870 строки
23 KiB
JavaScript
870 строки
23 KiB
JavaScript
(function(){d3.geo = {};
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var d3_geo_radians = Math.PI / 180;
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// TODO clip input coordinates on opposite hemisphere
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d3.geo.azimuthal = function() {
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var mode = "orthographic", // or stereographic, gnomonic, equidistant or equalarea
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origin,
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scale = 200,
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translate = [480, 250],
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x0,
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y0,
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cy0,
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sy0;
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function azimuthal(coordinates) {
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var x1 = coordinates[0] * d3_geo_radians - x0,
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y1 = coordinates[1] * d3_geo_radians,
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cx1 = Math.cos(x1),
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sx1 = Math.sin(x1),
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cy1 = Math.cos(y1),
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sy1 = Math.sin(y1),
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cc = mode !== "orthographic" ? sy0 * sy1 + cy0 * cy1 * cx1 : null,
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c,
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k = mode === "stereographic" ? 1 / (1 + cc)
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: mode === "gnomonic" ? 1 / cc
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: mode === "equidistant" ? (c = Math.acos(cc), c ? c / Math.sin(c) : 0)
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: mode === "equalarea" ? Math.sqrt(2 / (1 + cc))
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: 1,
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x = k * cy1 * sx1,
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y = k * (sy0 * cy1 * cx1 - cy0 * sy1);
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return [
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scale * x + translate[0],
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scale * y + translate[1]
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];
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}
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azimuthal.invert = function(coordinates) {
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var x = (coordinates[0] - translate[0]) / scale,
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y = (coordinates[1] - translate[1]) / scale,
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p = Math.sqrt(x * x + y * y),
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c = mode === "stereographic" ? 2 * Math.atan(p)
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: mode === "gnomonic" ? Math.atan(p)
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: mode === "equidistant" ? p
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: mode === "equalarea" ? 2 * Math.asin(.5 * p)
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: Math.asin(p),
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sc = Math.sin(c),
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cc = Math.cos(c);
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return [
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(x0 + Math.atan2(x * sc, p * cy0 * cc + y * sy0 * sc)) / d3_geo_radians,
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Math.asin(cc * sy0 - (p ? (y * sc * cy0) / p : 0)) / d3_geo_radians
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];
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};
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azimuthal.mode = function(x) {
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if (!arguments.length) return mode;
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mode = x + "";
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return azimuthal;
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};
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azimuthal.origin = function(x) {
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if (!arguments.length) return origin;
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origin = x;
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x0 = origin[0] * d3_geo_radians;
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y0 = origin[1] * d3_geo_radians;
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cy0 = Math.cos(y0);
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sy0 = Math.sin(y0);
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return azimuthal;
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};
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azimuthal.scale = function(x) {
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if (!arguments.length) return scale;
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scale = +x;
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return azimuthal;
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};
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azimuthal.translate = function(x) {
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if (!arguments.length) return translate;
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translate = [+x[0], +x[1]];
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return azimuthal;
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};
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return azimuthal.origin([0, 0]);
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};
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// Derived from Tom Carden's Albers implementation for Protovis.
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// http://gist.github.com/476238
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// http://mathworld.wolfram.com/AlbersEqual-AreaConicProjection.html
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d3.geo.albers = function() {
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var origin = [-98, 38],
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parallels = [29.5, 45.5],
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scale = 1000,
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translate = [480, 250],
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lng0, // d3_geo_radians * origin[0]
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n,
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C,
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p0;
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function albers(coordinates) {
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var t = n * (d3_geo_radians * coordinates[0] - lng0),
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p = Math.sqrt(C - 2 * n * Math.sin(d3_geo_radians * coordinates[1])) / n;
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return [
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scale * p * Math.sin(t) + translate[0],
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scale * (p * Math.cos(t) - p0) + translate[1]
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];
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}
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albers.invert = function(coordinates) {
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var x = (coordinates[0] - translate[0]) / scale,
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y = (coordinates[1] - translate[1]) / scale,
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p0y = p0 + y,
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t = Math.atan2(x, p0y),
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p = Math.sqrt(x * x + p0y * p0y);
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return [
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(lng0 + t / n) / d3_geo_radians,
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Math.asin((C - p * p * n * n) / (2 * n)) / d3_geo_radians
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];
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};
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function reload() {
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var phi1 = d3_geo_radians * parallels[0],
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phi2 = d3_geo_radians * parallels[1],
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lat0 = d3_geo_radians * origin[1],
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s = Math.sin(phi1),
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c = Math.cos(phi1);
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lng0 = d3_geo_radians * origin[0];
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n = .5 * (s + Math.sin(phi2));
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C = c * c + 2 * n * s;
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p0 = Math.sqrt(C - 2 * n * Math.sin(lat0)) / n;
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return albers;
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}
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albers.origin = function(x) {
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if (!arguments.length) return origin;
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origin = [+x[0], +x[1]];
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return reload();
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};
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albers.parallels = function(x) {
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if (!arguments.length) return parallels;
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parallels = [+x[0], +x[1]];
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return reload();
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};
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albers.scale = function(x) {
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if (!arguments.length) return scale;
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scale = +x;
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return albers;
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};
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albers.translate = function(x) {
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if (!arguments.length) return translate;
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translate = [+x[0], +x[1]];
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return albers;
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};
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return reload();
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};
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// A composite projection for the United States, 960x500. The set of standard
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// parallels for each region comes from USGS, which is published here:
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// http://egsc.usgs.gov/isb/pubs/MapProjections/projections.html#albers
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// TODO allow the composite projection to be rescaled?
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d3.geo.albersUsa = function() {
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var lower48 = d3.geo.albers();
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var alaska = d3.geo.albers()
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.origin([-160, 60])
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.parallels([55, 65]);
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var hawaii = d3.geo.albers()
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.origin([-160, 20])
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.parallels([8, 18]);
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var puertoRico = d3.geo.albers()
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.origin([-60, 10])
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.parallels([8, 18]);
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function albersUsa(coordinates) {
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var lon = coordinates[0],
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lat = coordinates[1];
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return (lat > 50 ? alaska
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: lon < -140 ? hawaii
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: lat < 21 ? puertoRico
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: lower48)(coordinates);
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}
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albersUsa.scale = function(x) {
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if (!arguments.length) return lower48.scale();
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lower48.scale(x);
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alaska.scale(x * .6);
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hawaii.scale(x);
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puertoRico.scale(x * 1.5);
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return albersUsa.translate(lower48.translate());
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};
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albersUsa.translate = function(x) {
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if (!arguments.length) return lower48.translate();
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var dz = lower48.scale() / 1000,
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dx = x[0],
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dy = x[1];
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lower48.translate(x);
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alaska.translate([dx - 400 * dz, dy + 170 * dz]);
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hawaii.translate([dx - 190 * dz, dy + 200 * dz]);
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puertoRico.translate([dx + 580 * dz, dy + 430 * dz]);
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return albersUsa;
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};
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return albersUsa.scale(lower48.scale());
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};
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d3.geo.equirectangular = function() {
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var scale = 500,
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translate = [480, 250];
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function equirectangular(coordinates) {
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var x = coordinates[0] / 360,
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y = -coordinates[1] / 360;
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return [
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scale * x + translate[0],
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scale * y + translate[1]
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];
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}
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equirectangular.invert = function(coordinates) {
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var x = (coordinates[0] - translate[0]) / scale,
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y = (coordinates[1] - translate[1]) / scale;
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return [
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360 * x,
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-360 * y
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];
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};
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equirectangular.scale = function(x) {
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if (!arguments.length) return scale;
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scale = +x;
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return equirectangular;
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};
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equirectangular.translate = function(x) {
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if (!arguments.length) return translate;
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translate = [+x[0], +x[1]];
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return equirectangular;
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};
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return equirectangular;
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};
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d3.geo.mercator = function() {
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var scale = 500,
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translate = [480, 250];
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function mercator(coordinates) {
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var x = coordinates[0] / 360,
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y = -(Math.log(Math.tan(Math.PI / 4 + coordinates[1] * d3_geo_radians / 2)) / d3_geo_radians) / 360;
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return [
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scale * x + translate[0],
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scale * Math.max(-.5, Math.min(.5, y)) + translate[1]
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];
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}
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mercator.invert = function(coordinates) {
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var x = (coordinates[0] - translate[0]) / scale,
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y = (coordinates[1] - translate[1]) / scale;
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return [
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360 * x,
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2 * Math.atan(Math.exp(-360 * y * d3_geo_radians)) / d3_geo_radians - 90
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];
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};
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mercator.scale = function(x) {
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if (!arguments.length) return scale;
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scale = +x;
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return mercator;
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};
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mercator.translate = function(x) {
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if (!arguments.length) return translate;
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translate = [+x[0], +x[1]];
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return mercator;
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};
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return mercator;
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};
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function d3_geo_type(types, defaultValue) {
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return function(object) {
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return object && object.type in types ? types[object.type](object) : defaultValue;
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};
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}
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/**
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* Returns a function that, given a GeoJSON object (e.g., a feature), returns
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* the corresponding SVG path. The function can be customized by overriding the
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* projection. Point features are mapped to circles with a default radius of
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* 4.5px; the radius can be specified either as a constant or a function that
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* is evaluated per object.
