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.
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July 20, 2019 01:01
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Clipped Map Tiles
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| license: gpl-3.0 | |
| redirect: https://observablehq.com/@d3/clipped-map-tiles |
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| d3.geo.tile=function(){function t(){var t=Math.max(Math.log(n)/Math.LN2-8,0),h=Math.round(t+e),o=Math.pow(2,t-h+8),u=[(r[0]-n/2)/o,(r[1]-n/2)/o],l=[],c=d3.range(Math.max(0,Math.floor(-u[0])),Math.max(0,Math.ceil(a[0]/o-u[0]))),M=d3.range(Math.max(0,Math.floor(-u[1])),Math.max(0,Math.ceil(a[1]/o-u[1])));return M.forEach(function(t){c.forEach(function(a){l.push([a,t,h])})}),l.translate=u,l.scale=o,l}var a=[960,500],n=256,r=[a[0]/2,a[1]/2],e=0;return t.size=function(n){return arguments.length?(a=n,t):a},t.scale=function(a){return arguments.length?(n=a,t):n},t.translate=function(a){return arguments.length?(r=a,t):r},t.zoomDelta=function(a){return arguments.length?(e=+a,t):e},t}; |
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| <!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/topojson.v1.min.js"></script> | |
| <script src="d3.geo.tile.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) { | |
| if (error) throw error; | |
| 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 "http://" + ["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> |
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