\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)
CGAL 4.5.1 - 2D Regularized Boolean Set-Operations
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CGAL::General_polygon_set_2< Traits, Dcel > Class Template Reference

#include <CGAL/General_polygon_set_2.h>

Definition

An object of the General_polygon_set_2 class-template represents a point set in the plane bounded by \( x\) monotone curves.

Points in the set lie on the boundary or on the positive side of the curves. This class template provides methods to apply regularized Boolean set-operations and few other utility methods. An Arrangement_2 data structure is internally used to represent the point set. The arrangement is represented as a doubly-connected edge-list (Dcel).

The Traits template-parameter should be instantiated with a model of the concept GeneralPolygonSetTraits_2. The traits class defines the types of points, \( x\)-monotone curves, general polygons, and general polygons with holes, that is Traits::Point_2, Traits::X_monotone_curve_2, Traits::Polygon_2, and Traits::Polygon_with_holes_2, respectively. Traits::Point_2 must be the type of the endpoints of Traits::X_monotone_curve_2, and Traits::X_monotone_curve_2 must be the type of the curves that comprise the boundaries of the general polygons. The traits class supports geometric operations on the types above. We sometimes use the term polygon instead of general polygon for simplicity hereafter.

The template parameter Dcel should be instantiated with a model of the concept GeneralPolygonSetDcel. It is instantiated by default with the type Gps_default_dcel<Traits>. You can override this default, with a different Dcel class, typically an extension of the Gps_default_dcel class template. Overriding the default is necessary only if you intend to obtain the underlying internal arrangement and process it further.

The input and output of the Boolean set-operations methods consist of one or more general polygons, some of which may have holes. In particular, these methods operate on pairs of objects of type General_polygon_set_2, or directly on objects of type Traits::Polygon_2 or Traits::Polygon_with_holes_2. An object of type Traits::Polygon_2 is a valid operand, only if it is simple and its boundary is oriented counterclockwise. An object of type Traits::Polygon_with_holes_2 is valid, only if its outer boundary bounds a relatively simple general polygon oriented counterclockwise, and each one of its holes is a simple polygon oriented clockwise. The holes are pairwise disjoint, except perhaps at the vertices, and are contained in the polygon bounded by the outer boundary. The outer boundary and the holes are also pairwise disjoint, except perhaps at the vertices.

See Also
Arrangement_2
ArrangementXMonotoneTraits_2
Nef_polyhedron_2
Examples:
Boolean_set_operations_2/bezier_traits_adapter2.cpp, Boolean_set_operations_2/circle_segment.cpp, Boolean_set_operations_2/dxf_union.cpp, and Boolean_set_operations_2/set_union.cpp.

Types

typedef unspecified_type Traits_2
 the traits class in use.
 
typedef unspecified_type Polygon_2
 the general polygon type. More...
 
typedef unspecified_type Polygon_with_holes_2
 the general polygon with holes type. More...
 
typedef unspecified_type Size
 number of polygons with holes size type.
 
typedef unspecified_type Arrangement_2
 the arrangement type used internally.
 

Creation

 General_polygon_set_2 ()
 constructs an empty set of polygons gps represented by an empty arrangement.
 
 General_polygon_set_2 (const Self &other)
 copy constructor.
 
 General_polygon_set_2 (Traits &traits)
 constructs an empty set of polygons gps that uses the given traits instance for performing the geometric operations.
 
 General_polygon_set_2 (const Polygon_2 &pgn)
 constructs a set of polygons gps that consists of the single polygon pgn.
 
 General_polygon_set_2 (const Polygon_with_holes_2 &pgn_with_holes)
 constructs a set of polygons gps that consists of the single polygon with holes pgn_with_holes.
 

Access Functions

template<class OutputIterator >
OutputIterator polygons_with_holes (OutputIterator out)
 obtains the polygons with holes represented by gps.
 
Size number_of_polygons_with_holes () const
 returns the total number of general polygons represented by gps.
 
bool is_empty () const
 returns true if gps represents an empty set.
 
bool is_plane () const
 returns true if gps represents the entire plane.
 
Traits & traits () const
 obtains an instance of the traits. More...
 
const Arrangement_2arrangement () const
 obtains the arrangement data structure that internally represents the general-polygon set.
 

