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Europe geo to square tiles animation with geo2rect
license: mit

The code I used to animate the geographic map of Europe to a square tile map in The Eurosearch Song Contest. It uses the great geo2rect by Sebastian Meier.

This map is basically a clone of one of Sebastian's examples. I created the geojson from Natural Earth data, selected the countries I needed (the Eurovision participants) in QGIS and simplified the geometries with mapshaper. Laying out the tile grid was a nice puzzle (yes, looking at you, Balkans).

Some remarks:

  • geo2rect filters out holes and only keeps the biggest polygon of multipolygons (tough luck, Northern Ireland and Northern Cyprus...)
  • I filtered out some smaller European countries and islands from the geojson, like Andorra and Liechtenstein.
  • I kept Australia in, as it participated in the Eurovision Song Contest. You can see it flying in from the bottom right corner.
  • I had to override the scale and center of the map in geo2rect.js. geo2rect calculates these from the geometries, but because Russia is so big and Australia is in there, I had to zoom in on Europe manually.

You can read the whole making-of of the Eurosearch Song Contest on my site.

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(function (global, factory) {
typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
typeof define === 'function' && define.amd ? define(['exports'], factory) :
(factory((global.geo2rect = global.geo2rect || {})));
}(this, function (exports) { 'use strict';
function compute (data) {
//TODO: check if data is in a valid format
data.features.forEach(function (d, di) {
//Preserve original coordinates
d.geometry["ocoordinates"] = d.geometry.coordinates;
//As we can only transform one polygon into a rectangle, we need to get rid of holes and small additional polygons (islands and stuff)
if (d.geometry.type === "MultiPolygon") {
//choose the largest polygon
d.geometry.coordinates = largestPoly(d.geometry);
d.geometry.type = "Polygon";
}
//Getting rid of holes
if (d.geometry.coordinates.length > 1) {
//We are too lazy to calculate if poly is clockwise or counter-clockwise, so we again just keep the largest poly
d.geometry.coordinates = largestPoly(d.geometry);
}
var b = turf.bbox(d);
d.geometry["centroid"] = [(b[2] - b[0]) / 2 + b[0], (b[1] - b[3]) / 2 + b[3]];
//Not supported geometries (length<4) we simply duplicate the first point
//TODO: the new points could be evenly distributed between the existing points
//TODO: but this only for triangles anyway, anything with (length<3) is actually an error
if (d.geometry.coordinates[0].length < 4) {
while (d.geometry.coordinates[0].length < 4) {
d.geometry.coordinates[0].push(d.geometry.coordinates[0][0]);
}
}
var geom = d.geometry.coordinates[0],
corners = [];
//Moving through the four corners of the rectangle we find the closest point on the polygon line, making sure the next point is always after the last
var _loop = function _loop(i) {
var corner = void 0,
dist = Number.MAX_VALUE,
pc = void 0;
switch (i) {
case 0:
pc = [b[0], b[3]];
break;
case 1:
pc = [b[2], b[3]];
break;
case 2:
pc = [b[2], b[1]];
break;
case 3:
pc = [b[0], b[1]];
break;
}
geom.forEach(function (dd, ddi) {
var t_dist = Math.abs(Math.sqrt(Math.pow(pc[0] - dd[0], 2) + Math.pow(pc[1] - dd[1], 2)));
if (t_dist < dist && (ddi < corners[0] || ddi > corners[corners.length - 1] || corners.length === 0)) {
dist = t_dist;
corner = ddi;
}
});
if (corners.length >= 1) {
//Counting the points already used up
var pointCount = 0;
if (corners.length >= 2) {
for (var _j = 1; _j < corners.length; _j++) {
var _c3 = corners[_j],
_c4 = corners[_j - 1],
_numPoints2 = void 0;
if (_c4 < _c3) {
_numPoints2 = _c3 - _c4;
} else {
_numPoints2 = _c3 + (geom.length - _c4);
