<!DOCTYPE html>

<html lang="en">

<head>

  <meta charset="UTF-8">

  <title>Heart Animation ❤️</title>

  <style>

    html, body {

      margin: 0;

      padding: 0;

      background-color: #000;

      overflow: hidden;

      height: 100%;

    }


    .box {

      width: 100vw;

      height: 100vh;

      display: flex;

      justify-content: center;

      align-items: center;

    }


    canvas {

      position: absolute;

      top: 0;

      left: 0;

    }

  </style>

</head>

<body>

  <div class="box">

    <canvas id="pinkboard"></canvas>

  </div>


  <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 (var i = firstActive; i < firstFree; i++) particles[i].draw(context, image);

        }

        if (firstFree < firstActive) {

          for (var i = firstActive; i < particles.length; i++) particles[i].draw(context, image);

          for (var 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,

        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) {

          return Math.round(t);

        }


        var gradient = context.createRadialGradient(

          settings.particles.size / 2,

          settings.particles.size / 2,

          0,

          settings.particles.size / 2,

          settings.particles.size / 2,

          settings.particles.size / 2

        );

        gradient.addColorStop(0, "rgba(255,0,0,1)");

        gradient.addColorStop(1, "rgba(255,0,0,0)");

        context.fillStyle = gradient;

        context.beginPath();

        context.arc(

          settings.particles.size / 2,

          settings.particles.size / 2,

          settings.particles.size / 2,

          0,

          Math.PI * 2

        );

        context.fill();


        return canvas;

      })();


      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 = window.innerWidth;

        canvas.height = window.innerHeight;

      }

      window.onresize = onResize;


      setTimeout(function () {

        onResize();

        render();

      }, 10);

    })(document.getElementById("pinkboard"));

  </script>

</body>

</html>