Elastic Bubbles

D3 visualization combining techniques from clustered force layouts and convex polygons as a form of pseudo elasticity. Also experimented with using non-rendering nodes to aid in generating and updating the shapes.

See Clustered Force Layout III, Convex Hull, and D3.js and Canvas.

<!DOCTYPE html>
<meta charset="utf-8">

<body>
  Drag the bubbles using your mouse (or finger).
</body>

var width = 960,
    height = 500,
    padding = 10, // separation between same-color circles
    maxRadius = 5,
    clusterPadding = 25; // separation between different-color circles
  
  var n =50, // total number of circles
    m = 5; // number of distinct clusters

//container
  var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);
  var allChartBg_vorinoi = svg.append("g");
  var allChartBg_group = svg.append("g");
  //*******************************************************
  
  
  
  
  //*******************************************************
  //function variables
  //*******************************************************
  //color generator
  var color = d3.scale.category10().domain(d3.range(m));
  
  //custom drag
  var drag = d3.behavior.drag()
      .origin(function(d) { return d; })
      .on("dragstart", dragstarted)
      .on("drag", dragged)
      .on("dragend", dragended);
  
  
  //path generator
  var groupFunction = d3.svg.line()
    .interpolate("basis-closed")
    .tension(0.0)
    .x(function(d) { return d[0]; })
    .y(function(d) { return d[1]; });
  //*******************************************************
  
  
  
  
  //*******************************************************
  //node generator
  //*******************************************************
  // The largest node for each cluster.
  var clusters = new Array(m);
  
  var nodes = d3.range(n).map(function() {
    var i = Math.floor(Math.random() * m),
      r = Math.sqrt((i + 1) / m * -Math.log(Math.random())) * maxRadius,
      d = {cluster: i, radius: r};
    if (!clusters[i] || (r > clusters[i].radius)) clusters[i] = d;
    return d;
  });
  //*******************************************************
  
  
  
  
  //*******************************************************
  //elements
  //*******************************************************
  //hidden circles
  var circle = svg.selectAll("custom.circle").data(nodes);
  circle.enter().append("custom")
    .classed("circle", true)
    .attr("id", function(d, i) { return (clusters[d.cluster] === d) ? "cluster_" + d.cluster : "circle_" + i; })
    .attr("r", function(d) { return d.radius; });
  
  
  //grouping bubble
  var groupPath;
  var groups = d3.nest().key(function (d) { return d.cluster + ""; }).entries(nodes);
  groups.forEach(function(n) {
    n.strokeWidth = d3.max(n.values, function(d) { return d.radius; });
  });    
  groupPath = allChartBg_group.selectAll(".groupPath").data(groups);
  groupPath.enter().append("path")
    .attr("class", "groupPath")
    .style("opacity", 1)
    .style("fill", function(d) { return color(d.key); })
    .style("stroke", function(d) { return color(d.key); })
    .style("stroke-linejoin", "round")
    .style("stroke-width", function(d) { return d.strokeWidth * 3; })
    .on("mousedown", function(d) {
      selectedCluster = d.key;
    })
    .call(drag);
  groupPath.exit().remove();
  //*******************************************************
  
  
  
  
  //*******************************************************
  //animation
  //*******************************************************
  var force = d3.layout.force()
      .nodes(nodes)
      .size([width, height])
      .gravity(0)
      .charge(0)
      .on("tick", tick)
      .start();
  
  function tick(e) {
    circle
        .each(cluster(10 * e.alpha * e.alpha))
        .each(collide(.25))
        .attr("cx", function(d) { return d.x; })
        .attr("cy", function(d) { return d.y; });
  
      //grouping bubble
      groupPath.attr("d", function(d) { return groupFunction(d3.geom.hull(d.values.map(function (i) { return [i.x, i.y]; }))); });
  }
  //*******************************************************

//*******************************************************
  // clustering function
  //*******************************************************
  // Move d to be adjacent to the cluster node.
  function cluster(alpha) {
    return function(d) {
      var cluster = clusters[d.cluster],
          k = 1;
  
      // For cluster nodes, apply custom gravity.
      if (cluster === d) {
        cluster.x = (cluster.x === undefined) ? width /2 : cluster.x;
        cluster.y = (cluster.y === undefined) ? height /2 : cluster.y;
        cluster = {x: width / 2, y: height / 2, radius: -d.radius};
        //cluster.radius = (cluster.radius === undefined) ? d.radius : cluster.radius;
        k = .1 * Math.sqrt(d.radius);
      }
  
      var x = d.x - cluster.x,
          y = d.y - cluster.y,
          l = Math.sqrt(x * x + y * y),
          r = d.radius + cluster.radius;
      if (l != r) {
        l = (l - r) / l * alpha * k;
        d.x -= x *= l;
        d.y -= y *= l;
        cluster.x += x;
        cluster.y += y;
      }
    };
  }
  //*******************************************************
  
  
  
  
  //*******************************************************
  // collision handler
  //*******************************************************
  // Resolves collisions between d and all other circles.
  function collide(alpha) {
    var quadtree = d3.geom.quadtree(nodes);
    return function(d) {
      var r = d.radius + maxRadius + Math.max(padding, clusterPadding),
          nx1 = d.x - r,
          nx2 = d.x + r,
          ny1 = d.y - r,
          ny2 = d.y + r;
      quadtree.visit(function(quad, x1, y1, x2, y2) {
        if (quad.point && (quad.point !== d)) {
          var x = d.x - quad.point.x,
              y = d.y - quad.point.y,
              l = Math.sqrt(x * x + y * y),
              r = d.radius + quad.point.radius + (d.cluster === quad.point.cluster ? padding : clusterPadding);
          if (l < r) {
            l = (l - r) / l * alpha;
            d.x -= x *= l;
            d.y -= y *= l;
            quad.point.x += x;
            quad.point.y += y;
          }
        }
        return x1 > nx2 || x2 < nx1 || y1 > ny2 || y2 < ny1;
      });
    };
  }
  //*******************************************************
  
  
  
  
  //*******************************************************
  //custom drag functions
  //*******************************************************
  function dragstarted(d) {
    d3.select(this).classed("dragging", true);
  }
  function dragged(d) {
    d3.select("#cluster_" + selectedCluster)
      .attr("cx", function(c) {
        c.x = d3.event.sourceEvent.x;
        return d3.event.sourceEvent.x;
      })
      .attr("cy", function(c) {
        c.y = d3.event.sourceEvent.y;
        return d3.event.sourceEvent.y;
      });
    force.start();
  }
  function dragended(d) {
    d3.select(this).classed("dragging", false);
  }
  //*******************************************************
  
</script>

Modified http://d3js.org/d3.v3.min.js to a secure url

https://d3js.org/d3.v3.min.js