jasondavies/README.md

## README.md

      
    Raw
  

              README.md
            
          
    Interrupted projections using the geo.projection D3 plugin.

  
## index.html
<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  height: 500px;
  position: relative;
  width: 960px;
  font-family: sans-serif;
}

#projection-menu {
  position: absolute;
  right: 10px;
  top: 10px;
}

#gores {
  position: absolute;
  left: 10px;
  top: 10px;
}

.background {
  fill: #a4bac7;
}

.foreground {
  fill: none;
  stroke: #333;
  stroke-width: 1.5px;
}

.graticule {
  fill: none;
  stroke: #fff;
  stroke-width: .5px;
}

.graticule:nth-child(2n) {
  stroke-dasharray: 2,2;
}

.land {
  fill: #d7c7ad;
  stroke: #766951;
}

.boundary {
  fill: none;
  stroke: #a5967e;
}

</style>
<body>
<select id="projection-menu"></select>
<input type="range" id="gores" step="1" min="1" max="12" value="3">
<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="https://raw.github.com/d3/d3-plugins/master/geo/projection/projection.js"></script>
<script>

var π = Math.PI;

var width = 960,
    height = 500;

var projection;

var interrupt, x = [], y;

var path = d3.geo.path();

function goreProjection() {
  return d3.geo.projection(function(λ, φ) {
    var coordinates = [λ *= 180 / π, φ *= 180 / π];
    for (var i = 1; i < x.length; i++) {
      if (λ < x[i] + 1e-6) {
        coordinates = projection([λ - (x[i - 1] + x[i]) / 2, φ]);
        coordinates[0] += (y[i - 1][0] + y[i][0]) / 2;
        coordinates[1] = -coordinates[1];
        break;
      }
    }
    return coordinates;
  }).scale(1).precision(0);
}

var graticule = d3.geo.graticule();

function lobes(n) {
  var dλ = (180 - -180) / n;
  return {
    type: "Polygon",
    coordinates: [hemilobes(n, -180, 180, 0, 90).concat(hemilobes(n, 180, -180, 0, -90))].map(resample),
    properties: {interruptions: d3.range(-180, 180 + dλ / 2, dλ)}
  };
}

function hemilobes(n, λ0, λ1, φ0, φ1) {
  var d = [],
      dλ = (λ1 - λ0) / n,
      δ = dλ / 1e6;
  λ0 += δ;
  for (var i = 0; i < n; i++) {
    d.push([λ0, φ0], [λ0, φ1], [λ0 += dλ - 2 * δ, φ1], [λ0, φ0]);
    λ0 += 2 * δ;
  }
  return d;
}

function resample(coordinates) {
  var n = coordinates.length;
  if (!n) return coordinates;
  var samples = 50,
      a = coordinates[0],
      b,
      resampled = [];
  for (var i = 0; ++i < n;) {
    b = coordinates[i];
    dx = (b[0] - a[0]) / samples;
    dy = (b[1] - a[1]) / samples;
    resampled.push(a);
    for (var j = 1; j < samples; j++) {
      resampled.push([dx ? a[0] + j * dx : a[0], dy ? a[1] + j * dy : a[1]]);
    }
    a = b;
  }
  if (b) resampled.push(b);
  return resampled;
}

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);

var clipPath = svg.append("defs").append("clipPath")
    .attr("id", "clip").append("path");

var background = svg.append("path")
    .attr("class", "background");

var graticules = svg.selectAll(".graticule")
    .data(graticule.lines)
  .enter().append("path")
    .attr("class", "graticule");

var foreground = svg.append("path")
    .attr("class", "foreground");

d3.select("#gores")
    .on("change", function() {
      gores();
      svg.selectAll("path").attr("d", path);
    });

function gores() {
  var n = +d3.select("#gores").property("value");
  d3.select("#gores-output").property("value", n);
  interrupt = lobes(n);
  x = interrupt.properties.interruptions;
  y = x.map(function(x) { return projection([x, 0]); });
  path.projection(goreProjection());

  clipPath.datum(interrupt);
  background.datum(interrupt);
  foreground.datum(interrupt);
}

d3.json("/d/3682676/readme-boundaries.json", function(err, collection) {
  svg.insert("g", ".graticule")
      .attr("class", "boundary")
      .attr("clip-path", "url(#clip)")
    .selectAll("path")
      .data(collection.geometries)
    .enter().append("path")
      .attr("d", path);
});

d3.json("/d/3682676/readme-land.json", function(err, collection) {
  svg.insert("g", ".graticule,.boundary")
      .attr("class", "land")
      .attr("clip-path", "url(#clip)")
    .selectAll("path")
      .data(collection.geometries)
    .enter().append("path")
      .attr("d", path);
});

