Voronoi Force-Directed Graph without the nodes and links

More experimenting with combining force-directed graphs and voronoi diagrams.

Also see:

<!DOCTYPE html>
<meta charset="utf-8">
<style>
body {
  margin:0;
  position:fixed;
  top:0;
  right:0;
  bottom:0;
  left:0; 
}

.nodes circle {
  stroke: #fff;
  stroke-width: 1.5px;
}

</style>
<svg></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

var svg = d3.select("svg"),
    width = innerWidth,
    height = innerHeight;

svg.attr("width", width)
  .attr("height", height)

var color = d3.scaleOrdinal(d3.schemeCategory20);

var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(function(d) { return d.id; }))
    .force("charge", d3.forceManyBody())
    .force("center", d3.forceCenter(width / 2, height / 2));

d3.json("miserables.json", function(error, graph) {
  if (error) throw error;

var voronoi = d3.voronoi().extent([[0,0], [width, height]]);

var polygons = svg.append("g")
      .attr("class", "polygons")
    .selectAll("polygon")
      .data(graph.nodes)
      .enter().append("polygon")
        .style("fill", function(d) { return color(d.group); })
        .style("fill-opacity", .2)
        .style("stroke", "black")
        .call(d3.drag()
          .on("start", dragstarted)
          .on("drag", dragged)
          .on("end", dragended));

simulation
      .nodes(graph.nodes)
      .on("tick", ticked);

simulation.force("link")
      .links(graph.links);

function ticked() {
    if (graph.nodes[0].x) {
      var polygonShapes = voronoi(graph.nodes.map(function(d) {return [d.x, d.y]})).polygons()

polygons.attr("points", function(d, i) {
        return polygonShapes[i]
      })
    }
  }
});

function dragstarted(d) {
  if (!d3.event.active) simulation.alphaTarget(0.3).restart();
  d.fx = d.x;
  d.fy = d.y;
}

function dragged(d) {
  d.fx = d3.event.x;
  d.fy = d3.event.y;
}

function dragended(d) {
  if (!d3.event.active) simulation.alphaTarget(0);
  d.fx = null;
  d.fy = null;
}

</script>

https://d3js.org/d3.v4.min.js