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0001 <chapter id="Glossary">
0002 <title>Glossary</title>
0004 <para>In this chapter you will find an explanation of most of the <quote>uncommon</quote> words that are used in the handbook.</para>
0006 <glosslist>
0007 <glossentry id="degrees">
0008 <glossterm>degrees</glossterm>
0009 <glossdef><para>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 <userinput>turnleft</userinput>, <userinput>turnright</userinput> and <userinput>direction</userinput> need an input in degrees.</para></glossdef>
0010 </glossentry>
0012 <glossentry id="input-output">
0013 <glossterm>input and output of commands</glossterm>
0014 <glossdef><para>Some commands take input, some commands give output, some commands take input <emphasis>and</emphasis> give output and some commands neither take input nor give output.</para>
0015 <para>Some examples of commands that only take input are:
0016 <screen>
0017 forward 50
0018 pencolor 255,0,0
0019 print "Hello!"
0020 </screen>
0021 The <userinput>forward</userinput> command takes <userinput>50</userinput> as input. <userinput>forward</userinput> needs this input to know how many <glossterm linkend="pixels">pixels</glossterm> it should go forward. <userinput>pencolor</userinput> takes a color as input and <userinput>print</userinput> takes a string (a piece of text) as input. Please note that the input can also be a container. The next example illustrates this:
0022 <screen>
0023 $x = 50
0024 print $x
0025 forward 50
0026 $str = "hello!"
0027 print $str
0028 </screen></para>
0030 <para>Now some examples of commands that give output:
0031 <screen>
0032 $x = ask "Please type something and press OK... thanks!"
0033 $r = random 1,100
0034 </screen>
0035 The <userinput>ask</userinput> command takes a string as input, and outputs the number or string that is entered. As you can see, the output of <userinput>ask</userinput> is stored in the container <userinput>x</userinput>. The <userinput>random</userinput> 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 <userinput>r</userinput>. Note that the containers <userinput>x</userinput> and <userinput>r</userinput> are not used in the example code above.</para>
0037 <para>There are also commands that neither need input nor give output. Here are some examples:
0038 <screen>
0039 clear
0040 penup
0041 </screen>
0042 </para></glossdef>
0043 </glossentry>
0045 <glossentry id="intuitive-highlighting">
0046 <glossterm>intuitive highlighting</glossterm>
0047 <glossdef><para>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 <link linkend="the-editor">the editor</link>.
0048 <table>
0049 <title>Different types of code and their highlight color</title>
0050 <tgroup cols="3">
0051 <tbody>
0052 <row>
0053 <entry>regular commands</entry>
0054 <entry>dark blue</entry>
0055 <entry>The regular commands are described <link linkend="commands">here</link>.</entry>
0056 </row>
0057 <row>
0058 <entry>execution controlling commands</entry>
0059 <entry>black (bold)</entry>
0060 <entry>These special commands control execution, read more on them <link linkend="controlling-execution">here</link>.</entry>
0061 </row>
0062 <row>
0063 <entry>comments</entry>
0064 <entry>gray</entry>
0065 <entry>Lines that are commented start with a comment characters (#). These lines are ignored when the code is executed. Comments allow the programmer to explain a bit about his code or can be used to temporarily prevent a certain piece of code from executing.</entry>
0066 </row>
0067 <row>
0068 <entry>brackets {, }</entry>
0069 <entry>dark green (bold)</entry>
0070 <entry>Brackets are used to group portions of code. Brackets are often used together with <link linkend="controlling-execution">execution controllers</link>.</entry>
0071 </row>
0072 <row>
0073 <entry>the <link linkend="learn">learn</link> command</entry>
0074 <entry>light green (bold)</entry>
0075 <entry>The <link linkend="learn">learn</link> command is used to create new commands.</entry>
0076 </row>
0077 <row>
0078 <entry>strings</entry>
0079 <entry>red</entry>
0080 <entry>Not much to say about (text) strings either, except that they always start and end with the double quotes (").</entry>