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*/
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d3.geo.path = function() {
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var pointRadius = 4.5,
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pointCircle = d3_path_circle(pointRadius),
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projection = d3.geo.albersUsa();
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function path(d, i) {
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if (typeof pointRadius === "function") {
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pointCircle = d3_path_circle(pointRadius.apply(this, arguments));
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}
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return pathType(d) || null;
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}
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function project(coordinates) {
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return projection(coordinates).join(",");
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}
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var pathType = d3_geo_type({
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FeatureCollection: function(o) {
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var path = [],
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features = o.features,
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i = -1, // features.index
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n = features.length;
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while (++i < n) path.push(pathType(features[i].geometry));
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return path.join("");
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},
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Feature: function(o) {
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return pathType(o.geometry);
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},
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Point: function(o) {
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return "M" + project(o.coordinates) + pointCircle;
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},
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MultiPoint: function(o) {
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var path = [],
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coordinates = o.coordinates,
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i = -1, // coordinates.index
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n = coordinates.length;
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while (++i < n) path.push("M", project(coordinates[i]), pointCircle);
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return path.join("");
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},
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LineString: function(o) {
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var path = ["M"],
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coordinates = o.coordinates,
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i = -1, // coordinates.index
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n = coordinates.length;
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while (++i < n) path.push(project(coordinates[i]), "L");
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path.pop();
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return path.join("");
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},
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MultiLineString: function(o) {
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var path = [],
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coordinates = o.coordinates,
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i = -1, // coordinates.index
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n = coordinates.length,
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subcoordinates, // coordinates[i]
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j, // subcoordinates.index
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m; // subcoordinates.length
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while (++i < n) {
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subcoordinates = coordinates[i];
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j = -1;
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m = subcoordinates.length;
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path.push("M");
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while (++j < m) path.push(project(subcoordinates[j]), "L");
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path.pop();
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}
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return path.join("");
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},
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Polygon: function(o) {
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var path = [],
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coordinates = o.coordinates,
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i = -1, // coordinates.index
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n = coordinates.length,
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subcoordinates, // coordinates[i]
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j, // subcoordinates.index
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m; // subcoordinates.length
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while (++i < n) {
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subcoordinates = coordinates[i];
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j = -1;
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if ((m = subcoordinates.length - 1) > 0) {
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path.push("M");
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while (++j < m) path.push(project(subcoordinates[j]), "L");
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path[path.length - 1] = "Z";
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}
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}
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return path.join("");
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},
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MultiPolygon: function(o) {
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var path = [],
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coordinates = o.coordinates,
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i = -1, // coordinates index
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n = coordinates.length,
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subcoordinates, // coordinates[i]
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j, // subcoordinates index
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m, // subcoordinates.length
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subsubcoordinates, // subcoordinates[j]
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k, // subsubcoordinates index
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p; // subsubcoordinates.length
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while (++i < n) {
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subcoordinates = coordinates[i];
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j = -1;
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m = subcoordinates.length;
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while (++j < m) {
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subsubcoordinates = subcoordinates[j];
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k = -1;
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if ((p = subsubcoordinates.length - 1) > 0) {
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path.push("M");
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while (++k < p) path.push(project(subsubcoordinates[k]), "L");
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path[path.length - 1] = "Z";
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}
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}
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}
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return path.join("");
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},
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GeometryCollection: function(o) {
