Skip to content

Instantly share code, notes, and snippets.

@iirvine
Forked from mbostock/.block
Last active December 17, 2015 12:19
Show Gist options
  • Star 0 You must be signed in to star a gist
  • Fork 0 You must be signed in to fork a gist
  • Save iirvine/5609255 to your computer and use it in GitHub Desktop.
Save iirvine/5609255 to your computer and use it in GitHub Desktop.

More hacking on mbostock's original Vector Tiles example, this time to play with rendering vec-tiles to canvas

<!DOCTYPE html>
<meta charset="utf-8">
<style>
body {
margin: 0;
}
.map {
position: relative;
overflow: hidden;
}
.layer {
position: absolute;
}
.tile {
position: absolute;
width: 256px;
height: 256px;
}
.info {
position: absolute;
bottom: 10px;
left: 10px;
}
</style>
<body>
<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/d3.geo.tile.v0.min.js"></script>
<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 << 21) / 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 << 18, 1 << 23])
.translate(projection([-74.0064, 40.7142]).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 layers = map.selectAll('div')
.data(["vectiles-buildings","vectiles-highroad"])
.enter().append('div')
.attr("class", function(d){ return "layer " + d });
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());
layers
.style(prefix + "transform", matrix3d(tiles.scale, tiles.translate))
.call(tileLayer, tiles)
}
function tileLayer(selection, tiles) {
selection.each(function(endpoint) {
var images = d3.select(this)
.selectAll('.tile')
.data(tiles, function(d) { return d; });
images.enter().append('div')
.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 canvas = d3.select(this)
.append("canvas")
.attr('width', "265px")
.attr('height', "256px");
this._xhr = d3.json("http://" + ["a", "b", "c"][(d[0] * 31 + d[1]) % 3] + ".tile.openstreetmap.us/" + endpoint + "/" + 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)
tilePath.context(canvas.node().getContext('2d'));
tilePath({type: "FeatureCollection", features:json.features});
tilePath.context().stroke()
});
});
images.exit()
.each(function(d) { this._xhr.abort(); })
.remove();
})
}
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>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment