code: function polar(lat, lng, _vector) {
      const
          vector = typeof _vector !== "undefined" ? _vector : new Float32Array(3),
          radius = Math.cos(lat),
          z = Math.sin(lat),
          x = radius * Math.cos(lng),
          y = radius * Math.sin(lng);
  
      vector[0] = x;
      vector[1] = y;
      vector[2] = z;
  
      return vector;
  }
docs: Imagine the earth oriented with the Z axis from south top north.
  This function will return a normalized vector from the center of the earth
  to the point located by (lat, lng).
  
  @param {float} lat - Latitude in range [-PI/2, +PI/2].
  @param {float} lng - Longitude in range [0, 2*PI].
  @param {Float32Array} _vector - The vector where to store the result.
  If missing, a new one will be created.
  
  @return {Float32Array} The resulting 3D vector.