Sankey Particles II

Using particles to indicate flow between reservoirs in a sankey diagram. This time with particles moving at the same speed and same size. An earlier example used particles of differing sizes and differing speeds moving in "bursts" between nodes.

Drag the nodes to adjust the paths of the particles.

<!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>
<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 = 2.5;
    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) {
          var offset = (Math.random() - .5) * d.dy;
          if (Math.random() < d.freq) {
            var length = this.getTotalLength();
            particles.push({link: d, time: elapsed, offset: offset, path: this, length: length, animateTime: length})
          }
//        }
/*        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;
        var currentPos = particles[x].path.getPointAtLength(particles[x].current);
        context.beginPath();
      context.fillStyle = particles[x].link.particleColor(particles[x].current/particles[x].path.getTotalLength());
        context.arc(currentPos.x,currentPos.y + particles[x].offset,particles[x].link.particleSize,0,2*Math.PI);
        context.fill();
    }
  }

});

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

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