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@powersa
Created April 6, 2014 06:40
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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.

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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"}}]}
<!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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