Clockface Edges

Edges represented only as a pointer from one node to another. They end up as vector edges? Clockface edges?

<!DOCTYPE html>

<html lang="en">
<head>
<meta charset="utf-8" />
<title>Sankey Particles</title>
<style>
.node rect {
  cursor: move;
  fill-opacity: .9;
  shape-rendering: crispEdges;
}

.node text {
  pointer-events: none;
  text-shadow: 0 1px 0 #fff;
}

.link {
  fill: none;
  stroke: #000;
  stroke-opacity: .05;
}

.link:hover {
  stroke-opacity: .25;
}

svg {
  position: absolute;
}

canvas {
  position: absolute;
}

</style>
</head>
<body>
<svg width="1000" height="1000" ></svg>

function arrowhead(d, headSize, bodySize) {
    var bodySize = 2;
      var diffX = d.target.y - d.source.y;
      var diffY = d.target.x - d.source.x;

var angle0 = ( Math.atan2( diffY, diffX ) + ( Math.PI / 2 ) );
      var angle1 = angle0 - ( Math.PI / 2 );
      var angle2 = angle0 + ( Math.PI / 2 );

var x1 = d.source.x + (headSize * Math.cos(angle1));
      var y1 = d.source.y - (headSize * Math.sin(angle1));
      var x2 = d.source.x + (headSize * Math.cos(angle2));
      var y2 = d.source.y - (headSize * Math.sin(angle2));

var x3 = d.target.x + (headSize * Math.cos(angle2));
      var y3 = d.target.y - (headSize * Math.sin(angle2));
      var x4 = d.target.x + (headSize * Math.cos(angle1));
      var y4 = d.target.y - (headSize * Math.sin(angle1));

var mx1 = d.source.x + (bodySize * Math.cos(angle1));
      var my1 = d.source.y - (bodySize * Math.sin(angle1));
      var mx2 = d.source.x + (bodySize * Math.cos(angle2));
      var my2 = d.source.y - (bodySize * Math.sin(angle2));

var mx3 = d.target.x + (bodySize * Math.cos(angle1));
      var my3 = d.target.y - (bodySize * Math.sin(angle1));
      var mx4 = d.target.x + (bodySize * Math.cos(angle2));
      var my4 = d.target.y - (bodySize * Math.sin(angle2));

var midY2 = (my1 + my3) / 2;
      var midX2 = (mx1 + mx3) / 2;
      var midY1 = (my2 + my4) / 2;
      var midX1 = (mx2 + mx4) / 2;

var midDiffY1 = my1 - my3;
      var midDiffX1 = mx1 - mx3;
      var midDiffY2 = my2 - my4;
      var midDiffX2 = mx2 - mx4;

var pythag = Math.sqrt((midDiffX1 * midDiffX1) + (midDiffY1 * midDiffY1));

var adjX1 =  mx1 - ((midDiffX1 * headSize) / pythag);
        var adjY1 = my1 - ((midDiffY1 * headSize) / pythag);
        var adjX2 =  mx1 - ((midDiffX2 * headSize) / pythag);
        var adjY2 = my1 - ((midDiffY2 * headSize) / pythag);

return "M" + mx1 + "," + my1 + "L" + adjX1 + "," + adjY1 + " L " + adjX2 + "," + adjY2 + " L " + mx2 + "," + my2 + "z";
    }
set3 = ["#8dd3c7","#ffffb3","#bebada","#fb8072","#80b1d3","#fdb462","#b3de69","#fccde5","#d9d9d9","#bc80bd","#ccebc5","#ffed6f"];

d3.json("network.json", makeViz)

function makeViz(data) {
  force = d3.layout.force().links(data.links).nodes(data.nodes)
  .charge(function (d) {return d.weight * -200})
  .size([1000,1000])
    .on("tick", tick)

d3.select("svg").selectAll("path.source").data(data.links)
    .enter()
    .append("path")
    .attr("class", "source")
    .style("fill", "lightgreen")
    .style("stroke", "black")
    .style("stroke-width", 1)

d3.select("svg").selectAll("path.target").data(data.links)
    .enter()
    .append("path")
    .attr("class", "target")
    .style("fill", "gold")
    .style("stroke", "black")
    .style("stroke-width", 1)

d3.select("svg").selectAll("circle").data(data.nodes)
    .enter()
    .append("circle")
    .attr("r", 20)
    .style("fill", function (d) {return set3[d.module]})
    .style("fill-opacity", 0.2)
    .style("stroke", "darkgray")
    .style("stroke-opacity", 0.3)
    .call(force.drag)

force.start();

function tick(e) {
    d3.selectAll("circle")
      .attr("cx", function (d) {return d.x})
      .attr("cy", function (d) {return d.y});

d3.selectAll("path.source")
      .attr("d", function (d) {return arrowhead(d, 20, 1)})

d3.selectAll("path.target")
      .attr("d", function (d) {return arrowhead({source: d.target, target: d.source}, 20, 1)})

}

</script>
</body>
</html>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.16/d3.min.js