}
pointCount += _numPoints2;
}
}
//get numpoints for new potential point
var _c = corners[corners.length - 1],
_c2 = corner,
_numPoints = void 0;
if (_c < _c2) {
_numPoints = _c2 - _c;
} else {
_numPoints = _c2 + (geom.length - _c);
}
//If there are not enough points left to finish the rectangle go step back
if (geom.length - _numPoints - pointCount < 4 - i) {
corner -= 4 - i;
if (corner < 0) {
corner += geom.length;
}
}
}
corners.push(corner);
};
for (var i = 0; i < 4; i++) {
_loop(i);
}
//NOTE: to myself Outer rings are counter clockwise
//Finding the closest point to each corner
var ngeom = {};
for (var i = 0; i < 4; i++) {
var p1 = void 0,
p2 = void 0,
ox = void 0,
oy = void 0;
switch (i) {
case 0:
ox = 0;oy = 0;
p1 = [b[0], b[3]];
p2 = [b[2], b[3]];
break;
case 1:
ox = 1;oy = 0;
p1 = [b[2], b[3]];
p2 = [b[2], b[1]];
break;
case 2:
ox = 1;oy = 1;
p1 = [b[2], b[1]];
p2 = [b[0], b[1]];
break;
case 3:
ox = 0;oy = 1;
p1 = [b[0], b[1]];
p2 = [b[0], b[3]];
break;
}
var x = p2[0] - p1[0],
y = p2[1] - p1[1];
if (x != 0) {
x = x / Math.abs(x);
}
if (y != 0) {
y = y / Math.abs(y);
}
y *= -1;
var c1 = corners[i],
c2 = i === corners.length - 1 ? corners[0] : corners[i + 1],
numPoints = void 0;
if (c1 < c2) {
numPoints = c2 - c1;
} else {
numPoints = c2 + (geom.length - c1);
}
for (var j = 0; j < numPoints; j++) {
var tp = c1 + j;
if (tp > geom.length - 1) {
tp -= geom.length;
}
ngeom[tp] = {
c: d.geometry.centroid,
x: ox + x / numPoints * j,
y: oy + y / numPoints * j
};
}
}
d.geometry['qcoordinates'] = [];
//Okey, i have no clue why the first point is broken (i=0 > i=1)
for (var _i = 1; _i < geom.length; _i++) {
if (_i === geom.length - 1) {
d.geometry.qcoordinates.push(ngeom[0]);
} else {
d.geometry.qcoordinates.push(ngeom[_i]);
}
}
});
//polys: d.geometry object (GeoJSON)
function largestPoly(geom) {
var size = -Number.MAX_VALUE,
poly = null;
//We will select the largest polygon from the multipolygon (this has worked out so far, for your project you might need to reconsider or just provide (single) polygons in the first place)
for (var c = 0; c < geom.coordinates.length; c++) {
//we are using turf.js area function
//if you don't want to include the full turf library, turf is build in modular fashion, npm install turf-area
var tsize = turf.area({
type: 'Feature',
properties: {},
geometry: {
type: 'Polygon',
coordinates: geom.type === 'MultiPolygon' ? [geom.coordinates[c][0]] : [geom.coordinates[c]]
}
});
if (tsize > size) {
size = tsize;
poly = c;
}
}
return [geom.type === 'MultiPolygon' ? geom.coordinates[poly][0] : geom.coordinates[poly]];
}
return data;
};
var asyncGenerator = function () {
function AwaitValue(value) {
this.value = value;
}
function AsyncGenerator(gen) {
var front, back;
function send(key, arg) {
return new Promise(function (resolve, reject) {
var request = {
key: key,
arg: arg,
resolve: resolve,
reject: reject,
next: null
};
if (back) {
back = back.next = request;
} else {
front = back = request;
resume(key, arg);
}
});
}
function resume(key, arg) {
try {
var result = gen[key](arg);
var value = result.value;
if (value instanceof AwaitValue) {
Promise.resolve(value.value).then(function (arg) {
resume("next", arg);
}, function (arg) {
resume("throw", arg);
});
} else {
settle(result.done ? "return" : "normal", result.value);
}
} catch (err) {
settle("throw", err);
}
}
function settle(type, value) {
switch (type) {
case "return":
front.resolve({
value: value,
done: true
});
break;
case "throw":
front.reject(value);
break;
default:
front.resolve({
value: value,
done: false
});
break;
}
front = front.next;
if (front) {
resume(front.key, front.arg);
} else {
back = null;
}
}
this._invoke = send;
if (typeof gen.return !== "function") {
this.return = undefined;
}
}
if (typeof Symbol === "function" && Symbol.asyncIterator) {
