3DLDF currently includes the following classes representing plane
geometric figures: Polygon, Reg_Cl_Plane_Curve
("Regular Closed Plane Curve"), Reg_Polygon ("Regular
Polygon"), Rectangle, Ellipse and
Circle. Polygon and Reg_Cl_Plane_Curve are derived
from Path, Reg_Polygon and Rectangle are derived
from Polygon, and Ellipse and Circle are derived
from Reg_Cl_Plane_Curve. Polygon and
Reg_Cl_Plane_Curve are meant to be used as base classes only, so
objects of these types should normally never be declared.
Since Reg_Polygon, Rectangle, Ellipse, and
Circle all ultimately derive from Path, they are really
just special kinds of Path.
In particular, they inherit their drawing and filling functions from
Path, and their transformation functions take the same arguments
as the Path versions.
They also have constructors
and setting functions that work in a similar way, with a few minor
differences, to account for their different natures.
See Polygon Reference, Rectangle Reference,
Ellipse Reference, and Circle Reference, for complete
information on these classes.