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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

HTML

              
                <link href='//fonts.googleapis.com/css?family=Raleway:100' rel='stylesheet' type='text/css'>
<link href='//fonts.googleapis.com/css?family=Berkshire+Swash' rel='stylesheet' type='text/css'>
<div class="intro">
  <h1>Let there be light</h1>
  <p>Paint with your cursor to create a galaxy</p>
</div>
              
            
!

CSS

              
                body {
  margin:0;
  background-color:#000;
  color:#fff;
  font-family: 'Raleway', sans-serif;
}

canvas {
  position:absolute;
  top:0;
  left:0;
  width:100%;
  height:100%;
}

.intro {
  position:absolute;
  z-index:2;
  top:25px;
  left:25%;
  width:50%;
  text-align:center;
  pointer-events:none;
}
h1 {
  margin:10px 0;
  text-shadow:0 0 20px rgba(255,255,255,.5);
  font-family: 'Berkshire Swash', cursive;
}
p {
  color:rgba(255,255,255,.75);
}
              
            
!

JS

              
                var w = window.innerWidth;
var h = window.innerHeight;

var dustCanvas = document.createElement('canvas');
var dustCtx = dustCanvas.getContext('2d');
var starCanvas = document.createElement('canvas');
var starCtx = starCanvas.getContext('2d');

document.body.appendChild(dustCanvas);
document.body.appendChild(starCanvas);

dustCanvas.width = starCanvas.width = w;
dustCanvas.height = starCanvas.height = h;

dustCtx.globalCompositeOperation = 'lighter';
starCtx.globalCompositeOperation = 'lighter';

var galaxies = [];

var mouse = {
  pos: {
    x: w * 0.5,
    y: h * 0.5
  },
  speed: 0
};

var randomNumbers = length => Array.from(new Array(length), () => Math.random());
var PI = Math.PI;
var TAU = PI * 2;
var r = () => Math.random();
var angle2 = (p1,p2) => Math.atan2(
  p2[1]-p1[1],
  p2[0]-p1[0]
);
var distance2 = (p1,p2) => Math.sqrt(
  Math.pow(p1[0]-p2[0], 2) + 
  Math.pow(p1[1]-p2[1], 2)
);

var createDustParticle = (color) => {
  
  var canvas = document.createElement('canvas');
  
  var w = 100;
  var h = 100;
  var cx = w * 0.5;
  var cy = h * 0.5;
  
  canvas.width = w;
  canvas.height = h;
  var ctx = canvas.getContext('2d');
  canvas.ctx = ctx;
  
  var xRand = -5 + (r()*10);
  var yRand = -5 + (r()*10);
  var xRand2 = 10 + (r()*(cx/2));
  var yRand2 = 10 + (r()*(cy/2));
  
  var color = color || {
    r: Math.round(150+(r()*100)),
    g: Math.round(50+(r()*100)),
    b: Math.round(50+(r()*100))
  };
  
  ctx.fillStyle = `rgba(${color.r},${color.g},${color.b},.02)`;
  
  Array
    .from(new Array(200), () => randomNumbers(3))
    .forEach( (p,i,arr) => {
      var length = arr.length;
      
      var x = Math.cos( TAU/xRand/length*i ) * p[2]*xRand2 + cx;
      var y = Math.sin( TAU/yRand/length*i ) * p[2]*yRand2 + cy;
      
      ctx.beginPath();
      ctx.moveTo(x, y);
      ctx.arc(x, y, p[2]*4, 0, TAU);
      ctx.fill();
    
    });
  
    return canvas;
};

var Galaxy = function(x,y) {
  
  var g = this;
  
  g.x = x;
  g.y = y;
  g.stars = [];
  g.dust = [];
  g.drag = r();
  
  g.angleOffsetX = TAU*r();
  g.angleOffsetY = TAU*r();
  g.realAngleOffsetX = 0;
  g.realAngleOffsetY = 0;
  
  g.color = {
    r: Math.round(50+(r()*100)),
    g: Math.round(50+(r()*100)),
    b: Math.round(150+(r()*100))
  };
  
  var calculateStarDustParams = o => {
    o.angle = angle2([g.x,g.y], [o.x,o.y]);
    o.distance = distance2([g.x,g.y], [o.x,o.y]);
    o.xAspect = [o.x/o.y];
    o.yAspect = [o.y/o.x];
  };
  
  g.calculateCenter = () => {
    if (!g.stars.length) return;
    g.x = g.stars
      .map(s => s.x)
      .reduce((previous,current) => previous + current)
      / g.stars.length;
    
    g.y = g.stars
      .map(s => s.y)
      .reduce((previous,current) => previous + current)
      / g.stars.length;
    
    g.stars.forEach(calculateStarDustParams);
    g.dust.forEach(calculateStarDustParams);
  };
  
