Published
Edited
Sep 27, 2022
5 stars
world = d3.json("https://unpkg.com/visionscarto-world-atlas/world/110m.json")
borders = taggedBorders(world.objects.countries.geometries, (a, b) =>
d3.extent([a.id, b.id]).join("-")
)
/*
* A tagged border is an arc that belongs to two polygons with a non-null tag
* supersedes https://github.com/topojson/topojson-client/pull/18
*/
function taggedBorders(geometries, tag = (a, b) => a !== b) {
const x = [];
for (const d of geometries) {
for (const i of d.type === "MultiPolygon"
? d.arcs.flat(2)
: d.type === "Polygon"
? d.arcs.flat(1)
: [])
x[i] = d;
}
const borders = new Map();
for (let i = 0; i < x.length; i++) {
const t = x[-i - 1] ? tag(x[i], x[-i - 1]) : null;
if (t != null && t !== false) {
borders.set(t, borders.get(t) || []);
borders.get(t).push(i);
}
}
return {
type: "GeometryCollection",
geometries: Array.from(borders, ([tag, arcs]) => {
const lines = arcs.map((i) => [i]);
return lines.length === 1
? {
type: "LineString",
arcs: lines[0],
properties: { tag }
}
: {
type: "MultiLineString",
arcs: lines,
properties: { tag }
};
})
};
}
rotation = {
do {
const rotate = [(Date.now() / 200) % 360, -35, 0];
map.update(rotate);
yield rotate;
} while (true);
}
color = d3.scaleOrdinal(d3.schemeTableau10)
height = width * 0.6
topojson = require("topojson-server@3", "topojson-client@3")
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