<!DOCTY
PE HTML>
<head>
<
;meta charset=utf-8" />
<t
ITle>
HTML5 canvas火焰效果</title>
<style type="text/css">
body{m
argin: 0; padding: 0;}
#canvas-keleyi-com {dis
play: block;}
</style>
</head>
<body>
<canvas id="canvas-keleyi-com"></canvas>
<script type="text/javascript">
window.onload = function(){
VAR keleyi_canvas = document.getElementById("canvas-kel"+"eyi-com");
var ctx = keleyi_canvas.getContext("2d");
var W = window.innerWidth, H = window.innerH
eight;
keleyi_canvas.width = W;
keleyi_canvas.height = H;</p>
<p>var particles = [];
var mouse = {};</p>
<p>//Lets create some particles now
var particle_count = 100;
for(var i = 0; i < particle_count;
i++)
{
particles.push(new particle());
}
keleyi_canvas.addEventListener('mou
SEMove', track_mouse, false);</p>
<p>function track_mouse(e)
{
mouse.x = e.pageX;
mouse.y = e.pageY;
}</p>
<p>function particle()
{
this.speed = {x: -2.5+Math.random()*5, y: -15+Math.random()*10};
//location = mouse coordinates
//Now the fl
ame follows the mouse coordinates
if(mouse.x
&& mouse.y)
{
this.location = {x: mouse.x, y: mouse.y};
}
else
{
this.location = {x: W/2, y: H/2};
}
//radius range = 10-30
this.radius = 10+Math.random()*20;
//life range = 20-30
this.life = 20+Math.random()*10;
this.rem
aining_life = this.life;
//colors
this.r = Math.round(Math.random()*255);
this.g = Math.round(Math.random()*255);
this.b = Math.round(Math.random()*255);
}</p>
<p>function draw()
{
ctx.globalComposite
operation = "source-over";
ctx.fillStyle = "black";
ctx.fillRect(0, 0, W, H);
ctx.globalCompositeOperation = "lighter";</p>
<p>for(var i = 0; i < particles.length; i++)
{
var p = particles[i];
ctx.be
ginPath();
p.opacity = Math.round(p.remaining_life/p.life*100)/100
var gra
dient = ctx.createRadialGradient(p.location.x, p.location.y, 0, p.location.x, p.location.y, p.radius);
gradient.addColorStop(0, "rgba("+p.r+", "+p.g+", "+p.b+", "+p.opacity+")");
gradient.addColorStop(0.5, "rgba("+p.r+", "+p.g+", "+p.b+", "+p.opacity+")");
gradient.addColorStop(1, "rgba("+p.r+", "+p.g+", "+p.b+", 0)");
ctx.fillStyle = gradient;
ctx.arc(p.location.x, p.location.y, p.radius, Math.PI*2, false);
ctx.fill();</p>
<p>
p.remaining_life--;
p.radius--;
p.location.x += p.speed.x;
p.location.y += p.speed.y;</p>
<p>if(p.remaining_life < 0 || p.radius < 0)
{
particles[i] = new particle();
}
}
}</p>
<p>setInterval(draw, 86);
}
</script>
</body>
</html>