Pygame小游戏练习四

@Python编程从入门到实践 Python项目练习

九、添加Play按钮

一、创建Button类

先让游戏一开始为非活动状态

# game_stats.py
# --snip--

self.game_active = False

# def reset_stats(self):
# --snip--

button类为带标签的实心矩形，将“play”字符串渲染为图像，放在矩形上方居中

# button.py
import pygame.font

class Button():

    def __init__(self, ai_settings, screen, msg):
        """初始化按钮的属性"""
        self.screen = screen
        self.screen_rect = screen.get_rect()

        # 设置按钮的尺寸和其他属性
        self.width, self.height = 200, 50
        self.button_color = (0, 0, 0)
        self.text_color = (255, 255, 255)
        self.font = pygame.font.SysFont(None, 48) # 指定字体

        # 创建按钮的rect对象，并使其居中
        self.rect = pygame.Rect(0, 0, self.width, self.height)
        self.rect.center = self.screen_rect.center

        # 按钮的标签只需创建一次，即将字符串msg渲染为图像
        self.prep_msg(msg)

    def prep_msg(self, msg):
        """将msg渲染为图像，并使其在居中"""
        self.msg_image = self.font.render(msg, True, self.text_color,
                                          self.button_color)  # 渲染为图像
        self.msg_image_rect = self.msg_image.get_rect()
        self.msg_image_rect.center = self.rect.center  # 使文字形成的图像居中

    def draw_button(self):
        # 绘制一个用颜色填充的按钮，再绘制文本图像，使其在上方
        self.screen.fill(self.button_color, self.rect)
        self.screen.blit(self.msg_image, self.msg_image_rect)

二、绘制按钮

在alien_invasion.py中创建实例，修改up_screen(),让游戏处于非活动状态显示按钮

# alien_invasion.py
# --snip--
    # 创建play按钮
    play_button = Button(ai_settings, screen, "Play")

    # 开始游戏主循环
    while True:
	# --snip--
        # 每次循环重绘窗口并更新屏幕
        gf.update_screen(ai_settings, screen, stats, ship, passenger_group, bullet_group,play_button)

# game_functions.py
# --snip--

    # 如果游戏处于非活动状态，就绘制Play按钮
    if not stats.game_active:
        play_button.draw_button()

# --snip--

三、点击按钮

玩家点击按钮时，应重置游戏统计信息，保证下次游戏不重复。而且，只有在游戏激活状态为False时，点击才有效。

# game_functions.py
#   for event in pygame.event.get():
#       if event.type == pygame.QUIT:
#          sys.exit()

#    --snip--
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x, mouse_y = pygame.mouse.get_pos()
            check_play_button(ai_settings, screen, stats, play_button, ship,
                              passenger_group, bullet_group, mouse_x, mouse_y)

def check_play_button(ai_settings, screen, stats, play_button, ship,
                      passenger_group, bullet_group, 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:  # 检查鼠标点击位置是否在play范围内
        # 隐藏光标
        pygame.mouse.set_visible(False)
        # 重置游戏统计信息
        stats.reset_stats()
        stats.game_active = True

        # 清空外星人列表和子弹列表
        passenger_group.empty()
        bullet_group.empty()

        # 创建一群新的外星人，并在飞船居中
        create_fleet(ai_settings, screen, ship, passenger_group)
        ship.center_ship()

注意，修改alien_invasion.py中，check_events的形参，与game_functions.py中的同步。

十、提高游戏难度

通过修改乘客、飞机移动速度不断增加游戏难度。

重构setting 类设置选项分为动态设置和静态设置，每一次消灭全部乘客后，将速度乘以speedup_scale。

# settings.py
class Settings(object):
    """设置所有设置的类"""
    def __init__(self):
        """初始化游戏的静态设置"""
        # 屏幕设置
        self.screen_width = 600
        self.screen_height = 400
        self.bg_color = (255, 255, 255)

        # 飞船设置
        self.ship_limit = 3

        # 子弹设置
        self.bullet_width = 3
        self.bullet_height = 15
        self.bullet_color = 60, 60, 60
        self.bullet_group_allowed = 3

        # 乘客设置
        self.fleet_drop_speed = 7

        # 以什么样的速度加快游戏的节奏
        self.speedup_scale = 1.1

        self.initialize_dynamic_settings()

    def initialize_dynamic_settings(self):
        """初始化随游戏进行而变化的动态设置"""
        self.ship_speed_factor = 1.5
        self.bullet_speed_factor = 3
        self.passenger_speed_factor = 1
        # fleet_direction为1表示向右移动，为-1表示向左移动
        self.fleet_direction = 1

    def increase_speed(self):
        """提高速度的设置"""
        self.ship_speed_factor *= self.speedup_scale
        self.bullet_speed_factor *= self.speedup_scale
        self.passenger_speed_factor *= self.speedup_scale

# game_functions.py
# def check_bullet_passenger_collisions(ai_settings, screen, ship, passenger_group,
#                                       bullet_group):
#    if len(passenger_group) == 0:
# --snip--
         # 删除现有子弹并新建一波新的乘客, 并加快游戏速度
		 # bullet_group.empty()
         ai_settings.increase_speed()

# game_functions.py
# def check_play_button(ai_settings, screen, stats, play_button, ship,
#                      passenger_group, bullet_group, 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:  # 检查鼠标点击位置是否在play范围内
		# 重置游戏速度设置
        ai_settings.initialize_dynamic_settings()

# --snip--