Vector Tiles in D3, darkened

Adapting d3.geo.tile to show OpenStreetMap vector tiles. Via Mike Bostock's example.

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

body {
  margin: 0;
  background:#031536;
}

.map {
  position: absolute;
  overflow: hidden;
  top:0px;
  bottom:0px;
}

.layer {
  position: absolute;
}

.tile {
  position: absolute;
  width: 256px;
  height: 256px;
}

.tile path {
  fill: none;
  stroke: #000;
  stroke-linejoin: round;
  stroke-linecap: round;
}

.tile .major_road { stroke: url(#grad2); stroke-width:1.8;}
.tile .minor_road { stroke: url(#grad3); stroke-width:1.2;}
.tile .highway { stroke: url(#grad1); stroke-width: 3px; stroke-linecap: round; stroke-linejoin: round; }
.tile .rail { stroke: url(#grad4); stroke-dasharray:4; stroke-dashoffset:4; stroke-width:1; }
.tile .path { stroke: url(#grad5); stroke-dasharray:2; stroke-dashoffset:4; stroke-width:0.8; }

.info {
  position: absolute;
  bottom: 10px;
  left: 10px;
  color:#fff;
}

</style>
</head>
<body>
<script src="https://d3js.org/d3.v3.min.js"></script>
<script src="https://d3js.org/d3.geo.tile.v0.min.js"></script>
  <svg>
    <defs>
      <linearGradient id='grad1'>
        <stop offset='0%' stop-color='#E8DDC9'/>
        <stop offset='100%' stop-color='#E8DDC9' stop-opacity='0' />
      </linearGradient>
      <linearGradient id='grad2'>
        <stop offset='0%' stop-color='#CCB479'/>
        <stop offset='100%' stop-color='#CCB479' stop-opacity='0' />
      </linearGradient>
      <linearGradient id='grad3'>
        <stop offset='0%' stop-color='#3C80A9'/>
        <stop offset='100%' stop-color='#3C80A9' stop-opacity='0' />
      </linearGradient>
      <linearGradient id='grad4'>
        <stop offset='0%' stop-color='#7de'/>
        <stop offset='100%' stop-color='#7de' stop-opacity='0' />
      </linearGradient>
      <linearGradient id='grad5'>
        <stop offset='0%' stop-color='#74DC9B'/>
        <stop offset='100%' stop-color='#74DC9B' stop-opacity='0' />
      </linearGradient>
    </defs>
  </svg>
<script>

var width = Math.max(960, window.innerWidth),
    height = Math.max(500, window.innerHeight),
    prefix = prefixMatch(["webkit", "ms", "Moz", "O"]);

var tile = d3.geo.tile()
    .size([width, height]);

var projection = d3.geo.mercator()
    .scale((1 << 23) / 2 / Math.PI)
    .translate([-width / 2, -height / 2]); // just temporary

var tileProjection = d3.geo.mercator();

var tilePath = d3.geo.path()
    .projection(tileProjection);

var zoom = d3.behavior.zoom()
    .scale(projection.scale() * 2 * Math.PI)
    .scaleExtent([1 << 20, 1 << 23])
    .translate(projection([-77.045446166, 38.89370499]).map(function(x) { return -x; }))
    .on("zoom", zoomed);

var map = d3.select("body").append("div")
    .attr("class", "map")
    .style("width", width + "px")
    .style("height", height + "px")
    .call(zoom)
    .on("mousemove", mousemoved);

var layer = map.append("div")
    .attr("class", "layer");

var info = map.append("div")
    .attr("class", "info");

zoomed();

function zoomed() {
  var tiles = tile
      .scale(zoom.scale())
      .translate(zoom.translate())
      ();

projection
      .scale(zoom.scale() / 2 / Math.PI)
      .translate(zoom.translate());

var image = layer
      .style(prefix + "transform", matrix3d(tiles.scale, tiles.translate))
    .selectAll(".tile")
      .data(tiles, function(d) { return d; });

image.exit()
      .each(function(d) { this._xhr.abort(); })
      .remove();

image.enter().append("svg")
      .attr("class", "tile")
      .style("left", function(d) { return d[0] * 256 + "px"; })
      .style("top", function(d) { return d[1] * 256 + "px"; })
      .each(function(d) {
        var svg = d3.select(this);
        this._xhr = d3.json("https://" + ["a", "b", "c"][(d[0] * 31 + d[1]) % 3] + ".tile.openstreetmap.us/vectiles-highroad/" + d[2] + "/" + d[0] + "/" + d[1] + ".json", function(error, json) {
          var k = Math.pow(2, d[2]) * 256; // size of the world in pixels

tilePath.projection()
              .translate([k / 2 - d[0] * 256, k / 2 - d[1] * 256]) // [0°,0°] in pixels
              .scale(k / 2 / Math.PI);

svg.selectAll("path")
              .data(json.features.sort(function(a, b) { return a.properties.sort_key - b.properties.sort_key; }))
              .enter().append("path")
              .attr("class", function(d) { return d.properties.kind; })
              .attr("d", tilePath);
        });
      });
}

function mousemoved() {
  info.text(formatLocation(projection.invert(d3.mouse(this)), zoom.scale()));
}

function matrix3d(scale, translate) {
  var k = scale / 256, r = scale % 1 ? Number : Math.round;
  return "matrix3d(" + [k, 0, 0, 0, 0, k, 0, 0, 0, 0, k, 0, r(translate[0] * scale), r(translate[1] * scale), 0, 1 ] + ")";
}

function prefixMatch(p) {
  var i = -1, n = p.length, s = document.body.style;
  while (++i < n) if (p[i] + "Transform" in s) return "-" + p[i].toLowerCase() + "-";
  return "";
}

function formatLocation(p, k) {
  var format = d3.format("." + Math.floor(Math.log(k) / 2 - 2) + "f");
  return (p[1] < 0 ? format(-p[1]) + "°S" : format(p[1]) + "°N") + " "
       + (p[0] < 0 ? format(-p[0]) + "°W" : format(p[0]) + "°E");
}

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

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

Modified http://d3js.org/d3.geo.tile.v0.min.js to a secure url

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

https://d3js.org/d3.geo.tile.v0.min.js