CWSpear/index.html

## index.html
<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">

  <title>Blob &middot; CodePen</title>
  <!--
    Copyright (c) 2012 Hakim El Hattab, http://codepen.io/hakimel

    Permission is hereby granted, free of charge, to any person obtaining
    a copy of this software and associated documentation files (the
    "Software"), to deal in the Software without restriction, including
    without limitation the rights to use, copy, modify, merge, publish,
    distribute, sublicense, and/or sell copies of the Software, and to
    permit persons to whom the Software is furnished to do so, subject to
    the following conditions:

    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
    LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  -->

  <style>
body {
    background-color: #333333;
    padding: 0;
    margin: 0;
    overflow: hidden;
}
p {
    position: absolute;
    z-index: 99;
    color: #cccccc;
    margin: 2px;
    padding: 0;
    font-family: Arial;
    font-size: 10px;
}
a {
		color: #f4f4f4;
		font-weight: bold;
}
  </style>

  <style>
    #codepen-footer, #codepen-footer * {
      -webkit-box-sizing: border-box !important;
      -moz-box-sizing: border-box !important;
      box-sizing: border-box !important;
    }
    #codepen-footer {
      display: block !important;
      position: fixed !important;
      bottom: 0 !important;
      left: 0 !important;
      width: 100% !important;
      padding: 0 10px !important;
      margin: 0 !important;
      height: 30px !important;
      line-height: 30px !important;
      font-size: 12px !important;
      color: #eeeeee !important;
      background-color: #505050 !important;
      text-align: left !important;
      background: -webkit-linear-gradient(top, #505050, #383838) !important;
      background: -moz-linear-gradient(top, #505050, #383838) !important;
      background: -ms-linear-gradient(top, #505050, #383838) !important;
      background: -o-linear-gradient(top, #505050, #383838) !important;
      border-top: 1px solid black !important;
      border-bottom: 1px solid black !important;
      border-radius: 0 !important;
      border-image: none !important;
      box-shadow: inset 0 1px 0 #6e6e6e, 0 2px 2px rgba(0, 0, 0, 0.4) !important;
      z-index: 300 !important;
      font-family: "Lucida Grande", "Lucida Sans Unicode", Tahoma, sans-serif !important;
      letter-spacing: 0 !important;
      word-spacing: 0 !important;
    }
    #codepen-footer a {
      color: #a7a7a7 !important;
      text-decoration: none !important;
    }
    #codepen-footer a:hover {
      color: white !important;
    }
  </style>
  <script>
    // Kill alerts, confirmations and prompts
    window.alert   = function(){};
    window.confirm = function(){};
    window.prompt  = function(){};
    window.open    = function(){};
    window.print   = function(){};
  </script>

</head>
<body>

  <p>Double click to split. <a id="keyboardUp" href="#">Increase</a> / <a id="keyboardDown" href="#">decrease</a> size or <a id="keyboardLeft" href="#">Previous</a> / <a id="keyboardRight" href="#">Next</a> skin.</p>
<canvas id='world'></canvas>

  <script>
(function() {

/**
* Best seen in fullscreen: http://hakim.se/experiments/html5/blob/03/
 */
BlobWorld = new function() {

  var SCREEN_WIDTH = window.innerWidth;
  var SCREEN_HEIGHT = window.innerHeight;

  var canvas;
  var context;
  var blobs = [];

  var dragBlob;

  var screenX = window.screenX;
  var screenY = window.screenY;

  var mouseX = (window.innerWidth - SCREEN_WIDTH);
  var mouseY = (window.innerHeight - SCREEN_HEIGHT);
  var mouseIsDown = false;
  var mouseDownOffset = { x: 0, y: 0 };

  // The bounds of the world
  var worldRect = { x: 0, y: 0, width: 0, height: 0 };

  // The world gravity, applied to all blobs
  var gravity = { x: 0, y: 1.2 };

  // A pair of blobs that should be merged
  var mergeQueue = { blobA: -1, blobB: -1 };

  var skinIndex = 0;
  var skins = [
       { fillStyle: 'rgba(0,200,250,1.0)', strokeStyle: '#ffffff', lineWidth: 5, debug: false },
       { fillStyle: '', strokeStyle: '', lineWidth: 0, debug: true },
     { fillStyle: 'rgba(0,0,0,0.1)', strokeStyle: 'rgba(255,255,255,1.0)', lineWidth: 6, debug: false },
       { fillStyle: 'rgba(0,230,110,1.0)', strokeStyle: 'rgba(0,0,0,1.0)', lineWidth: 2, debug: false },
       { fillStyle: 'rgba(255,255,0,1.0)', strokeStyle: 'rgba(0,0,0,1.0)', lineWidth: 4, debug: false },
       { fillStyle: 'rgba(255,255,255,1.0)', strokeStyle: 'rgba(0,0,0,1.0)', lineWidth: 4, debug: false }
  ];

  this.init = function() {

    canvas = document.getElementById( 'world' );

    if (canvas && canvas.getContext) {
      context = canvas.getContext('2d');

      // Register event listeners
      document.addEventListener('mousemove', documentMouseMoveHandler, false);
      canvas.addEventListener('mousedown', documentMouseDownHandler, false);
      canvas.addEventListener('dblclick', documentDoubleClickHandler, false);
      document.addEventListener('mouseup', documentMouseUpHandler, false);
      document.addEventListener('touchstart', documentTouchStartHandler, false);
      document.addEventListener('touchmove', documentTouchMoveHandler, false);
      document.addEventListener('touchend', documentTouchEndHandler, false);
      document.addEventListener('keydown', documentKeyDownHandler, false);
      window.addEventListener('resize', windowResizeHandler, false);

      document.getElementById( 'keyboardUp' ).addEventListener('click', keyboardUpHandler, false);
      document.getElementById( 'keyboardDown' ).addEventListener('click', keyboardDownHandler, false);
      document.getElementById( 'keyboardLeft' ).addEventListener('click', keyboardLeftHandler, false);
      document.getElementById( 'keyboardRight' ).addEventListener('click', keyboardRightHandler, false);

      createBlob( { x: SCREEN_WIDTH*0.5, y: SCREEN_HEIGHT*0.1 } );

      windowResizeHandler();

      setInterval( loop, 1000 / 60 );
    }
  };

  function createBlob( position ) {
    var blob = new Blob();

    blob.position.x = position.x;
    blob.position.y = position.y;

    blob.generateNodes();

    blobs.push( blob );
  }

  function splitBlob( blob ) {
    if( blob.quality > 8 ) {
      blobs.push( blob.split() );
    }
  }

  function mergeBlobs( blobA, blobB ) {
    var t = getTime();

    if( !blobs[blobA] || !blobs[blobB] ) {
      return;
    }

    if( t - blobs[blobA].lastSplitTime > 500 && t - blobs[blobB].lastSplitTime > 500 ) {
      // Merge blobB with blobA
      blobs[blobA].merge( blobs[blobB] );

      // Remove blobB since blobA will take over its body
      blobs.splice( blobB, 1 );
    }
  }

  function documentMouseMoveHandler(event) {
    mouseX = event.clientX - (window.innerWidth - SCREEN_WIDTH) * .5;
    mouseY = event.clientY - (window.innerHeight - SCREEN_HEIGHT) * .5;
  }

  function documentMouseDownHandler(event) {
    event.preventDefault();

    mouseIsDown = true;

    dragBlob = blobs[ findClosestBody( blobs, { x: mouseX, y: mouseY } ) ];
    var closestNodeIndex = findClosestBody( dragBlob.nodes, { x: mouseX, y: mouseY } );
    dragBlob.dragNodeIndex = closestNodeIndex;

    mouseDownOffset.y = 100;
  }

  function documentMouseUpHandler(event) {
    mouseIsDown = false;

    if( dragBlob ) {
      dragBlob.dragNodeIndex = -1;
      dragBlob = null;
    }
  }

  function documentTouchStartHandler(event) {
    if(event.touches.length == 1) {
      event.preventDefault();

      mouseIsDown = true;

      mouseX = event.touches[0].pageX - (window.innerWidth - SCREEN_WIDTH) * .5;
      mouseY = event.touches[0].pageY - (window.innerHeight - SCREEN_HEIGHT) * .5;

      dragBlob = blobs[ findClosestBody( blobs, { x: mouseX, y: mouseY } ) ];
      var closestNodeIndex = findClosestBody( dragBlob.nodes, { x: mouseX, y: mouseY } );
      dragBlob.dragNodeIndex = closestNodeIndex;

      mouseDownOffset.y = 100;
    }
  }

  function documentTouchMoveHandler(event) {
    if(event.touches.length == 1) {
      event.preventDefault();

      mouseX = event.touches[0].pageX - (window.innerWidth - SCREEN_WIDTH) * .5;
      mouseY = event.touches[0].pageY - (window.innerHeight - SCREEN_HEIGHT) * .5;
    }
  }

  function documentTouchEndHandler(event) {
    mouseIsDown = false;

    if( dragBlob ) {
      dragBlob.dragNodeIndex = -1;
      dragBlob = null;
    }
  }

