在 Canvas 中渲染粒子，提高 FireFox FPS

Question

我正在尝试在 Firefox 中将 FPS 提高到 30 以上。我真的不确定我还能做些什么来改进它。有什么建议吗？

Chrome 和 Opera 徘徊在 60 fps 左右，而 FF 卡在 10-20 之间，因此它会导致我页面的其余部分出现延迟问题。

http://jsfiddle.net/7vv2tur7/

window.requestAnimFrame = (function(){
    return window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    function( callback ) {
        window.setTimeout(callback, 1000 / 60);
    };
})();


(function() {

    particleCanvas();

    con = particle.getContext('2d');
    pxs = [];
    for(var i = 0; i < 25; i++) {
        pxs[i] = new Circle();
        pxs[i].reset();
    }

    requestAnimFrame(paintParticles);

    window.onresize = function(event) {
        particleCanvas();
    };

})();

function Circle() {

    // settings
    this.s = {

        ttl:10000,

        // speeds
        xmax:4,
        ymax:4,

        // max size
        size:1,

        rt:4,

        xdrift:60,
        ydrift:60,

        opacity: 0.3,
    };


    this.reset = function() {

        // randomise positioning for each particle
        this.x = particle.width * Math.random();
        this.y = particle.height * Math.random();

        // size
        this.r = ((this.s.size-1)*Math.random()) + 1;


        this.dx = (Math.random()*this.s.xmax) * (Math.random() < 0.5 ? -1 : 1);
        this.dy = (Math.random()*this.s.ymax) * (Math.random() < 0.5 ? -1 : 1);
        this.hl = this.s.ttl / 4 * (this.r/this.s.size);
        this.rt = Math.random()*this.hl;
        this.s.rt = Math.random() +1;
        this.stop = Math.random();
        this.s.xdrift *= Math.random() * (Math.random() < 0.5 ? -1 : 1);
        this.s.ydrift *= Math.random() * (Math.random() < 0.5 ? -1 : 1);
    };

    this.fade = function() {
        this.rt += 5 + this.s.rt;
    };

    this.draw = function() {

        if(this.rt >= this.hl) this.reset();
        var newo = 1 - (this.rt/this.hl);



        con.globalAlpha = this.s.opacity;


        con.beginPath();
        con.arc(this.x,this.y,this.r,0,Math.PI*2,true);
        con.closePath();
        var cr = this.r*newo;

        g = con.createRadialGradient(this.x, this.y, 0, this.x, this.y, (cr <= 0 ? 1 : 5));
        g.addColorStop(0.0, 'rgba(255,255,255,' + newo + ')');
        g.addColorStop(this.stop, 'rgba(255,255,255,' + 0.5 * newo + ')');
        g.addColorStop(1.0, 'rgba(255,255,255, 0)');


        con.fillStyle = g;
        con.fill();
    };

    this.move = function() {
        this.x += (this.rt/this.hl)*this.dx;
        this.y += (this.rt/this.hl)*this.dy;
        if(this.x > particle.width || this.x < 0) this.dx *= -1;
        if(this.y > particle.height || this.y < 0) this.dy *= -1;
    };

    this.getX = function() { return this.x; };
    this.getY = function() { return this.y; };
}

function particleCanvas() {
    particle.width  = document.querySelector('.start').offsetWidth / 2;
    particle.height = document.querySelector('.start').offsetHeight / 2;
}

function paintParticles() {

    requestAnimFrame(paintParticles);

    con.clearRect ( 0 , 0 , particle.width, particle.height );

    for(var i = 0; i < pxs.length; i++) {
        pxs[i].fade();
        pxs[i].move();
        pxs[i].draw();
    }

    var thisFrameFPS = 1000 / ((now=new Date()) - lastUpdate);
        fps += (thisFrameFPS - fps) / fpsFilter;
        lastUpdate = now;

}

var fps = 0, now,
    lastUpdate = (new Date())*1 - 1, fpsFilter = 50;



setInterval(function(){
    document.querySelector('.fps').innerHTML = fps.toFixed(1) + ' fps';
}, 1000);

