4.5.10.1. Demo¶

Python comes with a nice demonstartion program that allows you to learn some simple programming concepts while moving a turtle on the screen. It can be started with

python -m turtledemo

4.5.10.2. Program example¶

You can also create programs with your favorite editor and run it. Let us put the following code into the program turtle_demo.py. Never save a file with the name turtle.py because python will import it instead of the built-in turtle import that you need.

import turtle

window = turtle.Screen() 
robot = turtle.Turtle() 

robot.forward(50)   # Moves forward 50 pixels
robot.right(90)     # Rotate clockwise by 90 degrees

robot.forward(50)
robot.right(90)

robot.forward(50)
robot.right(90)

robot.forward(50)
robot.right(90)

turtle.done()

window.mainloop()

After saving it you can run it from a terminal with

$ python turtle_demo.py

4.5.10.3. Shape¶

shapes: “arrow”, “turtle”, “circle”, “square”, “triangle”, “classic”

You can change the shape of your turtle to any of these shapes with the Turtle method shape(name). For example, if you have an instance of the Turtle class called robot, you can make it appear as a turtle by calling robot.shape("turtle").

You can add your own shapes with the following functions:

turtle.register_shape(name, shape=None)

turtle.addshape(name, shape=None)

There are three different ways to call this function:

name is the name of a gif-file and shape is None: Install the corresponding image shape.

window.register_shape("turtle.gif")

Note: Image shapes do not rotate when turning the turtle, so they do not display the heading of the turtle!

name is an arbitrary string and shape is a tuple of pairs of coordinates: Install the corresponding polygon shape.

window.register_shape("triangle", ((5,-3), (0,5), (-5,-3)))

name is an arbitrary string and shape is a (compound) Shape object: Install the corresponding compound shape.

Add a turtle shape to TurtleScreen’s shapelist. Only thusly registered shapes can be used by issuing the command shape(shapename).

4.5.10.4. Links¶

• http://openbookproject.net/thinkcs/python/english3e/hello_little_turtles.html
• https://docs.python.org/3/library/turtle.html