from turtle import *
from random import randrange
from time import sleep

### 定义变量
snake = [[0,0],[10,0],[20,0],[30,0],[40,0],[50,0]]
apple_x = randrange(-20,20)*10 
apple_y = randrange(-20,20)*10 
aim_x = 10
aim_y = 0


def squre(x,y,size,color_name):
 up()
 goto(x,y)
 down()
 color(color_name)
 begin_fill()

 forward(size)
 left(90)
 forward(size)
 left(90)
 forward(size)
 left(90)
 forward(size)
 left(90)

 end_fill()

## 控制蛇
def change(x,y):
 global aim_x,aim_y
 aim_x = x;
 aim_y = y;
#判断撞墙
def inside():
 #判断是否在画布里面
 if -210 <= snake[-1][0]<=200 and -210 <= snake[-1][1]<=200:
 return True
 else:
 return False
#随机生成苹果
def gameLoop():
 global apple_x,apple_y,aim_x,aim_y,snake
 snake.append([snake[-1][0]+aim_x,snake[-1][1]+aim_y])
 if not inside():
 sleep(2)
 # snake = [[0,0],[10,0],[20,0],[30,0],[40,0],[50,0]]
 # apple_x = randrange(-20,20)*10 
 # apple_y = randrange(-20,20)*10 
 # aim_x = 10
 # aim_y = 0
 return
 #吃苹果
 if snake[-1][0] != apple_x or snake[-1][1]!=apple_y:
 snake.pop(0) # 加一个元素 删除一个元素 蛇就往前运行了
 else:
 apple_x = randrange(-20,20)*10 
 apple_y = randrange(-20,20)*10

 clear() # 清楚之前画的痕迹
 squre(apple_x,apple_y,10,'red') ## x y 位置 图形大小 颜色
 for n in range(len(snake)):
 squre(snake[n][0],snake[n][1],10,'black')

 ontimer(gameLoop,100) #每100毫秒运行一次
 update()

### 主程序
setup(420,420,0,0)
hideturtle() ## 隐藏箭头
tracer(False) ## 不延时
listen() #监听
onkey(lambda: change(0,10), "w")
onkey(lambda: change(0,-10), "s")
onkey(lambda: change(-10,0), "a")
onkey(lambda: change(10,0), "d")

gameLoop()
done()