AsyncGenerator.prototype[Symbol.asyncIterator] = function () {
return this;
};
}
AsyncGenerator.prototype.next = function (arg) {
return this._invoke("next", arg);
};
AsyncGenerator.prototype.throw = function (arg) {
return this._invoke("throw", arg);
};
AsyncGenerator.prototype.return = function (arg) {
return this._invoke("return", arg);
};
return {
wrap: function (fn) {
return function () {
return new AsyncGenerator(fn.apply(this, arguments));
};
},
await: function (value) {
return new AwaitValue(value);
}
};
}();
var classCallCheck = function (instance, Constructor) {
if (!(instance instanceof Constructor)) {
throw new TypeError("Cannot call a class as a function");
}
};
var createClass = function () {
function defineProperties(target, props) {
for (var i = 0; i < props.length; i++) {
var descriptor = props[i];
descriptor.enumerable = descriptor.enumerable || false;
descriptor.configurable = true;
if ("value" in descriptor) descriptor.writable = true;
Object.defineProperty(target, descriptor.key, descriptor);
}
}
return function (Constructor, protoProps, staticProps) {
if (protoProps) defineProperties(Constructor.prototype, protoProps);
if (staticProps) defineProperties(Constructor, staticProps);
return Constructor;
};
}();
var draw = function () {
function draw() {
classCallCheck(this, draw);
this._data = null;
this._svg = null;
this._col_size = 1;
this._row_size = 1;
this._cols = 1;
this._rows = 1;
this._init = false;
this._mode = 'geo';
this._rPath = d3.line();
this._path = d3.geoPath();
this._config = {
width: null,
height: null,
padding: 20,
key: null,
projection: d3.geoMercator(),
grid: null,
duration: 500
};
}
createClass(draw, [{
key: "update",
value: function update() {
var _this2 = this;
if (this._data !== null && this._config.width !== null && this._config.height !== null) {
(function () {
var init_zoom = 200;
_this2._config.projection
//ML: Overrule autocenter
//.center(d3.geoCentroid(_this2._data))
.center([20,50])
.scale(init_zoom)
.translate([_this2._config.width / 2, _this2._config.height / 2]);
console.log(d3.geoCentroid(_this2._data));
_this2._path.projection(_this2._config.projection);
//Calculate optimal zoom
var bounds = _this2._path.bounds(_this2._data),
dx = bounds[1][0] - bounds[0][0],
dy = bounds[1][1] - bounds[0][1],
scale = Math.max(1, 0.9 / Math.max(dx / (_this2._config.width - 2 * _this2._config.padding), dy / (_this2._config.height - 2 * _this2._config.padding)));
//ML: overrule autocalculated scale (Russia is too big)
//_this2._config.projection.scale(scale * init_zoom);
_this2._config.projection.scale(600);
console.log(scale*init_zoom);
_this2._data.features.forEach(function (f) {
f.geometry.qcoordinates.forEach(function (d) {
var pc = _this2._config.projection(d.c);
d["pc"] = pc;
});
});
var _this = _this2;
_this2._rPath.x(function (d) {
return (d.x - 0.5) * _this._col_size + d.pc[0];
}).y(function (d) {
return (d.y - 0.5) * _this._row_size + d.pc[1];
});
})();
}
this._init = true;
}
}, {
key: "draw",
value: function draw() {
var _this3 = this;
if (this._init) {
(function () {
var _this = _this3;
var tPath = _this3._svg.selectAll("path").data(_this3._data.features);
tPath.exit();
tPath.enter().append("path").attr('class', function (d) {
return 'id-' + _this.config.key(d);
});
_this3._svg.selectAll("path").transition().duration(_this3._config.duration).attr('transform', function (d) {
var tx = 0,
ty = 0;
if (_this.mode != 'geo') {
var g = _this.config.grid[_this.config.key(d)];
var pc = _this.config.projection(d.geometry.centroid);
tx = g.ox - pc[0];
ty = g.oy - pc[1];
}
return 'translate(' + tx + ',' + ty + ')';
}).attr('d', function (d, i) {
if (_this._mode === 'geo') {
return _this._path(d);
} else {
return _this._rPath(d.geometry.qcoordinates) + "Z";
}
});
})();
} else {
