1. Introduction to turtle

Turtles are objects that can be directed to move about on a screen.

The turtle can draw on the screen as it moves.

The turtle graphics window has a default coordinate system, where the origin (0, 0) is at the center of the window, the positive x-axis points to the right, the positive y-axis points to the top, and the angle 0 degrees corresponds to the rightward direction.

This section begins with some basic syntax for the screen and turtles.

Basic shapes, squares, rectangles and triangles, are drawn via sequencing, iteration and definitions.

The houses section puts together modules that group similar code together.

Module code is documented using a standard documentation layout.

---

1.1. turtle documentation

Docs: https://docs.python.org/3.12/library/turtle.html#module-turtle

See the docs for a full listing of methods.

---

1.2. Tutorial

Tutorial: https://www.geeksforgeeks.org/python-turtle-tutorial/

This has a large number of examples for specific syntax.

---

1.3. Academy

Academy: https://pythonturtle.academy/

Excellent, extensive challenges from easy to very hard, with images of what to make, with some sample code.

---

1.4. turtle uses tkinter

The turtle module uses tkinter for the underlying graphics.

Some of the methods have dual use depending on whether arguments are passed or not.

e.g s.bgcolor(“black”) sets the screen colour, while s.bgcolor() returns “black”.

---

1.5. Import turtle

Import the turtle library.

import turtle

---

1.6. Screen and turtles

For standalone usage, not within a tkinter based script, there are 2 classes used to set up the screen and to set up a turtle to draw with.

screen = turtle.Screen() sets up the window to draw in.

turtle = turtle.Turtle() sets up a turtle to draw with.

import turtle

screen = turtle.Screen()
turtle = turtle.Turtle()

---

In the sample code, the screen object is shortened to s. s = turtle.Screen()

In the sample code, the turtle object is shortened to t. t = turtle.Turtle()

Shortening object variables makes method calls on these objects shorter to type and read.

e.g. s.bgcolor("black") instead of screen.bgcolor("black")

e.g. t.pendown() instead of turtle.pendown()

import turtle

s = turtle.Screen()
t = turtle.Turtle()

---

1.7. Colours

Colours can be specified by (r,g,b), or hexadecimal digits “#33cc8c”, or colorstrings, which is a Tk color specification string, such as “red”, “yellow”. For hexadecimal vlaues see: https://www.tcl.tk/man/tcl8.4/TkCmd/colors.html For rgb vlaues see: https://www.tcl.tk/man/tcl8.5/TkCmd/colors.html