上篇文章Python实现贪吃蛇一，实现了一个贪吃蛇的基础版本，但存在一些不足，也缺乏一些乐趣。本篇文章将对其进行一些改进，主要修改/实现以下几点：
1、解决食物随机生成的位置与蛇身重合问题
2、蛇身移动加速/减速功能
3、增加一些音效
一、首先看如何解决食物随机生成的位置与蛇身重合问题，基础版本食物位置是随机生成的，这样有一定概率与蛇身重合，并且随着得分越来越高，重合的概率越来越大。思路是随机生成食物后检测食物位置是否与蛇身重合，如果重合，再次生成，直到不重合。修改后的代码片段如下：
python
def _update_food(self):
""" 更新食物 """
while True:
if self._check_food():
return
def _check_food(self):
""" 检查新生成的食物是否不与蛇身重合 """
food = self.food
food.rect.x = round(
random.randrange(20, self.settings.screen_width - self.settings.snake_width * 2) / 20.0) * 20.0
food.rect.y = round(
random.randrange(20, self.settings.screen_height - self.settings.snake_height * 2) / 20.0) * 20.0
for snake in self.snakes:
if snake.rect.colliderect(food.rect):
return False
return True二、蛇身移动加速/减速功能，计划实现的效果是按蛇身前进方向相同的按键时，速度加1，按相反的按键时速度减1，但是不能减到0。例如：蛇在向上移动时，此时按"向上"键，速度加1，按"向下"键，速度减1，按"向左"或"向右"键，速度不变，只变方向。代码实现如下：
python
def _check_keydown_events(self, event):
# 响应按键
if event.key == pygame.K_RIGHT:
if self.settings.snake_direction == 'right':
self._change_speed(1)
elif self.settings.snake_direction == 'left':
self._change_speed(-1)
else:
self.settings.snake_direction = 'right'
elif event.key == pygame.K_LEFT:
if self.settings.snake_direction == 'left':
self._change_speed(1)
elif self.settings.snake_direction == 'right':
self._change_speed(-1)
else:
self.settings.snake_direction = 'left'
elif event.key == pygame.K_UP:
if self.settings.snake_direction == 'up':
self._change_speed(1)
elif self.settings.snake_direction == 'down':
self._change_speed(-1)
else:
self.settings.snake_direction = 'up'
elif event.key == pygame.K_DOWN:
if self.settings.snake_direction == 'down':
self._change_speed(1)
elif self.settings.snake_direction == 'up':
self._change_speed(-1)
else:
self.settings.snake_direction = 'down'
elif event.key == pygame.K_q:
sys.exit()
def _change_speed(self, add):
# 改变蛇的移动速度
if (self.settings.game_speed + add) > 0:
self.settings.game_speed += add三、增加游戏音效：在游戏开始后，循环播放背景音乐；蛇吃到食物的时候播放一个吃食物的声音；每吃到十个食物播放鼓掌声；蛇撞到周边或自己身体时播放游戏结束声音。思路是，游戏初始化的时候加载声音，在相关的节点，播放对应的声音。代码如下：
声音类（game_sound.py）：
python
import pygame
class GameSound:
""" 游戏声音的类 """
def __init__(self, file_name):
""" 初始化声音 """
super().__init__()
self.file_name = file_name
# 加载音效
self.sound = pygame.mixer.Sound(f"sounds/{self.file_name}")
def play(self, times=1):
# 播放声音
self.sound.play(loops=times - 1)声音素材：
声音初始化：
python
# 初始化音频混合器
pygame.mixer.init()
# 初始化游戏声音
self.snake_eat_food_sound = GameSound('snake_eat_food.mp3')
self.snake_game_over_sound = GameSound('snake_game_over.mp3')
self.background_sound = GameSound('snake_background_sound.mp3')
self.cheer_sound = GameSound('snake_cheer_sound.mp3')播放声音的场景：
python
def _check_eat_food(self):
""" 检测蛇吃到食物 """
snake_head = self.snakes[0]
food = self.food
if snake_head.rect.colliderect(food.rect):
self.stats.score += self.settings.food_score
# 播放声音
if self.stats.score % 100 == 0:
self.cheer_sound.play(1)
else:
self.snake_eat_food_sound.play(1)
self.sb.prep_score()
self._update_food()
return True
else:
return False
def _game_over(self):
# 播放音乐
self.snake_game_over_sound.play(1)
self.stats.game_active = False
# 显示鼠标光标
pygame.mouse.set_visible(True)