console.error('You must run update() first.');
}
}
}, {
key: "toggle",
value: function toggle() {
if (this._mode == 'geo') {
this._mode = 'rect';
} else {
this._mode = 'geo';
}
}
}, {
key: "data",
get: function get() {
return this._data;
},
set: function set(d) {
if (d) {
this._data = d;
this.update();
}
}
}, {
key: "mode",
get: function get() {
return this._mode;
},
set: function set(m) {
if (m) {
this._mode = m;
}
}
}, {
key: "svg",
get: function get() {
return this._svg;
},
set: function set(s) {
if (s) {
this._svg = s;
this.update();
}
}
}, {
key: "config",
get: function get() {
return this._config;
},
set: function set(c) {
if (c) {
for (var key in this._config) {
if (this._config[key] === null && !(key in c)) {
console.error('The config object must provide ' + key);
} else if (key in c) {
this._config[key] = c[key];
}
}
var _g = this._config.grid;
for (var _key in _g) {
if (_g[_key].x + 1 > this._cols) {
this._cols = _g[_key].x + 1;
}
if (_g[_key].y + 1 > this._rows) {
this._rows = _g[_key].y + 1;
}
}
this._col_size = (this._config.width - this._config.padding * 2) / this._rows;
this._row_size = (this._config.height - this._config.padding * 2) / this._cols;
if (this._col_size < this._row_size) {
this._row_size = this._col_size;
} else {
this._col_size = this._row_size;
}
for (var _g in this._config.grid) {
this._config.grid[_g]['ox'] = this._config.width / 2 - this._cols / 2 * this._col_size + this._config.grid[_g].x * this._col_size + this._col_size / 2;
this._config.grid[_g]['oy'] = this._config.height / 2 - this._rows / 2 * this._row_size + this._config.grid[_g].y * this._row_size + this._row_size / 2;
}
this.update();
}
}
}]);
return draw;
}();
exports.compute = compute;
exports.draw = draw;
Object.defineProperty(exports, '__esModule', { value: true });
}));
<!DOCTYPE html>
<html>
<meta charset="utf-8">
<style>
path {
fill: rgba(0,0,55,0.5);
stroke:rgba(255,255,255,1);
stroke-width: 2;
}
</style>
<head>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://npmcdn.com/@turf/turf/turf.min.js"></script>
<script src="geo2rect.js"></script>
</head>
<body>
<button id="toggle">Toggle map</button><br />
<script>
var config = {
width : 1000,
height : 700,
padding : 70,
projection : d3.geoMercator(),
duration : 2000,
key:function(d){return d.properties.ISO_A3; },
grid : {
ALB: { x: 5, y: 8 },
ARM: { x: 9, y: 6 },
AUS: { x: 9, y: 9 },
AUT: { x: 4, y: 5 },
AZE: { x: 9, y: 5 },
BEL: { x: 2, y: 3 },
BGR: { x: 7, y: 6 },
BIH: { x: 5, y: 6 },
BLR: { x: 6, y: 3 },
CHE: { x: 3, y: 4 },
CYP: { x: 8, y: 7 },
CZE: { x: 4, y: 4 },
DEU: { x: 4, y: 3 },
DNK: { x: 4, y: 2 },
ESP: { x: 1, y: 5 },
EST: { x: 6, y: 1 },
FIN: { x: 6, y: 0 },
FRA: { x: 1, y: 4 },
GBR: { x: 1, y: 2 },
GEO: { x: 8, y: 5 },
GRC: { x: 6, y: 8 },
HUN: { x: 5, y: 5 },
HRV: { x: 4, y: 6 },
IRL: { x: 0, y: 2 },
ISL: { x: 0, y: 0 },
ISR: { x: 8, y: 8 },
ITA: { x: 3, y: 5 },
KOS: { x: 6, y: 7 },
LTU: { x: 6, y: 2 },
LUX: { x: 2, y: 4 },
LVA: { x: 7, y: 2 },
MDA: { x: 7, y: 5 },
MKD: { x: 7, y: 7 },
MLT: { x: 1, y: 7 },
MNE: { x: 5, y: 7 },
NLD: { x: 3, y: 3 },
NOR: { x: 4, y: 0 },
POL: { x: 5, y: 3 },
PRT: { x: 0, y: 5 },
ROU: { x: 6, y: 5 },
RUS: { x: 7, y: 3 },
SMR: { x: 2, y: 6 },
SRB: { x: 6, y: 6 },
SVK: { x: 5, y: 4 },
SVN: { x: 3, y: 6 },
SWE: { x: 5, y: 0 },
UKR: { x: 6, y: 4 },
TUR: { x: 8, y: 6 }
}
};
var svg = d3.select('body')
.append('svg')
.attr('width',config.width)
.attr('height',config.height);
var g2r = new geo2rect.draw();
d3.json('eurovis-countries-simplified.geojson', function(err, data){
var geojson = geo2rect.compute(data);
g2r.config = config;
g2r.data = geojson;
g2r.svg = svg.append('g');
g2r.draw();
});
d3.select('#toggle').on('click', function(){
g2r.toggle();
g2r.draw();
});
</script>
</body>
</html>
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