

Using commands you tell the turtle or KTurtle to do something. Some commands need input, some give output. In this section we explain all the commands that can be used in KTurtle. Please note that all build in commands we discuss here are highlighted with blue in the code editor, this can help you to distinguish them.
There are several commands to move the turtle over the screen.
gox X
gox using this command the turtle will move to X pixels from the left of the canvas whilst staying at the same height.
goy Y
gox using this command the turtle will move to Y pixels from the top of the canvas whilst staying at the same distance from the left border of the canvas.
Using the commands go, gox, goy and center the turtle will not draw a line, no matter if the pen is up or down.
The turtle has a pen that draws a line when the turtle moves. There are a few commands to control the pen. In this section we explain these commands.
penwidth X
penwidth sets the width of the pen (the line width) to an amount of X pixels. penwidth can be abbreviated to pw.
pencolor R,G,B
pencolor sets the color of the pen. pencolor takes an RGB combination as input. pencolor can be abbreviated to pc.
There are several commands to control the canvas.
canvascolor R,G,B
canvascolor set the color of the canvas. canvascolor takes an RGB combination as input. canvascolor can be abbreviated to cc.
There are two commands to clean up the canvas after you have made a mess.
reset
reset cleans much more thoroughly than the clear command. After a reset command everything is like is was when you had just started KTurtle. The turtle is positioned at the middle of the screen, the canvas color is white, the turtle draws a black line on the canvas and the canvassize is set to 400 x 400 pixels.
First a brief explanation of what sprites are: sprites are small pictures that can be moved around the screen, like we often see in computer games. Our turtle is also a sprite. For more info see the glossary on sprites.
Next you will find a full overview on all commands to work with sprites.
[The current version of KTurtle does not yet support the use of sprites other than the turtle. With future versions you will be able to change the turtle into something of your own design]
The answer is: “yes”. The turtle can write: it writes just about everything you command it to.
print X
The print command is used to command the turtle to write something on the canvas. print takes numbers and strings as input. You can print various numbers and strings using the “+” symbol. See here a small example:
$year = 2003 $author = "Cies" print $author + " started the KTurtle project in " + $year + " and still enjoys working on it!"
fontsize X
fontsize sets the size of the font that is used by print. fontsize takes one input which should be a number. The size is set in pixels.
There is one command that rolls dice for you, it is called random, and it is very useful for some unexpected results.
random X,Y
random is a command that takes input and gives output. As input are required two numbers, the first (X) sets the minimum output, the second (Y) sets the maximum. The output is a randomly chosen number that is equal or greater then the minimum and equal or smaller than the maximum. Here a small example:
repeat 500 {
$x = random 1,20
forward $x
turnleft 10 - $x
}
Using the random command you can add a bit of chaos to your program.
A dialog is a small pop-up window that provides some feedback or asks for some input. KTurtle has two commands for dialogs, namely: message and ask
ask X
ask takes a string as input. It shows a pop-up dialog containing the text from the string, just like the message. But in addition to it also puts an input field on the dialog. Through this input filed the user can enter a number or a string which can be stored in a container. For example
$in = ask "What is you age?" $out = 2003 - $in print "In 2003 you where " + $out + " years old at some point."
When a user cancels the input dialog, or does not enter anything at all the container is emptied.