4.4
GRAPHICS IN PYTHON USING TURTLE
Introduction to
Turtle
Turtle is a Python
module used to create drawings, shapes, patterns and designs on the screen. It
works by moving a virtual pen called a turtle using simple commands.
Turtle helps
beginners learn programming through visual output. Instead of printing only
text, it can draw shapes, patterns, and pictures.
Features of turtle
|
Feature |
Description |
|
Easy Learning |
Helps learn
programming through drawings and graphics. |
|
Fun Learning |
Makes coding
interesting by creating shapes and designs. |
|
Creativity |
Allows users to
create different drawings and patterns. |
|
Easy Error
Detection |
Mistakes can be
identified easily by looking at the drawing. |
|
Learn Shapes |
Helps understand
shapes, angles, and positions. |
|
Better Thinking |
Improves logical
thinking by following drawing steps. |
Basic Structure of
a Turtle Program
import turtle
Meaning: Imports the Turtle
module so Turtle commands can be used.
Simple
Explanation: Python
cannot draw by itself. This command loads the Turtle library.
Without it: Turtle programs
will not work.
import turtle as t
Meaning: Imports the Turtle
module and gives it a short name (t).
Simple
Explanation: Instead
of writing turtle every time, we can write only t.
screen =
turtle.Screen( )
Meaning: Creates a drawing
window where the turtle can move and draw.
Simple
Explanation: It
opens a blank screen or canvas for drawing.
Used for:
- Changing
background color
- Setting
window size
- Changing
window title
- Detecting
keyboard and mouse actions
pen = turtle.Turtle( )
Meaning: Creates a turtle object and stores it in the variable pen.
Simple
Explanation: This
creates the drawing turtle that will move and draw on the screen.
turtle.done( )
Meaning:
Keeps the Turtle graphics window open until it is closed manually.
Simple
Explanation:
Stops the program from closing immediately after drawing.
Without done(),
the window may close immediately after the drawing finishes. Humans do enjoy
spending ten minutes drawing a square only to watch the window vanish
instantly. 🐢
turtle.mainloop( )
Meaning:
Keeps the Turtle window open and waits for user actions.
Simple
Explanation:
It allows the program to keep running until the user closes the window.
Uses
- Keeps
the window open
- Waits
for keyboard or mouse events
- Prevents
the program from ending immediately
🐢 Important Turtle Commands
1. Turtle Motion
Commands
Turtle motion
commands are used to move the turtle on the screen. The turtle can move
forward, backward, left, and right while drawing.
|
Command |
Definition |
Syntax |
Example |
|
forward() / fd() |
Moves the turtle
forward by a specified distance. |
forward(distance) |
pen.forward(100) |
|
backward() /
bk() |
Moves the turtle
backward by a specified distance. |
backward(distance) |
pen.backward(50) |
|
right() / rt() |
Turns the turtle
clockwise by a specified angle. |
right(angle) |
pen.right(90) |
|
left() / lt() |
Turns the turtle
anticlockwise by a specified angle. |
left(angle) |
pen.left(90) |
2. Shape Command
|
Command |
Definition |
Syntax |
Example |
|
circle() |
Draws a circle
with a specified radius. |
circle(radius) |
pen.circle(50) |
3. Color and Style
Commands
These commands are
used to change the appearance of drawings.
|
Command |
Definition |
Syntax |
Example |
|
color() |
Changes the pen
color. |
color(color_name) |
pen.color("red") |
|
fillcolor() |
Sets the fill
color of a shape. |
fillcolor(color_name) |
pen.fillcolor("yellow") |
|
pensize() |
Changes the
thickness of the drawing line. |
pensize(size) |
pen.pensize(5) |
|
speed() |
Controls the
drawing speed of the turtle. |
speed(value) |
pen.speed(0) |
Speed Values
0 – Fastest , 1 –
Slowest , 3 – Slow , 5 – Medium , 10 - Fast
4. Pen Control
Commands
These commands
control whether the turtle draws while moving.
|
Command |
Definition |
Syntax |
Example |
|
penup() |
Lifts the pen so
movement does not draw lines. |
penup() |
pen.penup() |
|
pendown() |
Places the pen
down so movement draws lines. |
pendown() |
pen.pendown() |
Example
pen.penup()
pen.forward(100)
pen.pendown()
pen.forward(100)
The first movement
draws nothing. The second movement draws a line.
5. Position
Commands
These commands
control the turtle's position on the screen.
|
Command |
Definition |
Syntax |
Example |
|
goto() |
Moves the turtle
to a specific coordinate (x, y). |
goto(x,y) |
pen.goto(100,50) |
|
home() |
Returns the
turtle to the starting position (0,0). |
home() |
pen.home() |
|
Direction |
Coordinate Value |
|
Right |
Positive X (+X) |
|
Left |
Negative X (-X) |
|
Up |
Positive Y (+Y) |
|
Down |
Negative Y (-Y) |
📌 The center of the Turtle screen is (0,0).
6. Fill Commands
These commands are
used to fill shapes with color.
|
Command |
Definition |
Syntax |
Example |
|
begin_fill() |
Starts filling a
shape with color. |
begin_fill() |
pen.begin_fill() |
|
end_fill() |
Ends filling and
fills the shape. |
end_fill() |
pen.end_fill() |
7. Text Command
|
Command |
Definition |
Syntax |
Example |
|
write() |
Displays text on
the screen. |
write(text) |
pen.write("Hello
Python") |
Example
pen.write("Welcome
to Turtle Graphics")
8. Screen Commands
|
Command |
Definition |
Syntax |
Example |
|
clear() |
Removes all
drawings from the screen. |
clear() |
pen.clear() |
|
reset() |
Clears the
screen and returns the turtle to the starting position. |
reset() |
pen.reset() |
|
hideturtle() |
Hides the turtle
cursor. |
hideturtle() |
pen.hideturtle() |
|
showturtle() |
Displays the
turtle cursor. |
showturtle() |
pen.showturtle() |
|
bgcolor() |
Changes the
screen background color. |
screen.bgcolor(color) |
screen.bgcolor("lightblue") |
|
turtle.done() |
Keeps the Turtle
window open. |
turtle.done() |
turtle.done() |
9. Shape Command
pen.shape("turtle")
Definition : The shape()
function is used to change the appearance of the turtle cursor.
Syntax
pen.shape("turtle")
Common Shapes
|
Shape |
Example |
|
"arrow" |
Default arrow
cursor |
|
"turtle" |
Turtle shape |
|
"circle" |
Circle shape |
|
"square" |
Square shape |
|
"triangle" |
Triangle shape |
|
"classic" |
Classic turtle
cursor |
