@orca-fe/x-map/esm/utils/math.js

export const getCPoints = (p1, p2, alpha) => {
    const [x1, y1] = p1;
    const [x2, y2] = p2;
    const centerX = (x1 + x2) / 2;
    const centerY = (y1 + y2) / 2;
    const distance = Math.sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
    const a = distance / alpha;
    const atan = Math.atan((y2 - y1) / (x2 - x1));
    let deg = 0.5;
    if (x2 - x1 < 0)
        deg = 1.5;
    return {
        radii: a,
        distance,
        center: [centerX, centerY],
        cp: [centerX + a * Math.cos(Math.PI * deg + atan), centerY + a * Math.sin(Math.PI * deg + atan)],
    };
};
export const calcQuadBezierCurve = (a, c, b, d) => {
    const e = 1 - d;
    return e * e * a + 2 * e * d * c + d * d * b;
};
/**
 * 计算曲线某一刻坐标位置
 * @param p1 起始点
 * @param p2 中间点
 * @param p3 结束点
 * @param alpha 百分比
 * @returns {{x, y: *}}
 */
export const calcQuadBezierCurvePoint = (p1, p2, p3, alpha) => [
    calcQuadBezierCurve(p1[0], p2[0], p3[0], alpha),
    calcQuadBezierCurve(p1[1], p2[1], p3[1], alpha),
];
export const calcBezierCPHeight = (minHeight, maxHeight, num, allowNegative) => {
    /* 需要生成高度位置的数量 */
    const n = allowNegative ? (num + 1) / 2 : num;
    const res = [];
    const min = Math.min(minHeight, maxHeight);
    const step = (Math.max(minHeight, maxHeight) - min) / (n + 1);
    for (let i = 1; i <= num; i += 1) {
        res.push(min + step * i);
        if (allowNegative)
            res.push((min + step * i) * -1);
    }
    return res;
};
/**
 * caculate the great circle distance
 * 计算地球面上两个点之间的距离
 */
export const getGreatCircleDistance = (p1, p2) => {
    const [lng1, lat1] = p1;
    const [lng2, lat2] = p2;
    const EARTH_RADIUS = 6378137.0; // 单位M
    function getRad(d) {
        return (d * Math.PI) / 180.0;
    }
    const radLat1 = getRad(lat1);
    const radLat2 = getRad(lat2);
    const a = radLat1 - radLat2;
    const b = getRad(lng1) - getRad(lng2);
    let s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2) + Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(b / 2), 2)));
    s *= EARTH_RADIUS;
    s = Math.round(s * 10000) / 10000.0;
    return s;
};