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equirectangular projection (d3.js)
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| <!DOCTYPE html> | |
| <meta charset = "utf-8" > | |
| <title>equirectangular projection</title> | |
| <style> | |
| .land { | |
| fill: #eee; | |
| stroke: #888; | |
| stroke-width: .5px; | |
| } | |
| .boundary { | |
| fill: none; | |
| stroke: #ccc; | |
| } | |
| .spiral { | |
| fill: red; | |
| fill-opacity: .2; | |
| stroke: #f00; | |
| stroke-width: .5px; | |
| } | |
| .graticule { | |
| fill: none; | |
| stroke: #777; | |
| stroke-width: 0.3px; | |
| stroke-opacity: 0.5; | |
| } | |
| </style> | |
| <body> | |
| <script src= "https://d3js.org/d3.v4.min.js" > </script> | |
| <script src = "http://d3js.org/topojson.v3.min.js" > </script> | |
| <script> | |
| var nspiral = 12, | |
| dlat = 5, | |
| ndiv = 5, | |
| ndivRange = [3, 48], | |
| centerProjection = [-30, 0], | |
| rotationSpeed = 20; | |
| var width = 600, | |
| height = 320, | |
| SECOND = 1000; | |
| var spiral, timer, doRotation = true; | |
| var scaleProj = Math.min(width / 2, height) / Math.PI; | |
| var projection = d3.geoEquirectangular().translate([width / 2, height / 2]).scale(scaleProj).rotate([-centerProjection[0], -centerProjection[1]]); | |
| var path = d3.geoPath().projection(projection); | |
| var graticule = d3.geoGraticule(); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height) | |
| .on("wheel", redraw) | |
| .call(d3.drag() | |
| .subject(function() { | |
| var rotate = projection.rotate(); | |
| return { | |
| x: 2 * rotate[0], | |
| y: -2 * rotate[1] | |
| }; | |
| }) | |
| .on("start", function(d) { | |
| doRotation = false; | |
| clearTimeout(timer); | |
| }) | |
| .on("end", function(d) { | |
| restartRotation() | |
| }) | |
| .on("drag", function() { | |
| projection.rotate([d3.event.x / 2, -d3.event.y / 2, projection.rotate()[2]]); | |
| svg.selectAll("path").attr("d", path); | |
| })); | |
| svg.selectAll(".graticule") | |
| .data(graticule.lines) | |
| .enter().append("path") | |
| .attr("class", "graticule") | |
| .attr("d", path); | |
| drawSpiral(ndiv); | |
| function restartRotation() { | |
| timer = setTimeout(function() { | |
| doRotation = true | |
| }, 1 * SECOND); | |
| } | |
| function redraw() { | |
| ndiv *= Math.exp(d3.event.deltaY * 0.004); | |
| ndiv = clipRange(Math.ceil(ndiv), ndivRange); | |
| drawSpiral(ndiv); | |
| } | |
| function clipRange(x, xRange) { | |
| return Math.min(Math.max(x, xRange[0]), xRange[1]); | |
| } | |
| function makeSpiral(t, d) { | |
| if (!d) { | |
| d = 0 | |
| } | |
| return [normalise(360 * nspiral * t), (180 - dlat) * t - 90 + dlat * d]; | |
| } | |
| function normalise(x) { | |
| return (x + 180) % 360 - 180; | |
| } | |
| function drawSpiral(ndiv) { | |
| ndiv *= nspiral; | |
| if (spiral) { | |
| spiral.remove() | |
| } | |
| spiral = d3.range(0, ndiv + 1).map(function(w) { | |
| return makeSpiral(w / ndiv, 1); | |
| }).concat(d3.range(ndiv, -1, -1).map(function(w) { | |
| return makeSpiral(w / ndiv); | |
| })); | |
| spiral.push(spiral[0]); | |
| spiral = svg.append("path") | |
| .datum({ | |
| type: "Polygon", | |
| coordinates: [spiral] | |
| }) | |
| .attr("class", "spiral") | |
| .attr("d", path); | |
| } | |
| var url = "https://unpkg.com/world-atlas@1/world/110m.json"; | |
| d3.json(url, function(error, world) { | |
| svg.insert("path", ".graticule") | |
| .datum(topojson.feature(world, world.objects.land)) | |
| .attr("class", "land") | |
| .attr("d", path); | |
| svg.insert("g", ".graticule") | |
| .datum(topojson.mesh(world, world.objects.countries, function(a, b) { | |
| return a !== b; | |
| })) | |
| .attr("class", "boundary") | |
| .attr("d", path); | |
| function autoRotate() { | |
| if (doRotation) { | |
| var o0 = projection.rotate(); | |
| o0[0] += 1; | |
| projection.rotate(o0); | |
| svg.selectAll("path") | |
| .attr("d", path); | |
| } | |
| } | |
| setInterval(autoRotate, rotationSpeed); | |
| }); | |
| </script> | |
| </body> |
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