Modifiers

void clear ()
 clears gps.
 
void insert (Polygon_2 &pgn)
 inserts pgn into gps. More...
 
void insert (Polygon_with_holes_2 &pgn_with_holes)
 inserts pgn_with_holes into gps. More...
 
template<class InputIterator >
void insert (InputIterator begin, InputIterator end)
 inserts the range of polygons (or polygons with holes) into gps. More...
 
template<class InputIterator1 , class InputIterator2 >
void insert (InputIterator1 pgn_begin, InputIterator1 pgn_end, InputIterator2 pgn_with_holes_begin, InputIterator2 pgn_with_holes_end)
 inserts the two ranges of polygons and polygons with holes into gps. More...
 
void complement ()
 computes the complement of gps.
 
void complement (const Polygon_set_2 &other)
 computes the complement of other. More...
 

Univariate Operations

In the following univariate and bivariate methods the result is placed in gps after it is cleared.

void intersection (const General_polygon_set_2 &other)
 computes the intersection of gps and other.
 
void intersection (const Polygon_2 &pgn)
 computes the intersection of gps and pgn.
 
void intersection (const Polygon_with_holes_2 &pgn)
 computes the intersection of gps and pgn.
 
template<class InputIterator >
void intersection (InputIterator begin, InputIterator end)
 computes the intersection of a collection of point sets. More...
 
template<class InputIterator1 , class InputIterator2 >
void intersection (InputIterator1 pgn_begin, InputIterator1 pgn_end, InputIterator2 pgn_with_holes_begin, InputIterator2 pgn_with_holes_end)
 computes the intersection of a collection of point sets. More...
 
void join (const General_polygon_set_2 &other)
 computes the union of gps and other.
 
void join (const Polygon_2 &pgn)
 computes the union of gps and pgn.
 
void join (const Polygon_with_holes_2 &pgn)
 computes the union of gps and pgn.
 
template<class InputIterator >
void join (InputIterator begin, InputIterator end)
 computes the union of the polygons (or polygons with holes) in the given range and the point set represented by gps. More...
 
template<class InputIterator1 , class InputIterator2 >
void join (InputIterator1 pgn_begin, InputIterator1 pgn_end, InputIterator2 pgn_with_holes_begin, InputIterator2 pgn_with_holes_end)
 computes the union of the polygons and polygons with holes in the given two ranges and the point set represented by gps.
 
void difference (const General_polygon_set_2 &other)
 computes the difference between gps and other.
 
void difference (const Polygon_2 &pgn)
 computes the difference between gps and pgn.
 
void difference (const Polygon_with_holes_2 &pgn)
 computes the difference between gps and pgn.
 
void symmetric_difference (const General_polygon_set_2 &other)
 computes the symmetric difference between gps and other.
 
void symmetric_difference (const Polygon_2 &pgn)
 computes the symmetric difference between gps and pgn.
 
void symmetric_difference (const Polygon_with_holes_2 &pgn)
 computes the symmetric difference between gps and pgn.
 
template<class InputIterator >
void symmetric_difference (InputIterator begin, InputIterator end)
 computes the symmetric difference (xor) of a collection of point sets. More...
 
template<class InputIterator1 , class InputIterator2 >
void symmetric_difference (InputIterator1 pgn_begin, InputIterator1 pgn_end, InputIterator2 pgn_with_holes_begin, InputIterator2 pgn_with_holes_end)
 computes the symmetric difference (xor) of a collection of point sets. More...
 

Bivariate Operations

The following bivariate function replace gps with the result.

void intersection (const General_polygon_set_2 &gps1, const General_polygon_set_2 &gps2)
 computes the intersection of gps1 and gps2.
 
void join (const General_polygon_set_2 &gps1, const General_polygon_set_2 &gps2)
 computes the union of gps1 and gps2.
 
void difference (const General_polygon_set_2 &gps1, const General_polygon_set_2 &gps2)
 computes the difference between gps1 and gps2.
 
void symmetric_difference (const General_polygon_set_2 &gps1, const General_polygon_set_2 &gps2)
 computes the symmetric difference between gps1 and gps2.
 

