/// <summary>
/// Calculate the position of a geographical position for the current state of the globe.
/// </summary>
Point3D IPositionProvider.ProjectPosition(GeoPosition geoPos)
{
Point3D p = geoPos.ToSphere(_radius * 1.02)
.Transform(_rotation);
Double z = p.Z;
p = p.Transform(_projection);
return(new Point3D(p.X, p.Y, z > _clipZ ? 1 : -1));
}