def _check_play_button(self, mouse_pos):
""" 在玩家单击Play按钮时开始新游戏 """
button_clicked = self.play_button.rect.collidepoint(mouse_pos)
if button_clicked and not self.stats.game_active:
# 重置游戏设置
self.stats.game_active = True
# 播放背景音乐
self.background_sound.play(0)
# 隐藏鼠标光标
pygame.mouse.set_visible(False)下面是修改后的主程序类（gluttonous_snake.py）的完整代码：
python
import sys
import time
import pygame
import random
from settings import Settings
from snake import Snake
from game_stats import GameStats
from button import Button
from food import Food
from scoreboard import Scoreboard
from game_sound import GameSound
class GluttonousSnake:
""" 管理游戏资源和行为的类 """
def __init__(self):
""" 初始化游戏并创建游戏资源 """
pygame.init()
# 初始化音频混合器
pygame.mixer.init()
# 初始化游戏声音
self.snake_eat_food_sound = GameSound('snake_eat_food.mp3')
self.snake_game_over_sound = GameSound('snake_game_over.mp3')
self.background_sound = GameSound('snake_background_sound.mp3')
self.cheer_sound = GameSound('snake_cheer_sound.mp3')
self.settings = Settings()
self.screen = pygame.display.set_mode((self.settings.screen_width, self.settings.screen_height))
pygame.display.set_caption("贪吃蛇")
# 创建一个用于存储游戏统计信息的实例
self.stats = GameStats(self)
# 创建记分牌
self.sb = Scoreboard(self)
self.food = Food(self)
self.snakes = []
self._create_snakes()
# 创建Play按钮
self.play_button = Button(self, "Play")
def _create_snakes(self):
""" 初始化创建长度为3的蛇 """
for snake_number in range(3):
self._create_snake(snake_number)
def _create_snake(self, snake_number):
""" 创建一段蛇身 """
snake = Snake(self)
self.screen_rect = self.screen.get_rect()
snake.x = self.settings.screen_width / 2
snake.y = self.settings.screen_height / 2 + snake_number * self.settings.snake_height
snake.rect.x = snake.x
snake.rect.y = snake.y
self.snakes.append(snake)
def _check_events(self):
# 监视键盘和鼠标的事件
for event in pygame.event.get():
if event.type == pygame.QUIT:
sys.exit()
elif event.type == pygame.KEYDOWN:
self._check_keydown_events(event)
elif event.type == pygame.MOUSEBUTTONDOWN:
mouse_pos = pygame.mouse.get_pos()
self._check_play_button(mouse_pos)
def _check_play_button(self, mouse_pos):
""" 在玩家单击Play按钮时开始新游戏 """
button_clicked = self.play_button.rect.collidepoint(mouse_pos)
if button_clicked and not self.stats.game_active:
# 重置游戏设置
self.stats.game_active = True
# 播放背景音乐
self.background_sound.play(0)
# 隐藏鼠标光标
pygame.mouse.set_visible(False)
self.stats.score = 0
self.sb.prep_score()
self.settings.snake_direction = 'up'
self.settings.update_count = 0
self.settings.game_speed = 1
# 清空余下的蛇身
self.snakes.clear()
# 重新创建蛇身
self._create_snakes()
def _check_keydown_events(self, event):
# 响应按键
if event.key == pygame.K_RIGHT:
if self.settings.snake_direction == 'right':
self._change_speed(1)
elif self.settings.snake_direction == 'left':
self._change_speed(-1)
else:
self.settings.snake_direction = 'right'
elif event.key == pygame.K_LEFT:
if self.settings.snake_direction == 'left':
self._change_speed(1)
elif self.settings.snake_direction == 'right':
self._change_speed(-1)
else:
self.settings.snake_direction = 'left'
elif event.key == pygame.K_UP:
if self.settings.snake_direction == 'up':
self._change_speed(1)