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var path = [],
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geometries = o.geometries,
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i = -1, // geometries index
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n = geometries.length;
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while (++i < n) path.push(pathType(geometries[i]));
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return path.join("");
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}
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});
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var areaType = path.area = d3_geo_type({
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FeatureCollection: function(o) {
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var area = 0,
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features = o.features,
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i = -1, // features.index
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n = features.length;
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while (++i < n) area += areaType(features[i]);
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return area;
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},
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Feature: function(o) {
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return areaType(o.geometry);
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},
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Polygon: function(o) {
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return polygonArea(o.coordinates);
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},
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MultiPolygon: function(o) {
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var sum = 0,
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coordinates = o.coordinates,
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i = -1, // coordinates index
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n = coordinates.length;
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while (++i < n) sum += polygonArea(coordinates[i]);
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return sum;
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},
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GeometryCollection: function(o) {
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var sum = 0,
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geometries = o.geometries,
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i = -1, // geometries index
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n = geometries.length;
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while (++i < n) sum += areaType(geometries[i]);
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return sum;
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}
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}, 0);
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function polygonArea(coordinates) {
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var sum = area(coordinates[0]), // exterior ring
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i = 0, // coordinates.index
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n = coordinates.length;
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while (++i < n) sum -= area(coordinates[i]); // holes
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return sum;
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}
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function polygonCentroid(coordinates) {
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var polygon = d3.geom.polygon(coordinates[0].map(projection)), // exterior ring
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centroid = polygon.centroid(1),
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x = centroid[0],
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y = centroid[1],
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z = Math.abs(polygon.area()),
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i = 0, // coordinates index
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n = coordinates.length;
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while (++i < n) {
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polygon = d3.geom.polygon(coordinates[i].map(projection)); // holes
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centroid = polygon.centroid(1);
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x -= centroid[0];
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y -= centroid[1];
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z -= Math.abs(polygon.area());
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}
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return [x, y, 6 * z]; // weighted centroid
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}
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var centroidType = path.centroid = d3_geo_type({
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// TODO FeatureCollection
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// TODO Point
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// TODO MultiPoint
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// TODO LineString
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// TODO MultiLineString
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// TODO GeometryCollection
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Feature: function(o) {
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return centroidType(o.geometry);
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},
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Polygon: function(o) {
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var centroid = polygonCentroid(o.coordinates);
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return [centroid[0] / centroid[2], centroid[1] / centroid[2]];
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},
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MultiPolygon: function(o) {
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var area = 0,
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coordinates = o.coordinates,
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centroid,
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x = 0,
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y = 0,
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z = 0,
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i = -1, // coordinates index
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n = coordinates.length;
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while (++i < n) {
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centroid = polygonCentroid(coordinates[i]);
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x += centroid[0];
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y += centroid[1];
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z += centroid[2];
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}
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return [x / z, y / z];
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}
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});
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function area(coordinates) {
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return Math.abs(d3.geom.polygon(coordinates.map(projection)).area());
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}
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|
path.projection = function(x) {
|
|
projection = x;
|
|
return path;
|
|
};
|
|
|
|
path.pointRadius = function(x) {
|
|
if (typeof x === "function") pointRadius = x;
|
|
else {
|
|
pointRadius = +x;
|
|
pointCircle = d3_path_circle(pointRadius);
|
|
}
|
|
return path;
|
|
};
|
|
|
|
return path;
|
|
};
|
|
|
|
function d3_path_circle(radius) {
|
|
return "m0," + radius
|
|
+ "a" + radius + "," + radius + " 0 1,1 0," + (-2 * radius)
|
|
+ "a" + radius + "," + radius + " 0 1,1 0," + (+2 * radius)
|
|
+ "z";
|
|
}
|
|
/**
|
|
* Given a GeoJSON object, returns the corresponding bounding box. The bounding
|
|
* box is represented by a two-dimensional array: [[left, bottom], [right,
|
|
* top]], where left is the minimum longitude, bottom is the minimum latitude,
|
|
* right is maximum longitude, and top is the maximum latitude.
