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d3.geoPath.area recoloring on drag

Drag the globe to rotate it, countries are re-colored based on their graphical area. Sorry, Europe, your countries are too small to see any difference.

<html>
<head>
<style>
path.graticule {
fill: none;
stroke-width: 1;
stroke: #9A8B7A;
}
path.graticule.outline {
fill: none;
stroke: #9A8B7A;
}
</style>
</head>
<script src="https://d3js.org/d3.v4.js" type="text/JavaScript"></script>
<script src="https://d3js.org/d3-geo-projection.v1.min.js"></script>
<body>
<div id="vizcontainer">
<svg style="width:500px;height:500px;" />
</div>
<script type="text/javascript">
d3.json("world.geojson", createMap)
function createMap(countries) {
var projection = d3.geoOrthographic()
.scale(200)
.translate([250,250])
.center([0,0])
.rotate([0,0])
var geoPath = d3.geoPath().projection(projection);
var featureSize = d3.extent(countries.features, function(d) { return geoPath.area(d)})
var countryColor = d3.scaleQuantize()
.domain(featureSize).range(["#cdc597","#a4b77d","#72972f","#36611b","#113719"]);
d3.select("svg").selectAll("path").data(countries.features)
.enter()
.append("path")
.attr("d", geoPath)
.attr("class", "countries")
.style("fill", function(d) { return countryColor(geoPath.area(d))})
.style("stroke", function(d) { return d3.rgb(countryColor(geoPath.area(d))).darker()})
var graticule = d3.geoGraticule();
d3.select("svg").insert("path", "path.countries")
.datum(graticule)
.attr("class", "graticule line")
.attr("d", geoPath)
d3.select("svg").insert("path", "path.countries")
.datum(graticule.outline)
.attr("class", "graticule outline")
.attr("d", geoPath)
var mapZoom = d3.zoom()
.on("zoom", zoomed)
var zoomSettings = d3.zoomIdentity
.translate(0, 0)
.scale(200)
var rotateScale = d3.scaleLinear()
.domain([-500, 0, 500])
.range([-180, 0, 180]);
d3.select("svg")
.call(mapZoom)
.call(mapZoom.transform, zoomSettings)
function zoomed() {
var e = d3.event
var currentRotate = rotateScale(e.transform.x) % 360
projection
.rotate([currentRotate, 0])
.scale(e.transform.k)
d3.selectAll("path.graticule").attr("d", geoPath);
d3.selectAll("path.countries").attr("d", geoPath)
.style("fill", function(d) { return countryColor(geoPath.area(d))})
.style("stroke", function(d) { return d3.rgb(countryColor(geoPath.area(d))).darker()})
}
}
</script>
</body>
<footer>
</html>
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