geoCentroid function Spherical math

List<double> geoCentroid(Map object)

Returns the spherical centroid of the specified GeoJSON object.

This is the spherical equivalent of GeoPath.centroid.

Implementation

List<double> geoCentroid(Map object) {
  _w0 = _w1 = _x0 = _y0 = _z0 = _x1 = _y1 = _z1 = 0;
  _x2 = Adder();
  _y2 = Adder();
  _z2 = Adder();
  _centroidStream(object);

  var x = _x2.valueOf(),
      y = _y2.valueOf(),
      z = _z2.valueOf(),
      m = hypot([x, y, z]);

  // If the area-weighted ccentroid is undefined,
  // fall back to length-weighted ccentroid.
  if (m < epsilon2) {
    x = _x1;
    y = _y1;
    z = _z1;
    // If the feature has zero length,
    // fall back to arithmetic mean of point vectors.
    if (_w1 < epsilon) {
      x = _x0;
      y = _y0;
      z = _z0;
    }
    m = hypot([x, y, z]);
    // If the feature still has an undefined ccentroid, then return.
    if (m < epsilon2) return [double.nan, double.nan];
  }

  return [atan2(y, x) * degrees, asin(z / m) * degrees];
}