};

var Star = function(x, y, spread) {
  var s = this;
  s.x = x + Math.cos(TAU*r()) * spread;
  s.y = y + Math.sin(TAU*r()) * spread;
  s.radius = r()+0.25;
  s.speed = r();
};

var Dust = function(x, y, size) {
  var d = this;
  d.x = x;
  d.y = y;
  d.size = size;
  d.texture = createDustParticle();
  d.speed = r();
};

var updateStarDust = (s,g) => {
  if (g == currentGalaxy && drawingMode) return;
  s.angle += (0.5+(s.speed*0.5))/s.distance;
  s.x = g.x + (Math.cos(s.angle+g.realAngleOffsetX)*s.distance);
  s.y = g.y + (Math.sin(s.angle+g.realAngleOffsetY)*s.distance);
};

var update = () => {
  galaxies.forEach(g => {
    if (g != currentGalaxy) {
      g.realAngleOffsetX +=
        g.realAngleOffsetX < g.angleOffsetX
        ? (g.angleOffsetX-g.realAngleOffsetX)*0.05 : 0;
      g.realAngleOffsetY +=
        g.realAngleOffsetY < g.angleOffsetY
        ? (g.angleOffsetY-g.realAngleOffsetY)*0.05 : 0;
    }
    g.stars.forEach((s) => {
      /*s.distance -= s.distance < 2
        ? 0
        : TAU/s.distance;*/
      updateStarDust(s,g);
    });
    g.dust.forEach((d) => {
      /*d.distance -= d.distance < 50
        ? 0
        : TAU/d.distance;*/
      updateStarDust(d,g);
    });
  });
};

var render = () => {
  
  dustCtx.globalCompositeOperation = 'source-over';
  dustCtx.fillStyle = 'rgba(0,0,0,.05)';
  dustCtx.fillRect(0,0,w,h);
  dustCtx.globalCompositeOperation = 'lighter';

  starCtx.clearRect(0,0,w,h);
  starCtx.fillStyle = '#ffffff';
  starCtx.strokeStyle = 'rgba(255,255,255,.05)';
  starCtx.beginPath();
  
  if (drawingMode) galaxies.forEach(g => {
    starCtx.moveTo(g.x, g.y);
    starCtx.arc(g.x,g.y,2,0,TAU);
  });
  
  galaxies.forEach(g => {
    g.stars.forEach(s => {
      starCtx.moveTo(s.x, s.y);
      starCtx.arc(s.x,s.y,s.radius,0,TAU);
    });
    g.dust.forEach(d => {
      dustCtx.drawImage(d.texture, d.x-(d.size*0.5), d.y-(d.size*0.5), d.size, d.size)
    });
  });
  
  dustCtx.fill();
  starCtx.fill();
  
  if (drawingMode && currentGalaxy) {
    starCtx.beginPath();
    currentGalaxy.stars.forEach((s,i) => {
        starCtx.moveTo(s.x, s.y);
        starCtx.lineTo(currentGalaxy.x, currentGalaxy.y);
    });
    starCtx.stroke();
  }
  
};

var currentGalaxy = null;

var drawingMode = false;

var activateDraw = e => {
  drawingMode = true;
  mouse.pos.x = e.layerX;
  mouse.pos.y = e.layerY;
  currentGalaxy = new Galaxy(e.layerX, e.layerY);
  galaxies.push(currentGalaxy);
};
var disableDraw = e => {
  
  drawingMode = false;
  currentGalaxy = null;
};
var draw = e => {
  if (!drawingMode) return;
  
  currentGalaxy.stars.push(new Star(mouse.pos.x, mouse.pos.y, mouse.speed));
  currentGalaxy.stars.push(new Star(mouse.pos.x, mouse.pos.y, mouse.speed));
  currentGalaxy.stars.push(new Star(mouse.pos.x, mouse.pos.y, mouse.speed));
  
  if (mouse.speed*1.5 > 13 && mouse.speed < 100) currentGalaxy.dust.push(
    new Dust(
      (currentGalaxy.x + (Math.cos(TAU*r()) * mouse.speed*0.1)),
      (currentGalaxy.y + (Math.sin(TAU*r()) * mouse.speed*0.1)),
      mouse.speed*1.5
    )
  );
  
  currentGalaxy.calculateCenter();
  
};

var loop = () => {
  draw();
  update();
  render();
  window.requestAnimationFrame(loop);
};

loop();

var moveEvent = e => {
  mouse.speed =  distance2(
    [e.layerX,e.layerY],
    [mouse.pos.x,mouse.pos.y]
  );
  mouse.pos.x = e.layerX;
  mouse.pos.y = e.layerY;
  draw(e);
};

window.addEventListener('mousedown', activateDraw);
window.addEventListener('mousemove', moveEvent);
window.addEventListener('mouseup',disableDraw);

window.addEventListener('touchstart', activateDraw);
window.addEventListener('touchmove', moveEvent);
window.addEventListener('touchend',disableDraw);
              
            
!
999px

Console