elif self.settings.snake_direction == 'down':
self._change_speed(-1)
else:
self.settings.snake_direction = 'up'
elif event.key == pygame.K_DOWN:
if self.settings.snake_direction == 'down':
self._change_speed(1)
elif self.settings.snake_direction == 'up':
self._change_speed(-1)
else:
self.settings.snake_direction = 'down'
elif event.key == pygame.K_q:
sys.exit()
def _change_speed(self, add):
# 改变蛇的移动速度
if (self.settings.game_speed + add) > 0:
self.settings.game_speed += add
def _update_snakes(self):
""" 更新蛇 """
snake_head = self.snakes[0]
self._create_snake_head(snake_head.rect.x, snake_head.rect.y)
""" 检查是否吃到食物 """
eat_food = self._check_eat_food()
if not eat_food:
self.snakes.pop()
def _check_edges(self):
""" 蛇碰到边缘时采取相应的措施 """
snake_head = self.snakes[0]
if snake_head.check_edges():
self._game_over()
def _check_eat_self(self, snake_head):
""" 是否碰到自己 """
for snake in self.snakes:
if snake.rect.colliderect(snake_head.rect):
self._game_over()
break
def _game_over(self):
# 播放音乐
self.snake_game_over_sound.play(1)
self.stats.game_active = False
# 显示鼠标光标
pygame.mouse.set_visible(True)
def _check_eat_food(self):
""" 检测蛇吃到食物 """
snake_head = self.snakes[0]
food = self.food
if snake_head.rect.colliderect(food.rect):
self.stats.score += self.settings.food_score
# 播放声音
if self.stats.score % 100 == 0:
self.cheer_sound.play(1)
else:
self.snake_eat_food_sound.play(1)
self.sb.prep_score()
self._update_food()
return True
else:
return False
def _update_food(self):
""" 更新食物 """
while True:
if self._check_food():
return
def _check_food(self):
""" 检查新生成的食物是否不与蛇身重合 """
food = self.food
food.rect.x = round(
random.randrange(20, self.settings.screen_width - self.settings.snake_width * 2) / 20.0) * 20.0
food.rect.y = round(
random.randrange(20, self.settings.screen_height - self.settings.snake_height * 2) / 20.0) * 20.0
for snake in self.snakes:
if snake.rect.colliderect(food.rect):
return False
return True
def _create_snake_head(self, x, y):
""" 创建蛇头 """
snake = Snake(self)
if self.settings.snake_direction == 'up':
snake.x = x
snake.y = y - self.settings.snake_height
elif self.settings.snake_direction == 'down':
snake.x = x
snake.y = y + self.settings.snake_height
elif self.settings.snake_direction == 'right':
snake.x = x + self.settings.snake_width
snake.y = y
elif self.settings.snake_direction == 'left':
snake.x = x - self.settings.snake_width
snake.y = y
snake.rect.x = snake.x
snake.rect.y = snake.y
self._check_eat_self(snake)
self.snakes.insert(0, snake)
def run_game(self):
""" 开始游戏的主循环 """
while True:
self._check_events()
if self.stats.game_active:
if self.settings.update_count > 500: #控制游戏速度
self._update_snakes()
self._check_edges()
self.settings.update_count = 0
self.settings.update_count += self.settings.game_speed
self._update_screen()
def _update_screen(self):
# 每次循环时都会重绘屏幕
self.screen.fill(self.settings.bg_color)
self.food.draw_food()
for snake in self.snakes:
snake.draw_snake()
# 如果游戏处于非活动状态，就绘制Play按钮
if not self.stats.game_active:
self.play_button.draw_button()
# 显示得分
self.sb.show_score()
# 让最近绘制的屏幕可见
pygame.display.flip()
if __name__ == '__main__':
# 创建实例并运行游戏
ai = GluttonousSnake()
ai.run_game()