CGAL 4.12 - Spatial Sorting
SpatialSortingTraits_2 Concept Reference

## 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:

Any CGAL 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. More...

typedef unspecified_type Compute_y_2
Functor object type returning the $$y$$ coordinate of a Point_2. More...

typedef unspecified_type Less_x_2
Binary predicate object type comparing Point_2s along the $$x$$ coordinate. More...

typedef unspecified_type Less_y_2
Binary predicate object type comparing Point_2s along the $$y$$ coordinate. More...

## 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 ()

## ◆ 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

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

Binary predicate object type comparing Point_2s 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

Binary predicate object type comparing Point_2s 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.