  function documentDoubleClickHandler(event) {
    var mouse = { x: mouseX, y: mouseY };

    var blob = blobs[findClosestBody( blobs, mouse )];

    if( distanceBetween( blob.position, mouse ) < blob.radius + 30 ) {
      splitBlob( blob );
    }
  }

  function documentKeyDownHandler(event) {
    switch( event.keyCode ) {
      case 40:
        changeBlobRadius( -10 );
        event.preventDefault();
        break;
      case 38:
        changeBlobRadius( 10 );
        event.preventDefault();
        break;
      case 37:
        changeSkin( -1 );
        event.preventDefault();
        break;
      case 39:
        changeSkin( 1 );
        event.preventDefault();
        break;
    }
  }

  function keyboardUpHandler(event) {
    event.preventDefault();
    changeBlobRadius( 20 );
    }

  function keyboardDownHandler(event) {
    event.preventDefault();
    changeBlobRadius( -20 );
  }

  function keyboardLeftHandler(event) {
    event.preventDefault();
    changeSkin( -1 );
  }

  function keyboardRightHandler(event) {
    event.preventDefault();
    changeSkin( 1 );
  }

  function changeSkin( offset ) {
    skinIndex += offset;
    skinIndex = skinIndex < 0 ? skins.length-1 : skinIndex;
    skinIndex = skinIndex > skins.length-1 ? 0 : skinIndex;
  }

  function changeBlobRadius( offset ) {
    for( var i = 0, len = blobs.length; i < len; i++ ) {
      blob = blobs[i];

      var oldRadius = blob.radius;

      blob.radius += offset;
      blob.radius = Math.max( 40, Math.min( blob.radius, 280 ) );

      if( blob.radius != oldRadius ) {
        blob.updateNormals();
      }
    }
  }

  function findClosestBody( bodies, position ) {
    var closestDistance = 9999;
    var currentDistance = 9999;
    var closestIndex = -1;

    for( var i = 0, len = bodies.length; i < len; i++ ) {
      var body = bodies[i];

      currentDistance = distanceBetween( body.position, { x: position.x, y: position.y } );

      if( currentDistance < closestDistance ) {
        closestDistance = currentDistance;
        closestIndex = i;
      }
    }

    return closestIndex;
  }

  function windowResizeHandler() {
    SCREEN_WIDTH = window.innerWidth;
    SCREEN_HEIGHT = window.innerHeight;

    canvas.width = SCREEN_WIDTH;
    canvas.height = SCREEN_HEIGHT;

    worldRect.x = 3;
    worldRect.y = 3;
    worldRect.width = SCREEN_WIDTH-6;
    worldRect.height = SCREEN_HEIGHT-6;
  }

  function loop() {

    var skin = skins[skinIndex];

    // The area around the dirty region to include in the clear
    var dirtySpread = 80;

    var u1, u2, ulen, blob;

    // Clear the dirty rects of all blobs
    for( u1 = 0, ulen = blobs.length; u1 < ulen; u1++ ) {
      blob = blobs[u1];

      // Clear all pixels in the dirty region
      context.clearRect(blob.dirtyRegion.left-dirtySpread,blob.dirtyRegion.top-dirtySpread,blob.dirtyRegion.right-blob.dirtyRegion.left+(dirtySpread*2),blob.dirtyRegion.bottom-blob.dirtyRegion.top+(dirtySpread*2));

      // Reset the dirty region so that it can be expanded anew
      blob.dirtyRegion = { left: worldRect.x + worldRect.width, top: worldRect.y + worldRect.height, right: 0, bottom: 0 };
    }

    // If there is a merge queued, solve it now
    if( mergeQueue.blobA != -1 && mergeQueue.blobB != -1 ) {
      mergeBlobs( mergeQueue.blobA, mergeQueue.blobB );

      mergeQueue.blobA = -1;
      mergeQueue.blobB = -1;
    }

    // If the mouse is down, start adding the velocity needed to move towards the mouse position
    if( dragBlob ) {
      dragBlob.velocity.x += ( ( mouseX + mouseDownOffset.x ) - dragBlob.position.x ) * 0.01;
      dragBlob.velocity.y += ( ( mouseY + mouseDownOffset.y ) - dragBlob.position.y ) * 0.01;
    }

    for( u1 = 0, ulen = blobs.length; u1 < ulen; u1++ ) {
      blob = blobs[u1];

      for( u2 = 0; u2 < ulen; u2++ ) {
        var otherBlob = blobs[u2];

        if( otherBlob != blob ) {
          var distance = distanceBetween( { x: blob.position.x, y: blob.position.y }, { x: otherBlob.position.x, y: otherBlob.position.y } );

          if( distance < blob.radius + otherBlob.radius ) {
            mergeQueue.blobA = u1;
            mergeQueue.blobB = u2;
          }
        }
      }

      // Track window movement
      blob.velocity.x += ( window.screenX - screenX ) * (0.04 + (Math.random()*0.1));
      blob.velocity.y += ( window.screenY - screenY ) * (0.04 + (Math.random()*0.1));

      var friction = { x: 1.035, y: 1.035 };

      // Enforce horizontal world bounds
      if( blob.position.x > worldRect.x + worldRect.width ) {
        blob.velocity.x -= ( blob.position.x - worldRect.width ) * 0.05;
        friction.y = 1.07;
      }
      else if( blob.position.x < worldRect.x ) {
        blob.velocity.x += Math.abs( worldRect.x - blob.position.x ) * 0.05;
        friction.y = 1.07;
      }

      // Enforce vertical world bounds
      if( blob.position.y > worldRect.y + worldRect.height ) {
        blob.velocity.y -= ( blob.position.y - worldRect.height ) * 0.05;
        friction.x = 1.07;
      }
      else if( blob.position.y < worldRect.y ) {
        blob.velocity.y += Math.abs( worldRect.y - blob.position.y ) * 0.05;
        friction.x = 1.07;
      }

      // Gravity
      blob.velocity.x += gravity.x;
      blob.velocity.y += gravity.y;

      // Friction
      blob.velocity.x /= friction.x;
      blob.velocity.y /= friction.y;

      // Apply the velocity to the entire blob
      blob.position.x += blob.velocity.x;
      blob.position.y += blob.velocity.y;

      var i, j, len, node, joint, position;

      // Update all node ghosts (previous positions). All nodes need to be synced before the below
      // calculation loop to avoid tearing between the first nodes
      for (i = 0, len = blob.nodes.length; i < len; i++) {
        node = blob.nodes[i];

        node.ghost.x = node.position.x;
        node.ghost.y = node.position.y;
      }

      var dragNode = blob.nodes[blob.dragNodeIndex];
      if( dragNode ) {
        var angle = Math.atan2( mouseY - (blob.position.y-80), mouseX - blob.position.x );

        blob.rotation += ( angle - blob.rotation ) * 0.03;
        blob.updateNormals();
      }

      // Calculation loop
      for (i = 0, len = blob.nodes.length; i < len; i++) {
        node = blob.nodes[i];

        // Move towards the normal target
        node.normal.x += ( node.normalTarget.x - node.normal.x ) * 0.05;
        node.normal.y += ( node.normalTarget.y - node.normal.y ) * 0.05;

        // This point will be used as the new position for this node, after all factors have been applied
        position = { x: blob.position.x, y: blob.position.y };

        // Apply the joints
        for( j = 0; j < node.joints.length; j++ ) {
          joint = node.joints[j];

          // Determine the strain on the joints
          var strainX = ( (joint.node.ghost.x - node.ghost.x) - (joint.node.normal.x - node.normal.x) );
          var strainY = ( (joint.node.ghost.y - node.ghost.y) - (joint.node.normal.y - node.normal.y) );

          position.x += strainX * joint.strength;
          position.y += strainY * joint.strength;
        }

        // Offset by the normal
        position.x += node.normal.x;
        position.y += node.normal.y;

        // Apply the drag offset (if applicable)
        if( i == blob.dragNodeIndex ) {
          position.x += ( mouseX - position.x ) * 0.98;
          position.y += ( mouseY - position.y ) * 0.98;
        }

        // Apply the calculated position to the node (with easing)
        node.position.x += ( position.x - node.position.x ) * 0.1;
        node.position.y += ( position.y - node.position.y ) * 0.1;

        // Limit the node position to screen bounds
        node.position.x = Math.max( Math.min( node.position.x, worldRect.x + worldRect.width ), worldRect.x );
        node.position.y = Math.max( Math.min( node.position.y, worldRect.y + worldRect.height ), worldRect.y );

        // Expand the dirty rect if needed
        blob.dirtyRegion.left = Math.min(blob.dirtyRegion.left, node.position.x);
        blob.dirtyRegion.top = Math.min(blob.dirtyRegion.top, node.position.y);
        blob.dirtyRegion.right = Math.max(blob.dirtyRegion.right, node.position.x);
        blob.dirtyRegion.bottom = Math.max(blob.dirtyRegion.bottom, node.position.y);
      }

      if( !skin.debug ) {
           context.beginPath();
        context.fillStyle = skin.fillStyle;
        context.strokeStyle = skin.strokeStyle;
        context.lineWidth = skin.lineWidth;
      }

      var cn = getArrayElementByOffset( blob.nodes, 0, -1 ); // current node
      var nn = getArrayElementByOffset( blob.nodes, 0, 0 ); // next node

