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HTML

              
                canvas
p loading audio...

              
            
!

CSS

              
                body
  background: #000
  
canvas, p
  position: absolute
  top: 50%
  left: 50%
  transform: translate(-50%, -50%)
  
canvas
  cursor: pointer
  
p
  pointer-events: none
  margin: 4px 0 0 1px
  font-family: monospace
  color: #fff
  
  &:not(.fa)::after
    content: '💧'
    position: absolute
    font-size: 24px
    top: 124px
    left: 6px
  
  &.fa
    font-size: 24px
    color: #000

              
            
!

JS

              
                !function () {
  // play with these
  var MIN_RADIUS = 300;
  var JITTER_RANGE = 200;
  var NUM_NODES = 256; // only 1/2 of these are actually drawn
  var COLOR = [255, 255, 255];
  var SMOOTHING_TIME_CONSTANT = 0.6; // 0-1
  
  // derived
  var center = MIN_RADIUS + JITTER_RANGE;
  var size = center * 2;
  // the bottom 1/8 and top 3/8 of this song are pretty boring...
  var i0 = NUM_NODES / 8;
  var i1 = NUM_NODES * 5 / 8;
  var range = i1 - i0;
  
  // shared state
  var hovered = false;
  
  // math
  var PI = Math.PI;
  var sin = Math.sin;
  var cos = Math.cos;

  // canvas
  var canvas = document.querySelector('canvas');
  var ctx = canvas.getContext('2d');
  canvas.height = canvas.width = size;
  ctx.lineWidth = 2;
  ctx.strokeStyle = 'rgb(' + COLOR + ')';
  
  var leftOnly = ctx.createLinearGradient(0, 0, size, 0);
  leftOnly.addColorStop(0, '#fff');
  leftOnly.addColorStop(0.5, '#fff');
  leftOnly.addColorStop(0.5, 'transparent');
  
  // helper function
  function dbToXY (db, i) {
    var r = MIN_RADIUS + db / 255 * JITTER_RANGE;
    var theta = 2*PI * (i / range + 1/4);
    
		return {
      x: r * cos(theta) + center,
      y: r * sin(theta) + center,
    };
  }
  
  function smoothCurveTo (db1, db2, i) {
    var coords1 = dbToXY(db1, i);
    // midpoint between db1 and db2
    var coords2 = dbToXY((db1 + db2) / 2, i + 0.5);

    ctx.quadraticCurveTo(coords1.x, coords1.y, coords2.x, coords2.y);
  }
  
  // helper function
  function drawX (x, y, r, width) {
    ctx.save();
    ctx.beginPath();
    ctx.lineWidth = width;
    ctx.moveTo(x - r, y - r);
    ctx.lineTo(x + r, y + r);
    ctx.moveTo(x - r, y + r);
    ctx.lineTo(x + r, y - r);
    ctx.stroke();
    ctx.restore();
  }

  // main loop
  function update (analyser, freqArray) {
    var i;
    ctx.clearRect(0, 0, size, size);
    analyser.getByteFrequencyData(freqArray);
    
    var average = 0;
    for (i = i0; i < i1; ++i) {
      average += freqArray[i]; 
    }
    average /= range;
    
    // draw a straight line from i0 to i1 and add it to the
    // resultant shape to ensure the lo and hi nodes meet smoothly
    var lo = freqArray[i0];
    var hi = freqArray[i1];
    var slope = lo - hi;
    
    // also ensure that our average radius never changes
    var offset = (average + slope) / 2;

    ctx.beginPath();
    var firstDb = freqArray[i0] - offset;
    var lastDb = freqArray[i1 - 1] + (range - 1) * slope / range - offset;
    var initialCoords = dbToXY((lastDb + firstDb) / 2, range - 0.5);
    ctx.moveTo.apply(ctx, [initialCoords.x, initialCoords.y]);
    
    var prevDb, db = firstDb;
    for (i = i0 + 1; i < i1; ++i) {
      prevDb = db;
      db = freqArray[i] + (i - i0) * slope / range - offset;
      smoothCurveTo(prevDb, db, i - i0 - 1);
    }
    smoothCurveTo(lastDb, firstDb, range - 1);    
    ctx.stroke();


    // draw face
    if (hovered) {
      ctx.fill();
    } else {
      // eyes
      var x1 = center - MIN_RADIUS / 2.5;
      var x2 = center + MIN_RADIUS / 2.5;
      drawX(x1, x2 - 20, 16, 6);
      drawX(x2, x2 - 20, 16, 6);
      
      // mouth
      ctx.beginPath();
      ctx.moveTo(center - 20, x2 + 10);
      ctx.lineTo(center + 20, x2 + 10);
      ctx.stroke();
    }

    requestAnimationFrame(update.bind(this, analyser, freqArray));
  }
  
  function loadSound (url, cb) {
    var request = new XMLHttpRequest();
    request.open('GET', url, true);
    request.responseType = 'arraybuffer';
    request.onload = function () { cb(request.response); };
    request.send();
  }
  
  // load the mp3 and initialize our visualizer
  loadSound('https://raw.githubusercontent.com/muhammederdem/mini-player/master/mp3/4.mp3', function (res) {
    var audioContext = new (window.AudioContext || window.webkitAudioContext)();
    audioContext.decodeAudioData(res, function (buffer) {
      var analyser = audioContext.createAnalyser();
      var freqArray = new Uint8Array(analyser.frequencyBinCount);
      var sourceNode = audioContext.createBufferSource();
      analyser.smoothingTimeConstant = SMOOTHING_TIME_CONSTANT;
      analyser.fftSize = NUM_NODES * 2;
      analyser.minDecibels = -90;
      analyser.maxDecibels = -10;
      sourceNode.buffer = buffer;
      analyser.connect(audioContext.destination);
      sourceNode.connect(analyser, freqArray);
      sourceNode.start(0);
      update(analyser, freqArray);
      
      // add play/pause control
      var playing = true;
      var control = document.querySelector('p');
      control.textContent = '';
      control.className = '';
      
      canvas.addEventListener('click', function () {
        playing = !playing;
        
        // this doesn't actually pause anything, just fakes it...
				sourceNode[(playing ? '' : 'dis') + 'connect'](analyser);
        control.className = 'fa fa-' + (playing ? 'pause' : 'play');
			}, false);
      
      canvas.addEventListener('mouseenter', function () {
				ctx.fillStyle = 'rgba(' + COLOR + ', 0.24)';
        control.className = 'fa fa-' + (playing ? 'pause' : 'play');
        hovered = true;
			}, false);
      
      canvas.addEventListener('mouseleave', function () {
				ctx.fillStyle = 'rgba(' + COLOR + ', 0)';
        control.className = '';
        hovered = false;
			}, false);
    });
  });
}();

              
            
!
999px

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