Pygame贪吃蛇实现吃食物后新增随机位置敌人的方法

原代码用单个变量enemy_position存储敌人坐标，同一时间只能记录1个敌人的位置，自然无法实现敌人累加效果。只需要把单个敌人变量替换为存储所有敌人坐标的列表，对应修改生成、绘制、碰撞判定三个环节的逻辑即可实现需求。

• 替换原单个敌人变量为敌人列表，初始化时先放入1个初始敌人，对应0分时场上存在1个敌人的初始状态
• 吃到食物的逻辑分支中，新增生成新敌人坐标、追加到敌人列表的操作，保证每吃1个食物多1个敌人
• 把原来绘制单个敌人的逻辑改为遍历敌人列表，逐个绘制所有红色方块
• 把原来单个敌人的碰撞判定改为遍历敌人列表，只要蛇头碰到任意一个敌人就触发游戏结束
• 新增坐标合法性校验：生成敌人、食物时避开蛇身、已有物体的位置，避免出现刚生成就撞脸、重叠的bug

import sys,pygame
import random

 
pygame.display.set_caption('Snake Game')
screen_width, screen_height = 600,470
screen = pygame.display.set_mode((screen_width, screen_height))

fps = pygame.time.Clock()
 
snake_speed = 22
 
# 修正原代码重复定义颜色的问题
white = pygame.Color(250, 250, 250)
green = pygame.Color(0, 250, 0)
blue = pygame.Color(0, 0, 255)
black = pygame.Color(0, 0, 0)
red = pygame.Color(255, 0, 0)

pygame.init()

snake_position = [100, 50]
 
# 修正原代码蛇身初始坐标重复的笔误
snake_body = [  [150, 80],
                [100, 50],
                [90, 50],
                [80, 50]
            ]

food_position = [random.randrange(1, (screen_width//10)) * 10,
                  random.randrange(1, (screen_height//10)) * 10]
food_spawn = True

# 敌人列表存储所有敌人坐标，初始生成1个敌人
enemy_list = []
def generate_new_enemy():
    while True:
        new_enemy = [random.randrange(1, (screen_width//10)) * 10,
                      random.randrange(1, (screen_height//10)) * 10]
        if new_enemy not in snake_body and new_enemy not in enemy_list and new_enemy != food_position:
            return new_enemy
enemy_list.append(generate_new_enemy())


direction = 'RIGHT'
score = 0
 

def show_score(choice, color, font, size):
    score_font = pygame.font.SysFont(font, size)
    score_surface = score_font.render('Score : ' + str(score), True, color)
    score_rect = score_surface.get_rect()
    screen.blit(score_surface, score_rect)

def game_over():
    my_font = pygame.font.SysFont('comic sans', 50)
    game_over_surface = my_font.render('Your Score is : ' + str(score), True, red)
    game_over_rect = game_over_surface.get_rect()
    game_over_rect.midtop = (screen_width/2, screen_height/4)
    screen.blit(game_over_surface, game_over_rect)
    pygame.display.flip()
    while True:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                sys.exit()
    
    
while True:
    change_to = direction
    for event in pygame.event.get():
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                change_to = 'UP'
            if event.key == pygame.K_DOWN:
                change_to = 'DOWN'
            if event.key == pygame.K_LEFT:
                change_to = 'LEFT'
            if event.key == pygame.K_RIGHT:
                change_to = 'RIGHT'
    
   
    if change_to == 'UP' and direction != 'DOWN':
        direction = 'UP'
    if change_to == 'DOWN' and direction != 'UP':
        direction = 'DOWN'
    if change_to == 'LEFT' and direction != 'RIGHT':
        direction = 'LEFT'
    if change_to == 'RIGHT' and direction != 'LEFT':
        direction = 'RIGHT'

    if direction == 'UP':
        snake_position[1] -= 10
    if direction == 'DOWN':
        snake_position[1] += 10
    if direction == 'LEFT':
        snake_position[0] -= 10
    if direction == 'RIGHT':
        snake_position[0] += 10
 
    
    snake_body.insert(0, list(snake_position))
    if snake_position[0] == food_position[0] and snake_position[1] == food_position[1]:
        score += 1
        food_spawn = False
        # 吃到食物时追加1个新敌人
        enemy_list.append(generate_new_enemy())
    else:
        snake_body.pop()
         
    if not food_spawn:
        # 生成食物时避开蛇身和敌人
        while True:
            food_position = [random.randrange(1, (screen_width//10)) * 10,
                              random.randrange(1, (screen_height//10)) * 10]
            if food_position not in snake_body and food_position not in enemy_list:
                break
        food_spawn = True
    screen.fill(black)
     
    for pos in snake_body:
        pygame.draw.rect(screen, blue, pygame.Rect(
          pos[0], pos[1], 10, 10))
         
    pygame.draw.rect(screen, green, pygame.Rect(
      food_position[0], food_position[1], 10, 10))
    
    # 遍历绘制所有敌人
    for enemy_pos in enemy_list:
        pygame.draw.rect(screen, red, pygame.Rect(
          enemy_pos[0], enemy_pos[1], 10, 10))

    # 遍历判定和所有敌人的碰撞
    for enemy_pos in enemy_list:
        if snake_position[0] == enemy_pos[0] and snake_position[1] == enemy_pos[1]:
            game_over()

    # 撞墙判定
    if snake_position[0] < 0 or snake_position[0] > screen_width-10:
        game_over()
    if snake_position[1] < 0 or snake_position[1] > screen_height-10:
        game_over()
     
    # 撞自身判定
    for block in snake_body[1:]:
        if snake_position[0] == block[0] and snake_position[1] == block[1]:
            game_over()
    
    show_score(1, white, 'comic sans', 20)
     
    pygame.display.update()
    fps.tick(snake_speed)

• 初始场上固定1个红色敌人
• 每吃1个绿色食物加1分，同时在随机空位生成1个新的红色敌人，已生成的敌人永久保留
• 吃到5个食物时场上总计存在6个敌人，完全匹配需求
• 同步修复了原代码中颜色重复定义、蛇身初始坐标重复、食物可能刷在障碍物上的小问题

内容的提问来源于stack exchange，提问作者Idkmane