      // Move to the first anchor
      context.moveTo( cn.position.x + ( nn.position.x - cn.position.x ) / 2, cn.position.y + ( nn.position.y - cn.position.y ) / 2 );

      // Rendering loop
      for (i = 0, len = blob.nodes.length; i < len; i++) {
        cn = getArrayElementByOffset( blob.nodes, i, 0 );
        nn = getArrayElementByOffset( blob.nodes, i, 1 );

        if( skin.debug ) {
          context.beginPath();
          context.lineWidth = 1;
          context.strokeStyle = "#ababab";

          for( j = 0; j < cn.joints.length; j++ ) {
            joint = cn.joints[j];
            context.moveTo( cn.position.x, cn.position.y );
            context.lineTo( joint.node.position.x, joint.node.position.y );
          }

          context.stroke();

          context.beginPath();
          context.fillStyle = i == 0? "#00ff00" : "#dddddd";
          context.arc(cn.position.x, cn.position.y, 5, 0, Math.PI*2, true);
          context.fill();
        }
        else {
          context.quadraticCurveTo( cn.position.x, cn.position.y, cn.position.x + ( nn.position.x - cn.position.x ) / 2, cn.position.y + ( nn.position.y - cn.position.y ) / 2 );
        }
      }

      if( skin.debug ) {
//        context.beginPath();
//        context.fillStyle = "rgba(100,255,100,0.3)";
//        context.fillRect(blob.dirtyRegion.left-dirtySpread,blob.dirtyRegion.top-dirtySpread,blob.dirtyRegion.right-blob.dirtyRegion.left+(dirtySpread*2),blob.dirtyRegion.bottom-blob.dirtyRegion.top+(dirtySpread*2));
//        context.fill();
      }

      context.stroke();
      context.fill();
    }

    screenX = window.screenX;
    screenY = window.screenY;
  }

};

function Blob() {
  this.position = { x: 0, y: 0 };
  this.velocity = { x: 0, y: 0 };
  this.radius = 120;
  this.quality = 32;
  this.nodes = [];
  this.rotation = -Math.PI * 0.5;
  this.dragNodeIndex = -1;
  this.dirtyRegion = { left: 0, top: 0, right: 0, bottom: 0 };
  this.lastSplitTime = 0;

  this.generateNodes = function() {
    this.nodes = [];

    var i, n;

    for (i = 0; i < this.quality; i++) {
      n = {
        normal: { x: 0, y: 0 },
        normalTarget: { x: 0, y: 0 },
        position: { x: this.position.x, y: this.position.y },
        ghost: { x: this.position.x, y: this.position.y },
        angle: 0
      };

      this.nodes.push( n );
    }

    this.updateJoints();

    this.updateNormals();
  };

  this.updateJoints = function() {
    for (var i = 0; i < this.quality; i++) {
      var n = this.nodes[i];

      n.joints = [
        {
          node: getArrayElementByOffset( this.nodes, i, -1 ),
          strength: 2.2
        },
        {
          node: getArrayElementByOffset( this.nodes, i, 1 ),
          strength: 2.2
        }
      ];

      n.joints.push( {
        node: getArrayElementByOffset( this.nodes, i, -2 ),
        strength: 2.2
      } );

      n.joints.push( {
        node: getArrayElementByOffset( this.nodes, i, 2 ),
        strength: 2.2
      } );

    }
  };

  this.updateNormals = function() {
    var i, j, n;

    for (i = 0; i < this.quality; i++) {

      var n = this.nodes[i];

      if( this.dragNodeIndex != -1 ) {
        j = i - this.dragNodeIndex;
        j = j < 0 ? this.quality + j : j;
      }
      else {
        j = i;
      }

      n.angle = ( (j / this.quality ) * Math.PI * 2 ) + this.rotation;

      n.normalTarget.x = Math.cos( n.angle ) * this.radius;
      n.normalTarget.y = Math.sin( n.angle ) * this.radius;

      if( n.normal.x == 0 && n.normal.y == 0 ) {
        n.normal.x = n.normalTarget.x;
        n.normal.y = n.normalTarget.y;
      }
    }
  };

  this.split = function() {

    var velocitySpread = this.radius / 10;
    var nodeSpread = Math.round( this.nodes.length * 0.5 );
    var radiusSpread = this.radius * 0.5;

    var sibling = new Blob();

    sibling.position.x = this.position.x;
    sibling.position.y = this.position.y;

    sibling.velocity.x = velocitySpread;
    sibling.velocity.y = this.velocity.y;

    sibling.nodes = [];

    var i = 0;
    while( i++ < nodeSpread ) {
      sibling.nodes.push( this.nodes.shift() );
    }

    sibling.radius = radiusSpread;
    sibling.quality = sibling.nodes.length;

    this.velocity.x = -velocitySpread;
    this.radius = radiusSpread;
    this.quality = this.nodes.length;

    this.dragNodeIndex = -1;
    this.updateJoints();
    this.updateNormals();

    sibling.dragNodeIndex = -1;
    sibling.updateJoints();
    sibling.updateNormals();

    sibling.lastSplitTime = getTime();
    this.lastSplitTime = getTime();

    return sibling;

  };

  this.merge = function( sibling ) {
    this.velocity.x *= 0.5;
    this.velocity.y *= 0.5;

    this.velocity.x += sibling.velocity.x * 0.5;
    this.velocity.y += sibling.velocity.y * 0.5;

    while( sibling.nodes.length ) {
      this.nodes.push( sibling.nodes.shift() );
    }

    this.quality = this.nodes.length;
    this.radius += sibling.radius;

    this.dragNodeIndex = -1;

    this.updateNormals();
    this.organizeNodesByProximity();
    this.updateJoints();
  };

  this.organizeNodesByProximity = function() {
    var i, j, outer, inner;

    var closestDistance, currentDistance, closestIndex;

    var newNodes = this.nodes.concat();
    var blackListed = [];

    for (i = 0; i < this.quality; i++) {
      outer = newNodes[i];

      currentDistance = 9999;
      closestDistance = 9999;
      closestIndex = -1;

      for(j = 0; j < this.quality; j++) {
        inner = newNodes[j];

        currentDistance = distanceBetween( inner.position, outer.position );

        if( currentDistance < closestDistance && blackListed.indexOf(inner) === -1 ) {
          closestDistance = currentDistance;
          closestIndex = j;
        }
      }

      this.nodes[i] = newNodes[closestIndex];
    }

  };
}

function getArrayElementByOffset( array, index, offset ) {
  if( array[index+offset] ) {
    return array[index+offset];
  }

  if( index+offset > array.length-1 ) {
    return array[index - array.length + offset];
  }

  if( index+offset < 0 ) {
    return array[array.length + ( index + offset )];
  }
}

function sortByField( list, field ) {
  var sortOnField = function( a, b ) {
    return a[field] - b[field];
  };

  list.sort( sortOnField );
}

function getTime() {
  return new Date().getTime();
}

function distanceBetween(p1,p2) {
  var dx = p2.x-p1.x;
  var dy = p2.y-p1.y;
  return Math.sqrt(dx*dx + dy*dy);
}

BlobWorld.init();

})();
  </script>

  <div id="codepen-footer">
    <a style="color: #f73535 !important;" href="https://codepen.wufoo.com/forms/m7x3r3/def/field14=" onclick="window.open(this.href,  null, 'height=517, width=680, toolbar=0, location=0, status=1, scrollbars=1, resizable=1'); return false">Report Abuse</a>

    &nbsp;

    <a href="/hakimel/pen/blob/1">Edit this Pen</a>
  </div>

</body>

</html>

## index.js
/**
* Best seen in fullscreen: http://hakim.se/experiments/html5/blob/03/
 */
BlobWorld = new function() {

  var SCREEN_WIDTH = window.innerWidth;
  var SCREEN_HEIGHT = window.innerHeight;

  var canvas;
  var context;
  var blobs = [];

  var dragBlob;

  var screenX = window.screenX;
  var screenY = window.screenY;

  var mouseX = (window.innerWidth - SCREEN_WIDTH);
  var mouseY = (window.innerHeight - SCREEN_HEIGHT);
  var mouseIsDown = false;
  var mouseDownOffset = { x: 0, y: 0 };

  // The bounds of the world
  var worldRect = { x: 0, y: 0, width: 0, height: 0 };

  // The world gravity, applied to all blobs
  var gravity = { x: 0, y: 1.2 };

