Mercurial > defr > drupal > scald > dnd

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<html>
<head>
	<title>ExplorerCanvas Example 1</title>
	<!--[if IE]><script type="text/javascript" src="../excanvas.js"></script><![endif]-->
	<script type="text/javascript">
		var canvas, ctx;
		var particles = [];
		var NUM_PARTICLES = 20;

		function Particle() {
			this.x = Math.random() * canvas.width;
			this.y = Math.random() * canvas.height;

			this.xvel = Math.random() * 5 - 2.5;
			this.yvel = Math.random() * 5 - 2.5;
		}

		Particle.prototype.update = function() {
			this.x += this.xvel;
			this.y += this.yvel;

			this.yvel += 0.1;

			if (this.x > canvas.width || this.x < 0) {
				this.xvel = -this.xvel;
			}

			if (this.y > canvas.height || this.y < 0) {
				this.yvel = -this.yvel;
			}
		}

		function loop() {
			ctx.clearRect(0, 0, canvas.width, canvas.height);

			for(var i = 0; i < NUM_PARTICLES; i++) {
				particles[i].update();

				ctx.beginPath();
				ctx.moveTo(particles[i].x, particles[i].y);
				ctx.lineTo(particles[i].x - particles[i].xvel,
									 particles[i].y - particles[i].yvel);
				ctx.stroke();
				ctx.closePath();
			}

			setTimeout(loop, 10);
		}

		function load() {
			canvas = document.getElementById("cv");
			ctx = canvas.getContext("2d");

			for(var i = 0; i < NUM_PARTICLES; i++) {
				particles[i] = new Particle();
			}

			ctx.lineWidth = "2";
			ctx.strokeStyle = "rgb(255, 255, 255)";
			loop();
		}
	</script>
	<style>
		body {
			background-color:black;
			margin:50px;
			text-align:center;
		}

		canvas {
			border:1px solid #444;
		}
	</style>
</head>
<body onload="load();">
	<canvas id="cv" width="400" height="300"></canvas>
</body>
</html>
author	David Eads <eads@chicagotech.org>
date	Fri, 06 Mar 2009 14:11:46 -0600
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