Python海龟等待按键
我想通过让用户在每次移动前按一个键,一步一步地跟随海龟的绘画 我可以通过以下方式请求用户输入:Python海龟等待按键,python,turtle-graphics,fractals,Python,Turtle Graphics,Fractals,我想通过让用户在每次移动前按一个键,一步一步地跟随海龟的绘画 我可以通过以下方式请求用户输入: def wait(): input('Press a key') 但这是一个可怕的解决方案,因为焦点离开了海龟窗口 我知道screen.listen(),可以使用screen.onkeypress()-例如my_screen.onkeypress('wait'),但不确定如何实现这一点 编辑:我意识到我应该更具体一些。我试图追踪科赫曲线的递归。到目前为止,我的代码如下: import tur
def wait():
input('Press a key')
但这是一个可怕的解决方案,因为焦点离开了海龟窗口
我知道screen.listen()
,可以使用screen.onkeypress()
-例如my_screen.onkeypress('wait')
,但不确定如何实现这一点
编辑:我意识到我应该更具体一些。我试图追踪科赫曲线的递归。到目前为止,我的代码如下:
import turtle
def koch(t, order, size):
"""
Make turtle t draw a Koch fractal of 'order' and 'size'.
Leave the turtle facing the same direction.
"""
wait_for_keypress()
if order == 0: # The base case is just a straight line
t.forward(size)
else:
koch(t, order-1, size/3) # Go 1/3 of the way
t.left(60)
koch(t, order-1, size/3)
t.right(120)
koch(t, order-1, size/3)
t.left(60)
koch(t, order-1, size/3)
def wait_for_keypress():
input('Press a key') # There must be a better way
t = turtle.Turtle()
s = turtle.Screen()
s.listen()
koch(t, 3, 100)
turtle.done()
这听起来像是递归生成器的工作!我们开始运行分形代码,但我们使用
yield
和yield from
使其停止前进的每一步。然后,我们让屏幕单击事件在生成器上执行next()
:
from turtle import Turtle, Screen
def koch(t, order, size):
"""
Make turtle t draw a Koch fractal of 'order' and 'size'.
Leave the turtle facing the same direction.
"""
if order == 0:
t.forward(size) # The base case is just a straight line
yield
else:
yield from koch(t, order - 1, size / 3) # Go 1/3 of the way
t.left(60)
yield from koch(t, order - 1, size / 3)
t.right(120)
yield from koch(t, order - 1, size / 3)
t.left(60)
yield from koch(t, order - 1, size / 3)
def click_handler(x, y):
screen.onclick(None) # disable handler while in handler
try:
next(generator)
except StopIteration:
return
screen.onclick(click_handler)
screen = Screen()
turtle = Turtle()
generator = koch(turtle, 3, 200)
screen.onclick(click_handler)
screen.mainloop()
运行程序。每次在窗口上单击鼠标时,都会得到Koch分形的附加部分。我们还可以通过一个键事件来实现这一点,使导入和koch()
例程保持不变:
...
def key_handler():
screen.onkey(None, "Up") # disable handler while in handler
try:
next(generator)
except StopIteration:
return
screen.onkey(key_handler, "Up")
screen = Screen()
turtle = Turtle()
generator = koch(turtle, 3, 200)
screen.onkey(key_handler, "Up")
screen.listen()
screen.mainloop()
请注意,这是对turtle图形窗口中的向上箭头键的响应,而不是对控制台中的键的响应。如下更改您的功能:
def wait_for_keypress():
print("'Press a key'")
fd = sys.stdin.fileno()
try:
tty.setraw(fd)
ch = sys.stdin.read(1)
except:
pass
基于
注:
您必须导入sys
、termios
和tty