  // A pair of blobs that should be merged
  var mergeQueue = { blobA: -1, blobB: -1 };

  var skinIndex = 0;
  var skins = [
       { fillStyle: 'rgba(0,200,250,1.0)', strokeStyle: '#ffffff', lineWidth: 5, debug: false },
       { fillStyle: '', strokeStyle: '', lineWidth: 0, debug: true },
     { fillStyle: 'rgba(0,0,0,0.1)', strokeStyle: 'rgba(255,255,255,1.0)', lineWidth: 6, debug: false },
       { fillStyle: 'rgba(0,230,110,1.0)', strokeStyle: 'rgba(0,0,0,1.0)', lineWidth: 2, debug: false },
       { fillStyle: 'rgba(255,255,0,1.0)', strokeStyle: 'rgba(0,0,0,1.0)', lineWidth: 4, debug: false },
       { fillStyle: 'rgba(255,255,255,1.0)', strokeStyle: 'rgba(0,0,0,1.0)', lineWidth: 4, debug: false }
  ];

  this.init = function() {

    canvas = document.getElementById( 'world' );

    if (canvas && canvas.getContext) {
      context = canvas.getContext('2d');

      // Register event listeners
      document.addEventListener('mousemove', documentMouseMoveHandler, false);
      canvas.addEventListener('mousedown', documentMouseDownHandler, false);
      canvas.addEventListener('dblclick', documentDoubleClickHandler, false);
      document.addEventListener('mouseup', documentMouseUpHandler, false);
      document.addEventListener('touchstart', documentTouchStartHandler, false);
      document.addEventListener('touchmove', documentTouchMoveHandler, false);
      document.addEventListener('touchend', documentTouchEndHandler, false);
      document.addEventListener('keydown', documentKeyDownHandler, false);
      window.addEventListener('resize', windowResizeHandler, false);

      document.getElementById( 'keyboardUp' ).addEventListener('click', keyboardUpHandler, false);
      document.getElementById( 'keyboardDown' ).addEventListener('click', keyboardDownHandler, false);
      document.getElementById( 'keyboardLeft' ).addEventListener('click', keyboardLeftHandler, false);
      document.getElementById( 'keyboardRight' ).addEventListener('click', keyboardRightHandler, false);

      createBlob( { x: SCREEN_WIDTH*0.5, y: SCREEN_HEIGHT*0.1 } );

      windowResizeHandler();

      setInterval( loop, 1000 / 60 );
    }
  };

  function createBlob( position ) {
    var blob = new Blob();

    blob.position.x = position.x;
    blob.position.y = position.y;

    blob.generateNodes();

    blobs.push( blob );
  }

  function splitBlob( blob ) {
    if( blob.quality > 8 ) {
      blobs.push( blob.split() );
    }
  }

  function mergeBlobs( blobA, blobB ) {
    var t = getTime();

    if( !blobs[blobA] || !blobs[blobB] ) {
      return;
    }

    if( t - blobs[blobA].lastSplitTime > 500 && t - blobs[blobB].lastSplitTime > 500 ) {
      // Merge blobB with blobA
      blobs[blobA].merge( blobs[blobB] );

      // Remove blobB since blobA will take over its body
      blobs.splice( blobB, 1 );
    }
  }

  function documentMouseMoveHandler(event) {
    mouseX = event.clientX - (window.innerWidth - SCREEN_WIDTH) * .5;
    mouseY = event.clientY - (window.innerHeight - SCREEN_HEIGHT) * .5;
  }

  function documentMouseDownHandler(event) {
    event.preventDefault();

    mouseIsDown = true;

    dragBlob = blobs[ findClosestBody( blobs, { x: mouseX, y: mouseY } ) ];
    var closestNodeIndex = findClosestBody( dragBlob.nodes, { x: mouseX, y: mouseY } );
    dragBlob.dragNodeIndex = closestNodeIndex;

    mouseDownOffset.y = 100;
  }

  function documentMouseUpHandler(event) {
    mouseIsDown = false;

    if( dragBlob ) {
      dragBlob.dragNodeIndex = -1;
      dragBlob = null;
    }
  }

  function documentTouchStartHandler(event) {
    if(event.touches.length == 1) {
      event.preventDefault();

      mouseIsDown = true;

      mouseX = event.touches[0].pageX - (window.innerWidth - SCREEN_WIDTH) * .5;
      mouseY = event.touches[0].pageY - (window.innerHeight - SCREEN_HEIGHT) * .5;

      dragBlob = blobs[ findClosestBody( blobs, { x: mouseX, y: mouseY } ) ];
      var closestNodeIndex = findClosestBody( dragBlob.nodes, { x: mouseX, y: mouseY } );
      dragBlob.dragNodeIndex = closestNodeIndex;

      mouseDownOffset.y = 100;
    }
  }

  function documentTouchMoveHandler(event) {
    if(event.touches.length == 1) {
      event.preventDefault();

      mouseX = event.touches[0].pageX - (window.innerWidth - SCREEN_WIDTH) * .5;
      mouseY = event.touches[0].pageY - (window.innerHeight - SCREEN_HEIGHT) * .5;
    }
  }

  function documentTouchEndHandler(event) {
    mouseIsDown = false;

    if( dragBlob ) {
      dragBlob.dragNodeIndex = -1;
      dragBlob = null;
    }
  }

  function documentDoubleClickHandler(event) {
    var mouse = { x: mouseX, y: mouseY };

    var blob = blobs[findClosestBody( blobs, mouse )];

    if( distanceBetween( blob.position, mouse ) < blob.radius + 30 ) {
      splitBlob( blob );
    }
  }

  function documentKeyDownHandler(event) {
    switch( event.keyCode ) {
      case 40:
        changeBlobRadius( -10 );
        event.preventDefault();
        break;
      case 38:
        changeBlobRadius( 10 );
        event.preventDefault();
        break;
      case 37:
        changeSkin( -1 );
        event.preventDefault();
        break;
      case 39:
        changeSkin( 1 );
        event.preventDefault();
        break;
    }
  }

  function keyboardUpHandler(event) {
    event.preventDefault();
    changeBlobRadius( 20 );
    }

  function keyboardDownHandler(event) {
    event.preventDefault();
    changeBlobRadius( -20 );
  }

  function keyboardLeftHandler(event) {
    event.preventDefault();
    changeSkin( -1 );
  }

  function keyboardRightHandler(event) {
    event.preventDefault();
    changeSkin( 1 );
  }

  function changeSkin( offset ) {
    skinIndex += offset;
    skinIndex = skinIndex < 0 ? skins.length-1 : skinIndex;
    skinIndex = skinIndex > skins.length-1 ? 0 : skinIndex;
  }

  function changeBlobRadius( offset ) {
    for( var i = 0, len = blobs.length; i < len; i++ ) {
      blob = blobs[i];

      var oldRadius = blob.radius;

      blob.radius += offset;
      blob.radius = Math.max( 40, Math.min( blob.radius, 280 ) );

      if( blob.radius != oldRadius ) {
        blob.updateNormals();
      }
    }
  }

  function findClosestBody( bodies, position ) {
    var closestDistance = 9999;
    var currentDistance = 9999;
    var closestIndex = -1;

    for( var i = 0, len = bodies.length; i < len; i++ ) {
      var body = bodies[i];

      currentDistance = distanceBetween( body.position, { x: position.x, y: position.y } );

      if( currentDistance < closestDistance ) {
        closestDistance = currentDistance;
        closestIndex = i;
      }
    }

    return closestIndex;
  }

  function windowResizeHandler() {
    SCREEN_WIDTH = window.innerWidth;
    SCREEN_HEIGHT = window.innerHeight;

    canvas.width = SCREEN_WIDTH;
    canvas.height = SCREEN_HEIGHT;

    worldRect.x = 3;
    worldRect.y = 3;
    worldRect.width = SCREEN_WIDTH-6;
    worldRect.height = SCREEN_HEIGHT-6;
  }

  function loop() {

    var skin = skins[skinIndex];

    // The area around the dirty region to include in the clear
    var dirtySpread = 80;

    var u1, u2, ulen, blob;

    // Clear the dirty rects of all blobs
    for( u1 = 0, ulen = blobs.length; u1 < ulen; u1++ ) {
      blob = blobs[u1];

      // Clear all pixels in the dirty region
      context.clearRect(blob.dirtyRegion.left-dirtySpread,blob.dirtyRegion.top-dirtySpread,blob.dirtyRegion.right-blob.dirtyRegion.left+(dirtySpread*2),blob.dirtyRegion.bottom-blob.dirtyRegion.top+(dirtySpread*2));

      // Reset the dirty region so that it can be expanded anew
      blob.dirtyRegion = { left: worldRect.x + worldRect.width, top: worldRect.y + worldRect.height, right: 0, bottom: 0 };
    }

