CGAL::Orthtree_traits_base< GeomTraits, dim > Struct Template Reference

#include <CGAL/Orthtree_traits_base.h>

Inherited by CGAL::Orthtree_traits_point< GeomTraits, PointRange, PointMap, hypercubic_nodes, dimension >, and CGAL::Orthtree_traits_polygons< GeomTraits >.

Definition

template<typename GeomTraits, int dim>
struct CGAL::Orthtree_traits_base< GeomTraits, dim >

The class Orthtree_traits_base is a base class providing common choices for types and functors.

The base class is extended by CGAL::Orthtree_traits_point<GeomTraits, PointRange, PointMap, dimension> and by CGAL::Orthtree_traits_face_graph<PolygonMesh, VertexPointMap>.

Template Parameters

GeomTraits	a model of Kernel.
dim	dimension of the ambient Euclidean space.

See also

CGAL::Orthtree_traits_point<GeomTraits, PointRange, PointMap, dim>

CGAL::Orthtree_traits_face_graph<PolygonMesh, VertexPointMap>

Types
using	Adjacency = int
	Adjacency type.

Member Typedef Documentation

Adjacency

template<typename GeomTraits , int dim>

using CGAL::Orthtree_traits_base< GeomTraits, dim >::Adjacency = int

Adjacency type.

Note

This type is used to identify adjacency directions with easily understandable keywords (left, right, up, down, ...) and is thus mainly useful in 2D and 3D. In higher dimensions, such keywords do not exist and this type is simply an integer. Conversions from this integer to bitsets still work but do not provide any user-friendly API for adjacency selection.

Two directions along each axis in Cartesian space, relative to a node.

Directions are mapped to numbers as 3-bit integers in the 3D case or as 2-bit integers in the 2D case. In the 3d case the numbers 6 and 7 are not used because there are only 6 different directions.

The first two bits indicate the axis (00 = x, 01 = y, 10 = z), the third bit indicates the direction along that axis (0 = -, 1 = +).

The following diagram and table showing the 3D case may be a useful reference (2D case is identical with one dimension less):

       3 *
         |  * 4
         | /                  y+
         |/                   *
0 *------+------* 1           |
        /|                    |
       / |                    +-----* x+
    5 *  |                   /
         * 2                /
                           * z+

This lookup table may also be helpful:

Direction	bitset	number	Enum
-x	000	0	LEFT
+x	001	1	RIGHT
-y	010	2	DOWN
+y	011	3	UP
-z	100	4	BACK
+z	101	5	FRONT