的矩形，再设置正确的位置
        self.rect = pygame.Rect(0, 0, ai_settings.bullet_width,
                        ai_settings.bullet_height)

        # x代表坐标，centerx代表中心的x坐标, 子弹的矩形中心x坐标等于飞船的矩形中心x坐标
        self.rect.centerx = ship.rect.centerx
        # 子弹的顶在飞船的矩形顶
        self.rect.top = ship.rect.top

        # 存储用小数表示的子弹位置
        self.y = float(self.rect.y)

        self.color = ai_settings.bullet_color
        self.speed_factor = ai_settings.bullet_speed_factor

    def update(self):
        """向上移动子弹"""
        # 更新表示子弹位置的小数值
        self.y -= self.speed_factor
        # 更新表示子弹的rect的位置
        self.rect.y = self.y

    def draw_bullet(self):
        """在屏幕上绘制子弹"""
        pygame.draw.rect(self.screen, self.color, self.rect)

1.2.6创建alien.py
实现功能如下：

创建名为Alien类，实现外星人具备的功能模块
源码如下：

import pygame
from pygame.sprite import Sprite

class Alien(Sprite):
    """表示单个外星人的类"""

    def __init__(self, ai_settings, screen):
        """初始化外星人并设置其起始位置"""
        super(Alien, self).__init__()
        self.screen = screen
        self.ai_settings = ai_settings

        # 加载外星人图像，并设置其rect属性
        self.image = pygame.image.load('images/alien.bmp')
        self.rect = self.image.get_rect()

        # 每个外星人最初都在屏幕左上角附近
        self.rect.x = self.rect.width
        self.rect.y = self.rect.height


        # 存储外星人的准确位置
        self.x = float(self.rect.x)

    def blitme(self):
        """在指定位置绘制外星人"""
        self.screen.blit(self.image, self.rect)


    def update(self):
        """向左或向右移动外星人"""
        self.x += (self.ai_settings.alien_speed_factor * self.ai_settings.fleet_direction)
        self.rect.x = self.x


    def check_edges(self):
        """如果外星人位于屏幕边缘， 就返回True"""
        screen_rect = self.screen.get_rect()
        if self.rect.right >= screen_rect.right:
            return True
        elif self.rect.left <= 0:
            return True

1.2.7创建game_stats.py
实现如下功能：

标志游戏状态
源码如下：

class GameStats():
    """跟踪游戏的统计信息"""

    def __init__(self, ai_settings):
        """初始化统计信息"""
        self.ai_settings = ai_settings
        self.reset_stats()

        # 游戏刚启动时处于活动状态
        self.game_active = True 

    def reset_stats(self):
        """初始化在游戏运行期间可能变化的统计信息"""

        self.ships_left = self.ai_settings.ship_limit

游戏运行画面如下：