This map demonstrates a problem I have animating d3 transitions across the antimeridian. Click the update button to see what I mean. On update the map transitions from .rotate([-160, 0]) (eastern hemisphere) to .rotate([160, 0]) (western hemisphere). Rather than cross the antimeridian, the transition travels the long way round.
Created
April 6, 2014 06:40
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| {"type": "FeatureCollection", "features": [{"geometry": {"type": "Point", "coordinates": [160, 0]}, "type": "Feature", "properties": {"name": "noname"}}, {"geometry": {"type": "Point", "coordinates": [-160, 0]}, "type": "Feature", "properties": {"name": "noname"}}]} |
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| body { | |
| background: #fcfcfa; | |
| } | |
| .stroke { | |
| fill: none; | |
| stroke: #000; | |
| stroke-width: 3px; | |
| } | |
| .fill { | |
| fill: #fff; | |
| } | |
| .graticule { | |
| fill: none; | |
| stroke: #777; | |
| stroke-width: .5px; | |
| stroke-opacity: .5; | |
| } | |
| .land { | |
| fill: #222; | |
| } | |
| .points { | |
| fill: #3182bd; | |
| stroke-width: .1; | |
| } | |
| .boundary { | |
| fill: none; | |
| stroke: #fff; | |
| stroke-width: .5px; | |
| } | |
| </style> | |
| <body> | |
| <div id="option"> | |
| <input name="updateButton" | |
| type="button" | |
| value="Update" | |
| onclick="updateData()" /> | |
| </div> | |
| <script src="http://d3js.org/d3.v3.min.js"></script> | |
| <script src="http://d3js.org/topojson.v1.min.js"></script> | |
| <script> | |
| var width = 425, | |
| height =425, | |
| rotate = [10, -10], | |
| velocity = [.003, -.001], | |
| time = Date.now(); | |
| var projection = d3.geo.orthographic() | |
| .scale(200) | |
| .translate([width / 2, height / 2]) | |
| .clipAngle(90) | |
| .rotate([-160, 0]) | |
| .precision(.1); | |
| var path = d3.geo.path() | |
| .projection(projection); | |
| var graticule = d3.geo.graticule(); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height); | |
| svg.append("defs").append("path") | |
| .datum({type: "Sphere"}) | |
| .attr("id", "sphere") | |
| .attr("d", path); | |
| svg.append("use") | |
| .attr("class", "stroke") | |
| .attr("xlink:href", "#sphere"); | |
| svg.append("use") | |
| .attr("class", "fill") | |
| .attr("xlink:href", "#sphere"); | |
| svg.append("path") | |
| .datum(graticule) | |
| .attr("class", "graticule") | |
| .attr("d", path); | |
| d3.json("110m_land.json", function(error, world) { | |
| svg.insert("path") | |
| .datum(topojson.feature(world, world.objects.ne_110m_land)) | |
| .attr("class", "land") | |
| .attr("d", path); | |
| svg.insert("path", ".graticule") | |
| .datum(topojson.mesh(world, world.objects.countries, function(a, b) { return a !== b; })) | |
| .attr("class", "boundary") | |
| .attr("d", path); | |
| }); | |
| d3.json("HISPEED_1000.json", function(json) { | |
| svg.selectAll("g") | |
| .data(json.features) | |
| .enter() | |
| .append("path") | |
| .attr("class", "points") | |
| .attr("lat", function(d) { return d.geometry.coordinates[0]; }) | |
| .attr("lon", function(d) { return d.geometry.coordinates[1]; }) | |
| .attr("d", path); | |
| }); | |
| var transition = d3.transition() | |
| .duration(2500); | |
| function updateData() { | |
| d3.transition() | |
| .duration(3000) | |
| .tween("rotate", function() { | |
| var r = d3.interpolate(projection.rotate(), [160, 0]); | |
| return function(t) { | |
| projection.rotate(r(t)); | |
| svg.selectAll("path").attr("d", path); | |
| }; | |
| }) | |
| }; | |
| </script> |
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