How can I get the LatLon coordinates by tap on earth?

[take2make]

I tried to get coordinates by using the following code:

 void _handleTap(TapUpDetails details) {
    final Vector3 focalCoord = canvasPointToVector3(_lastFocalPoint);
    final Vector3 tapCoord = canvasPointToVector3(details.localPosition);
    Quaternion q = quaternionFromTwoVectors(focalCoord, tapCoord);
    if (_lastQuaternion != null) {
      final _quaternion =
          _lastQuaternion! * q * Quaternion.axisAngle(Vector3(0, 0, 1), 0.0);
      print("ON HANDLE TAP = ${quaternionToLatLon(_quaternion)}");
    }
  }

But it seems that the coordinate calculates from the previous rotation. Do you have any idea or suggestions how can I achieve coordinates on the earth?

[take2make]

I found the solution:

 void _handleTap(TapUpDetails details) async {
    final Vector3 focalCoord =
        canvasPointToVector3(Offset(width / 2, height / 2));
    final Vector3 tapCoord = canvasPointToVector3(details.localPosition);
    Quaternion q = quaternionFromTwoVectors(focalCoord, tapCoord);
    q *= Quaternion.axisAngle(Vector3(0, 0, 1.0), 0.0);
    if (_lastQuaternion != null) {
      final _quaternion = _lastQuaternion! * q;
      print("ON HANDLE TAP = ${quaternionToLatLon(_quaternion)}");
    }
  }