|
|
*/
|
|
d3.geo.bounds = function(feature) {
|
|
var left = Infinity,
|
|
bottom = Infinity,
|
|
right = -Infinity,
|
|
top = -Infinity;
|
|
d3_geo_bounds(feature, function(x, y) {
|
|
if (x < left) left = x;
|
|
if (x > right) right = x;
|
|
if (y < bottom) bottom = y;
|
|
if (y > top) top = y;
|
|
});
|
|
return [[left, bottom], [right, top]];
|
|
};
|
|
|
|
function d3_geo_bounds(o, f) {
|
|
if (o.type in d3_geo_boundsTypes) d3_geo_boundsTypes[o.type](o, f);
|
|
}
|
|
|
|
var d3_geo_boundsTypes = {
|
|
Feature: d3_geo_boundsFeature,
|
|
FeatureCollection: d3_geo_boundsFeatureCollection,
|
|
LineString: d3_geo_boundsLineString,
|
|
MultiLineString: d3_geo_boundsMultiLineString,
|
|
MultiPoint: d3_geo_boundsLineString,
|
|
MultiPolygon: d3_geo_boundsMultiPolygon,
|
|
Point: d3_geo_boundsPoint,
|
|
Polygon: d3_geo_boundsPolygon
|
|
};
|
|
|
|
function d3_geo_boundsFeature(o, f) {
|
|
d3_geo_bounds(o.geometry, f);
|
|
}
|
|
|
|
function d3_geo_boundsFeatureCollection(o, f) {
|
|
for (var a = o.features, i = 0, n = a.length; i < n; i++) {
|
|
d3_geo_bounds(a[i].geometry, f);
|
|
}
|
|
}
|
|
|
|
function d3_geo_boundsLineString(o, f) {
|
|
for (var a = o.coordinates, i = 0, n = a.length; i < n; i++) {
|
|
f.apply(null, a[i]);
|
|
}
|
|
}
|
|
|
|
function d3_geo_boundsMultiLineString(o, f) {
|
|
for (var a = o.coordinates, i = 0, n = a.length; i < n; i++) {
|
|
for (var b = a[i], j = 0, m = b.length; j < m; j++) {
|
|
f.apply(null, b[j]);
|
|
}
|
|
}
|
|
}
|
|
|
|
function d3_geo_boundsMultiPolygon(o, f) {
|
|
for (var a = o.coordinates, i = 0, n = a.length; i < n; i++) {
|
|
for (var b = a[i][0], j = 0, m = b.length; j < m; j++) {
|
|
f.apply(null, b[j]);
|
|
}
|
|
}
|
|
}
|
|
|
|
function d3_geo_boundsPoint(o, f) {
|
|
f.apply(null, o.coordinates);
|
|
}
|
|
|
|
function d3_geo_boundsPolygon(o, f) {
|
|
for (var a = o.coordinates[0], i = 0, n = a.length; i < n; i++) {
|
|
f.apply(null, a[i]);
|
|
}
|
|
}
|
|
// TODO breakAtDateLine?
