Skip to content

Instantly share code, notes, and snippets.

@mbostock
Forked from mbostock/.block
Last active Sep 30, 2019
Embed
What would you like to do?
Raster & Vector III
license: gpl-3.0
redirect: https://observablehq.com/@d3/zoomable-raster-vector
<!DOCTYPE html>
<meta charset="utf-8">
<style>
body {
margin: 0;
}
path {
fill: none;
stroke: red;
stroke-linejoin: round;
stroke-width: 1.5px;
}
</style>
<svg></svg>
<script src="//d3js.org/d3.v4.min.js"></script>
<script src="//d3js.org/d3-tile.v0.0.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>
var pi = Math.PI,
tau = 2 * pi;
var width = Math.max(960, window.innerWidth),
height = Math.max(500, window.innerHeight);
// Initialize the projection to fit the world in a 1×1 square centered at the origin.
var projection = d3.geoMercator()
.scale(1 / tau)
.translate([0, 0]);
var path = d3.geoPath()
.projection(projection);
var tile = d3.tile()
.size([width, height]);
var zoom = d3.zoom()
.scaleExtent([1 << 11, 1 << 14])
.on("zoom", zoomed);
var svg = d3.select("svg")
.attr("width", width)
.attr("height", height);
var raster = svg.append("g");
var vector = svg.append("path");
d3.json("/mbostock/raw/4090846/us.json", function(error, us) {
if (error) throw error;
// Compute the projected initial center.
var center = projection([-98.5, 39.5]);
// Apply a zoom transform equivalent to projection.{scale,translate,center}.
svg
.call(zoom)
.call(zoom.transform, d3.zoomIdentity
.translate(width / 2, height / 2)
.scale(1 << 12)
.translate(-center[0], -center[1]));
vector
.attr("d", path(topojson.mesh(us, us.objects.counties)));
});
function zoomed() {
var transform = d3.event.transform;
var tiles = tile
.scale(transform.k)
.translate([transform.x, transform.y])
();
vector
.attr("transform", transform)
.style("stroke-width", 1 / transform.k);
var image = raster
.attr("transform", stringify(tiles.scale, tiles.translate))
.selectAll("image")
.data(tiles, function(d) { return d; });
image.exit().remove();
image.enter().append("image")
.attr("xlink:href", function(d) { return "http://" + "abc"[d[1] % 3] + ".tile.openstreetmap.org/" + d[2] + "/" + d[0] + "/" + d[1] + ".png"; })
.attr("x", function(d) { return d[0] * 256; })
.attr("y", function(d) { return d[1] * 256; })
.attr("width", 256)
.attr("height", 256);
}
function stringify(scale, translate) {
var k = scale / 256, r = scale % 1 ? Number : Math.round;
return "translate(" + r(translate[0] * scale) + "," + r(translate[1] * scale) + ") scale(" + k + ")";
}
</script>
@tomgasson

This comment has been minimized.

Copy link

@tomgasson tomgasson commented Jul 3, 2013

Thank you. I've used this method with great success here

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment