HTML5超炫酷粒子效果的进度条

/*========================================================*/  /* Light Loader/*========================================================*/var lightLoader = function(c, cw, ch){var _this = this;this.c = c;this.ctx = c.getContext('2d');this.cw = cw;this.ch = ch;this.loaded = 0;this.loaderSpeed = .6;this.loaderHeight = 10;this.loaderWidth = 310;this.loader = {x: (this.cw/2) - (this.loaderWidth/2),y: (this.ch/2) - (this.loaderHeight/2)};this.particles = [];this.particleLift = 180;this.hueStart = 0this.hueEnd = 120;this.hue = 0;this.gravity = .15;this.particleRate = 4;/*========================================================*//* Initialize/*========================================================*/this.init = function(){this.loop();};/*========================================================*//* Utility Functions/*========================================================*/this.rand = function(rMi, rMa){return ~~((Math.random()*(rMa-rMi+1))+rMi);};this.hitTest = function(x1, y1, w1, h1, x2, y2, w2, h2){return !(x1 + w1 < x2 || x2 + w2 < x1 || y1 + h1 < y2 || y2 + h2 < y1);};/*========================================================*//* Update Loader/*========================================================*/this.updateLoader = function(){if(this.loaded < 100){this.loaded += this.loaderSpeed;} else {this.loaded = 0;}};/*========================================================*//* Render Loader/*========================================================*/this.renderLoader = function(){this.ctx.fillStyle = '#000';this.ctx.fillRect(this.loader.x, this.loader.y, this.loaderWidth, this.loaderHeight);this.hue = this.hueStart + (this.loaded/100)*(this.hueEnd - this.hueStart);var newWidth = (this.loaded/100)*this.loaderWidth;this.ctx.fillStyle = 'hsla('+this.hue+', 100%, 40%, 1)';this.ctx.fillRect(this.loader.x, this.loader.y, newWidth, this.loaderHeight);this.ctx.fillStyle = '#222';this.ctx.fillRect(this.loader.x, this.loader.y, newWidth, this.loaderHeight/2);};/*========================================================*//* Particles/*========================================================*/this.Particle = function(){this.x = _this.loader.x + ((_this.loaded/100)*_this.loaderWidth) - _this.rand(0, 1);this.y = _this.ch/2 + _this.rand(0,_this.loaderHeight)-_this.loaderHeight/2;this.vx = (_this.rand(0,4)-2)/100;this.vy = (_this.rand(0,_this.particleLift)-_this.particleLift*2)/100;this.width = _this.rand(1,4)/2;this.height = _this.rand(1,4)/2;this.hue = _this.hue;};this.Particle.prototype.update = function(i){this.vx += (_this.rand(0,6)-3)/100; this.vy += _this.gravity;this.x += this.vx;this.y += this.vy;if(this.y > _this.ch){_this.particles.splice(i, 1);}};this.Particle.prototype.render = function(){_this.ctx.fillStyle = 'hsla('+this.hue+', 100%, '+_this.rand(50,70)+'%, '+_this.rand(20,100)/100+')';_this.ctx.fillRect(this.x, this.y, this.width, this.height);};this.createParticles = function(){var i = this.particleRate;while(i--){this.particles.push(new this.Particle());};};this.updateParticles = function(){var i = this.particles.length;while(i--){var p = this.particles[i];p.update(i);};};this.renderParticles = function(){var i = this.particles.length;while(i--){var p = this.particles[i];p.render();};};/*========================================================*//* Clear Canvas/*========================================================*/this.clearCanvas = function(){this.ctx.globalCompositeOperation = 'source-over';this.ctx.clearRect(0,0,this.cw,this.ch);this.ctx.globalCompositeOperation = 'lighter';};/*========================================================*//* Animation Loop/*========================================================*/this.loop = function(){var loopIt = function(){requestAnimationFrame(loopIt, _this.c);_this.clearCanvas();_this.createParticles();_this.updateLoader();_this.updateParticles();_this.renderLoader();_this.renderParticles();};loopIt();};};/*========================================================*//* Check Canvas Support/*========================================================*/var isCanvasSupported = function(){var elem = document.createElement('canvas');return !!(elem.getContext && elem.getContext('2d'));};/*========================================================*//* Setup requestAnimationFrame/*========================================================*/var setupRAF = function(){var lastTime = 0;var vendors = ['ms', 'moz', 'webkit', 'o'];for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x){window.requestAnimationFrame = window[vendors[x]+'RequestAnimationFrame'];window.cancelAnimationFrame = window[vendors[x]+'CancelAnimationFrame'] || window[vendors[x]+'CancelRequestAnimationFrame'];};if(!window.requestAnimationFrame){window.requestAnimationFrame = function(callback, element){var currTime = new Date().getTime();var timeToCall = Math.max(0, 16 - (currTime - lastTime));var id = window.setTimeout(function() { callback(currTime + timeToCall); }, timeToCall);lastTime = currTime + timeToCall;return id;};};if (!window.cancelAnimationFrame){window.cancelAnimationFrame = function(id){clearTimeout(id);};};};/*========================================================*//* Define Canvas and Initialize/*========================================================*/if(isCanvasSupported){  var c = document.createElement('canvas');  c.width = 400;  c.height = 100;  var cw = c.width;  var ch = c.height;  document.body.appendChild(c);  var cl = new lightLoader(c, cw, ch);  setupRAF();  cl.init();}