基于 HTML5 的爱心表白动画特效

2022-11-10
四川
本文字数：3523 字
阅读完需：约 12 分钟

从视觉上看，它也是一个爱心轮廓，但是不同的是这个爱心轮廓由许多跳动的小爱心组成，更加有一种 3D 立体的效果。

1. 运行效果

2. 代码构成

<!doctype html><html><head><meta charset="utf-8"><title>爱心表白</title>
<style>html, body {  height: 100%;  padding: 0;  margin: 0;  background: #000;}canvas {  width: 100%;  height: 100%;}</style>
</head><body>
<div style="text-align:center;clear:both;"><script src="/gg_bd_ad_720x90.js" type="text/javascript"></script><script src="/follow.js" type="text/javascript"></script></div>
<canvas id="pinkboard"></canvas>
<script>var settings = {  particles: {    length:   500,    duration:   2,    velocity: 100,    effect: -0.75,    size:      30,  },};
(function(){var b=0;var c=["ms","moz","webkit","o"];for(var a=0;a<c.length&&!window.requestAnimationFrame;++a){window.requestAnimationFrame=window[c[a]+"RequestAnimationFrame"];window.cancelAnimationFrame=window[c[a]+"CancelAnimationFrame"]||window[c[a]+"CancelRequestAnimationFrame"]}if(!window.requestAnimationFrame){window.requestAnimationFrame=function(h,e){var d=new Date().getTime();var f=Math.max(0,16-(d-b));var g=window.setTimeout(function(){h(d+f)},f);b=d+f;return g}}if(!window.cancelAnimationFrame){window.cancelAnimationFrame=function(d){clearTimeout(d)}}}());
var Point = (function() {  function Point(x, y) {    this.x = (typeof x !== 'undefined') ? x : 0;    this.y = (typeof y !== 'undefined') ? y : 0;  }  Point.prototype.clone = function() {    return new Point(this.x, this.y);  };  Point.prototype.length = function(length) {    if (typeof length == 'undefined')      return Math.sqrt(this.x * this.x + this.y * this.y);    this.normalize();    this.x *= length;    this.y *= length;    return this;  };  Point.prototype.normalize = function() {    var length = this.length();    this.x /= length;    this.y /= length;    return this;  };  return Point;})();
var Particle = (function() {  function Particle() {    this.position = new Point();    this.velocity = new Point();    this.acceleration = new Point();    this.age = 0;  }  Particle.prototype.initialize = function(x, y, dx, dy) {    this.position.x = x;    this.position.y = y;    this.velocity.x = dx;    this.velocity.y = dy;    this.acceleration.x = dx * settings.particles.effect;    this.acceleration.y = dy * settings.particles.effect;    this.age = 0;  };  Particle.prototype.update = function(deltaTime) {    this.position.x += this.velocity.x * deltaTime;    this.position.y += this.velocity.y * deltaTime;    this.velocity.x += this.acceleration.x * deltaTime;    this.velocity.y += this.acceleration.y * deltaTime;    this.age += deltaTime;  };  Particle.prototype.draw = function(context, image) {    function ease(t) {      return (--t) * t * t + 1;    }    var size = image.width * ease(this.age / settings.particles.duration);    context.globalAlpha = 1 - this.age / settings.particles.duration;    context.drawImage(image, this.position.x - size / 2, this.position.y - size / 2, size, size);  };  return Particle;})();
var ParticlePool = (function() {  var particles,      firstActive = 0,      firstFree   = 0,      duration    = settings.particles.duration;    function ParticlePool(length) {    particles = new Array(length);    for (var i = 0; i < particles.length; i++)      particles[i] = new Particle();  }  ParticlePool.prototype.add = function(x, y, dx, dy) {    particles[firstFree].initialize(x, y, dx, dy);        firstFree++;    if (firstFree   == particles.length) firstFree   = 0;    if (firstActive == firstFree       ) firstActive++;    if (firstActive == particles.length) firstActive = 0;  };  ParticlePool.prototype.update = function(deltaTime) {    var i;        if (firstActive < firstFree) {      for (i = firstActive; i < firstFree; i++)        particles[i].update(deltaTime);    }    if (firstFree < firstActive) {      for (i = firstActive; i < particles.length; i++)        particles[i].update(deltaTime);      for (i = 0; i < firstFree; i++)        particles[i].update(deltaTime);    }        while (particles[firstActive].age >= duration && firstActive != firstFree) {      firstActive++;      if (firstActive == particles.length) firstActive = 0;    }          };  ParticlePool.prototype.draw = function(context, image) {    if (firstActive < firstFree) {      for (i = firstActive; i < firstFree; i++)        particles[i].draw(context, image);    }    if (firstFree < firstActive) {      for (i = firstActive; i < particles.length; i++)        particles[i].draw(context, image);      for (i = 0; i < firstFree; i++)        particles[i].draw(context, image);    }  };  return ParticlePool;})();
(function(canvas) {  var context = canvas.getContext('2d'),      particles = new ParticlePool(settings.particles.length),      particleRate = settings.particles.length / settings.particles.duration, // particles/sec      time;    function pointOnHeart(t) {    return new Point(      160 * Math.pow(Math.sin(t), 3),      130 * Math.cos(t) - 50 * Math.cos(2 * t) - 20 * Math.cos(3 * t) - 10 * Math.cos(4 * t) + 25    );  }    var image = (function() {    var canvas  = document.createElement('canvas'),        context = canvas.getContext('2d');    canvas.width  = settings.particles.size;    canvas.height = settings.particles.size;    function to(t) {      var point = pointOnHeart(t);      point.x = settings.particles.size / 2 + point.x * settings.particles.size / 350;      point.y = settings.particles.size / 2 - point.y * settings.particles.size / 350;      return point;    }    context.beginPath();    var t = -Math.PI;    var point = to(t);    context.moveTo(point.x, point.y);    while (t < Math.PI) {      t += 0.01;       point = to(t);      context.lineTo(point.x, point.y);    }    context.closePath();    context.fillStyle = '#ea80b0';    context.fill();      var image = new Image();    image.src = canvas.toDataURL();    return image;  })();    function render() {    requestAnimationFrame(render);        var newTime   = new Date().getTime() / 1000,        deltaTime = newTime - (time || newTime);    time = newTime;        context.clearRect(0, 0, canvas.width, canvas.height);        var amount = particleRate * deltaTime;    for (var i = 0; i < amount; i++) {      var pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random());      var dir = pos.clone().length(settings.particles.velocity);      particles.add(canvas.width / 2 + pos.x, canvas.height / 2 - pos.y, dir.x, -dir.y);    }        particles.update(deltaTime);    particles.draw(context, image);  }    function onResize() {    canvas.width  = canvas.clientWidth;    canvas.height = canvas.clientHeight;  }  window.onresize = onResize;    setTimeout(function() {    onResize();    render();  }, 10);})(document.getElementById('pinkboard'));</script>
</body></html>