forked from ppfun/pixelplanet
61 lines
1.6 KiB
JavaScript
61 lines
1.6 KiB
JavaScript
/*
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* @flow
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* Convert a list of countrycodes to latlong -> canvas coordinates
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*/
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import fs from 'fs';
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import countryCodeLatLong from './countrycode-latlong-array.json';
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const CANVAS_SIZE = 256 * 256;
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const CANVAS_MIN_XY = -(CANVAS_SIZE / 2);
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/*
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* Converts lat/long to canvas coordinates
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* NOTE: our projection if off by the factor 265/256 in Y direction from common other
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* common map projections
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* parses geo coords (lat/long) to canvas coordinates
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* @param coords lat / long
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* @return canvas coords x / y
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*/
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function latlong2Coords(coords) {
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const [ lat, lng ] = coords;
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const x = Math.floor(CANVAS_SIZE * ((lng + 180) / 360)) + CANVAS_MIN_XY;
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const y = (Math.floor((1-Math.log(Math.tan(lat*Math.PI/180) + 1/Math.cos(lat*Math.PI/180))/Math.PI)/2 * CANVAS_SIZE) + CANVAS_MIN_XY) * 265/256;
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return [x, y];
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}
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/*
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* gets canvas coords to country
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* @param countryCode ISO two letter country code
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* @return canvas coords x / y
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*/
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export function country2Coords(countryCode) {
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try {
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const coords = countryCodeLatLong[countryCode].map(z => parseFloat(z));
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return latlong2Coords(coords)
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}
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catch(err) {
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console.log(`Country ${countryCode} not found.`);
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return [0, 0];
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}
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}
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/*
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* creates json file with country code to canvas coords
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* @param countryLatLang array with country codes to lat long
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* @param filename Output filename
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*/
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function createCoordsJson(filename) {
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let output = {};
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for (var cc in countryCodeLatLong) {
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output[cc] = country2Coords(cc);
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}
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fs.writeFile(filename, JSON.stringify(output), 'utf8', (a) => {});
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}
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createCoordsJson('countrycode-coords-array.json');
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