Pen Settings

HTML

CSS

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

+ add another resource

JavaScript

Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource

Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

Behavior

Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.

HTML

              
                <canvas id="stars"></canvas>
              
            
!

CSS

              
                #stars {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  background-color: #ff2222;
  z-index: -1;
}
              
            
!

JS

              
                (function() {
  var ShootingStars, Star, debounce, extend, requestAnimationFrame;
  Star = function Star(size, rotate, points, outerRadius, innerRadius, borderColor, fillColor, x, y, starCanvas) {
    var self;
    self = this;
    self.x = x;
    self.y = y;
    self.size = size;
    self.color = fillColor;
    self.border = borderColor;
    self.outerRad = outerRadius;
    self.innerRad = innerRadius;
    self.rotation = rotate;
    self.points = points;
    self.opacity = 0;
    self.scale = 0;
    self.vx = Math.random() * 2 - 1;
    self.vy = Math.random() * 2 - 1;
    self.life = 0;
    self.ss = starCanvas;
    return self;
  };
  Star.prototype.update = function() {
    var canvas, maxLife, particlePool, particles;
    this.x += this.vx;
    this.y += this.vy;
    canvas = this.ss.canvas;
    maxLife = this.ss.maxLife;
    particlePool = this.ss.particlePool;
    particles = this.ss.particles;
    if (this.opacity < 1 && this.life < maxLife / 6) {
      this.opacity += 100 / (maxLife / 6) / 100;
      this.scale += 100 / (maxLife / 6) / 100;
    }
    this.life++;
    if (maxLife - this.life < maxLife / 6) {
      this.scale -= 100 / (maxLife / 6) / 100;
    }
    if (maxLife - this.life < maxLife / 3) {
      this.vy *= 1.075;
      this.vx *= 1.075;
      this.opacity = (maxLife - this.life) / 100;
    } else if (this.life % 2 === 0) {
      this.rotation++;
    }
    if (this.life >= maxLife) {
      this.life = 0;
      this.scale = 0;
      this.x = Math.floor(Math.random() * canvas.width + 1);
      this.y = Math.floor(Math.random() * canvas.height + 1);
      this.vx = Math.random() - 0.5;
      this.vy = Math.random() - 0.5;
      self.vx = Math.random() * 2 - 1;
      self.vy = Math.random() * 2 - 1;
      particlePool.push(particles.shift());
    }
    return this;
  };
  Star.prototype.render = function(context) {
    var i, rad, rotation, star, starCanvas, starContext;
    star = this;
    starCanvas = document.createElement('canvas');
    starCanvas.width = star.size;
    starCanvas.height = star.size;
    starContext = starCanvas.getContext('2d');
    starContext.save();
    starContext.fillStyle = star.color;
    starContext.strokeStyle = star.border;
    starContext.globalAlpha = star.opacity;
    starContext.translate(star.size / 2, star.size / 2);
    starContext.rotate(star.rotation * Math.PI / 180);
    starContext.translate(-(star.size / 2), -(star.size / 2));
    starContext.scale(star.scale, star.scale);
    starContext.beginPath();
    i = 0;
    while (i <= star.points * 2) {
      rotation = i * Math.PI / star.points;
      rad = i % 2 === 0 ? star.outerRad : star.innerRad;
      starContext.lineTo(star.size / 2 + rad * Math.cos(rotation), star.size / 2 + rad * Math.sin(rotation));
      ++i;
    }
    starContext.fill();
    starContext.stroke();
    starContext.restore();
    return context.drawImage(starCanvas, star.x, star.y);
  };
  debounce = function debounce(func, delay) {
    var inDebounce;
    inDebounce = void 0;
    inDebounce = void 0;
    return function() {
      var args, context;
      args = void 0;
      context = void 0;
      context = this;
      args = arguments;
      clearTimeout(inDebounce);
      return inDebounce = setTimeout(function() {
        return func.apply(context, args);
      }, delay);
    };
  };
  extend = function extend(a, b) {
    var key;
