html5烟花绽放效果

前端开发whqet,csdn,王海庆,whqet,前端开发专家

今天来看一个利用canvas+javascript实现的烟花绽放效果，大家可以到我的codepen看看DEMO，在线观看或是下载研究，悉听尊便。

首先来看看html，里面就放了一个canvas对象。

<!-- setup our canvas element -->
<canvas id="canvas">Canvas is not supported in your browser.</canvas>

css文件

body {background: #000;margin: 0;
}
canvas {cursor: crosshair;display: block;
}

接着是JS，首先使用“RequestAnimationFrame”实现动画，可以有效解决setTimeout和setInterval的浪费CPU问题。关于RequestAnimationFrame方法的特性和优势，大家可以参考以下几篇文章。

CSS-Tricks上的《Using requestAnimationFrame》

Treehouse Blog上的《Efficient Animations with requestAnimationFrame》

W3c的候选推荐标准《Timing control for script-based animations》

以及Erik Möller提供的polyfill（在旧版浏览器上模拟标准 API 的 JavaScript 补充）。

// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
// http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating
// requestAnimationFrame polyfill by Erik Möller. fixes from Paul Irish and Tino Zijdel
// MIT license(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);};
}());

本案例需要两个类烟花沫粒子和烟花。首先来看烟花沫类

// create particle
function Particle( x, y ) {this.x = x;this.y = y;// track the past coordinates of each particle to create a trail effect, increase the coordinate count to create more prominent trailsthis.coordinates = [];this.coordinateCount = 5;while( this.coordinateCount-- ) {this.coordinates.push( [ this.x, this.y ] );}// set a random angle in all possible directions, in radiansthis.angle = random( 0, Math.PI * 2 );this.speed = random( 1, 10 );// friction will slow the particle downthis.friction = 0.95;// gravity will be applied and pull the particle downthis.gravity = 1;// set the hue to a random number +-20 of the overall hue variablethis.hue = random( hue - 20, hue + 20 );this.brightness = random( 50, 80 );this.alpha = 1;// set how fast the particle fades outthis.decay = random( 0.015, 0.03 );
}// update particle
Particle.prototype.update = function( index ) {// remove last item in coordinates arraythis.coordinates.pop();// add current coordinates to the start of the arraythis.coordinates.unshift( [ this.x, this.y ] );// slow down the particlethis.speed *= this.friction;// apply velocitythis.x += Math.cos( this.angle ) * this.speed;this.y += Math.sin( this.angle ) * this.speed + this.gravity;// fade out the particlethis.alpha -= this.decay;// remove the particle once the alpha is low enough, based on the passed in indexif( this.alpha <= this.decay ) {particles.splice( index, 1 );}
}// draw particle
Particle.prototype.draw = function() {ctx. beginPath();// move to the last tracked coordinates in the set, then draw a line to the current x and yctx.moveTo( this.coordinates[ this.coordinates.length - 1 ][ 0 ], this.coordinates[ this.coordinates.length - 1 ][ 1 ] );ctx.lineTo( this.x, this.y );ctx.strokeStyle = 'hsla(' + this.hue + ', 100%, ' + this.brightness + '%, ' + this.alpha + ')';ctx.stroke();
}

生成粒子的函数

// create particle group/explosion
function createParticles( x, y ) {// increase the particle count for a bigger explosion, beware of the canvas performance hit with the increased particles thoughvar particleCount = 30;while( particleCount-- ) {particles.push( new Particle( x, y ) );}
}

