交通灯乌龟Python

Question

让我的程序等待用户键Spacebar开始程序，我遇到了一些麻烦。我必须使用Turtle图形来构建一个Python程序，以模拟该程序开始使用空白屏幕执行的交通信号灯。还可以创建一个按键事件（“空间”）和处理程序，以绘制带有绿灯的停止灯，并带有一个带有计时器事件的事件处理程序，该时间表事件在5秒钟内就发生了。这是我拥有的。有人有建议吗？

import turtle

wn = turtle.Screen()
wn.title("traffic light")
wn.bgcolor("sky blue")

def draw_housing():
    house = turtle.Turtle()
    house.pensize(3)
    house.color("black", "darkgrey")
    house.begin_fill()
    house.forward(80)
    house.left(90)
    house.forward(200)
    house.circle(40, 180)
    house.forward(200)
    house.left(90)
    house.end_fill()

def draw_post():
    post = turtle.Turtle()
    post.pensize(3)
    post.color("black")
    post.penup()
    post.goto(50,0)
    post.pendown()
    post.begin_fill()
    for i in range(2):
        post.right(90)
        post.forward(80)
        post.right(90)
        post.forward(25)
    post.end_fill()

# This function will draw 3 black lights which will work as off signal lights

def draw_off_lights():
    distance = 50
    for i in range(3):
        off_turtle = turtle.Turtle()
        off_turtle.speed(0)
        off_turtle.penup()
        off_turtle.forward(40)
        off_turtle.left(90)
        off_turtle.forward(distance)
        off_turtle.shape("circle")
        off_turtle.shapesize(3)
        off_turtle.fillcolor("white")
        distance+=70

draw_post()
draw_housing()
draw_off_lights()


light = turtle.Turtle()
light.penup()
# Position first onto the place where the green light should be
light.forward(40)
light.left(90)
light.forward(50)
light.shape('circle')
light.shapesize(3)
light.fillcolor('green')

# This variable holds the current state of the machine
state_num = 0

def state_machine():
    global state_num
    
    if state_num == 0: # Transition from state 0 to state 1
        state_num = 1
        light.forward(70)
        light.fillcolor('yellow')
        wn.ontimer(state_machine, '2000')
    elif state_num == 1: # Transition from state 1 to state 2
        state_num = 2
        light.forward(70)
        light.fillcolor('red')
        wn.ontimer(state_machine, '5000')
    else: # Transition from state 2 to state 0
        state_num = 0
        light.back(140)
        light.fillcolor('green')
        wn.ontimer(state_machine, '5000')
        

state_machine()
wn.onkey(draw_post, 'space')
wn.listen
wn.mainloop()

Answer 1

以下是我对您的代码进行的重新处理，该代码解决了讨论的问题（listan（），将绘制功能的调用捆绑到一个由onkey，state_num 未定义）它还解决了您可能会发现的其他一些问题，并通过使绘图中心在窗口中而不是中心的右侧来简化代码：

from turtle import Screen, Turtle

DISTANCE = 70

def draw_housing():
    housing.begin_fill()
    housing.forward(40)
    housing.left(90)
    housing.forward(200)
    housing.circle(40, 180)
    housing.forward(200)
    housing.left(90)
    housing.forward(40)
    housing.end_fill()

def draw_post():
    post.begin_fill()
    for _ in range(2):
        post.forward(12.5)
        post.right(90)
        post.forward(80)
        post.right(90)
        post.forward(12.5)
    post.end_fill()

# This function will draw 3 black lights which will work as off signal lights

def draw_off_lights():
    off_turtle.forward(50)

    for _ in range(3):
        off_turtle.stamp()
        off_turtle.forward(DISTANCE)

def user_started():
    screen.onkey(None, 'space')  # prevent double activation

    draw_post()
    draw_housing()
    draw_off_lights()

    # Position first onto the place where the green light should be
    light.forward(50 + DISTANCE*2)
    light.showturtle()

    state_machine()

screen = Screen()
screen.title("traffic light")
screen.bgcolor("sky blue")

housing = Turtle()
housing.hideturtle()
housing.pensize(3)
housing.fillcolor("darkgrey")

post = Turtle()
post.hideturtle()
post.pensize(3)

off_turtle = Turtle()
off_turtle.hideturtle()
off_turtle.shape("circle")
off_turtle.shapesize(3)
off_turtle.penup()
off_turtle.setheading(90)

light = off_turtle.clone()
light.fillcolor('green')

# This variable holds the current state of the machine
state_num = 2

def state_machine():
    global state_num

    if state_num == 0:  # Transition from state 0 to state 1
        state_num = 1
        light.forward(DISTANCE)
        light.fillcolor('yellow')
        screen.ontimer(state_machine, 2000)
    elif state_num == 1:  # Transition from state 1 to state 2
        state_num = 2
        light.forward(DISTANCE)
        light.fillcolor('red')
        screen.ontimer(state_machine, 5000)
    else:  # Transition from state 2 to state 0
        state_num = 0
        light.back(DISTANCE*2)
        light.fillcolor('green')
        screen.ontimer(state_machine, 5000)

screen.onkey(user_started, 'space')
screen.listen()

screen.mainloop()