Custom Shapes in Force Diagram

Instead of appending circles, we can append a path. The data holds the "d" attribute that makes the shape

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

.link {
  stroke: black;
  stroke-opacity: 0.5;
}

</style>
<body>
<script src="https://d3js.org/d3.v3.min.js"></script>

var width = 1960,
    height = 1800;

var color = d3.scale.category20();

var force = d3.layout.force()
    .charge(-4000)
    .linkDistance(450)
    .size([width, height]);

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);

d3.json("raw.json", function(error, graph) {
  force
      .nodes(graph.nodes)
      .links(graph.links)
      .start();

var link = svg.selectAll(".link")
      .data(graph.links)
    .enter().append("line")
      .attr("class", "link")
      .style("stroke-width", function(d) { return 10; });

force.on("tick", function() {
    link.attr("x1", function(d) { return d.source.x; })
        .attr("y1", function(d) { return d.source.y; })
        .attr("x2", function(d) { return d.target.x; })
        .attr("y2", function(d) { return d.target.y; });

circle.attr("transform", function(d) { return "translate("+(d.x -d.offx)+ "," +(d.y-d.offy) + ")" ;});
        
        
    /*text.attr("x", function(d) { return d.x; })
        .attr("y", function(d) { return d.y+(d.size*10); });*/

});
});

</script>

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

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