///<summary>
/// Returns whether this Geometry is greater than, equal to, or less than another Geometry. If their
/// classes are different, they are compared using the following ordering:
/// <list type="bullet">
/// <item><term>Point (lowest)</term></item>
/// <item><term>MultiPoint</term></item>
/// <item><term>LineString</term></item>
/// <item><term>LinearRing</term></item>
/// <item><term>MultiLineString</term></item>
/// <item><term>Polygon</term></item>
/// <item><term>MultiPolygon</term></item>
/// <item><term>GeometryCollection (highest)</term></item>
/// </list>
/// If the two Geometrys have the same class, their first elements are compared.
/// If those are the same, the second elements are compared, etc.
///</summary>
///<param name="obj">A Geometry with which to compare to this Geometry.</param>
///<returns>
/// Returns a positive number, 0, or a negative number, depending on whether this object
/// is greater than, equal to, or less than the other geometry.
///</returns>
public virtual int CompareTo(object obj)
{
Geometry geometry = obj as Geometry;
if ( geometry != null )
{
if ( GetClassSortIndex() != geometry.GetClassSortIndex() )
{
return GetClassSortIndex() - geometry.GetClassSortIndex();
}
if ( IsEmpty() && geometry.IsEmpty() )
{
return 0;
}
if ( IsEmpty() )
{
return -1;
}
if ( geometry.IsEmpty() )
{
return 1;
}
return CompareToSameClass( geometry );
}
else
{
throw new ArgumentException("object geometry is not of type Geometry");
}
}