    // If there is a merge queued, solve it now
    if( mergeQueue.blobA != -1 && mergeQueue.blobB != -1 ) {
      mergeBlobs( mergeQueue.blobA, mergeQueue.blobB );

      mergeQueue.blobA = -1;
      mergeQueue.blobB = -1;
    }

    // If the mouse is down, start adding the velocity needed to move towards the mouse position
    if( dragBlob ) {
      dragBlob.velocity.x += ( ( mouseX + mouseDownOffset.x ) - dragBlob.position.x ) * 0.01;
      dragBlob.velocity.y += ( ( mouseY + mouseDownOffset.y ) - dragBlob.position.y ) * 0.01;
    }

    for( u1 = 0, ulen = blobs.length; u1 < ulen; u1++ ) {
      blob = blobs[u1];

      for( u2 = 0; u2 < ulen; u2++ ) {
        var otherBlob = blobs[u2];

        if( otherBlob != blob ) {
          var distance = distanceBetween( { x: blob.position.x, y: blob.position.y }, { x: otherBlob.position.x, y: otherBlob.position.y } );

          if( distance < blob.radius + otherBlob.radius ) {
            mergeQueue.blobA = u1;
            mergeQueue.blobB = u2;
          }
        }
      }

      // Track window movement
      blob.velocity.x += ( window.screenX - screenX ) * (0.04 + (Math.random()*0.1));
      blob.velocity.y += ( window.screenY - screenY ) * (0.04 + (Math.random()*0.1));

      var friction = { x: 1.035, y: 1.035 };

      // Enforce horizontal world bounds
      if( blob.position.x > worldRect.x + worldRect.width ) {
        blob.velocity.x -= ( blob.position.x - worldRect.width ) * 0.05;
        friction.y = 1.07;
      }
      else if( blob.position.x < worldRect.x ) {
        blob.velocity.x += Math.abs( worldRect.x - blob.position.x ) * 0.05;
        friction.y = 1.07;
      }

      // Enforce vertical world bounds
      if( blob.position.y > worldRect.y + worldRect.height ) {
        blob.velocity.y -= ( blob.position.y - worldRect.height ) * 0.05;
        friction.x = 1.07;
      }
      else if( blob.position.y < worldRect.y ) {
        blob.velocity.y += Math.abs( worldRect.y - blob.position.y ) * 0.05;
        friction.x = 1.07;
      }

      // Gravity
      blob.velocity.x += gravity.x;
      blob.velocity.y += gravity.y;

      // Friction
      blob.velocity.x /= friction.x;
      blob.velocity.y /= friction.y;

      // Apply the velocity to the entire blob
      blob.position.x += blob.velocity.x;
      blob.position.y += blob.velocity.y;

      var i, j, len, node, joint, position;

      // Update all node ghosts (previous positions). All nodes need to be synced before the below
      // calculation loop to avoid tearing between the first nodes
      for (i = 0, len = blob.nodes.length; i < len; i++) {
        node = blob.nodes[i];

        node.ghost.x = node.position.x;
        node.ghost.y = node.position.y;
      }

      var dragNode = blob.nodes[blob.dragNodeIndex];
      if( dragNode ) {
        var angle = Math.atan2( mouseY - (blob.position.y-80), mouseX - blob.position.x );

        blob.rotation += ( angle - blob.rotation ) * 0.03;
        blob.updateNormals();
      }

      // Calculation loop
      for (i = 0, len = blob.nodes.length; i < len; i++) {
        node = blob.nodes[i];

        // Move towards the normal target
        node.normal.x += ( node.normalTarget.x - node.normal.x ) * 0.05;
        node.normal.y += ( node.normalTarget.y - node.normal.y ) * 0.05;

        // This point will be used as the new position for this node, after all factors have been applied
        position = { x: blob.position.x, y: blob.position.y };

        // Apply the joints
        for( j = 0; j < node.joints.length; j++ ) {
          joint = node.joints[j];

          // Determine the strain on the joints
          var strainX = ( (joint.node.ghost.x - node.ghost.x) - (joint.node.normal.x - node.normal.x) );
          var strainY = ( (joint.node.ghost.y - node.ghost.y) - (joint.node.normal.y - node.normal.y) );

          position.x += strainX * joint.strength;
          position.y += strainY * joint.strength;
        }

        // Offset by the normal
        position.x += node.normal.x;
        position.y += node.normal.y;

        // Apply the drag offset (if applicable)
        if( i == blob.dragNodeIndex ) {
          position.x += ( mouseX - position.x ) * 0.98;
          position.y += ( mouseY - position.y ) * 0.98;
        }

        // Apply the calculated position to the node (with easing)
        node.position.x += ( position.x - node.position.x ) * 0.1;
        node.position.y += ( position.y - node.position.y ) * 0.1;

        // Limit the node position to screen bounds
        node.position.x = Math.max( Math.min( node.position.x, worldRect.x + worldRect.width ), worldRect.x );
        node.position.y = Math.max( Math.min( node.position.y, worldRect.y + worldRect.height ), worldRect.y );

        // Expand the dirty rect if needed
        blob.dirtyRegion.left = Math.min(blob.dirtyRegion.left, node.position.x);
        blob.dirtyRegion.top = Math.min(blob.dirtyRegion.top, node.position.y);
        blob.dirtyRegion.right = Math.max(blob.dirtyRegion.right, node.position.x);
        blob.dirtyRegion.bottom = Math.max(blob.dirtyRegion.bottom, node.position.y);
      }

      if( !skin.debug ) {
           context.beginPath();
        context.fillStyle = skin.fillStyle;
        context.strokeStyle = skin.strokeStyle;
        context.lineWidth = skin.lineWidth;
      }

      var cn = getArrayElementByOffset( blob.nodes, 0, -1 ); // current node
      var nn = getArrayElementByOffset( blob.nodes, 0, 0 ); // next node

      // Move to the first anchor
      context.moveTo( cn.position.x + ( nn.position.x - cn.position.x ) / 2, cn.position.y + ( nn.position.y - cn.position.y ) / 2 );

      // Rendering loop
      for (i = 0, len = blob.nodes.length; i < len; i++) {
        cn = getArrayElementByOffset( blob.nodes, i, 0 );
        nn = getArrayElementByOffset( blob.nodes, i, 1 );

        if( skin.debug ) {
          context.beginPath();
          context.lineWidth = 1;
          context.strokeStyle = "#ababab";

          for( j = 0; j < cn.joints.length; j++ ) {
            joint = cn.joints[j];
            context.moveTo( cn.position.x, cn.position.y );
            context.lineTo( joint.node.position.x, joint.node.position.y );
          }

          context.stroke();

          context.beginPath();
          context.fillStyle = i == 0? "#00ff00" : "#dddddd";
          context.arc(cn.position.x, cn.position.y, 5, 0, Math.PI*2, true);
          context.fill();
        }
        else {
          context.quadraticCurveTo( cn.position.x, cn.position.y, cn.position.x + ( nn.position.x - cn.position.x ) / 2, cn.position.y + ( nn.position.y - cn.position.y ) / 2 );
        }
      }

      if( skin.debug ) {
//        context.beginPath();
//        context.fillStyle = "rgba(100,255,100,0.3)";
//        context.fillRect(blob.dirtyRegion.left-dirtySpread,blob.dirtyRegion.top-dirtySpread,blob.dirtyRegion.right-blob.dirtyRegion.left+(dirtySpread*2),blob.dirtyRegion.bottom-blob.dirtyRegion.top+(dirtySpread*2));
//        context.fill();
      }

      context.stroke();
      context.fill();
    }

    screenX = window.screenX;
    screenY = window.screenY;
  }


};

function Blob() {
  this.position = { x: 0, y: 0 };
  this.velocity = { x: 0, y: 0 };
  this.radius = 120;
  this.quality = 32;
  this.nodes = [];
  this.rotation = -Math.PI * 0.5;
  this.dragNodeIndex = -1;
  this.dirtyRegion = { left: 0, top: 0, right: 0, bottom: 0 };
  this.lastSplitTime = 0;

  this.generateNodes = function() {
    this.nodes = [];

    var i, n;

    for (i = 0; i < this.quality; i++) {
      n = {
        normal: { x: 0, y: 0 },
        normalTarget: { x: 0, y: 0 },
        position: { x: this.position.x, y: this.position.y },
        ghost: { x: this.position.x, y: this.position.y },
        angle: 0
      };

      this.nodes.push( n );
    }

    this.updateJoints();

    this.updateNormals();
  };

  this.updateJoints = function() {
    for (var i = 0; i < this.quality; i++) {
      var n = this.nodes[i];

      n.joints = [
        {
          node: getArrayElementByOffset( this.nodes, i, -1 ),
          strength: 2.2
        },
        {
          node: getArrayElementByOffset( this.nodes, i, 1 ),
          strength: 2.2
        }
      ];

      n.joints.push( {
        node: getArrayElementByOffset( this.nodes, i, -2 ),
        strength: 2.2
      } );

      n.joints.push( {
        node: getArrayElementByOffset( this.nodes, i, 2 ),
        strength: 2.2
      } );

