Albers Tiles

Rendering Nelson Minar’s river vector tiles in the Albers equal-area projection. The set of tiles are currently hard-coded, but it would be nice to compute them automatically from the viewport.

<!DOCTYPE html>
<meta charset="utf-8">
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/queue.v1.min.js"></script>
<script>

var width = 960,
    height = 600;

var dz = 2,
    z = 5 + dz,
    x = d3.range(5 << dz, 10 << dz),
    y = d3.range(11 << dz, 15 << dz);

var projection = d3.geo.albers()
    .scale(1285)
    .translate([width / 2, height / 2]);

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)
    .context(context);

var q = queue(6);

x.forEach(function(x) {
  y.forEach(function(y) {
    q.defer(renderTile, x, y, z);
  });
});

function renderTile(x, y, z, callback) {
  d3.json("https://www.somebits.com:8001/rivers/" + z + "/" + x + "/" + y + ".json", function(error, json) {
    context.beginPath();
    path(json);
    context.stroke();
    callback(null);
  });
}

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

</script>

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

https://d3js.org/queue.v1.min.js