function Computational(canvas) {
                var xScale = d3.scale.linear().domain([-1, 1]).range([0, 1000]);
                var yScale = d3.scale.linear().domain([-0.2, 1.2]).range([1000, 0]);

                var ctx = canvas.getContext('2d');

                ctx.fillStyle = "rgb(0,0,0)";
                ctx.fillRect(0, 0, 1000, 800);
                
                // 3 colours, one for extremities, another for insides, another for in-betweens
                var colors = {
                  HipCenter : '#ff7f0e',
                  Spine : '#ff7f0e',
                  ShoulderCenter : '#ff7f0e',
                  Head : '#e7cb94',
                  ShoulderLeft : '#bd9e39',
                  ElbowLeft : '#bd9e39',
                  WristLeft : '#bd9e39',
                  HandLeft : '#e7cb94',
                  ShoulderRight : '#bd9e39',
                  ElbowRight : '#bd9e39',
                  WristRight : '#bd9e39',
                  HandRight : '#e7cb94',
                  HipLeft : '#bd9e39',
                  KneeLeft : '#bd9e39',
                  AnkleLeft : '#bd9e39',
                  FootLeft : '#e7cb94',
                  HipRight : '#bd9e39',
                  KneeRight : '#bd9e39',
                  AnkleRight : '#bd9e39',
                  FootRight : '#e7cb94'
                }

                // Colour coded hands + feet
                // var colors = {
                //   HipCenter : '#5254a3',
                //   Spine : '#5254a3',
                //   ShoulderCenter : '#5254a3',
                //   Head : '#5254a3',
                //   ShoulderLeft : '#5254a3',
                //   ElbowLeft : '#5254a3',
                //   WristLeft : '#5254a3',
                //   HandLeft : '#637939',
                //   ShoulderRight : '#5254a3',
                //   ElbowRight : '#5254a3',
                //   WristRight : '#5254a3',
                //   HandRight : '#8c6d31',
                //   HipLeft : '#5254a3',
                //   KneeLeft : '#5254a3',
                //   AnkleLeft : '#5254a3',
                //   FootLeft : '#843c39',
                //   HipRight : '#5254a3',
                //   KneeRight : '#5254a3',
                //   AnkleRight : '#5254a3',
                //   FootRight : '#7b4173'
                // }

                function getAllJoints(json) {
                  var joints = [];
                  _.each(json.Skeletons, function(skeleton) {
                    _.each(skeleton.Joints, function(joint) {
                      joints.push(joint);
                    });
                  });
                  return joints;
                }

                function getJointsOfSkeleton(json, skeleton) {
                  var joints = [];
                  if(json.Skeletons === undefined)
                    return [];
                  if(skeleton > json.Skeletons.length - 1)
                    return [];
                  _.each(json.Skeletons[skeleton].Joints, function(joint) {
                    joints.push(joint);
                  });
                  return joints;
                }

                function clear() {
                  ctx.globalAlpha = 1;
                  ctx.fillStyle = "rgb(0,0,0)";
                  ctx.fillRect(0, 0, 1000, 800);
                }
                
                this.draw = function(json) {
                  // console.log(json);
                  if(json === undefined) {
                    return;
                  }

                  var joints = getJointsOfSkeleton(json, 0);
                  ctx.globalAlpha = 0.03;

                  _.each(joints, function(joint, i) {
                    // console.log(joint.JointType)
                    ctx.fillStyle = colors[joint.JointType];
                    drawCircle(ctx, xScale(joint.Position.X), yScale(joint.Position.Y), 3);
                  });
                };
              };

              // You can choose one of these to visualise a different dance
              var DATASET_ALGORITHM = 'https://d10u56tzn9e9rq.cloudfront.net/algorithm_';

              var DATASET_BINARY = 'https://d10u56tzn9e9rq.cloudfront.net/binary_';

              var DATASET_WHOLEPIECE = 'https://d10u56tzn9e9rq.cloudfront.net/wholepiece_';

              var dataFetcher = new ChunkedDataFetcher(DATASET_ALGORITHM);
              var computational = new Computational( document.getElementById('mycanvas'));
              dataFetcher.drawFunction = function(json) {computational.draw(json);
              }