CGAL 6.2 - Spatial Sorting

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SpatialSortingTraits_2 Concept Reference
Reference Manual » Concepts

## Definition

All 2D spatial sorting algorithms provided in CGAL are parameterized by a traits class `Traits`, which defines the primitives (objects and predicates) that the sorting algorithms use. `SpatialSortingTraits_2` defines the complete set of primitives required in these functions and functors.

Has models
  All models of the CGAL concept `Kernel`
  `CGAL::Spatial_sort_traits_adapter_2<Base_traits,PointPropertyMap>`

## Types
typedef unspecified_type | Point_2
| The point type on which the sorting algorithms operate.
typedef unspecified_type | Compute_x_2
| Functor object type returning the \( x\) coordinate of a `Point_2`.
typedef unspecified_type | Compute_y_2
| Functor object type returning the \( y\) coordinate of a `Point_2`.
typedef unspecified_type | Less_x_2
| Binary predicate object type comparing `Point_2`s along the \( x\) coordinate.
typedef unspecified_type | Less_y_2
| Binary predicate object type comparing `Point_2`s along the \( y\) coordinate.

## Creation
Only a copy constructor is required.
| SpatialSortingTraits_2 (const SpatialSortingTraits_2 &t)

## Operations
The following member functions to create instances of the above predicate object types must exist.
Compute_x_2 | compute_x_2_object ()
Compute_y_2 | compute_y_2_object ()
Less_x_2 | less_x_2_object ()
Less_y_2 | less_y_2_object ()

## Member Typedef Documentation

## ◆ Compute_x_2

typedef unspecified_type SpatialSortingTraits_2::Compute_x_2

Functor object type returning the \( x\) coordinate of a `Point_2`.

Must provide `FT operator()(Point_2 p)` where `FT` can be used as argument of `CGAL::to_double`.

## ◆ Compute_y_2

typedef unspecified_type SpatialSortingTraits_2::Compute_y_2

Functor object type returning the \( y\) coordinate of a `Point_2`.

Must provide `FT operator()(Point_2 p)` where `FT` can be used as argument of `CGAL::to_double`.

## ◆ Less_x_2

typedef unspecified_type SpatialSortingTraits_2::Less_x_2

Binary predicate object type comparing `Point_2`s along the \( x\) coordinate.

Must provide `bool operator()(Point_2 p, Point_2 q)` where `true` is returned iff \( p_x < q_x\), where \( p_x\) and \( q_x\) denote \( x\) coordinate of point \( p\) and \( q\), respectively.

## ◆ Less_y_2

typedef unspecified_type SpatialSortingTraits_2::Less_y_2

Binary predicate object type comparing `Point_2`s along the \( y\) coordinate.

Must provide `bool operator()(Point_2 p, Point_2 q)` where `true` is returned iff \( p_y < q_y\), where \( p_y\) and \( q_y\) denote \( y\) coordinate of point \( p\) and \( q\), respectively.