烟花类

// create firework
function Firework( sx, sy, tx, ty ) {// actual coordinatesthis.x = sx;this.y = sy;// starting coordinatesthis.sx = sx;this.sy = sy;// target coordinatesthis.tx = tx;this.ty = ty;// distance from starting point to targetthis.distanceToTarget = calculateDistance( sx, sy, tx, ty );this.distanceTraveled = 0;// track the past coordinates of each firework to create a trail effect, increase the coordinate count to create more prominent trailsthis.coordinates = [];this.coordinateCount = 3;// populate initial coordinate collection with the current coordinateswhile( this.coordinateCount-- ) {this.coordinates.push( [ this.x, this.y ] );}this.angle = Math.atan2( ty - sy, tx - sx );this.speed = 2;this.acceleration = 1.05;this.brightness = random( 50, 70 );// circle target indicator radiusthis.targetRadius = 1;
}// update firework
Firework.prototype.update = function( index ) {// remove last item in coordinates arraythis.coordinates.pop();// add current coordinates to the start of the arraythis.coordinates.unshift( [ this.x, this.y ] );// cycle the circle target indicator radiusif( this.targetRadius < 8 ) {this.targetRadius += 0.3;} else {this.targetRadius = 1;}// speed up the fireworkthis.speed *= this.acceleration;// get the current velocities based on angle and speedvar vx = Math.cos( this.angle ) * this.speed,vy = Math.sin( this.angle ) * this.speed;// how far will the firework have traveled with velocities applied?this.distanceTraveled = calculateDistance( this.sx, this.sy, this.x + vx, this.y + vy );// if the distance traveled, including velocities, is greater than the initial distance to the target, then the target has been reachedif( this.distanceTraveled >= this.distanceToTarget ) {createParticles( this.tx, this.ty );// remove the firework, use the index passed into the update function to determine which to removefireworks.splice( index, 1 );} else {// target not reached, keep travelingthis.x += vx;this.y += vy;}
}// draw firework
Firework.prototype.draw = function() {ctx.beginPath();// move to the last tracked coordinate in the set, then draw a line to the current x and yctx.moveTo( this.coordinates[ this.coordinates.length - 1][ 0 ], this.coordinates[ this.coordinates.length - 1][ 1 ] );ctx.lineTo( this.x, this.y );ctx.strokeStyle = 'hsl(' + hue + ', 100%, ' + this.brightness + '%)';ctx.stroke();ctx.beginPath();// draw the target for this firework with a pulsing circlectx.arc( this.tx, this.ty, this.targetRadius, 0, Math.PI * 2 );ctx.stroke();
}

定义好了主要的类，我们来设置一些常见的变量和函数。

// now we will setup our basic variables for the demo
var canvas = document.getElementById( 'canvas' ),ctx = canvas.getContext( '2d' ),// full screen dimensionscw = window.innerWidth,ch = window.innerHeight,// firework collectionfireworks = [],// particle collectionparticles = [],// starting huehue = 120,// when launching fireworks with a click, too many get launched at once without a limiter, one launch per 5 loop tickslimiterTotal = 5,limiterTick = 0,// this will time the auto launches of fireworks, one launch per 80 loop tickstimerTotal = 80,timerTick = 0,mousedown = false,// mouse x coordinate,mx,// mouse y coordinatemy;// set canvas dimensions
canvas.width = cw;
canvas.height = ch;// now we are going to setup our function placeholders for the entire demo// get a random number within a range
function random( min, max ) {return Math.random() * ( max - min ) + min;
}// calculate the distance between two points
function calculateDistance( p1x, p1y, p2x, p2y ) {var xDistance = p1x - p2x,yDistance = p1y - p2y;return Math.sqrt( Math.pow( xDistance, 2 ) + Math.pow( yDistance, 2 ) );
}

不断释放烟花的函数，需要利用RequestAnimationFrame不断地执行函数。

// main demo loop
function loop() {// this function will run endlessly with requestAnimationFramerequestAnimFrame( loop );// increase the hue to get different colored fireworks over timehue += 0.5;// normally, clearRect() would be used to clear the canvas// we want to create a trailing effect though// setting the composite operation to destination-out will allow us to clear the canvas at a specific opacity, rather than wiping it entirelyctx.globalCompositeOperation = 'destination-out';// decrease the alpha property to create more prominent trailsctx.fillStyle = 'rgba(0, 0, 0, 0.5)';ctx.fillRect( 0, 0, cw, ch );// change the composite operation back to our main mode// lighter creates bright highlight points as the fireworks and particles overlap each otherctx.globalCompositeOperation = 'lighter';// loop over each firework, draw it, update itvar i = fireworks.length;while( i-- ) {fireworks[ i ].draw();fireworks[ i ].update( i );}// loop over each particle, draw it, update itvar i = particles.length;while( i-- ) {particles[ i ].draw();particles[ i ].update( i );}// launch fireworks automatically to random coordinates, when the mouse isn't downif( timerTick >= timerTotal ) {if( !mousedown ) {// start the firework at the bottom middle of the screen, then set the random target coordinates, the random y coordinates will be set within the range of the top half of the screenfireworks.push( new Firework( cw / 2, ch, random( 0, cw ), random( 0, ch / 2 ) ) );timerTick = 0;}} else {timerTick++;}// limit the rate at which fireworks get launched when mouse is downif( limiterTick >= limiterTotal ) {if( mousedown ) {// start the firework at the bottom middle of the screen, then set the current mouse coordinates as the targetfireworks.push( new Firework( cw / 2, ch, mx, my ) );limiterTick = 0;}} else {limiterTick++;}
}