Query Functions

bool do_intersect (const General_polygon_set_2 &other)
 returns true if gps and other intersect in their interior, and false otherwise.
 
bool do_intersect (const Polygon_2 &pgn)
 returns true if gps and pgn intersect in their interior, and false otherwise.
 
bool do_intersect (const Polygon_with_holes_2 &pgn)
 returns true if gps and pgn intersect in their interior, and false otherwise.
 
template<class InputIterator >
void do_intersect (InputIterator begin, InputIterator end)
 returns true if the interior of the point sets in a collection intersect, and false otherwise. More...
 
template<class InputIterator1 , class InputIterator2 >
void do_intersect (InputIterator1 pgn_begin, InputIterator1 pgn_end, InputIterator2 pgn_with_holes_begin, InputIterator2 pgn_with_holes_end)
 returns true if the interior of the point sets in a collection intersect, and false otherwise. More...
 
bool locate (const Point_2 &p, Polygon_with_holes_2 &pgn)
 obtains a polygon with holes that contains the query point p, if exists, through pgn, and returns true. More...
 
Oriented_side oriented_side (const Point_2 &q)
 returns either the constant ON_ORIENTED_BOUNDARY, ON_POSITIVE_SIDE, or ON_NEGATIVE_SIDE, iff p lies on the boundary, properly on the positive side, or properly on the negative side of gps respectively.
 
Oriented_side oriented_side (const General_polygon_set_2 &other)
 returns either the constant ON_NEGATIVE_SIDE, ON_ORIENTED_BOUNDARY, or ON_POSITIVE_SIDE, iff other and gps are completely disjoint, in contact, or intersect in their interior, respectively.
 
Oriented_side oriented_side (const Polygon_2 &pgn)
 returns either the constant ON_NEGATIVE_SIDE, ON_ORIENTED_BOUNDARY, or ON_POSITIVE_SIDE, iff pgn and gps are completely disjoint, in contact, or intersect in their interior, respectively.
 
Oriented_side oriented_side (const Polygon_with_holes_2 &pgn)
 returns either the constant ON_NEGATIVE_SIDE, ON_ORIENTED_BOUNDARY, or ON_POSITIVE_SIDE, iff pgn and gps are completely disjoint, in contact, or intersect in their interior, respectively.
 

Miscellaneous

bool is_valid () const
 returns true if gps represents a valid point set.
 

Member Typedef Documentation

template<typename Traits, typename Dcel>
typedef unspecified_type CGAL::General_polygon_set_2< Traits, Dcel >::Polygon_2

the general polygon type.

Must model the GpsTraitsGeneralPolygon_2 concept.

template<typename Traits, typename Dcel>
typedef unspecified_type CGAL::General_polygon_set_2< Traits, Dcel >::Polygon_with_holes_2

the general polygon with holes type.

Must model the GpsTraitsGeneralPolygonWithHoles_2 concept.

Member Function Documentation

template<typename Traits, typename Dcel>
void CGAL::General_polygon_set_2< Traits, Dcel >::complement ( const Polygon_set_2 other)

computes the complement of other.

gps is overridden by the result.

template<typename Traits, typename Dcel>
template<class InputIterator >
void CGAL::General_polygon_set_2< Traits, Dcel >::do_intersect ( InputIterator  begin,
InputIterator  end 
)

returns true if the interior of the point sets in a collection intersect, and false otherwise.

The collection consists of the polygons (or polygons with holes) in the given range and the point set represented by gps. (The value type of the input iterator is used to distinguish between the two options.)

template<typename Traits, typename Dcel>
template<class InputIterator1 , class InputIterator2 >
void CGAL::General_polygon_set_2< Traits, Dcel >::do_intersect ( InputIterator1  pgn_begin,
InputIterator1  pgn_end,
InputIterator2  pgn_with_holes_begin,
InputIterator2  pgn_with_holes_end 
)

returns true if the interior of the point sets in a collection intersect, and false otherwise.

The collection consists of the polygons and polygons with holes in the given two ranges and the point set represented by gps.

template<typename Traits, typename Dcel>
void CGAL::General_polygon_set_2< Traits, Dcel >::insert ( Polygon_2 pgn)

inserts pgn into gps.

