动态爱心

<META NAME="Generator" CONTENT="EditPlus">
<META NAME="Author" CONTENT="">
<META NAME="Keywords" CONTENT="">
<META NAME="Description" CONTENT="">
<style>
  html, body {
    height: 100%;
    padding: 0;
    margin: 0;
    background: #000;
  }
  canvas {
    position: absolute;
    width: 100%;
    height: 100%;
  }
</style>

<canvas id="pinkboard"></canvas>
<script>
  /*

var settings = {
  particles: {
    length: 500, // maximum amount of particles
    duration: 2, // particle duration in sec
    velocity: 100, // particle velocity in pixels/sec
    effect: -0.75, // play with this for a nice effect
    size: 30, // particle size in pixels
  },
};
/*

(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)}}}());
  /*
  * Point class
  */
  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;
  })();
  /*
  * Particle class
  */
  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;
  })();
  /*
  * ParticlePool class
  */
  var ParticlePool = (function() {
  var particles,
  firstActive = 0,
  firstFree = 0,
  duration = settings.particles.duration;
  function ParticlePool(length) {
  // create and populate particle pool
  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);
  // handle circular queue
  firstFree++;
  if (firstFree == particles.length) firstFree = 0;
  if (firstActive == firstFree ) firstActive++;
  if (firstActive == particles.length) firstActive = 0;
  };
  ParticlePool.prototype.update = function(deltaTime) {
  var i;
  // update active particles
  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);
  }
  // remove inactive particles
  while (particles[firstActive].age >= duration && firstActive != firstFree) {
  firstActive++;
  if (firstActive == particles.length) firstActive = 0;
  }
  };
  ParticlePool.prototype.draw = function(context, image) {
  // draw active particles
  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;
  })();
  /*
  * Putting it all together
  */
  (function(canvas) {
  var context = canvas.getContext('2d'),
  particles = new ParticlePool(settings.particles.length),
  particleRate = settings.particles.length / settings.particles.duration, // particles/sec
  time;
  // get point on heart with -PI <= t <= PI
  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
  );
  }
  // creating the particle image using a dummy canvas
  var image = (function() {
  var canvas = document.createElement('canvas'),
  context = canvas.getContext('2d');
  canvas.width = settings.particles.size;
  canvas.height = settings.particles.size;
  // helper function to create the path
  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;
  }
  // create the path
  context.beginPath();
  var t = -Math.PI;
  var point = to(t);
  context.moveTo(point.x, point.y);
  while (t < Math.PI) {
  t += 0.01; // baby steps!
  point = to(t);
  context.lineTo(point.x, point.y);
  }
  context.closePath();
  // create the fill
  context.fillStyle = '#ea80b0';
  context.fill();
  // create the image
  var image = new Image();
  image.src = canvas.toDataURL();
  return image;
  })();
  // render that thing!
  function render() {
  // next animation frame
  requestAnimationFrame(render);
  // update time
  var newTime = new Date().getTime() / 1000,
  deltaTime = newTime - (time || newTime);
  time = newTime;
  // clear canvas
  context.clearRect(0, 0, canvas.width, canvas.height);
  // create new particles
  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);
  }
  // update and draw particles
  particles.update(deltaTime);
  particles.draw(context, image);
  }
  // handle (re-)sizing of the canvas
  function onResize() {
  canvas.width = canvas.clientWidth;
  canvas.height = canvas.clientHeight;
  }
  window.onresize = onResize;
  // delay rendering bootstrap
  setTimeout(function() {
  onResize();
  render();
  }, 10);
  })(document.getElementById('pinkboard'));
  </script>
  </BODY>
  </HTML>