Demonstrates the d3.geo.tile plug-in used in conjunction with the d3.geo.mercator projection to clip MapBox Natural Earth II raster tiles. The outline of the United States is loaded in TopoJSON format.
<!DOCTYPE html>
<meta charset="utf-8">
<style>
.stroke {
fill: none;
stroke: #000;
stroke-width: .5;
}
</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/d3.geo.tile.v0.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>
var width = 960,
height = 500;
var projection = d3.geo.mercator()
.center([-96, 38.3])
.scale(890);
var path = d3.geo.path()
.projection(projection);
var tile = d3.geo.tile()
.scale(projection.scale() * 2 * Math.PI)
.translate(projection([0, 0]))
.zoomDelta((window.devicePixelRatio || 1) - .5);
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
d3.json("/mbostock/raw/4090846/us.json", function(error, topology) {
var tiles = tile();
var defs = svg.append("defs");
defs.append("path")
.attr("id", "land")
.datum(topojson.feature(topology, topology.objects.land))
.attr("d", path);
defs.append("clipPath")
.attr("id", "clip")
.append("use")
.attr("xlink:href", "#land");
svg.append("g")
.attr("clip-path", "url(#clip)")
.selectAll("image")
.data(tiles)
.enter().append("image")
.attr("xlink:href", function(d) { return "//" + ["a", "b", "c", "d"][Math.random() * 4 | 0] + ".tiles.mapbox.com/v3/mapbox.natural-earth-2/" + d[2] + "/" + d[0] + "/" + d[1] + ".png"; })
.attr("width", Math.round(tiles.scale))
.attr("height", Math.round(tiles.scale))
.attr("x", function(d) { return Math.round((d[0] + tiles.translate[0]) * tiles.scale); })
.attr("y", function(d) { return Math.round((d[1] + tiles.translate[1]) * tiles.scale); });
svg.append("use")
.attr("xlink:href", "#land")
.attr("class", "stroke");
});
</script>