Answer 1

您的性能杀手正在为每个动画帧中的每个粒子创建渐变。

您可以将昂贵的gradient 换成相对便宜的globalAlpha。

这是一个使用 globalAlpha 而不是渐变的重构。我留给你调整 globalAlpha 以匹配你的效果，但这种重构在 Firefox 上要快得多（在我的机器上是 59+）。

您的代码中还有其他可能的优化，但使用渐变是性能杀手...

window.requestAnimFrame = (function(){
  return window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    function( callback ) {
    window.setTimeout(callback, 1000 / 60);
  };
})();


(function() {

  particleCanvas();

  con = particle.getContext('2d');
  pxs = [];
  for(var i = 0; i < 25; i++) {
    pxs[i] = new Circle();
    pxs[i].reset();
  }

  requestAnimFrame(paintParticles);

  window.onresize = function(event) {
    particleCanvas();
  };

})();

function Circle() {

  // settings
  this.s = {

    ttl:10000,

    // speeds
    xmax:4,
    ymax:4,

    // max size
    size:1,

    rt:4,

    xdrift:60,
    ydrift:60,

    opacity: 0.7,
  };


  this.reset = function() {

    // randomise positioning for each particle
    this.x = particle.width * Math.random();
    this.y = particle.height * Math.random();

    // size
    this.r = ((this.s.size-1)*Math.random()) + 1;


    this.dx = (Math.random()*this.s.xmax) * (Math.random() < 0.5 ? -1 : 1);
    this.dy = (Math.random()*this.s.ymax) * (Math.random() < 0.5 ? -1 : 1);
    this.hl = this.s.ttl / 4 * (this.r/this.s.size);
    this.rt = Math.random()*this.hl;
    this.s.rt = Math.random() +1;
    this.stop = Math.random();
    this.s.xdrift *= Math.random() * (Math.random() < 0.5 ? -1 : 1);
    this.s.ydrift *= Math.random() * (Math.random() < 0.5 ? -1 : 1);

    this.s.opacity=0.70;
  };

  this.fade = function() {
    this.rt += 5 + this.s.rt;
    this.s.opacity-=.005;
  };

  this.draw = function() {

    if(this.rt >= this.hl) this.reset();
    var newo = 1 - (this.rt/this.hl);

    con.globalAlpha = this.s.opacity;

    con.beginPath();
    con.arc(this.x,this.y,this.r,0,Math.PI*2,true);
    con.closePath();
    var cr = this.r*newo;
    con.fill();
  };

  this.move = function() {
    this.x += (this.rt/this.hl)*this.dx;
    this.y += (this.rt/this.hl)*this.dy;
    if(this.x > particle.width || this.x < 0) this.dx *= -1;
    if(this.y > particle.height || this.y < 0) this.dy *= -1;
  };

  this.getX = function() { return this.x; };
  this.getY = function() { return this.y; };
}

function particleCanvas() {
  particle.width 	= document.querySelector('body').offsetWidth / 2;
  particle.height = document.querySelector('body').offsetHeight / 2;
}

function paintParticles() {

  requestAnimFrame(paintParticles);

  con.clearRect ( 0 , 0 , particle.width, particle.height );

  con.fillStyle = 'white';
  for(var i = 0; i < pxs.length; i++) {
    pxs[i].fade();
    pxs[i].move();
    pxs[i].draw();
  }

  var thisFrameFPS = 1000 / ((now=new Date()) - lastUpdate);
  fps += (thisFrameFPS - fps) / fpsFilter;
  lastUpdate = now;

}

var fps = 0, now,
    lastUpdate = (new Date())*1 - 1, fpsFilter = 50;



setInterval(function(){
  document.querySelector('.fps').innerHTML = fps.toFixed(1) + ' fps';
}, 1000);

html,
body {height:100%;width:100%;display:block;margin:0;padding:0;background:black}

* {box-sizing:border-box}

span {
  position:absolute;
  top:50px;
  left:50px;
  font-size:28px;
  color:white;
  font-family:mono;
}
canvas {width:100%;height:100%}    </style>

<canvas id="particle"></canvas>
<span class="fps"></span>