|
|
// TODO use 90 degrees rather than 89 degrees
|
|
|
|
d3.geo.circle = function() {
|
|
var origin = [0, 0],
|
|
degrees = 89,
|
|
radians = degrees * d3_geo_radians,
|
|
arc = d3.geo.greatArc().target(Object);
|
|
|
|
function circle() {
|
|
// TODO
|
|
// var o = typeof origin === "function" ? origin.apply(this, arguments) : origin;
|
|
// return d3_geo_greatCircleArc({
|
|
// source: [o[0] - 180, o[1] - degrees],
|
|
// target: [o[0] + 180, o[1] - degrees]
|
|
// });
|
|
}
|
|
|
|
// TODO
|
|
//
|
|
// function visible(point) {
|
|
// return arc.distance(point) < radians;
|
|
// }
|
|
|
|
circle.clip = function(d) {
|
|
arc.source(typeof origin === "function" ? origin.apply(this, arguments) : origin);
|
|
return clipType(d);
|
|
};
|
|
|
|
var clipType = d3_geo_type({
|
|
|
|
FeatureCollection: function(o) {
|
|
var features = o.features.map(clipType).filter(Object);
|
|
return features && (o = Object.create(o), o.features = features, o);
|
|
},
|
|
|
|
Feature: function(o) {
|
|
var geometry = clipType(o.geometry);
|
|
return geometry && (o = Object.create(o), o.geometry = geometry, o);
|
|
},
|
|
|
|
// TODO
|
|
//
|
|
// Point: function(o) {
|
|
// return visible(o.coordinates) && o;
|
|
// },
|
|
//
|
|
// MultiPoint: function(o) {
|
|
// var coordinates = o.coordinates.filter(visible);
|
|
// return coordinates.length && {
|
|
// type: o.type,
|
|
// coordinates: coordinates
|
|
// };
|
|
// },
|
|
|
|
LineString: function(o) {
|
|
var coordinates = clip(o.coordinates);
|
|
return coordinates.length && (o = Object.create(o), o.coordinates = coordinates, o);
|
|
},
|
|
|
|
MultiLineString: function(o) {
|
|
var coordinates = o.coordinates.map(clip).filter(function(d) { return d.length; });
|
|
return coordinates.length && (o = Object.create(o), o.coordinates = coordinates, o);
|
|
},
|
|
|
|
Polygon: function(o) {
|
|
var coordinates = o.coordinates.map(clip);
|
|
return coordinates[0].length && (o = Object.create(o), o.coordinates = coordinates, o);
|
|
},
|
|
|
|
MultiPolygon: function(o) {
|
|
var coordinates = o.coordinates.map(function(d) { return d.map(clip); }).filter(function(d) { return d[0].length; });
|
|
return coordinates.length && (o = Object.create(o), o.coordinates = coordinates, o);
|
|
},
|
|
|
|
GeometryCollection: function(o) {
|
|
var geometries = o.geometries.map(clipType).filter(Object);
|
|
return geometries.length && (o = Object.create(o), o.geometries = geometries, o);
|
|
}
|
|
|
|
});
|
|
|
|
function clip(coordinates) {
|
|
var i = -1,
|
|
n = coordinates.length,
|
|
clipped = [],
|
|
p0,
|
|
p1,
|
|
p2,
|
|
d0,
|
|
d1;
|
|
|
|
while (++i < n) {
|
|
d1 = arc.distance(p2 = coordinates[i]);
|
|
if (d1 < radians) {
|
|
if (p1) clipped.push(d3_geo_greatArcInterpolate(p1, p2)((d0 - radians) / (d0 - d1)));
|
|
clipped.push(p2);
|
|
p0 = p1 = null;
|
|
} else {
|
|
p1 = p2;
|
|
if (!p0 && clipped.length) {
|
|
clipped.push(d3_geo_greatArcInterpolate(clipped[clipped.length - 1], p1)((radians - d0) / (d1 - d0)));
|
|
p0 = p1;
|
|
}
|
|
}
|
|
d0 = d1;
|
|
}
|
|
|
|
if (p1 && clipped.length) {
|
|
d1 = arc.distance(p2 = clipped[0]);
|
|
clipped.push(d3_geo_greatArcInterpolate(p1, p2)((d0 - radians) / (d0 - d1)));
|
|
}
|
|
|
|
return resample(clipped);
|
|
}
|
|
|
|
// Resample coordinates, creating great arcs between each.
|
|
function resample(coordinates) {
|
|
var i = 0,
|
|
n = coordinates.length,
|
|
j,
|
|
m,
|
|
resampled = n ? [coordinates[0]] : coordinates,
|
|
resamples,
|
|
origin = arc.source();
|
|
|
|
while (++i < n) {
|
|
resamples = arc.source(coordinates[i - 1])(coordinates[i]).coordinates;
|
|
for (j = 0, m = resamples.length; ++j < m;) resampled.push(resamples[j]);
|
|
}
|
|
|
|
arc.source(origin);
|
|
return resampled;
|
|
}
|
|
|
|
circle.origin = function(x) {
|
|
if (!arguments.length) return origin;
|
|
origin = x;
|
|
return circle;
|
|
};
|
|
|
|
circle.angle = function(x) {
|
|
if (!arguments.length) return degrees;
|
|
degrees = +x;
|
|
return circle;
|
|
};
|
|
|
|
// Precision is specified in degrees.
