js 大地坐标转经纬度

// 坐标系的转换

var pi_180 = Math.PI / 180;
var _180_pi = 180 / Math.PI;

var projectionTypes = {};
projectionTypes.bj54 = {
  a: 6378245,//长半轴
  e2: 0.006693421622966//第一偏心率平方
};
projectionTypes.wgs84 = {
  a: 6378137,//长半轴
  e2: 0.00669437999013//第一偏心率平方
};

module.exports = {
  // 7坐标系统转换方法
  // sourceType:源投影类型 targetType：目标投影类型 params： 7参数 blh：源大地坐标
  coordinateTransfUse7params(sourceType, targetType, params, blh) {
    sourceType = sourceType.toLowerCase();
    targetType = targetType.toLowerCase();
    var XYZ1 = _BLH2XYZ(sourceType, blh);
    var XYZ2 = _transXYZBy7params(XYZ1, params);
    var blh2 = _XYZ2BLH(targetType, XYZ2);
    console.log(blh2);
  },

  _BLH2XYZ(projectionType, blhObj) { //将大地坐标喜欢换为空间直角坐标系
    var e2 = projectionTypes[projectionType].e2; //第一偏心率平方值
    var a = projectionTypes[projectionType].a; //长半轴
    var N = a / Math.sqrt(1 - e2 * Math.sin(blhObj.b * pi_180) * Math.sin(blhObj.b * pi_180));
    var X = (N + blhObj.h) * Math.cos(blhObj.b * pi_180) * Math.cos(blhObj.l * pi_180);
    var Y = (N + blhObj.h) * Math.cos(blhObj.b * pi_180) * Math.sin(blhObj.l * pi_180);
    var Z = [N * (1 - e2) + blhObj.h] * Math.sin(blhObj.b * pi_180);
    var resultObj = {};
    resultObj.X = X;
    resultObj.Y = Y;
    resultObj.Z = Z;
    return resultObj;
  },

  _transXYZBy7params(xyz0, params) { //根据7参数对空间直角坐标系进行运算
    var x0 = xyz0.X;
    var y0 = xyz0.Y;
    var z0 = xyz0.Z;
    var dx = params.dx;
    var dy = params.dy;
    var dz = params.dz;
    var rx = params.rx;
    var ry = params.ry;
    var rz = params.rz;
    var m = params.m;
    var x1 = dx + (1 + m) * x0 + Math.sin(rz / 60 / 60 * pi_180) * y0 - Math.sin(ry / 60 / 60 * pi_180) * z0;
    var y1 = dy + (1 + m) * y0 - Math.sin(rz / 60 / 60 * pi_180) * x0 + Math.sin(rx / 60 / 60 * pi_180) * z0;
    var z1 = dz + (1 + m) * z0 + Math.sin(ry / 60 / 60 * pi_180) * x0 - Math.sin(rx / 60 / 60 * pi_180) * y0;
    var resultObj = {};
    resultObj.X = x1;
    resultObj.Y = y1;
    resultObj.Z = z1;
    return resultObj;
  },

  _XYZ2BLH(projectionType, xyz1) { 
    var a = projectionTypes[projectionType].a;
    var e2 = projectionTypes[projectionType].e2; //第一偏心率平方值 bj54

    // console.log('哈哈哈哈1-----',xyz1.X,'----', xyz1.Y, '----', xyz1.Z);

    var X = xyz1.X;
    var Y = xyz1.Y;
    var Z = xyz1.Z;

    var L
    if(X >= 0){
      L = Math.atan(Y/X) * _180_pi;
    } else {
      L = Math.atan(Y/X) * _180_pi;
      if(L >= 0){
        L = L - 180;
      } else {
        L = L + 180; 
      }
    }    

    // console.log('哈哈哈哈2-----', L);

    var B = Math.atan(Z / Math.sqrt(X * X + Y * Y));
    while (true) { //迭代计算
      var N = a / Math.sqrt(1 - e2 * Math.sin(B) * Math.sin(B));
      var tempB = Math.atan((N * e2 * Math.sin(B) + Z) / Math.sqrt(X * X + Y * Y));
      B = Math.atan((Z + N * e2 * Math.sin(tempB)) / Math.sqrt(X * X + Y * Y));
      if (tempB == B) {        
        break;
      }
    }
    var H = Z / Math.sin(B) - N * (1 - e2);
    B = B * _180_pi;
    var resultObj = {};
    resultObj.L = L;
    resultObj.B = B;
    resultObj.H = H;
    // if (resultObj.B < 0) {
    //   resultObj.B = resultObj.B + 180;
    // }
    // if (resultObj.L < 0) {
    //   resultObj.L = resultObj.L + 180;
    // }
    // console.log('哈哈哈哈3-----',resultObj.L,'----', resultObj.B)
    return resultObj;
  }
}