Turtle

Turtle is a basic shape drawing package.

If you have learn't how to use Logo lots of the commands will be familiar.

Setting up a Turtle screen

import turtle

t=turtle.Turtle()

wn=turtle.Screen()

t.fd(300)

wn.exitonclick()

#To use turtle graphics you must import this library at the top of #your program

#Create a turtle in a variable called t (Note the CAPITAL)

#Create a turtle screen in a variable called wn

#Move turtle t forward 300

#Allow turtle window to close when clicked on (goes at end)

This would output as

Basic Commands

import turtle

g=turtle.Turtle()

m=turtle.Turtle()

wn=turtle.Screen()

g.fd(50)

g.rt(90)

g.bk(50)

g.lt(90)

g.fd(50)

g.home()

m.pensize(10)

m.pencolor("red")

m.pu()

m.bk(200)

m.pd()

m.fd(150)

wn.exitonclick()

#fd for forward

#rt for right in degrees

#bk for back

#lt for left in degrees

#home goes back to start pos

#sets pensize

#sets line colour (NB American spelling

#pu to lift pen up and not draw

#pd to put pendown and draw

This would output as

NOTE How the home() command still draws a line home

Turtle Circle

import turtle

g=turtle.Turtle()

wn=turtle.Screen()

g.circle(100)

g.bk(150)

g.circle(40,180)

wn.exitonclick()

#import turtle commands

#setup variable g as turtle

#setup window for turtles

#draw a circle with radius of 100

#back 150

#draw a circle of radius 40 which only goes through #180 degrees (half circle)

#allow user to close the turtle window

This would output as

Using Turtle to demonstrate other Python Commands

Basic Functions

import turtle

g=turtle.Turtle()

wn=turtle.Screen()

def square():

g.fd(100)

g.rt(90)

g.fd(100)

g.rt(90)

g.fd(100)

g.rt(90)

g.fd(100)

g.rt(90)

square()

wn.exitonclick()

#Define a square function

#Running square function

This would output as a square

Find out more about functions

For i in range()

import turtle

g=turtle.Turtle()

wn=turtle.Screen()

for i in range(4):

g.fd(200)

g.lt(90)

wn.exitonclick()

#Repeat what is underneath 4 times

This would output as a square

To find out more about for i in range()

Variables

import turtle

g=turtle.Turtle()

wn=turtle.Screen()

diff = 90

for i in range(4):

g.fd(diff)

g.lt(diff)

wn.exitonclick()

#Create variable diff put 90 inside it

#Repeat everything underneath 4 times

#Forward whatever is in diff

#Left whatever is in diff

This would output as a square

Now the same program changing diff by one every time

import turtle

g=turtle.Turtle()

wn=turtle.Screen()

diff = 90

for i in range(20):

g.fd(diff)

g.lt(diff)

diff = diff +1

wn.exitonclick()

This would output as

To find out more about variables

Other Useful Turtle Commands

t=turtle.Turtle() or using RawTurtle at bottom

t.clear()

t.width(1)

t.shape("arrow")

t.speed(10)

t.setpos(-100,-100)

t.home()

t.stamp()

t.ht()

t.st()

t.pencolor("green")

t.fillcolor("Blue")

t.undo(6)

#Clears the screen of all lines drawn

#Sets line width

#turtle shape, “circle”, “square”, “triangle”, “classic”

#0=instant 1=slowest 10=fast 6=normal

#uses cartesian coordinates to move turtle

#turtle returns to start position

#Stamps a copy of turtle

#Hide turtle

#Show turtle

#set pen colour to green (can use rgb values)

#shapes filled will be blue inside #NOTE US Spelling of colour

#undo last 6 turtle commands

NOTE this doesn't reset the turtle(s) back to the start position

Turtle on a better screen canvas

I have found that the screen which comes with turtle can freeze in Windows

This code although more complex leads to a better screen

You have to define the turtle using RawTurtle instead of turtle.Turtle

from turtle import TurtleScreen, RawTurtle, TK

root = TK.Tk()

cv1 = TK.Canvas(root, width=500, height=500, bg="#ddffff")

cv1.pack()

s1 = TurtleScreen(cv1)

s1.bgcolor("orange")

p = RawTurtle(s1)

t = RawTurtle(s1)

#Insert turtle moves here

TK.mainloop()

#Set width and height of #screen

#Could use(0.85, 0.85, 1)

#Colour of background

#Define turtle in variable p

#Define turtle in variable t

#This must go on the end

Programming a button below your Turtle Screen

from turtle import TurtleScreen, RawTurtle, TK

root = TK.Tk()

cv1 = TK.Canvas(root, width=500, height=500, bg="#ddffff")

cv1.pack()

s1 = TurtleScreen(cv1)

s1.bgcolor("orange")

p = RawTurtle(s1)

#define what your button is going to do inside a function

def rt90():

p.rt(90)

#code to create the button, text sets what text will be on button,

#command refers back to function you created above

right90=TK.Button(text="Right 90",command=rt90)

#This line places the button on the canvas

#side determines where (left right centre)

right90.pack(side="left")

TK.mainloop()

This example shows two buttons after the square button has been pressed

The drawing canvas has been reduced to 200x200

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