GeoJsonのデータをgl.linesで使えるjsonファイルに書き出し

geo-json-to-line.ts

import fs from 'fs';
import jsonfile from 'jsonfile';
import { IGeoJson } from './geo-json';
const eartDataUrl ='earth-line.json';

fs.readFile('./json/ne_110m_land.json', 'utf-8', (err, data) => {
	const geoData = JSON.parse(data) as IGeoJson;
	const pointData = [];
	const indices = [];
	const vertices = [];
	let cnt = 0;
	for (const feature of geoData.features) {
		if (cnt > 0) {
			// break;
		}
		for (const coordiantes of feature.geometry.coordinates) {
			const pointArr = [];
			for (const coordinate of coordiantes) {
				const vec3 = lonLatToVec3(coordinate[0], coordinate[1]);
				pointArr.push(vec3);
			}
			pointData.push(pointArr);
		}
		cnt = cnt + 1;
	}

	let startCnt = 0;
	for (const pointArr of pointData) {
		const pointSize = pointArr.length;

		for (const point of pointArr) {
			vertices.push(point[0], point[1], point[2]);
		}

		for (let ii = 0; ii < pointSize; ii = ii + 1) {
			const index0 = startCnt + ii;
			const index1 = startCnt + ((ii + 1) % pointSize);
			indices.push(index0, index1);
		}

		startCnt = startCnt + pointArr.length;
	}

	const polygonData = { vertices: vertices, indices: indices };

	jsonfile.writeFile(eartDataUrl, polygonData, () => {});
});

function lonLatToVec3(_lng: number, _lat: number) {
	const lng = (_lng / 180) * Math.PI;
	const lat = Math.PI / 2 - (_lat / 180) * Math.PI;

	const x = Math.sin(lat) * Math.sin(lng);
	const y = Math.cos(lat);
	const z = Math.sin(lat) * Math.cos(lng);

	return [parseFloat(x.toFixed(3)), parseFloat(y.toFixed(3)), parseFloat(z.toFixed(3))];
}