var options = [
  {name: "Aitoff", projection: d3.geo.aitoff()},
//  {name: "Albers", projection: d3.geo.albers().scale(145).parallels([20, 50]).origin([0, 0]).translate([width * .500, height * .750])},
//  {name: "Bonne", projection: d3.geo.bonne().scale(120).translate([width * .500, height * .425])},
//  {name: "Collignon", projection: d3.geo.collignon().scale(93)},
  {name: "Eckert I", projection: d3.geo.eckert1().scale(165)},
  {name: "Eckert II", projection: d3.geo.eckert2().scale(165)},
  {name: "Eckert III", projection: d3.geo.eckert3().scale(180)},
  {name: "Eckert IV", projection: d3.geo.eckert4().scale(180)},
  {name: "Eckert V", projection: d3.geo.eckert5().scale(170)},
  {name: "Eckert VI", projection: d3.geo.eckert6().scale(170)},
//  {name: "Equirectangular (Plate Carrée)", projection: d3.geo.equirectangular().scale(950)},
//  {name: "Hammer", projection: d3.geo.hammer().scale(165)},
  {name: "Goode Homolosine", projection: d3.geo.homolosine()},
  {name: "Kavrayskiy VII", projection: d3.geo.kavrayskiy7()},
//  {name: "Lambert cylindrical equal-area", projection: d3.geo.cylindricalEqualArea()},
  {name: "Larrivée", projection: d3.geo.larrivee().scale(95)},
//  {name: "Mercator", projection: d3.geo.mercator().scale(490)},
//  {name: "Miller", projection: d3.geo.miller().scale(100)},
  {name: "Mollweide", projection: d3.geo.mollweide().scale(165)},
  {name: "Nell–Hammer", projection: d3.geo.nellHammer()},
  {name: "Polyconic", projection: d3.geo.polyconic().scale(100)},
  {name: "Robinson", projection: d3.geo.robinson()},
  {name: "Sinusoidal", projection: d3.geo.sinusoidal()},
  {name: "van der Grinten", projection: d3.geo.vanDerGrinten().scale(75)},
  {name: "Wagner VI", projection: d3.geo.wagner6()},
  {name: "Winkel Tripel", projection: d3.geo.winkel3()}
];

var interval = setInterval(loop, 1500),
    i = 0,
    n = options.length - 1;

var menu = d3.select("#projection-menu")
    .on("change", change);

menu.selectAll("option")
    .data(options)
  .enter().append("option")
    .text(function(d) { return d.name; });

function loop() {
  var j = Math.floor(Math.random() * n);
  menu.property("selectedIndex", i = j + (j >= i));
  update(options[i]);
}

function change() {
  clearInterval(interval);
  update(options[this.selectedIndex]);
}

function update(option) {
  projection = option.projection;
  gores();
  svg.selectAll("path").transition()
      .duration(750)
      .attr("d", path);
}

loop();

</script>
	<!DOCTYPE html>
	<meta charset="utf-8">
	<style>

	body {
	height: 500px;
	position: relative;
	width: 960px;
	font-family: sans-serif;
	}

	#projection-menu {
	position: absolute;
	right: 10px;
	top: 10px;
	}

	#gores {
	position: absolute;
	left: 10px;
	top: 10px;
	}

	.background {
	fill: #a4bac7;
	}

	.foreground {
	fill: none;
	stroke: #333;
	stroke-width: 1.5px;
	}

	.graticule {
	fill: none;
	stroke: #fff;
	stroke-width: .5px;
	}

	.graticule:nth-child(2n) {
	stroke-dasharray: 2,2;
	}

	.land {
	fill: #d7c7ad;
	stroke: #766951;
	}

	.boundary {
	fill: none;
	stroke: #a5967e;
	}

	</style>
	<body>
	<select id="projection-menu"></select>
	<input type="range" id="gores" step="1" min="1" max="12" value="3">
	<script src="http://d3js.org/d3.v3.min.js"></script>
	<script src="https://raw.github.com/d3/d3-plugins/master/geo/projection/projection.js"></script>
	<script>

	var π = Math.PI;

	var width = 960,
	height = 500;

	var projection;

	var interrupt, x = [], y;

	var path = d3.geo.path();

	function goreProjection() {
	return d3.geo.projection(function(λ, φ) {
	var coordinates = [λ = 180 / π, φ = 180 / π];
	for (var i = 1; i < x.length; i++) {
	if (λ < x[i] + 1e-6) {
	coordinates = projection([λ - (x[i - 1] + x[i]) / 2, φ]);
	coordinates[0] += (y[i - 1][0] + y[i][0]) / 2;
	coordinates[1] = -coordinates[1];
	break;
	}
	}
	return coordinates;
	}).scale(1).precision(0);
	}

	var graticule = d3.geo.graticule();

	function lobes(n) {
	var dλ = (180 - -180) / n;
	return {
	type: "Polygon",
	coordinates: [hemilobes(n, -180, 180, 0, 90).concat(hemilobes(n, 180, -180, 0, -90))].map(resample),
	properties: {interruptions: d3.range(-180, 180 + dλ / 2, dλ)}
	};
	}

	function hemilobes(n, λ0, λ1, φ0, φ1) {
	var d = [],
	dλ = (λ1 - λ0) / n,
	δ = dλ / 1e6;
	λ0 += δ;
	for (var i = 0; i < n; i++) {
	d.push([λ0, φ0], [λ0, φ1], [λ0 += dλ - 2 * δ, φ1], [λ0, φ0]);
	λ0 += 2 * δ;
	}
	return d;
	}

