29 lines
1.0 KiB
JavaScript
29 lines
1.0 KiB
JavaScript
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import {geoProjection as projection} from "d3-geo";
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import {abs, epsilon} from "./math";
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export function naturalEarthRaw(lambda, phi) {
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var phi2 = phi * phi, phi4 = phi2 * phi2;
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return [
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lambda * (0.8707 - 0.131979 * phi2 + phi4 * (-0.013791 + phi4 * (0.003971 * phi2 - 0.001529 * phi4))),
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phi * (1.007226 + phi2 * (0.015085 + phi4 * (-0.044475 + 0.028874 * phi2 - 0.005916 * phi4)))
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];
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}
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naturalEarthRaw.invert = function(x, y) {
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var phi = y, i = 25, delta;
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do {
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var phi2 = phi * phi, phi4 = phi2 * phi2;
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phi -= delta = (phi * (1.007226 + phi2 * (0.015085 + phi4 * (-0.044475 + 0.028874 * phi2 - 0.005916 * phi4))) - y) /
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(1.007226 + phi2 * (0.015085 * 3 + phi4 * (-0.044475 * 7 + 0.028874 * 9 * phi2 - 0.005916 * 11 * phi4)));
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} while (abs(delta) > epsilon && --i > 0);
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return [
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x / (0.8707 + (phi2 = phi * phi) * (-0.131979 + phi2 * (-0.013791 + phi2 * phi2 * phi2 * (0.003971 - 0.001529 * phi2)))),
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phi
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];
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};
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export default function() {
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return projection(naturalEarthRaw)
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.scale(175.295);
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}
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