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

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Time Narration
00:01 Hello everybody. Welcome to this tutorial on Special Commands in KTurtle.
00:08 In this tutorial, we will learn about:
  • “learn” command and
  • “random” command.
00:15 To record this tutorial, I am using:
  • Ubuntu Linux OS version 12.04
  • KTurtle version 0.8.1 beta.
00:28 We assume that you have basic working knowledge of 'KTurtle'.
00:33 If not, for relevant tutorials, please visit our website:

http://spoken-tutorial.org

00:39 Let's open a new KTurtle Application.
00:42 Click on Dash home.
00:44 In the Search bar, type: "kturtle".
00:47 Click on the KTurtle icon.
00:50 Let's first look at learn command.
00:53 learn is a special command as it is used to create your own commands.
01:01 learn command takes input and returns output.
01:05 Let's take a look at how a new command is created.
01:10 Let me zoom the program text to have a clear view.
01:14 Let's type a code in the editor to draw a square:
01:19 repeat 4 within curly brackets

{ forward 10 turnleft 90 }

01:31 Here, the number 10 specifies the length of the side of the square.
01:37 Now, let's learn the commands involved to draw a square, using the learn command.
01:45 We will name this set of commands, to draw a square, as square.
01:50 The command 'learn' is followed by the name of the command to be learnt. In this case, it is "square".
01:59 Let us type the following code:
02:02 learn space square space $x.
02:10 Let's include curly brackets.
02:13 Let's replace 10 by $x.
02:19 New command that we have defined is called square.
02:23 square takes one input argument, $x, to set the size of the square.
02:31 Note that when you run this code, square returns no output.
02:37 The command learn is just 'learning' other command square, to be used later.
02:43 square command can now be used like a normal command in the rest of the code.
02:51 Let me add few more lines here.
02:54 Let's type:

go 200,200 square 100

03:04 Using the command square 100, Turtle draws a square of dimension 100.
03:11 Let's Run the code now.
03:13 Turtle draws a square on the canvas.
03:17 Let's now replace 100 by 50.
03:22 Let's run again.
03:23 Turtle draws another square with dimension 50.
03:28 Please note that this command can be used only within the scope of this program.
03:35 I will clear the current code from editor.
03:38 Type "clear" command and Run to clean the canvas.
03:44 Next, we will learn about “random” command.
03:48 random command takes input and returns output.
03:52 Syntax for the random command is: “random X,Y”
03:57 where X and Y are two inputs.
04:01 X sets minimum output and Y sets maximum output.
04:07 Output is randomly chosen number between X and Y.
04:13 Let's put the “random” command to use in the application.
04:18 I already have a code in a text-editor.
04:22 I will explain the code now.
04:24 “reset” command sets Turtle to default position.
04:29 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'.
04:44 repeat command and the commands within curly brackets draw a circle.
04:51 I will copy the code from text editor and paste it into KTurtle's editor.
04:58 Pause the tutorial here and type the program into your KTurtle editor.
05:03 Resume the tutorial after typing the program.
05:08 When we run this code,
05:10 Turtle draws a circle with radius between 1 and 20 on the canvas.
05:16 Let us execute this code a few times.
05:20 You can see that a circle with a different size is generated each time.
05:26 Every time you execute this code, a circle with a different radius is drawn on the canvas.
05:33 Let us now use both learn and random commands in an example.
05:39 I will clear the current code from the editor. Type "clear" command and Run to clean the canvas.
05:48 I already have a program in the Text-editor.
05:52 I will explain the code now.
05:55 “reset” command sets Turtle to its default position.
06:00 canvassize 300,300 sets the width and height of the canvas to 300 pixels each.
06:09 $R, $G and $B are three variables to which I am assigning random values between 0 and 255.
06:19 In the command canvascolor $R, $G and $B,
06:23 the Red-Green-Blue combination is replaced by the values assigned to the variables 'R', 'G' and 'B' in the previous step.
06:34 The canvas color is randomly set when this command is executed.
06:41 $red, $blue, $green are another set of variables
06:45 to which random values between 0 and 255 are assigned randomly.
06:53 pencolor $red, $blue and $green the Red-Blue-Green combination values are replaced by the variables.
07:02 $red, $green and $blue to which random values were assigned in the previous step.
07:10 The color of the pen is also set randomly when the command is executed.
07:18 penwidth 2 sets the width of pen to 2 pixels.
07:25 Next, I have entered the code to learn to draw a circle.
07:30 Here $x represents the size of the circle.
07:35 repeat command followed by the code in curly brackets draws a circle.
07:43 The next set of commands, that is, go command followed by circle command draw circles with the specified sizes.
07:54 For example: circle with size 5, draws a circle with size 5
08:01 at the co-ordinates specified at 'X' and 'Y' positions, in the go command.
08:09 For each circle, I have specified different positions on the canvas.
08:16 I will copy the code from text-editor and paste it into KTurtle's editor.
08:23 Pause the tutorial here and type the program into your KTurtle editor.
08:29 Resume the tutorial after typing the program.
08:33 I will execute this code in Fullspeed.
08:37 You can execute this code at any of the speeds specified in the Run option.
08:43 I will run this code a few times.
08:46 You can see the difference in randomly set values of pen color and canvas color.
08:54 Note the change in the color of the pen and the canvas on each execution.
09:01 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.

09:15 With this we come to the end of this tutorial.
09:20 Let's summarize.
09:22 In this tutorial, we have learnt about:
  • “learn” command and
  • “random” command.
09:30 As an assignment for you to solve,
09:32 using learn command- draw a
  • pentagon
  • square
  • rectangle
  • hexagon

on all four corners of your canvas and

09:45 a circle at the centre of the canvas.
09:49 Using the “random” command, create various colors and
09:55 customize your geometric shapes and canvas.
10:00 Watch the video available at this URL:

http://spoken-tutorial.org/What_is_a_Spoken-Tutorial

10:04 It summarizes the Spoken Tutorial project.
10:08 If you do not have good bandwidth, you can download and watch it.
10:13 The Spoken Tutorial Project team :
10:15 * Conducts workshops using spoken tutorials.
10:19 * Gives certificates to those who pass an online test.
10:22 For more details, please write to:

contact@spoken-tutorial.org

10:29 Spoken Tutorial project is a part of the Talk to a Teacher project.
10:33 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
10:40 More information on this mission is available at this link:

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

10:46 This script is contributed by IT for change, Bangaluru.
10:50 This is Madhuri Ganpathi from IIT Bombay, signing off. Thank you for joining.

Contributors and Content Editors

Krupali, Madhurig, PoojaMoolya, Pratik kamble, Pravin1389, Sandhya.np14, Sneha