	function resample(coordinates) {
	var n = coordinates.length;
	if (!n) return coordinates;
	var samples = 50,
	a = coordinates[0],
	b,
	resampled = [];
	for (var i = 0; ++i < n;) {
	b = coordinates[i];
	dx = (b[0] - a[0]) / samples;
	dy = (b[1] - a[1]) / samples;
	resampled.push(a);
	for (var j = 1; j < samples; j++) {
	resampled.push([dx ? a[0] + j * dx : a[0], dy ? a[1] + j * dy : a[1]]);
	}
	a = b;
	}
	if (b) resampled.push(b);
	return resampled;
	}

	var svg = d3.select("body").append("svg")
	.attr("width", width)
	.attr("height", height);

	var clipPath = svg.append("defs").append("clipPath")
	.attr("id", "clip").append("path");

	var background = svg.append("path")
	.attr("class", "background");

	var graticules = svg.selectAll(".graticule")
	.data(graticule.lines)
	.enter().append("path")
	.attr("class", "graticule");

	var foreground = svg.append("path")
	.attr("class", "foreground");

	d3.select("#gores")
	.on("change", function() {
	gores();
	svg.selectAll("path").attr("d", path);
	});

	function gores() {
	var n = +d3.select("#gores").property("value");
	d3.select("#gores-output").property("value", n);
	interrupt = lobes(n);
	x = interrupt.properties.interruptions;
	y = x.map(function(x) { return projection([x, 0]); });
	path.projection(goreProjection());

	clipPath.datum(interrupt);
	background.datum(interrupt);
	foreground.datum(interrupt);
	}

	d3.json("/d/3682676/readme-boundaries.json", function(err, collection) {
	svg.insert("g", ".graticule")
	.attr("class", "boundary")
	.attr("clip-path", "url(#clip)")
	.selectAll("path")
	.data(collection.geometries)
	.enter().append("path")
	.attr("d", path);
	});

	d3.json("/d/3682676/readme-land.json", function(err, collection) {
	svg.insert("g", ".graticule,.boundary")
	.attr("class", "land")
	.attr("clip-path", "url(#clip)")
	.selectAll("path")
	.data(collection.geometries)
	.enter().append("path")
	.attr("d", path);
	});

	var options = [
	{name: "Aitoff", projection: d3.geo.aitoff()},
	// {name: "Albers", projection: d3.geo.albers().scale(145).parallels([20, 50]).origin([0, 0]).translate([width * .500, height * .750])},
	// {name: "Bonne", projection: d3.geo.bonne().scale(120).translate([width * .500, height * .425])},
	// {name: "Collignon", projection: d3.geo.collignon().scale(93)},
	{name: "Eckert I", projection: d3.geo.eckert1().scale(165)},
	{name: "Eckert II", projection: d3.geo.eckert2().scale(165)},
	{name: "Eckert III", projection: d3.geo.eckert3().scale(180)},
	{name: "Eckert IV", projection: d3.geo.eckert4().scale(180)},
	{name: "Eckert V", projection: d3.geo.eckert5().scale(170)},
	{name: "Eckert VI", projection: d3.geo.eckert6().scale(170)},
	// {name: "Equirectangular (Plate Carrée)", projection: d3.geo.equirectangular().scale(950)},
	// {name: "Hammer", projection: d3.geo.hammer().scale(165)},
	{name: "Goode Homolosine", projection: d3.geo.homolosine()},
	{name: "Kavrayskiy VII", projection: d3.geo.kavrayskiy7()},
	// {name: "Lambert cylindrical equal-area", projection: d3.geo.cylindricalEqualArea()},
	{name: "Larrivée", projection: d3.geo.larrivee().scale(95)},
	// {name: "Mercator", projection: d3.geo.mercator().scale(490)},
	// {name: "Miller", projection: d3.geo.miller().scale(100)},
	{name: "Mollweide", projection: d3.geo.mollweide().scale(165)},
	{name: "Nell–Hammer", projection: d3.geo.nellHammer()},
	{name: "Polyconic", projection: d3.geo.polyconic().scale(100)},
	{name: "Robinson", projection: d3.geo.robinson()},
	{name: "Sinusoidal", projection: d3.geo.sinusoidal()},
	{name: "van der Grinten", projection: d3.geo.vanDerGrinten().scale(75)},
	{name: "Wagner VI", projection: d3.geo.wagner6()},
	{name: "Winkel Tripel", projection: d3.geo.winkel3()}
	];

	var interval = setInterval(loop, 1500),
	i = 0,
	n = options.length - 1;

	var menu = d3.select("#projection-menu")
	.on("change", change);

	menu.selectAll("option")
	.data(options)
	.enter().append("option")
	.text(function(d) { return d.name; });

	function loop() {
	var j = Math.floor(Math.random() * n);
	menu.property("selectedIndex", i = j + (j >= i));
	update(options[i]);
	}

	function change() {
	clearInterval(interval);
	update(options[this.selectedIndex]);
	}

	function update(option) {
	projection = option.projection;
	gores();
	svg.selectAll("path").transition()
	.duration(750)
	.attr("d", path);
	}

	loop();

	</script>