0081 </row>
0082 <row>
0083 <entry>numbers</entry>
0084 <entry>dark red</entry>
0085 <entry>Numbers, well not much to say about them.</entry>
0086 </row>
0087 <row>
0088 <entry>boolean values</entry>
0089 <entry>dark red</entry>
0090 <entry>There are exactly two boolean values, namely: true and false.</entry>
0091 </row>
0092 <row>
0093 <entry>variables</entry>
0094 <entry>purple</entry>
0095 <entry>Start with a '$' and can contain numbers, strings or boolean values.</entry>
0096 </row>
0097 <row>
0098 <entry>mathematical operators</entry>
0099 <entry>gray</entry>
0100 <entry>These are the mathematical operators: <userinput>+</userinput>, <userinput>-</userinput>, <userinput>*</userinput>, <userinput>/</userinput> and <userinput>^</userinput>.</entry>
0101 </row>
0102 <row>
0103 <entry>comparison operators</entry>
0104 <entry>light blue (bold)</entry>
0105 <entry>These are the comparison operators: <userinput>==</userinput>, <userinput>!=</userinput>, <userinput>&lt;</userinput>, <userinput>&gt;</userinput>, <userinput>&lt;=</userinput> and <userinput>&gt;=</userinput>.</entry>
0106 </row>
0107 <row>
0108 <entry>boolean operators</entry>
0109 <entry>pink (bold)</entry>
0110 <entry>These are the boolean operators: <userinput>and</userinput>, <userinput>or</userinput> and <userinput>not</userinput>.</entry>
0111 </row>
0112 <row>
0113 <entry>regular text</entry>
0114 <entry>black</entry>
0115 <entry></entry>
0116 </row>
0117 </tbody>
0118 </tgroup>
0119 </table>
0120 </para></glossdef>
0121 </glossentry>
0123 <glossentry id="pixels">
0124 <glossterm>pixels</glossterm>
0125 <glossdef><para>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.</para>
0126 <para>A lot of commands need a number of pixels as input. These commands are: <userinput>forward</userinput>, <userinput>backward</userinput>, <userinput>go</userinput>, <userinput>gox</userinput>, <userinput>goy</userinput>, <userinput>canvassize</userinput> and <userinput>penwidth</userinput>.</para>
0127 <para>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.</para>
0128 </glossdef>
0129 </glossentry>
0131 <glossentry id="rgb">
0132 <glossterm>RGB combinations (color codes)</glossterm>
0133 <glossdef><para>RGB combinations are used to describe colors. The <quote>R</quote> stand for <quote>red</quote>, the <quote>G</quote> stands for <quote>green</quote> and the <quote>B</quote> stands for <quote>blue</quote>. An example of an RGB combination is <userinput>255,0,0</userinput>: the first value (<quote>red</quote>) 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:
0134 <table frame="none">
0135 <title>Often used RGB combinations</title>
0136 <tgroup cols="2" colsep="5" rowsep="1">
0137 <colspec colname="c1"/>
0138 <tbody>
0139 <row><entry><userinput>0,0,0</userinput></entry><entry>black</entry></row>
0140 <row><entry><userinput>255,255,255</userinput></entry><entry>white</entry></row>
0141 <row><entry><userinput>255,0,0</userinput></entry><entry>red</entry></row>
0142 <row><entry><userinput>150,0,0</userinput></entry><entry>dark red</entry></row>
0143 <row><entry><userinput>0,255,0</userinput></entry><entry>green</entry></row>
0144 <row><entry><userinput>0,0,255</userinput></entry><entry>blue</entry></row>
0145 <row><entry><userinput>0,255,255</userinput></entry><entry>light blue</entry></row>
0146 <row><entry><userinput>255,0,255</userinput></entry><entry>pink</entry></row>
0147 <row><entry><userinput>255,255,0</userinput></entry><entry>yellow</entry></row>
0148 </tbody>
0149 </tgroup>
0150 </table>
0151 </para>
0152 <para>Two commands need an RGB combination as input: these commands are <userinput>canvascolor</userinput> and <userinput>pencolor</userinput>.</para></glossdef>
0153 </glossentry>
0155 <glossentry id="sprite">
0156 <glossterm>sprite</glossterm>
0157 <glossdef><para>A sprite is a small picture that can be moved around the screen. Our beloved turtle, for instance, is a sprite.
0158 <note><para>With this version of &kturtle; the sprite cannot be changed from a turtle into something else. Future versions of &kturtle; will be able to do this.</para></note></para></glossdef>
0159 </glossentry>
0161 </glosslist>
0163 </chapter>