Pretty Fractal Trees using HTML-5 Canvas & Random Numbers ~ Tic Droid

Last week I sat down to see how I can generate a fractal tree on a web page. It turned out to be a very interesting exercise using HTML5 Canvas and simple Math trigonometric functions. Using random numbers for changing the length of the tree branch, and the angle of branch split -- I was quite successful in generating very realistic looking trees!

Each time you render the HTML, the trees look quite different. I can see how Game creators can create interesting looking forests for "heroes" to travel in using such techniques.

HTML 5 Canvas with a Fractal Tree

Here is the code (also posted on github):


	<html>

	<head>

	<script type="text/javascript">

	window.onload = draw;

	function draw(){
	var canvas = document.getElementById('myCanvas');
	if (canvas.getContext){
	var context = canvas.getContext('2d');
	drawFractalTree(context);
	}
	else{
	alert("HTML5 Canvas isn't supported by your browser!");
	}
	}

	function drawFractalTree(context){

	drawTree(context, 800, 800, -90, 11);
	}

	function drawTree(context, x1, y1, angle, depth){

	var BRANCH_LENGTH = random(0, 20);

	if (depth != 0){
	var x2 = x1 + (cos(angle) * depth * BRANCH_LENGTH);
	var y2 = y1 + (sin(angle) * depth * BRANCH_LENGTH);

	drawLine(context, x1, y1, x2, y2, depth);
	drawTree(context, x2, y2, angle - random(15,20), depth - 1);
	drawTree(context, x2, y2, angle + random(15,20), depth - 1);
	}
	}

	function drawLine(context, x1, y1, x2, y2, thickness){
	context.fillStyle = '#000';
	if(thickness > 6)
	context.strokeStyle = 'rgb(139,126, 102)'; //Brown
	else
	context.strokeStyle = 'rgb(34,139,34)'; //Green

	context.lineWidth = thickness * 1.5;
	context.beginPath();

	context.moveTo(x1,y1);
	context.lineTo(x2, y2);

	context.closePath();
	context.stroke();
	}


	function cos (angle) {
	return Math.cos(deg_to_rad(angle));
	}

	function sin (angle) {
	return Math.sin(deg_to_rad(angle));
	}

	function deg_to_rad(angle){
	return angle*(Math.PI/180.0);
	}

	function random(min, max){
	return min + Math.floor(Math.random()*(max+1-min));
	}

	</script>

	<style type="text/css">
	canvas { border: 1px solid white; }
	</style>

	</head>

	<body>
	<canvas id="myCanvas" width="1500" height="800"></canvas>
	</body>

	</html>

view raw tree_html5.html hosted with ❤ by GitHub

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