html5使用canvas实现跟随光标跳动的火焰效果

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本效果的完整代码如下,把代码保存到HTML文件中打开也能查看效果,火焰会跟随光标:

代码如下:

<!DOCTYPE HTML>

<head>

<title>HTML5 Canvas火焰效果</title>

body{margin: 0; padding: 0;}

#canvas-keleyi-com {display: block;}

</style>

</head>

<body>

window.onload = function(){

var keleyi_canvas = document.getElementById("canvas-kel"+"eyi-com");

var ctx = keleyi_canvas.getContext("2d");

var W = window.innerWidth, H = window.innerHeight;

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('mousemove', 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 flame 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.remaining_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.globalCompositeOperation = "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.beginPath();

p.opacity = Math.round(p.remaining_life/p.life*100)/100

var gradient = 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>

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