codepens/moonriverpure-javascript/dist/script.js

(function () {
  'use strict';
  window.addEventListener('load', function () {
    var canvas = document.getElementById('canvas');

    if (!canvas || !canvas.getContext) {
      return false;
    }

    /********************
      Random Number
    ********************/

    function rand(min, max) {
      return Math.floor(Math.random() * (max - min + 1) + min);
    }

    /********************
      Var
    ********************/

    var ctx = canvas.getContext('2d');
    var X = canvas.width = window.innerWidth;
    var Y = canvas.height = window.innerHeight;
    var mouseX = X / 2;
    var mouseY = Y / 2;
    var shapes = [];
    var shapeNum = Y / 4;

    /********************
      Animation
    ********************/

    window.requestAnimationFrame =
      window.requestAnimationFrame ||
      window.mozRequestAnimationFrame ||
      window.webkitRequestAnimationFrame ||
      window.msRequestAnimationFrame ||
      function(cb) {
        setTimeout(cb, 17);
      };

    /********************
      Shape
    ********************/
    
    function Shape(ctx, x, y, i) {
      this.ctx = ctx;
      this.init(x, y, i);
    }
    
    Shape.prototype.init = function(x, y, i) {
      this.x = x;
      this.y = y;
      this.i = i;
      this.r = 2;
      this.a = rand(0, 360);
      this.rad = this.a * Math.PI / 180;
      this.ga = Math.random() * Math.random() * Math.random();
      this.inA = Math.random();
      this.scaleX = 100 - i / 2;
      this.dist = shapeNum - i;
    };

    Shape.prototype.draw = function() {
      var ctx  = this.ctx;
      ctx.save();
      ctx.fillStyle = 'white';
      ctx.globalCompositeOperation = 'lighter';
      ctx.globalAlpha = this.ga;
      ctx.translate(Math.sin(this.rad) * this.dist + this.x, this.y);
      ctx.scale(this.scaleX, 1);
      ctx.translate(-Math.sin(this.rad) * this.dist - this.x, -this.y);
      ctx.beginPath();
      ctx.arc(Math.sin(this.rad) * this.dist + this.x, this.y, this.r, 0, Math.PI * 2, false);
      ctx.fill();
      ctx.restore();
    };

    Shape.prototype.updateParams = function() {
      this.a += this.inA;
      this.rad = this.a * Math.PI / 180;
    };

    Shape.prototype.render = function() {
      this.updateParams();
      this.draw();
    };
    
    for (var i = 0; i < shapeNum; i++) {
      var s = new Shape(ctx, X / 2, Y - i * 1, i);
      shapes.push(s);
    }

    /********************
      Moon
    ********************/
    
    var radius = 150;

    if (X < 768) {
      radius = 100;
    }

    function drawMoon() {
      ctx.save();
      ctx.beginPath();
      ctx.fillStyle = 'white';
      ctx.shadowColor = 'white';
      ctx.shadowBlur = 100;
      ctx.arc(X / 2, Y / 3, radius, 0, Math.PI * 2, false);
      ctx.fill();
      ctx.restore();
    }
    
    /********************
      Kirakira
    ********************/

    var particleNum = 500;
    var particles = [];
    
    function Particle(ctx, x, y) {
      this.ctx = ctx;
      this.init(x, y);
    }
    
    Particle.prototype.init = function(x, y) {
      this.x = x;
      this.y = y;
      this.r = rand(5, 10);
      this.ga = Math.random() * Math.random() * Math.random() * Math.random();
      this.v = {
        x: 0,
        y: -Math.random() * Math.random()
      };
      this.l = rand(10, 50);
    };

    Particle.prototype.draw = function() {
      var ctx  = this.ctx;
      ctx.save();
      ctx.fillStyle = 'white';
      ctx.globalCompositeOperation = 'lighter';
      ctx.globalAlpha = this.ga;
      ctx.beginPath();
      ctx.arc(this.x, this.y, this.r, 0, Math.PI * 2, false);
      ctx.fill();
      ctx.restore();
    };

    Particle.prototype.updateParams = function() {
      this.a += this.inA;
      this.rad = this.a * Math.PI / 180;
      this.l -= 0.1;
      if (this.l < 0) {
        this.init(rand(0, X), rand(Y - Y / 4, Y));
      }
    };

    Particle.prototype.updatePositon = function() {
      this.y += this.v.y;
    };

    Particle.prototype.render = function() {
      this.updatePositon();
      this.updateParams();
      this.draw();
    };
    
    for (var i = 0; i < particleNum; i++) {
      var p = new Particle(ctx, rand(0, X), rand(Y - Y / 4, Y));
      particles.push(p);
    }

    /********************
      Render
    ********************/
    
    function render() {
      ctx.clearRect(0, 0, X, Y);
      drawMoon();
      for (var i = 0; i < shapes.length; i++) {
        shapes[i].render(i);
      }
      for (var i = 0; i < particles.length; i++) {
        particles[i].render(i);
      }
      requestAnimationFrame(render);
    }

    render();

    /********************
      Event
    ********************/
    
    function onResize() {
      X = canvas.width = window.innerWidth;
      Y = canvas.height = window.innerHeight;
      shapes = [];
      if (X < 768) {
        radius = 100;
      } else {
        radius = 150;
      }
      for (var i = 0; i < shapeNum; i++) {
        var s = new Shape(ctx, X / 2, Y - i * 1, i);
        shapes.push(s);
      }
    }

    window.addEventListener('resize', function() {
      onResize();
    });

  });
  // Author
  console.log('File Name / moonRiver.js\nCreated Date / July 10, 2020\nAuthor / Toshiya Marukubo\nTwitter / https://twitter.com/toshiyamarukubo');
})();