The struct Plane is defined in planes.web.
Planes are not Shapes. They are used for
performing vector operations. A Plane is defined by a
Point representing a point on the plane, a Point
representing the normal to the plane, and the distance of the plane from
the origin.
The most common use of Planes is to represent the
plane in which an existing plane figure lies. Therefore, they
most likely to be created by using Path::get_plane().
See Path Reference; Querying. However, class
Plane does have constructors for creating Planes directly, if
desired.
See Planes Reference; Constructors.