    for (key in b) {
      if (b.hasOwnProperty(key) && b[key] !== void 0) {
        a[key] = b[key];
      }
    }
    return a;
  };
  requestAnimationFrame = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.msRequestAnimationFrame || function(callback) {
    return setTimeout(callback, 1000 / 60);
  };
  window.ShootingStars = ShootingStars = function ShootingStars(config) {
    var canvas, canvasId, defaults, self;
    self = this;
    canvasId = config.id;
    defaults = {
      particleLife: 300,
      particleRenderProbability: 0.05,
      amount: 5,
      resizePoll: 250,
      star: {
        size: {
          upper: 50,
          lower: 25
        },
        rotateLimit: 45,
        points: 5,
        innerRadius: 0.5,
        borderColor: '#000',
        fillColor: 'red'
      }
    };
    self.options = extend(defaults, config);
    self.canvas = canvas = document.getElementById(canvasId);
    canvas.width = window.innerWidth;
    canvas.height = window.innerHeight;
    canvas.ctx = canvas.getContext('2d');
    self.maxLife = self.options.particleLife;
    self.particles = [];
    self.particlePool = [];
    self.particleProbability = self.options.particleRenderProbability;
    self.poolSize = self.options.amount;
    window.addEventListener('resize', debounce(function() {
      self.canvas.width = window.innerWidth;
      self.canvas.height = window.innerHeight;
      self.flushPool();
    }, self.options.resizePoll));
    return self;
  };
  ShootingStars.prototype.flushPool = function() {
    var canvas, getRandomFromRange, i, particlePool, particles, poolSize, results, rotation, size, that;
    that = this;
    canvas = that.canvas;
    particlePool = that.particlePool = [];
    particles = that.particles = [];
    poolSize = self.poolSize = that.options.amount;
    if (canvas.width < 450) {
      poolSize = self.poolSize = poolSize / 2;
    }
    i = 0;
    results = [];
    while (i < poolSize) {
      getRandomFromRange = function getRandomFromRange(max, min) {
        return Math.floor(Math.random() * (max - min + 1) + min);
      };
      size = getRandomFromRange(that.options.star.size.upper, that.options.star.size.lower);
      rotation = getRandomFromRange(that.options.star.rotateLimit, 0);
      particlePool.push(new Star(size, rotation, 5, size / 2, size / 2 * that.options.star.innerRadius, this.options.star.borderColor, this.options.star.fillColor, Math.floor(Math.random() * canvas.width + 1), Math.floor(Math.random() * canvas.height + 1), that));
      results.push(i++);
    }
    return results;
  };
  ShootingStars.prototype.render = function() {
    var canvas, ctx, p, particlePool, particles, that;
    that = this;
    canvas = that.canvas;
    ctx = canvas.ctx;
    particlePool = that.particlePool;
    particles = that.particles;
    ctx.save();
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    if (Math.random() > that.particleProbability && particles.length < that.poolSize && particlePool.length > 0) {
      particles.push(particlePool.shift());
    }
    p = 0;
    while (p < particles.length) {
      particles[p].update();
      if (particles[p]) {
        particles[p].render(ctx);
      }
      p++;
    }
    /*
    FOR A TRIPPY EFFECT - If you render a star every frame in a different
    position and then wipe the canvas every frame you get a pretty trippy
    effect whereby the star will be blinking all over the canvas at close
    to 60 FPS.
    */
    ctx.restore();
    return requestAnimationFrame(function() {
      return that.render();
    });
  };
}).call(undefined);
var config = {
  id: 'stars',
  particleLife: 300,
  particleRenderProbability: 0.95,
  amount: 50,
  star: {
    size: {
      upper: 50,
      lower: 25
    },
    rotateLimit: 90,
    points: 5,
    innerRadius: 0.5,
    borderColor: '#290f5a',
    fillColor: '#ffcc00'
  }
};
var myCanvas = new ShootingStars(config);
myCanvas.flushPool();
myCanvas.render();
              
            
!
999px

Console