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Last active March 13, 2019 17:06
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Tissot’s Indicatrix
license: gpl-3.0
redirect: https://observablehq.com/@d3/tissots-indicatrix
<!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;
}
.boundary {
fill: none;
stroke: #fff;
stroke-width: .5px;
}
.tissot {
fill: orange;
fill-opacity: .4;
stroke: brown;
}
</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>
var width = 960,
height = 960;
var projection = d3.geo.orthographic()
.scale(475)
.translate([width / 2, height / 2])
.clipAngle(90)
.precision(.1);
var path = d3.geo.path()
.projection(projection);
var graticule = d3.geo.graticule();
var xz = d3.range(-180, 181, 30),
yz = d3.range(-60, 61, 30),
circle = d3.geo.circle().angle(7).origin(function(x, y) { return [x, y]; }),
circles = d3.merge(xz.map(function(x) { return yz.map(function(y) { return circle(x, y); }); }));
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);
svg.append("path")
.datum({type: "GeometryCollection", geometries: circles})
.attr("class", "tissot")
.attr("d", path);
d3.json("/mbostock/raw/4090846/world-50m.json", function(error, world) {
if (error) throw error;
svg.insert("path", ".graticule")
.datum(topojson.feature(world, world.objects.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.select(self.frameElement).style("height", height + "px");
</script>
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