Undersea Cables II by mbostock

index.html

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

body {
  background: #fcfcfa;
}

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/d3.geo.projection.v0.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>

var width = 960,
    height = 960,
    speed = 1e-2;

var sphere = {type: "Sphere"};

var projection = d3.geo.orthographic()
    .clipAngle(90)
    .translate([width / 2, height / 2])
    .precision(.5);

var graticule = d3.geo.graticule();

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

var context = canvas.node().getContext("2d");

var path = d3.geo.path()
    .projection(projection)
    .pointRadius(1.5)
    .context(context);

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

  var land = topojson.feature(topo, topo.objects.land),
      borders = topojson.mesh(topo, topo.objects.countries, function(a, b) { return a !== b; }),
      cables = topojson.feature(topo, topo.objects.cables),
      landings = topojson.feature(topo, topo.objects.landings),
      grid = graticule();

  cables.features.forEach(function(cable) {
    if (cable.geometry.type === "LineString") resample(cable.geometry.coordinates);
    else cable.geometry.coordinates.forEach(resample);
  });

  d3.timer(function(elapsed) {
    projection.rotate([speed * elapsed, -15]);

    context.clearRect(0, 0, width, height);

    projection.scale(width / 2.2).clipAngle(90);

    context.beginPath();
    path(sphere);
    context.fillStyle = "#fff";
    context.fill();

    context.beginPath();
    path(grid);
    context.lineWidth = .5;
    context.strokeStyle = "#ddd";
    context.stroke();

    context.beginPath();
    path(land);
    context.fillStyle = "#ddd";
    context.fill();

    context.beginPath();
    path(borders);
    context.lineWidth = 1;
    context.strokeStyle = "#fff";
    context.stroke();

    projection.scale(width / 2.1).clipAngle(107);

    context.beginPath();
    path(cables);
    context.lineWidth = .5;
    context.strokeStyle = "#333";
    context.stroke();

    context.beginPath();
    path(landings);
    context.fillStyle = "#555";
    context.fill();

    projection.scale(width / 2.2).clipAngle(90);

    context.beginPath();
    path(sphere);
    context.lineWidth = 1.5;
    context.strokeStyle = "#000";
    context.stroke();
  });
});

// Takes a sparse line string that assumes Cartesian interpolation in spherical
// coordinates and inserts interstitial points for greater accuracy when
// rendering with D3, which assumes spherical interpolation.
function resample(coordinates) {
  var i = 0,
      j = -1,
      n = coordinates.length,
      source = coordinates.slice(),
      p0, x0, y0,
      p1 = coordinates[0], x1 = p1[0], y1 = p1[1],
      dx, dy, d2,
      m2 = 10; // squared minimum angular distance
  while (++i < n) {
    p0 = p1, x0 = x1, y0 = y1;
    p1 = source[i], x1 = p1[0], y1 = p1[1];
    dx = x1 - x0, dy = y1 - y0, d2 = dx * dx + dy * dy;
    coordinates[++j] = p0;
    if (d2 > m2) for (var k = 1, m = Math.ceil(Math.sqrt(d2 / m2)); k < m; ++k) {
      coordinates[++j] = [x0 + dx * k / m, y0 + dy * k / m];
    }
  }
  coordinates[++j] = p1;
  coordinates.length = j + 1;
}

d3.select(self.frameElement).style("height", height + "px");

</script>