Turtle Graphics

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Revision as of 13:39, 21 December 2008 by A WASSERMANN (talk | contribs)
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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();
}

Category:Turtle Graphics