算下蟒蛇的生活

Question

I am trying to create a simple python turtle game where the turtle needs to make it to the circle, while avoiding the moving square. I would like the code to count down lives and move the turtle back to the beginning until there are 0 lives left. The code below allows for one play and then the motion loop does not repeat.

I have tried a recursive function (move(3)), but then the onkey commands don't work....

import turtle, random, time

#background
canvas = turtle.Screen()
canvas.bgcolor('black')

#Pen
pen = turtle.Turtle()
pen.penup()
pen.color('white')
pen.hideturtle()
pen.penup()

#Lilypad
pad = turtle.Turtle()
pad.hideturtle()
pad.color('yellow')
pad.shape('circle')
pad.penup()
pad.setposition(0,290)
pad.showturtle()

#Turtle
player = turtle.Turtle()
player.hideturtle()
player.shape('turtle')
player.color('green')
player.penup()
player.left(90)
player.setposition(0, -290)
player.showturtle()

#truck
truck1 = turtle.Turtle()
truck1.hideturtle()
truck1.shape('square')
truck1.color('blue')
truck1.penup()
truck1.showturtle()

speed = random.randint(1,5)

def move():
  #move player and truck
  player.forward(2)
  truck1.forward(speed)
  if truck1.xcor() > 300 or truck1.xcor() < -300:
    truck1.right(180)

 #win if hit the lilypad
  if player.distance(pad)<10:
    pen.penup()
    pen.setposition(0,-50)
    pen.write('You win!', align='left', font=('Arial', 36, 'normal'))
    done()

  #lose a life if hit the truck
  if player.distance(truck1) < 30:
    player.setposition(0,-290)
    life = life - 1
    while life > 0:
      pen.penup()
      pen.setposition(0,-60)
      pen.write('Try again', align='left', font=('Arial', 36, 'normal'))
      time.sleep(1)
      pen.clear()
      move()

    #game over if 0 lives left
    pen.penup()
    pen.setposition(0,-60)
    pen.write('Game over!', align='left', font=('Arial', 36, 'normal'))
    done()

  canvas.ontimer(move,10)

canvas.onkey(lambda:player.setheading(90),'Up')
canvas.onkey(lambda:player.setheading(180),'Left')
canvas.onkey(lambda:player.setheading(0),'Right')
canvas.onkey(lambda:player.setheading(270),'Down')
canvas.listen()

life = 3
move()
canvas.mainloop()

Answer 1

The key to this is to move all your initialization code into a function, which invokes your move() function as it's last step. The first thing that the initialization code does is call canvas.clear() which pretty much wipes out everything. Then your move() function makes a choice at the end whether to call itself on the next timer iteration, or call the initialize code on the next timer iteration to reset everything and start a new game.

Below is your code reworked along the above lines as well as various teaks:

from turtle import Screen, Turtle
from random import randint
from time import sleep

FONT = ('Arial', 36, 'normal')

def initialize():
    global pen, pad, player, truck, speed, life

    canvas.clear()  # assume that this resets *everything*
    # background
    canvas.bgcolor('black')

    # Pen
    pen = Turtle(visible=False)
    pen.color('white')
    pen.penup()

    # Lilypad
    pad = Turtle('circle', visible=False)
    pad.color('yellow')
    pad.penup()
    pad.setposition(0, 290)
    pad.showturtle()

    # Turtle
    player = Turtle('turtle', visible=False)
    player.color('green')
    player.penup()
    player.setheading(90)
    player.setposition(0, -290)
    player.showturtle()

    # truck
    truck = Turtle('square', visible=False)
    truck.color('blue')
    truck.penup()
    truck.showturtle()

    speed = randint(1, 5)

    canvas.onkey(lambda: player.setheading(90), 'Up')
    canvas.onkey(lambda: player.setheading(180), 'Left')
    canvas.onkey(lambda: player.setheading(0), 'Right')
    canvas.onkey(lambda: player.setheading(270), 'Down')
    canvas.listen()

    life = 3

    move()

def move():
    global life

    # move player and truck
    player.forward(2)

    truck.forward(speed)
    if not -300 < truck.xcor() < 300:
        truck.right(180)

    # lose a life if hit the truck
    if player.distance(truck) < 20:
        player.setposition(0, -290)
        life -= 1

        if life > 0:
            pen.setposition(0, -60)
            pen.write('Try again', font=FONT)
            sleep(1)
            pen.clear()

    # win if hit the lilypad
    if player.distance(pad) < 20:
        pen.setposition(0, -50)
        pen.write('You win!', font=FONT)
        canvas.ontimer(initialize, 1000)
    elif life == 0:  # game over if 0 lives left
        pen.setposition(0, -60)
        pen.write('Game over!', font=FONT)
        canvas.ontimer(initialize, 1000)
    else:
        canvas.ontimer(move, 10)

canvas = Screen()

pen = None
pad = None
player = None
truck = None
speed = -1
life = -1

initialize()

canvas.mainloop()

This should let you play over again whether you win or run out of lives.