在海龟赛跑中，如何让海龟停在特定坐标？

Question

我正在创建一场乌龟比赛，我想让乌龟在到达终点线时停下来。

圆圈部分是终点线，位于 x 坐标 220。 到目前为止，这是我的代码：

import turtle as trtl

#add the background
wn = trtl.Screen()
wn.setup(width = 1.0 , height = 1.0)
wn.bgpic("image.png")

# Make the turtle racers
BlueTurtle = trtl.Turtle()
BlueTurtle.shape("turtle")
BlueTurtle.color("blue")
BlueTurtle.speed(4)
BlueTurtle.penup()
BlueTurtle.goto(-220,-0)
BlueTurtle.pendown()

RedTurtle = trtl.Turtle()
RedTurtle.color("red")
RedTurtle.speed(4)
RedTurtle.shape("turtle")
RedTurtle.penup()
RedTurtle.goto(-220,-75)
RedTurtle.pendown()

# Game configuration variables
def move_blue():
    BlueTurtle.forward(10)

def move_red():
    RedTurtle.forward(10)

# Create numbers and the title
pen = trtl.Turtle()
pen.pensize(10)
pen.speed(10)
pen.speed(20)
pen.penup()
pen.goto(-100, 70)
pen.pendown()
pen.write("Turtle Race", font=("Times New Roman", 40, "normal"))
numbers = ["1","2"]
coordinates = -200,50
for i in range(2):
  pen.penup()
  pen.goto(coordinates)
  pen.pendown()
  pen.write(numbers[i])
  coordinates = (coordinates[0], coordinates[1] + -100)

# Make the lines that divide the racers and the finish line
pen.penup()
pen.goto(-180, -40)
pen.pendown()
pen.forward(400)
pen.penup()
pen.goto(-180, 40)
pen.pendown()
pen.forward(400)
pen.penup()
pen.goto(-180, -110)
pen.pendown()
pen.forward(400)
pen.pensize(0)
pen.penup()
pen.goto(230, 60)
pen.pendown()
pen.right(90)
pen.forward(175)
pen.hideturtle()

# Personalizes it so that the player can move their turtle with any key they like
key1 = input("Type a letter to use to move your turtle - Blue Turtle")
key2 = input("Type a letter to use to move your turtle - Red Turtle")

# Listen for events
wn = trtl.Screen()
wn.onkeypress(move_blue, key1)
wn.onkeypress(move_red, key2)
wn.listen()

# The function for the game to stop if one of the turtles touches the finish line
keepPlaying = True
while keepPlaying:
    if BlueTurtle.pos() == (220, 0):
        pen.penup()
        pen.goto(-220, -220)
        pen.pendown()
        pen.write("The Blue Turtle hit the finish line - the blue turtle wins!" , font = 
("Arial", 20, "normal"))
        keepPlaying = False
    if RedTurtle.pos() == (220, 0):
        pen.penup()
        pen.goto(-220, -220)
        pen.pendown()
        pen.write("The Red Turtle hit the finsh line = the red turtle wins!" , font =("Arial", 
20, "normal"))
        keepPlaying = False
wn.mainloop()

最后一个区域显示“如果其中一只海龟触及终点线，游戏将停止”。是我到目前为止所尝试的。 它不会在终端中显示任何错误，但是当它执行时，它似乎总是说“v.s. 代码没有响应”，如果没有该部分，它可以正常工作。

Answer 1

红色从(-220,-75) 开始，所以if RedTurtle.pos() == (220, 0): 永远不会是真的。但是，除此之外，您还混合了事件驱动编程和游戏循环编程。

在

wn.onkeypress(move_blue, key1)
wn.onkeypress(move_red, key2)
wn.listen()

您设置了 2 个事件并告诉应用开始侦听这些事件。发生时会调用相应的函数。

但是在这里：

keepPlaying = True
while keepPlaying:
   ...

您有一个繁忙的循环，不断检查海龟的位置。但这会阻止到达最后一行 wn.mainloop()。

您可以将该循环更改为检查海龟是否在终点线的函数。使用全局变量来标记游戏何时结束：

game_over = False
def move_blue():
    if not game_over:
        BlueTurtle.forward(10)
        check_for_win()

def move_red():
    if not game_over:
        RedTurtle.forward(10)
        check_for_win()

然后再把循环改成函数

def check_for_win():
    global game_over
    if BlueTurtle.pos() == (220, 0):
        pen.penup()
        pen.goto(-220, -220)
        pen.pendown()
        pen.write("The Blue Turtle hit the finish line - the blue turtle wins!" , font = 
("Arial", 20, "normal"))
        game_over = True
    if RedTurtle.pos() == (220, -75):
        pen.penup()
        pen.goto(-220, -220)
        pen.pendown()
        pen.write("The Red Turtle hit the finsh line = the red turtle wins!" , font =("Arial", 
20, "normal"))
        game_over = True

还有其他需要改进的地方，但我认为这是您问题的核心。