Difference between revisions of "Turtle Graphics"

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There is a predefined turtle object ''t''. Therefore, all commands
 
There is a predefined turtle object ''t''. Therefore, all commands
 
start with ''t'', like ''t.fd(100)'';
 
start with ''t'', like ''t.fd(100)'';
 +
<source lang="javascript">
 
* t.forward(len); or t.fd(len);
 
* t.forward(len); or t.fd(len);
 
* t.back(len); or t.bk(len);
 
* t.back(len); or t.bk(len);
Line 18: Line 19:
 
* t.setPenSize(size); (size: number)
 
* t.setPenSize(size); (size: number)
 
* t.setPenColor(col); (col: colorString, e.g. 'red' or '#ff0000')
 
* t.setPenColor(col); (col: colorString, e.g. 'red' or '#ff0000')
 +
</source>
  
 
===Snowflake and Branches Example===
 
===Snowflake and Branches Example===

Revision as of 12:35, 21 December 2008

This is a very basic implementation of turtle graphics in JavaScript with JSXGraph. Here, we use SVG (on Firefox, Safari, Opera and Chrome) and VML (on Internet Explorer). CanvasTurtle does the same on browsers which support the canvas element.

List of available commands

There is a predefined turtle object t. Therefore, all commands start with t, like t.fd(100);

* t.forward(len); or t.fd(len);
* t.back(len); or t.bk(len);
* t.right(angle); or t.rt(angle); (<math>0\leq angle \leq 360</math>)
* t.left(angle); or t.lt(angle);
* t.penUp(); or t.pu();
* t.penDown(); or t.pd();
* t.clearScreen(); or t.cs();
* t.clean();
* t.setPos(x,y); 
* t.home();
* t.hideTurtle(); or t.ht();
* t.showTurtle(); or t.st();
* t.setPenSize(size); (size: number)
* t.setPenColor(col); (col: colorString, e.g. 'red' or '#ff0000')

Snowflake and Branches Example


References

  • The snowflake and branches example have been adapted from the excellent CanvasTurtle

The turtle graphics code

<link rel="stylesheet" type="text/css" href="http://jsxgraph.uni-bayreuth.de/distrib/jsxgraph.css" />
<script type="text/javascript" src="http://jsxgraph.uni-bayreuth.de/distrib/prototype.js"></script>
<script type="text/javascript" src="http://jsxgraph.uni-bayreuth.de/distrib/jsxgraphcore.js"></script>
<script type="text/javascript" src="http://jsxgraph.uni-bayreuth.de/distrib/jsxturtle.js"></script>
<div id="box" class="jxgbox" style="width:600px; height:600px;"></div>
<form><textarea id="input1" rows=7 cols=35 wrap="off" style="width:300px; float:left;">
turtle code...
</textarea>
<input type="button" value="run example 1" onClick="run(1)">
var brd = JXG.JSXGraph.initBoard('box', {originX: 300, originY: 300, unitX: 1, unitY: 1});
var t = new JSXTurtleObj(brd);

function run(nr) {
  brd.suspendUpdate();
  eval($('input'+nr).value);
  brd.unsuspendUpdate();
}