KTurtle/C3/Special-Commands-in-KTurtle/English

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Title of the tutorial: Special-Commands-in-KTurtle

Author: ITfC Bangaluru

Key words: learn, random, clear commands, Video tutorial.


Visual Cue Narration
Slide Number 1

Title slide

Hello everybody.

Welcome to this tutorial on Special Commands in KTurtle.

Slide Number 2

Learning Objectives

In this tutorial, we will learn about
  • “learn” command and
  • “random” Command
Slide Number 3

System Requirement

To record this tutorial I am using,

Ubuntu Linux OS version. 12.04.

KTurtle version. 0.8.1 beta.

Slide Number 4

Pre-requisites

We assume that you have basic working knowledge of KTurtle

If not,

for relevant tutorials, please visit our website.

http://spoken-tutorial.org

Switch to KTurtle Application

Dash home >>In the Search bar type KTurtle.

Click on the KTurtle icon.

Let's open a new KTurtle Application.

Click on Dash home.

In the Search bar, type KTurtle.

Click on the KTurtle icon.

Let's first look at “learn” command
Slide Number 5

learn command

learn is special command as it is used to create your own commands.

'learn' Command can takes input and returns output.

New command Let's take a look at how a new command is created.
Zoom text Let me zoom the program text to have a clear view.

Switch to Kturtle Window

repeat 4

{

forward 10

turnleft 90

}

Let's type a code in the editor to draw a square:

repeat 4 within curly brackets

{ forward 10

turnleft 90

}

Here the number 10 specfies the length of the side of the square.

Highlight learn and square commands Now let's learn the commands involved to draw a square, using the learn command.

We will name of this set of commands to draw a square as square.

The command 'learn' is followed by the name of the command to be learnt, in this case it is a square.

Type the code Let's type the following code

learn space square space $x

let's include curly brackets {

repeat 4 {

let's replace 10 by $x

forward $x

turnleft 90 } }

Highlight square command New command that we have defined is called a square.

square takes one input argument, $x to set the size of the square.

Note that when you run this code, square returns no output.

The command learn is just 'learning' other command square to be used later.

square command can now be used like a normal command in the rest of the code.

Type the code Let me add few more lines here.

Let's type

learn square $x

{

repeat 4

{

forward $x

turnleft 90

} }

go 200,200

square 100

Using the command square 100 Turtle draws a square of dimension 100.

Run the code Let's click on Run code now

Turtle draws a square on the canvas.

Replace 100 by 50. Let's now replace 100 by 50.
Run the code Let's run again

Turtle draws another square with dimension 50.

Please note that this command can be used only within the scope of this program

Clear code I will clear the current code from editor.

Type “clear” command and Run to clean the canvas.

Next we will learn about “random” command.
Slide Number 6

"random" command

  • random command takes input and returns output.
  • Syntax for the random command is “random X,Y”
  • where X and Y are two inputs.
  • X sets minimum output and Y sets maximum output.
  • Output is a randomly chosen number between X and Y.
Let's put the “random” command to use in the application.
Show code I already have a code in a text editor.

Let me explain the code.

Highlight reset “reset” command sets Turtle to default position
Highlight random 1,20 Here, the command random 1,20 selects a number which is equal or greater than 1 and equal or less than 20,

and assigns it to the variable x.

Highlight repeat 36

{

forward $x

turnleft 10 }

repeat command and the commands within curly brackets draw a circle
reset

$x=random 1,20

repeat 36

{

forward $x

turnleft 10

}

I will copy the code from text editor and paste it into KTurtle's editor.

Pause the tutorial and type the program into your KTurtle editor.

Resume the tutorial after typing the program

Run the code When we run this code,

Turtle draws a circle with radius between 1 and 20 on the canvas.

Let us execute this code a few times,

You can see that a circle with different size is generated each time.

Every time you execute this code, a circle with a different radius is drawn on the canvas.