    }
  };

  this.updateNormals = function() {
    var i, j, n;

    for (i = 0; i < this.quality; i++) {

      var n = this.nodes[i];

      if( this.dragNodeIndex != -1 ) {
        j = i - this.dragNodeIndex;
        j = j < 0 ? this.quality + j : j;
      }
      else {
        j = i;
      }

      n.angle = ( (j / this.quality ) * Math.PI * 2 ) + this.rotation;

      n.normalTarget.x = Math.cos( n.angle ) * this.radius;
      n.normalTarget.y = Math.sin( n.angle ) * this.radius;

      if( n.normal.x == 0 && n.normal.y == 0 ) {
        n.normal.x = n.normalTarget.x;
        n.normal.y = n.normalTarget.y;
      }
    }
  };

  this.split = function() {

    var velocitySpread = this.radius / 10;
    var nodeSpread = Math.round( this.nodes.length * 0.5 );
    var radiusSpread = this.radius * 0.5;

    var sibling = new Blob();

    sibling.position.x = this.position.x;
    sibling.position.y = this.position.y;

    sibling.velocity.x = velocitySpread;
    sibling.velocity.y = this.velocity.y;

    sibling.nodes = [];

    var i = 0;
    while( i++ < nodeSpread ) {
      sibling.nodes.push( this.nodes.shift() );
    }

    sibling.radius = radiusSpread;
    sibling.quality = sibling.nodes.length;

    this.velocity.x = -velocitySpread;
    this.radius = radiusSpread;
    this.quality = this.nodes.length;

    this.dragNodeIndex = -1;
    this.updateJoints();
    this.updateNormals();

    sibling.dragNodeIndex = -1;
    sibling.updateJoints();
    sibling.updateNormals();

    sibling.lastSplitTime = getTime();
    this.lastSplitTime = getTime();

    return sibling;

  };

  this.merge = function( sibling ) {
    this.velocity.x *= 0.5;
    this.velocity.y *= 0.5;

    this.velocity.x += sibling.velocity.x * 0.5;
    this.velocity.y += sibling.velocity.y * 0.5;

    while( sibling.nodes.length ) {
      this.nodes.push( sibling.nodes.shift() );
    }

    this.quality = this.nodes.length;
    this.radius += sibling.radius;

    this.dragNodeIndex = -1;

    this.updateNormals();
    this.organizeNodesByProximity();
    this.updateJoints();
  };

  this.organizeNodesByProximity = function() {
    var i, j, outer, inner;

    var closestDistance, currentDistance, closestIndex;

    var newNodes = this.nodes.concat();
    var blackListed = [];

    for (i = 0; i < this.quality; i++) {
      outer = newNodes[i];

      currentDistance = 9999;
      closestDistance = 9999;
      closestIndex = -1;

      for(j = 0; j < this.quality; j++) {
        inner = newNodes[j];

        currentDistance = distanceBetween( inner.position, outer.position );

        if( currentDistance < closestDistance && blackListed.indexOf(inner) === -1 ) {
          closestDistance = currentDistance;
          closestIndex = j;
        }
      }

      this.nodes[i] = newNodes[closestIndex];
    }

  };
}

function getArrayElementByOffset( array, index, offset ) {
  if( array[index+offset] ) {
    return array[index+offset];
  }

  if( index+offset > array.length-1 ) {
    return array[index - array.length + offset];
  }

  if( index+offset < 0 ) {
    return array[array.length + ( index + offset )];
  }
}

function sortByField( list, field ) {
  var sortOnField = function( a, b ) {
    return a[field] - b[field];
  };

  list.sort( sortOnField );
}

function getTime() {
  return new Date().getTime();
}

function distanceBetween(p1,p2) {
  var dx = p2.x-p1.x;
  var dy = p2.y-p1.y;
  return Math.sqrt(dx*dx + dy*dy);
}


BlobWorld.init();


## markup.html
<p>Double click to split. <a id="keyboardUp" href="#">Increase</a> / <a id="keyboardDown" href="#">decrease</a> size or <a id="keyboardLeft" href="#">Previous</a> / <a id="keyboardRight" href="#">Next</a> skin.</p>
<canvas id='world'></canvas>

## style.css
body {
    background-color: #333333;
    padding: 0;
    margin: 0;
    overflow: hidden;
}
p {
    position: absolute;
    z-index: 99;
    color: #cccccc;
    margin: 2px;
    padding: 0;
    font-family: Arial;
    font-size: 10px;
}
a {
		color: #f4f4f4;
		font-weight: bold;
}
	/**
	* Best seen in fullscreen: http://hakim.se/experiments/html5/blob/03/
	*/
	BlobWorld = new function() {

	var SCREEN_WIDTH = window.innerWidth;
	var SCREEN_HEIGHT = window.innerHeight;

	var canvas;
	var context;
	var blobs = [];

	var dragBlob;

	var screenX = window.screenX;
	var screenY = window.screenY;

	var mouseX = (window.innerWidth - SCREEN_WIDTH);
	var mouseY = (window.innerHeight - SCREEN_HEIGHT);
	var mouseIsDown = false;
	var mouseDownOffset = { x: 0, y: 0 };

	// The bounds of the world
	var worldRect = { x: 0, y: 0, width: 0, height: 0 };

	// The world gravity, applied to all blobs
	var gravity = { x: 0, y: 1.2 };

	// A pair of blobs that should be merged
	var mergeQueue = { blobA: -1, blobB: -1 };

	var skinIndex = 0;
	var skins = [
	{ fillStyle: 'rgba(0,200,250,1.0)', strokeStyle: '#ffffff', lineWidth: 5, debug: false },
	{ fillStyle: '', strokeStyle: '', lineWidth: 0, debug: true },
	{ fillStyle: 'rgba(0,0,0,0.1)', strokeStyle: 'rgba(255,255,255,1.0)', lineWidth: 6, debug: false },
	{ fillStyle: 'rgba(0,230,110,1.0)', strokeStyle: 'rgba(0,0,0,1.0)', lineWidth: 2, debug: false },
	{ fillStyle: 'rgba(255,255,0,1.0)', strokeStyle: 'rgba(0,0,0,1.0)', lineWidth: 4, debug: false },
	{ fillStyle: 'rgba(255,255,255,1.0)', strokeStyle: 'rgba(0,0,0,1.0)', lineWidth: 4, debug: false }
	];

	this.init = function() {

	canvas = document.getElementById( 'world' );

	if (canvas && canvas.getContext) {
	context = canvas.getContext('2d');

	// Register event listeners
	document.addEventListener('mousemove', documentMouseMoveHandler, false);
	canvas.addEventListener('mousedown', documentMouseDownHandler, false);
	canvas.addEventListener('dblclick', documentDoubleClickHandler, false);
	document.addEventListener('mouseup', documentMouseUpHandler, false);
	document.addEventListener('touchstart', documentTouchStartHandler, false);
	document.addEventListener('touchmove', documentTouchMoveHandler, false);
	document.addEventListener('touchend', documentTouchEndHandler, false);
	document.addEventListener('keydown', documentKeyDownHandler, false);
	window.addEventListener('resize', windowResizeHandler, false);

	document.getElementById( 'keyboardUp' ).addEventListener('click', keyboardUpHandler, false);
	document.getElementById( 'keyboardDown' ).addEventListener('click', keyboardDownHandler, false);
	document.getElementById( 'keyboardLeft' ).addEventListener('click', keyboardLeftHandler, false);
	document.getElementById( 'keyboardRight' ).addEventListener('click', keyboardRightHandler, false);

	createBlob( { x: SCREEN_WIDTH0.5, y: SCREEN_HEIGHT0.1 } );

	windowResizeHandler();

	setInterval( loop, 1000 / 60 );
	}
	};

	function createBlob( position ) {
	var blob = new Blob();

	blob.position.x = position.x;
	blob.position.y = position.y;

	blob.generateNodes();

	blobs.push( blob );
	}

	function splitBlob( blob ) {
	if( blob.quality > 8 ) {
	blobs.push( blob.split() );
	}
	}

	function mergeBlobs( blobA, blobB ) {
	var t = getTime();

	if( !blobs[blobA] \|\| !blobs[blobB] ) {
	return;
	}

	if( t - blobs[blobA].lastSplitTime > 500 && t - blobs[blobB].lastSplitTime > 500 ) {
	// Merge blobB with blobA
	blobs[blobA].merge( blobs[blobB] );