Precondition
pgn and the point set represented by gps are disjoint. This precondition enables the use of very efficient insertion methods. Use the respective overloaded method that inserts a polygon of type Polygon_with_holes_2, if only a relaxed precondition can be guaranteed. If even the relaxed precondition cannot be guaranteed, use the join method.
template<typename Traits, typename Dcel>
void CGAL::General_polygon_set_2< Traits, Dcel >::insert ( Polygon_with_holes_2 pgn_with_holes)

inserts pgn_with_holes into gps.

Precondition
pgn_with_holes does not intersect with the point set represented by gps, except maybe at the vertices. If this relaxed precondition cannot be guaranteed, use the join method.
template<typename Traits, typename Dcel>
template<class InputIterator >
void CGAL::General_polygon_set_2< Traits, Dcel >::insert ( InputIterator  begin,
InputIterator  end 
)

inserts the range of polygons (or polygons with holes) into gps.

(The value type of the input iterator is used to distinguish between the two.)

Precondition
If the given range contains objects of type Polygon_with_holes_2, then these polygons and the point set represented by gps are pairwise disjoint, except maybe at the vertices. If the given range contains objects of type Polygon_2, then these polygons and the point set represented by gps are pairwise disjoint without any exceptions.
template<typename Traits, typename Dcel>
template<class InputIterator1 , class InputIterator2 >
void CGAL::General_polygon_set_2< Traits, Dcel >::insert ( InputIterator1  pgn_begin,
InputIterator1  pgn_end,
InputIterator2  pgn_with_holes_begin,
InputIterator2  pgn_with_holes_end 
)

inserts the two ranges of polygons and polygons with holes into gps.

Precondition
All polygons in the first range, all polygon with holes in the second range, and the point set represented by gps are pairwise disjoint, except maybe at the vertices
template<typename Traits, typename Dcel>
template<class InputIterator >
void CGAL::General_polygon_set_2< Traits, Dcel >::intersection ( InputIterator  begin,
InputIterator  end 
)

computes the intersection of a collection of point sets.

The collection consists of the polygons (or polygons with holes) in the given range and the point set represented by gps. (The value type of the input iterator is used to distinguish between the two options.)

template<typename Traits, typename Dcel>
template<class InputIterator1 , class InputIterator2 >
void CGAL::General_polygon_set_2< Traits, Dcel >::intersection ( InputIterator1  pgn_begin,
InputIterator1  pgn_end,
InputIterator2  pgn_with_holes_begin,
InputIterator2  pgn_with_holes_end 
)

computes the intersection of a collection of point sets.

The collection consists of the polygons and polygons with holes in the given two ranges and the point set represented by gps.

template<typename Traits, typename Dcel>
template<class InputIterator >
void CGAL::General_polygon_set_2< Traits, Dcel >::join ( InputIterator  begin,
InputIterator  end 
)

computes the union of the polygons (or polygons with holes) in the given range and the point set represented by gps.

(The value type of the input iterator is used to distinguish between the two options.)

template<typename Traits, typename Dcel>
bool CGAL::General_polygon_set_2< Traits, Dcel >::locate ( const Point_2 p,
Polygon_with_holes_2 pgn 
)

obtains a polygon with holes that contains the query point p, if exists, through pgn, and returns true.

Otherwise, returns false.

template<typename Traits, typename Dcel>
template<class InputIterator >
void CGAL::General_polygon_set_2< Traits, Dcel >::symmetric_difference ( InputIterator  begin,
InputIterator  end 
)

computes the symmetric difference (xor) of a collection of point sets.

The collection consists of the polygons (or polygons with holes) in the given range and the point set represented by gps. (The value type of the input iterator is used to distinguish between the two options.)

template<typename Traits, typename Dcel>
template<class InputIterator1 , class InputIterator2 >
void CGAL::General_polygon_set_2< Traits, Dcel >::symmetric_difference ( InputIterator1  pgn_begin,
InputIterator1  pgn_end,
InputIterator2  pgn_with_holes_begin,
InputIterator2  pgn_with_holes_end 
)

computes the symmetric difference (xor) of a collection of point sets.

The collection consists of the polygons and polygons with holes in the given two ranges and the point set represented by gps.

template<typename Traits, typename Dcel>
Traits& CGAL::General_polygon_set_2< Traits, Dcel >::traits ( ) const

obtains an instance of the traits.

If the traits was passed as a parameter to the constructor of gps, it is returned. Otherwise, a newly created instance is returned.