绑定鼠标事件

// mouse event bindings
// update the mouse coordinates on mousemove
canvas.addEventListener( 'mousemove', function( e ) {mx = e.pageX - canvas.offsetLeft;my = e.pageY - canvas.offsetTop;
});// toggle mousedown state and prevent canvas from being selected
canvas.addEventListener( 'mousedown', function( e ) {e.preventDefault();mousedown = true;
});canvas.addEventListener( 'mouseup', function( e ) {e.preventDefault();mousedown = false;
});

在窗口加载完毕，单击鼠标前，我们也需要一些烟花

// once the window loads, we are ready for some fireworks!
window.onload = loop;

完毕。

---------------------------------------------------------------

前端开发whqet，关注web前端开发技术，分享网页相关资源。
---------------------------------------------------------------

html5烟花绽放效果相关推荐

python写新年快乐程序_新年快乐! python实现绚烂的烟花绽放效果
新年快乐! python实现绚烂的烟花绽放效果来源:中文源码网浏览: 次日期:2019年11月5日 [下载文档: 新年快乐! python实现绚烂的烟花绽放效果.txt ] (友情 ...
python画静态烟花_新年快乐! python实现绚烂的烟花绽放效果
做了一个Python的小项目.利用了一点python的可视化技巧,做出烟花绽放的效果,文章的灵感来自网络上一位大神. 一.编译环境 Pycharm 二.模块 1.tkinter:这个小项目的主角,是一 ...
python 新年_新年快乐! python实现绚烂的烟花绽放效果
做了一个Python的小项目.利用了一点python的可视化技巧,做出烟花绽放的效果,文章的灵感来自网络上一位大神. 一.编译环境 Pycharm 二.模块 1.tkinter:这个小项目的主角,是一 ...
python 烟花效果_新年快乐! python实现绚烂的烟花绽放效果
做了一个Python的小项目.利用了一点python的可视化技巧,做出烟花绽放的效果,文章的灵感来自网络上一位大神. 一.编译环境 Pycharm 二.模块 1.tkinter:这个小项目的主角,是一 ...
matlab烟花动图程序,用PS制作漂亮烟花绽放效果的GIF图片
作者制作动画非常巧妙,直接在智能对象中设置动画,设置好动画后,再把智能对象多复制一些,按一定规律排列,就可以组成非常壮观的动画效果.最终效果一.新建一个500×900px(取决于烟花绽放尺寸)的画布 ...
python实现绚烂的烟花绽放效果
前言本文的文字及图片来源于网络,仅供学习.交流使用,不具有任何商业用途,如有问题请及时联系我们以作处理. PS:如有需要Python学习资料的小伙伴可以加点击下方链接自行获取 python免费学习资 ...
css烟花绽放效果代码,css3+js实现烟花绽放的动画效果（代码示例）
本篇文章给大家介绍通过js+css3的transforms属性和keyframes属性来实现烟花绽放的动画效果的方法.有一定的参考价值,有需要的朋友可以参考一下,希望对你们有所帮助. 首先我们来看看效 ...
棒呆！如何用css3实现烟花绽放效果
闲聊就在上周六,我去听了一场分享会,分享会大概分享了几个大主题: 如何及时在线上debug到错误信息,并且处理以及记录(window.onerror) web动画实践以及技巧(mvp非他莫属,这也是 ...
手搓一个“七夕限定”，用3D Engine 5分钟实现烟花绽放效果
七夕来咯!又到了给重要的人送惊喜的时刻. 今年,除了将心意融入花和礼物,作为程序员,用自己的代码本事手搓一个技术感十足"七夕限定"惊喜,我觉得,这是不亚于车马慢时代手写信的古典主义 ...

html5烟花绽放效果

html5烟花绽放效果相关推荐

最新文章

热门文章