	// Remove blobB since blobA will take over its body
	blobs.splice( blobB, 1 );
	}
	}

	function documentMouseMoveHandler(event) {
	mouseX = event.clientX - (window.innerWidth - SCREEN_WIDTH) * .5;
	mouseY = event.clientY - (window.innerHeight - SCREEN_HEIGHT) * .5;
	}

	function documentMouseDownHandler(event) {
	event.preventDefault();

	mouseIsDown = true;

	dragBlob = blobs[ findClosestBody( blobs, { x: mouseX, y: mouseY } ) ];
	var closestNodeIndex = findClosestBody( dragBlob.nodes, { x: mouseX, y: mouseY } );
	dragBlob.dragNodeIndex = closestNodeIndex;

	mouseDownOffset.y = 100;
	}

	function documentMouseUpHandler(event) {
	mouseIsDown = false;

	if( dragBlob ) {
	dragBlob.dragNodeIndex = -1;
	dragBlob = null;
	}
	}

	function documentTouchStartHandler(event) {
	if(event.touches.length == 1) {
	event.preventDefault();

	mouseIsDown = true;

	mouseX = event.touches[0].pageX - (window.innerWidth - SCREEN_WIDTH) * .5;
	mouseY = event.touches[0].pageY - (window.innerHeight - SCREEN_HEIGHT) * .5;

	dragBlob = blobs[ findClosestBody( blobs, { x: mouseX, y: mouseY } ) ];
	var closestNodeIndex = findClosestBody( dragBlob.nodes, { x: mouseX, y: mouseY } );
	dragBlob.dragNodeIndex = closestNodeIndex;

	mouseDownOffset.y = 100;
	}
	}

	function documentTouchMoveHandler(event) {
	if(event.touches.length == 1) {
	event.preventDefault();

	mouseX = event.touches[0].pageX - (window.innerWidth - SCREEN_WIDTH) * .5;
	mouseY = event.touches[0].pageY - (window.innerHeight - SCREEN_HEIGHT) * .5;
	}
	}

	function documentTouchEndHandler(event) {
	mouseIsDown = false;

	if( dragBlob ) {
	dragBlob.dragNodeIndex = -1;
	dragBlob = null;
	}
	}

	function documentDoubleClickHandler(event) {
	var mouse = { x: mouseX, y: mouseY };

	var blob = blobs[findClosestBody( blobs, mouse )];

	if( distanceBetween( blob.position, mouse ) < blob.radius + 30 ) {
	splitBlob( blob );
	}
	}

	function documentKeyDownHandler(event) {
	switch( event.keyCode ) {
	case 40:
	changeBlobRadius( -10 );
	event.preventDefault();
	break;
	case 38:
	changeBlobRadius( 10 );
	event.preventDefault();
	break;
	case 37:
	changeSkin( -1 );
	event.preventDefault();
	break;
	case 39:
	changeSkin( 1 );
	event.preventDefault();
	break;
	}
	}

	function keyboardUpHandler(event) {
	event.preventDefault();
	changeBlobRadius( 20 );
	}

	function keyboardDownHandler(event) {
	event.preventDefault();
	changeBlobRadius( -20 );
	}

	function keyboardLeftHandler(event) {
	event.preventDefault();
	changeSkin( -1 );
	}

	function keyboardRightHandler(event) {
	event.preventDefault();
	changeSkin( 1 );
	}

	function changeSkin( offset ) {
	skinIndex += offset;
	skinIndex = skinIndex < 0 ? skins.length-1 : skinIndex;
	skinIndex = skinIndex > skins.length-1 ? 0 : skinIndex;
	}

	function changeBlobRadius( offset ) {
	for( var i = 0, len = blobs.length; i < len; i++ ) {
	blob = blobs[i];

	var oldRadius = blob.radius;

	blob.radius += offset;
	blob.radius = Math.max( 40, Math.min( blob.radius, 280 ) );

	if( blob.radius != oldRadius ) {
	blob.updateNormals();
	}
	}
	}

	function findClosestBody( bodies, position ) {
	var closestDistance = 9999;
	var currentDistance = 9999;
	var closestIndex = -1;

	for( var i = 0, len = bodies.length; i < len; i++ ) {
	var body = bodies[i];

	currentDistance = distanceBetween( body.position, { x: position.x, y: position.y } );

	if( currentDistance < closestDistance ) {
	closestDistance = currentDistance;
	closestIndex = i;
	}
	}

	return closestIndex;
	}

	function windowResizeHandler() {
	SCREEN_WIDTH = window.innerWidth;
	SCREEN_HEIGHT = window.innerHeight;

	canvas.width = SCREEN_WIDTH;
	canvas.height = SCREEN_HEIGHT;

	worldRect.x = 3;
	worldRect.y = 3;
	worldRect.width = SCREEN_WIDTH-6;
	worldRect.height = SCREEN_HEIGHT-6;
	}

	function loop() {

	var skin = skins[skinIndex];

	// The area around the dirty region to include in the clear
	var dirtySpread = 80;

	var u1, u2, ulen, blob;

	// Clear the dirty rects of all blobs
	for( u1 = 0, ulen = blobs.length; u1 < ulen; u1++ ) {
	blob = blobs[u1];

	// Clear all pixels in the dirty region
	context.clearRect(blob.dirtyRegion.left-dirtySpread,blob.dirtyRegion.top-dirtySpread,blob.dirtyRegion.right-blob.dirtyRegion.left+(dirtySpread2),blob.dirtyRegion.bottom-blob.dirtyRegion.top+(dirtySpread2));

	// Reset the dirty region so that it can be expanded anew
	blob.dirtyRegion = { left: worldRect.x + worldRect.width, top: worldRect.y + worldRect.height, right: 0, bottom: 0 };
	}

	// If there is a merge queued, solve it now
	if( mergeQueue.blobA != -1 && mergeQueue.blobB != -1 ) {
	mergeBlobs( mergeQueue.blobA, mergeQueue.blobB );

	mergeQueue.blobA = -1;
	mergeQueue.blobB = -1;
	}

	// If the mouse is down, start adding the velocity needed to move towards the mouse position
	if( dragBlob ) {
	dragBlob.velocity.x += ( ( mouseX + mouseDownOffset.x ) - dragBlob.position.x ) * 0.01;
	dragBlob.velocity.y += ( ( mouseY + mouseDownOffset.y ) - dragBlob.position.y ) * 0.01;
	}

	for( u1 = 0, ulen = blobs.length; u1 < ulen; u1++ ) {
	blob = blobs[u1];

	for( u2 = 0; u2 < ulen; u2++ ) {
	var otherBlob = blobs[u2];

	if( otherBlob != blob ) {
	var distance = distanceBetween( { x: blob.position.x, y: blob.position.y }, { x: otherBlob.position.x, y: otherBlob.position.y } );

	if( distance < blob.radius + otherBlob.radius ) {
	mergeQueue.blobA = u1;
	mergeQueue.blobB = u2;
	}
	}
	}

	// Track window movement
	blob.velocity.x += ( window.screenX - screenX ) * (0.04 + (Math.random()*0.1));
	blob.velocity.y += ( window.screenY - screenY ) * (0.04 + (Math.random()*0.1));

	var friction = { x: 1.035, y: 1.035 };

	// Enforce horizontal world bounds
	if( blob.position.x > worldRect.x + worldRect.width ) {
	blob.velocity.x -= ( blob.position.x - worldRect.width ) * 0.05;
	friction.y = 1.07;
	}
	else if( blob.position.x < worldRect.x ) {
	blob.velocity.x += Math.abs( worldRect.x - blob.position.x ) * 0.05;
	friction.y = 1.07;
	}

	// Enforce vertical world bounds
	if( blob.position.y > worldRect.y + worldRect.height ) {
	blob.velocity.y -= ( blob.position.y - worldRect.height ) * 0.05;
	friction.x = 1.07;
	}
	else if( blob.position.y < worldRect.y ) {
	blob.velocity.y += Math.abs( worldRect.y - blob.position.y ) * 0.05;
	friction.x = 1.07;
	}

	// Gravity
	blob.velocity.x += gravity.x;
	blob.velocity.y += gravity.y;

	// Friction
	blob.velocity.x /= friction.x;
	blob.velocity.y /= friction.y;

	// Apply the velocity to the entire blob
	blob.position.x += blob.velocity.x;
	blob.position.y += blob.velocity.y;

	var i, j, len, node, joint, position;

	// Update all node ghosts (previous positions). All nodes need to be synced before the below
	// calculation loop to avoid tearing between the first nodes
	for (i = 0, len = blob.nodes.length; i < len; i++) {
	node = blob.nodes[i];

	node.ghost.x = node.position.x;
	node.ghost.y = node.position.y;
	}

	var dragNode = blob.nodes[blob.dragNodeIndex];
	if( dragNode ) {
	var angle = Math.atan2( mouseY - (blob.position.y-80), mouseX - blob.position.x );

	blob.rotation += ( angle - blob.rotation ) * 0.03;
	blob.updateNormals();
	}

	// Calculation loop
	for (i = 0, len = blob.nodes.length; i < len; i++) {
	node = blob.nodes[i];

	// Move towards the normal target
	node.normal.x += ( node.normalTarget.x - node.normal.x ) * 0.05;
	node.normal.y += ( node.normalTarget.y - node.normal.y ) * 0.05;

	// This point will be used as the new position for this node, after all factors have been applied
	position = { x: blob.position.x, y: blob.position.y };

	// Apply the joints
	for( j = 0; j < node.joints.length; j++ ) {
	joint = node.joints[j];

	// Determine the strain on the joints
	var strainX = ( (joint.node.ghost.x - node.ghost.x) - (joint.node.normal.x - node.normal.x) );
	var strainY = ( (joint.node.ghost.y - node.ghost.y) - (joint.node.normal.y - node.normal.y) );

	position.x += strainX * joint.strength;
	position.y += strainY * joint.strength;
	}

	// Offset by the normal
	position.x += node.normal.x;
	position.y += node.normal.y;

	// Apply the drag offset (if applicable)
	if( i == blob.dragNodeIndex ) {
	position.x += ( mouseX - position.x ) * 0.98;
	position.y += ( mouseY - position.y ) * 0.98;
	}

