## PolyhedronTraits_3

Required types and member functions for the PolyhedronTraits_3 concept. This geometric traits concept is used in the polyhedral surface data structure CGAL::Polyhedron_3<Traits>. This concept is a subset of the 3d kernel traits and any CGAL kernel model can be used directly as template argument.

### Refines

CopyConstructable, Assignable.

### Types

PolyhedronTraits_3::Point_3
| point type.
PolyhedronTraits_3::Plane_3
| plane equation. Even if plane equations are not supported with a particular polyhedral surface this type has to be defined (some dummy type).
PolyhedronTraits_3::Construct_opposite_plane_3
| is an unary function object that reverses the plane orientation. Must provide Plane_3 operator()(Plane_3 plane) that returns the reversed plane. Required only if plane equations are supported and the inside_out() method is used to reverse the polyhedral surface orientation.

### Creation

PolyhedronTraits_3 traits ( traits2);
| copy constructor.

PolyhedronTraits_3&
| traits = traits2 | assignment.

### Operations

Construct_opposite_plane_3
| traits.construct_opposite_plane_3_object ()
|  | returns an instance of this function object.

### Has Models

CGAL::Polyhedron_traits_3<Kernel>
CGAL::Polyhedron_traits_with_normals_3<Kernel>
All models of the CGAL::Kernel concept, e.g., Simple_cartesian<FieldNumberType>.

### See Also

CGAL::Polyhedron_3<Traits>