Chapter 5. Glossary

Degrees are units to measure angles or turns. A full turn is 360 degrees, a half turn 180 degrees and a quarter turn 90 degrees. The commands turnleft, turnright and direction need an input in degrees.

Some commands take input, some commands give output, some commands take input and give output and some commands neither take input nor give output.

Some examples of commands that only take input are:

forward 50
pencolor 255,0,0
print "Hello!"

The forward command takes 50 as input. forward needs this input to know how many pixels it should go forward. pencolor takes a color as input and print takes a string (a piece of text) as input. Please note that the input can also be a container. The next example illustrates this:

$x = 50
print $x
forward 50
$str = "hello!"
print $str

Now some examples of commands that give output:

$x = ask "Please type something and press OK... thanks!"
$r = random 1,100

The ask command takes a string as input, and outputs the number or string that is entered. As you can see, the output of ask is stored in the container x. The random command also gives output. In this case it outputs a number between 1 and 100. The output of the random is again stored in a container, named r. Note that the containers x and r are not used in the example code above.

There are also commands that neither need input nor give output. Here are some examples:

clear
penup

This is a feature of KTurtle that makes coding even easier. With intuitive highlighting the code that you write gets a color that indicates what type of code it is. In the next list you will find the different types of code and the color they get in the editor.

A pixel is a dot on the screen. If you look very close you will see that the screen of your monitor uses pixels. All images on the screen are built with these pixels. A pixel is the smallest thing that can be drawn on the screen.

A lot of commands need a number of pixels as input. These commands are: forward, backward, go, gox, goy, canvassize and penwidth.

In early versions of KTurtle the canvas was essentially a raster image, yet for recent versions the canvas is a vector drawing. This means that the canvas can be zoomed in and out, therefore a pixel does not necessarily have to translate to one dot on the screen.

RGB combinations are used to describe colors. The “R” stand for “red”, the “G” stands for “green” and the “B” stands for “blue”. An example of an RGB combination is 255,0,0: the first value (“red”) is 255 and the others are 0, so this represents a bright shade of red. Each value of an RGB combination has to be in the range 0 to 255. Here a small list of some often used colors:

Two commands need an RGB combination as input: these commands are canvascolor and pencolor.

A sprite is a small picture that can be moved around the screen. Our beloved turtle, for instance, is a sprite.