	// Apply the calculated position to the node (with easing)
	node.position.x += ( position.x - node.position.x ) * 0.1;
	node.position.y += ( position.y - node.position.y ) * 0.1;

	// Limit the node position to screen bounds
	node.position.x = Math.max( Math.min( node.position.x, worldRect.x + worldRect.width ), worldRect.x );
	node.position.y = Math.max( Math.min( node.position.y, worldRect.y + worldRect.height ), worldRect.y );

	// Expand the dirty rect if needed
	blob.dirtyRegion.left = Math.min(blob.dirtyRegion.left, node.position.x);
	blob.dirtyRegion.top = Math.min(blob.dirtyRegion.top, node.position.y);
	blob.dirtyRegion.right = Math.max(blob.dirtyRegion.right, node.position.x);
	blob.dirtyRegion.bottom = Math.max(blob.dirtyRegion.bottom, node.position.y);
	}

	if( !skin.debug ) {
	context.beginPath();
	context.fillStyle = skin.fillStyle;
	context.strokeStyle = skin.strokeStyle;
	context.lineWidth = skin.lineWidth;
	}

	var cn = getArrayElementByOffset( blob.nodes, 0, -1 ); // current node
	var nn = getArrayElementByOffset( blob.nodes, 0, 0 ); // next node

	// Move to the first anchor
	context.moveTo( cn.position.x + ( nn.position.x - cn.position.x ) / 2, cn.position.y + ( nn.position.y - cn.position.y ) / 2 );

	// Rendering loop
	for (i = 0, len = blob.nodes.length; i < len; i++) {
	cn = getArrayElementByOffset( blob.nodes, i, 0 );
	nn = getArrayElementByOffset( blob.nodes, i, 1 );

	if( skin.debug ) {
	context.beginPath();
	context.lineWidth = 1;
	context.strokeStyle = "#ababab";

	for( j = 0; j < cn.joints.length; j++ ) {
	joint = cn.joints[j];
	context.moveTo( cn.position.x, cn.position.y );
	context.lineTo( joint.node.position.x, joint.node.position.y );
	}

	context.stroke();

	context.beginPath();
	context.fillStyle = i == 0? "#00ff00" : "#dddddd";
	context.arc(cn.position.x, cn.position.y, 5, 0, Math.PI*2, true);
	context.fill();
	}
	else {
	context.quadraticCurveTo( cn.position.x, cn.position.y, cn.position.x + ( nn.position.x - cn.position.x ) / 2, cn.position.y + ( nn.position.y - cn.position.y ) / 2 );
	}
	}

	if( skin.debug ) {
	// context.beginPath();
	// context.fillStyle = "rgba(100,255,100,0.3)";
	// context.fillRect(blob.dirtyRegion.left-dirtySpread,blob.dirtyRegion.top-dirtySpread,blob.dirtyRegion.right-blob.dirtyRegion.left+(dirtySpread2),blob.dirtyRegion.bottom-blob.dirtyRegion.top+(dirtySpread2));
	// context.fill();
	}

	context.stroke();
	context.fill();
	}

	screenX = window.screenX;
	screenY = window.screenY;
	}


	};

	function Blob() {
	this.position = { x: 0, y: 0 };
	this.velocity = { x: 0, y: 0 };
	this.radius = 120;
	this.quality = 32;
	this.nodes = [];
	this.rotation = -Math.PI * 0.5;
	this.dragNodeIndex = -1;
	this.dirtyRegion = { left: 0, top: 0, right: 0, bottom: 0 };
	this.lastSplitTime = 0;

	this.generateNodes = function() {
	this.nodes = [];

	var i, n;

	for (i = 0; i < this.quality; i++) {
	n = {
	normal: { x: 0, y: 0 },
	normalTarget: { x: 0, y: 0 },
	position: { x: this.position.x, y: this.position.y },
	ghost: { x: this.position.x, y: this.position.y },
	angle: 0
	};

	this.nodes.push( n );
	}

	this.updateJoints();

	this.updateNormals();
	};

	this.updateJoints = function() {
	for (var i = 0; i < this.quality; i++) {
	var n = this.nodes[i];

	n.joints = [
	{
	node: getArrayElementByOffset( this.nodes, i, -1 ),
	strength: 2.2
	},
	{
	node: getArrayElementByOffset( this.nodes, i, 1 ),
	strength: 2.2
	}
	];

	n.joints.push( {
	node: getArrayElementByOffset( this.nodes, i, -2 ),
	strength: 2.2
	} );

	n.joints.push( {
	node: getArrayElementByOffset( this.nodes, i, 2 ),
	strength: 2.2
	} );

	}
	};

	this.updateNormals = function() {
	var i, j, n;

	for (i = 0; i < this.quality; i++) {

	var n = this.nodes[i];

	if( this.dragNodeIndex != -1 ) {
	j = i - this.dragNodeIndex;
	j = j < 0 ? this.quality + j : j;
	}
	else {
	j = i;
	}

	n.angle = ( (j / this.quality ) * Math.PI * 2 ) + this.rotation;

	n.normalTarget.x = Math.cos( n.angle ) * this.radius;
	n.normalTarget.y = Math.sin( n.angle ) * this.radius;

	if( n.normal.x == 0 && n.normal.y == 0 ) {
	n.normal.x = n.normalTarget.x;
	n.normal.y = n.normalTarget.y;
	}
	}
	};

	this.split = function() {

	var velocitySpread = this.radius / 10;
	var nodeSpread = Math.round( this.nodes.length * 0.5 );
	var radiusSpread = this.radius * 0.5;

	var sibling = new Blob();

	sibling.position.x = this.position.x;
	sibling.position.y = this.position.y;

	sibling.velocity.x = velocitySpread;
	sibling.velocity.y = this.velocity.y;

	sibling.nodes = [];

	var i = 0;
	while( i++ < nodeSpread ) {
	sibling.nodes.push( this.nodes.shift() );
	}

	sibling.radius = radiusSpread;
	sibling.quality = sibling.nodes.length;

	this.velocity.x = -velocitySpread;
	this.radius = radiusSpread;
	this.quality = this.nodes.length;

	this.dragNodeIndex = -1;
	this.updateJoints();
	this.updateNormals();

	sibling.dragNodeIndex = -1;
	sibling.updateJoints();
	sibling.updateNormals();

	sibling.lastSplitTime = getTime();
	this.lastSplitTime = getTime();

	return sibling;

	};

	this.merge = function( sibling ) {
	this.velocity.x *= 0.5;
	this.velocity.y *= 0.5;

	this.velocity.x += sibling.velocity.x * 0.5;
	this.velocity.y += sibling.velocity.y * 0.5;

	while( sibling.nodes.length ) {
	this.nodes.push( sibling.nodes.shift() );
	}

	this.quality = this.nodes.length;
	this.radius += sibling.radius;

	this.dragNodeIndex = -1;

	this.updateNormals();
	this.organizeNodesByProximity();
	this.updateJoints();
	};

	this.organizeNodesByProximity = function() {
	var i, j, outer, inner;

	var closestDistance, currentDistance, closestIndex;

	var newNodes = this.nodes.concat();
	var blackListed = [];

	for (i = 0; i < this.quality; i++) {
	outer = newNodes[i];

	currentDistance = 9999;
	closestDistance = 9999;
	closestIndex = -1;

	for(j = 0; j < this.quality; j++) {
	inner = newNodes[j];

	currentDistance = distanceBetween( inner.position, outer.position );

	if( currentDistance < closestDistance && blackListed.indexOf(inner) === -1 ) {
	closestDistance = currentDistance;
	closestIndex = j;
	}
	}

	this.nodes[i] = newNodes[closestIndex];
	}

	};
	}

	function getArrayElementByOffset( array, index, offset ) {
	if( array[index+offset] ) {
	return array[index+offset];
	}

	if( index+offset > array.length-1 ) {
	return array[index - array.length + offset];
	}

	if( index+offset < 0 ) {
	return array[array.length + ( index + offset )];
	}
	}

	function sortByField( list, field ) {
	var sortOnField = function( a, b ) {
	return a[field] - b[field];
	};

	list.sort( sortOnField );
	}

	function getTime() {
	return new Date().getTime();
	}

	function distanceBetween(p1,p2) {
	var dx = p2.x-p1.x;
	var dy = p2.y-p1.y;
	return Math.sqrt(dxdx + dydy);
	}


	BlobWorld.init();
	<p>Double click to split. <a id="keyboardUp" href="#">Increase</a> / <a id="keyboardDown" href="#">decrease</a> size or <a id="keyboardLeft" href="#">Previous</a> / <a id="keyboardRight" href="#">Next</a> skin.</p>
	<canvas id='world'></canvas>
	body {
	background-color: #333333;
	padding: 0;
	margin: 0;
	overflow: hidden;
	}
	p {
	position: absolute;
	z-index: 99;
	color: #cccccc;
	margin: 2px;
	padding: 0;
	font-family: Arial;
	font-size: 10px;
	}
	a {
	color: #f4f4f4;
	font-weight: bold;
	}