Sankey Particles III

Using particles to indicate flow between reservoirs in a sankey diagram. This time with particles moving at varying speeds and maintaining the color of the source node. You can drag the reservoirs (the rectangles) to adjust the path of the flows.

Other examples of sankeys with particles:

Fixed speed particles transitioning in color from source node color to target node color.
Particles of differing sizes and differing speeds moving in "bursts" between nodes.

<!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: .15;
}

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

svg {
  position: absolute;
}

canvas {
  position: absolute;
}

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

var margin = {top: 1, right: 1, bottom: 6, left: 1},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var formatNumber = d3.format(",.0f"),
    format = function(d) { return formatNumber(d) + " TWh"; },
    color = d3.scale.category20();

var svg = d3.select("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var sankey = d3.sankey()
    .nodeWidth(15)
    .nodePadding(10)
    .size([width, height]);

var path = sankey.link();

var freqCounter = 1;

d3.json("energy.json", function(energy) {

sankey
      .nodes(energy.nodes)
      .links(energy.links)
      .layout(32);

var link = svg.append("g").selectAll(".link")
      .data(energy.links)
    .enter().append("path")
      .attr("class", "link")
      .attr("d", path)
      .style("stroke-width", function(d) { return Math.max(1, d.dy); })
      .sort(function(a, b) { return b.dy - a.dy; });

link.append("title")
      .text(function(d) { return d.source.name + " → " + d.target.name + "\n" + format(d.value); });

node.append("rect")
      .attr("height", function(d) { return d.dy; })
      .attr("width", sankey.nodeWidth())
      .style("fill", function(d) { return d.color = color(d.name.replace(/ .*/, "")); })
      .style("stroke", "none")
    .append("title")
      .text(function(d) { return d.name + "\n" + format(d.value); });

node.append("text")
      .attr("x", -6)
      .attr("y", function(d) { return d.dy / 2; })
      .attr("dy", ".35em")
      .attr("text-anchor", "end")
      .attr("transform", null)
      .text(function(d) { return d.name; })
    .filter(function(d) { return d.x < width / 2; })
      .attr("x", 6 + sankey.nodeWidth())
      .attr("text-anchor", "start");

function dragmove(d) {
    d3.select(this).attr("transform", "translate(" + d.x + "," + (d.y = Math.max(0, Math.min(height - d.dy, d3.event.y))) + ")");
    sankey.relayout();
    link.attr("d", path);
  }

var linkExtent = d3.extent(energy.links, function (d) {return d.value});
  var frequencyScale = d3.scale.linear().domain(linkExtent).range([0.05,1]);
  var particleSize = d3.scale.linear().domain(linkExtent).range([1,5]);

energy.links.forEach(function (link) {
    link.freq = frequencyScale(link.value);
    link.particleSize = 2;
    link.particleColor = d3.scale.linear().domain([0,1])
    .range([link.source.color, link.target.color]);
  })

var t = d3.timer(tick, 1000);
  var particles = [];

function tick(elapsed, time) {

particles = particles.filter(function (d) {return d.current < d.path.getTotalLength()});

d3.selectAll("path.link")
    .each(
      function (d) {
//        if (d.freq < 1) {
        for (var x = 0;x<2;x++) {
          var offset = (Math.random() - .5) * (d.dy - 4);
          if (Math.random() < d.freq) {
            var length = this.getTotalLength();
            particles.push({link: d, time: elapsed, offset: offset, path: this, length: length, animateTime: length, speed: 0.5 + (Math.random())})
          }
        }

//        }
/*        else {
          for (var x = 0; x<d.freq; x++) {
            var offset = (Math.random() - .5) * d.dy;
            particles.push({link: d, time: elapsed, offset: offset, path: this})
          }
        } */
      });

particleEdgeCanvasPath(elapsed);
  }

function particleEdgeCanvasPath(elapsed) {
    var context = d3.select("canvas").node().getContext("2d")

context.clearRect(0,0,1000,1000);

context.fillStyle = "gray";
      context.lineWidth = "1px";
    for (var x in particles) {
        var currentTime = elapsed - particles[x].time;
//        var currentPercent = currentTime / 1000 * particles[x].path.getTotalLength();
        particles[x].current = currentTime * 0.15 * particles[x].speed;
        var currentPos = particles[x].path.getPointAtLength(particles[x].current);
        context.beginPath();
      context.fillStyle = particles[x].link.particleColor(0);
        context.arc(currentPos.x,currentPos.y + particles[x].offset,particles[x].link.particleSize,0,2*Math.PI);
        context.fill();
    }
  }

});

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

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

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