|
|
circle.precision = function(x) {
|
|
if (!arguments.length) return arc.precision();
|
|
arc.precision(x);
|
|
return circle;
|
|
};
|
|
|
|
return circle;
|
|
}
|
|
d3.geo.greatArc = function() {
|
|
var source = d3_geo_greatArcSource,
|
|
target = d3_geo_greatArcTarget,
|
|
precision = 6 * d3_geo_radians;
|
|
|
|
function greatArc() {
|
|
var a = typeof source === "function" ? source.apply(this, arguments) : source,
|
|
b = typeof target === "function" ? target.apply(this, arguments) : target,
|
|
i = d3_geo_greatArcInterpolate(a, b),
|
|
dt = precision / i.d,
|
|
t = 0,
|
|
coordinates = [a];
|
|
while ((t += dt) < 1) coordinates.push(i(t));
|
|
coordinates.push(b);
|
|
return {
|
|
type: "LineString",
|
|
coordinates: coordinates
|
|
};
|
|
}
|
|
|
|
// Length returned in radians; multiply by radius for distance.
|
|
greatArc.distance = function() {
|
|
var a = typeof source === "function" ? source.apply(this, arguments) : source,
|
|
b = typeof target === "function" ? target.apply(this, arguments) : target;
|
|
return d3_geo_greatArcInterpolate(a, b).d;
|
|
};
|
|
|
|
greatArc.source = function(x) {
|
|
if (!arguments.length) return source;
|
|
source = x;
|
|
return greatArc;
|
|
};
|
|
|
|
greatArc.target = function(x) {
|
|
if (!arguments.length) return target;
|
|
target = x;
|
|
return greatArc;
|
|
};
|
|
|
|
// Precision is specified in degrees.
|
|
greatArc.precision = function(x) {
|
|
if (!arguments.length) return precision / d3_geo_radians;
|
|
precision = x * d3_geo_radians;
|
|
return greatArc;
|
|
};
|
|
|
|
return greatArc;
|
|
};
|
|
|
|
function d3_geo_greatArcSource(d) {
|
|
return d.source;
|
|
}
|
|
|
|
function d3_geo_greatArcTarget(d) {
|
|
return d.target;
|
|
}
|
|
|
|
function d3_geo_greatArcInterpolate(a, b) {
|
|
var x0 = a[0] * d3_geo_radians, cx0 = Math.cos(x0), sx0 = Math.sin(x0),
|
|
y0 = a[1] * d3_geo_radians, cy0 = Math.cos(y0), sy0 = Math.sin(y0),
|
|
x1 = b[0] * d3_geo_radians, cx1 = Math.cos(x1), sx1 = Math.sin(x1),
|
|
y1 = b[1] * d3_geo_radians, cy1 = Math.cos(y1), sy1 = Math.sin(y1),
|
|
d = interpolate.d = Math.acos(Math.max(-1, Math.min(1, sy0 * sy1 + cy0 * cy1 * Math.cos(x1 - x0)))),
|
|
sd = Math.sin(d);
|
|
|
|
// From http://williams.best.vwh.net/avform.htm#Intermediate
|
|
function interpolate(t) {
|
|
var A = Math.sin(d - (t *= d)) / sd,
|
|
B = Math.sin(t) / sd,
|
|
x = A * cy0 * cx0 + B * cy1 * cx1,
|
|
y = A * cy0 * sx0 + B * cy1 * sx1,
|
|
z = A * sy0 + B * sy1;
|
|
return [
|
|
Math.atan2(y, x) / d3_geo_radians,
|
|
Math.atan2(z, Math.sqrt(x * x + y * y)) / d3_geo_radians
|
|
];
|
|
}
|
|
|
|
return interpolate;
|
|
}
|
|
d3.geo.greatCircle = d3.geo.circle;
|
|
})();
|