Let us now use both learn and random commands in an example.

clear current code I will clear the current code from the editor type clear command and Run to clean the canvas.
Show code I already have a program in the Text editor.

I will explain the code now.

Highlight reset

“reset” command sets Turtle to its default position.
Highlight canvassize 300,300 canvassize 300,300 sets the width and height of the canvas to 300 pixels each.
Highlight $R, $G, and $B $R, $G, and $B are three variables to which I am assigning random values between 0 and 255.
Highlight canvascolor $R,$G,$B , In the command canvascolor $R,$G, and $B ,

the Red-Green-Blue combination is replaced by the values assigned to the variables R, G, and B in the previous step.

The canvas color is randomly set when this command is executed.

Highlight $red, $green and $blue $red, $blue, $green are another set of variables

to which random values between 0 and 255 are assigned randomly.

pencolor $red, $blue and $green the Red-Blue -Green combination values are replaced by the variables

$red, $green and $blue to which random values were assigned in the previous step.

Highlight pencolor $red,$blue,$green The color of the pen is also set randomly when the command is executed.
Highlight penwidth 2 penwidth 2 sets the width of pen to 2 pixels.
code to a circle Next I have entered the code to learn to draw a circle.

Here $x represents the size of the circle.

repeat command followed by the code in curly brackets draws a circle.

Highlight go commands and circle commands

The next set of commands that is go commands followed by circle commands draw circles with the specified sizes.

Example circle For example:

circle with size 5 draws a circle with size 5

At the co-ordinates specified at X and Y positions in the go command.

For each circle, I have specified different positions on the canvas.

reset

canvassize 300,300

$R= random 0,255

$G=random 0,255

$B=random 0,255

canvascolor $R,$G,$B

$red=random 0,255

$blue=random 0,255

$green=random 0,255

pencolor $red,$blue,$green

penwidth 2

learn circle $x{

repeat 36{

forward $x

turnleft 10 } }

go 85,85

circle 5

go 115,115

circle 5

go 145,145

circle 5

go 190,190

circle 5

go 220,220

circle 10

go 0,0

I will copy this code from text editor and paste it into KTurtle's editor.

Pause the tutorial here and type the program into your KTurtle editor.

Resume the tutorial after typing the program.

Execute code I will execute this code in Fullspeed.

You can execute this code at any of the speeds specified in the Run option.

I will run this code a few times.

You can see the difference in randomly set values of pen color and canvas color.

Note the change in the color of the pen and the canvas on each execution.

You can execute the code how many ever times you want and note the changes in the randomly set values of the pen and canvas.

With this we come to the end of this tutorial.

Let's summarize

Slide Number 7

Summary

In this tutorial we have learnt about,
  • “learn” command and
  • “random” command.
Slide Number 8

Switch to KTurtle Window & Show Assignment

As an assignment for you to solve,
  • Using learn command, draw a
  • pentagon
  • square
  • rectangle
  • hexagon on all four corners of your canvas and
  • a circle at the centre of the canvas.
  • Using the “random” command create various colors and
  • Customize your geometric shapes and canvas.
Slide number 9

Acknowledgement

Watch the video available at this URL

http://spoken-tutorial.org/What is a Spoken Tutorial It summarises the Spoken Tutorial project

If you do not have good bandwidth, you can download and watch it

Slide Number 10 The Spoken Tutorial Project Team :

Conducts workshops using spoken tutorials

Gives certificates to those who pass an online test

For more details, please write to

contact@spoken-tutorial.org

Slide number 11 Spoken Tutorial Project is a part of the Talk to a Teacher project

It is supported by the National Mission on Education through ICT, MHRD, Government of India

More information on this Mission is available at this link

http://spoken-tutorial.org/NMEICT-Intro ]

This script is contributed by IT for change, Bangaluru.

This is Madhuri Ganpathi from IIT Bombay signing off. Thank you for joining.

Contributors and Content Editors

Madhurig