CGAL 6.0 - 2D Segment Delaunay Graphs
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SegmentDelaunayGraphTraits_2 Concept Reference

Definition

Refines
TriangulationTraits_2

The concept SegmentDelaunayGraphTraits_2 provides the traits requirements for the CGAL::Segment_Delaunay_graph_2<Gt,St,DS> and CGAL::Segment_Delaunay_graph_hierarchy_2<Gt,St,STag,DS> classes. In particular, it provides a type Site_2, which must be a model of the concept SegmentDelaunayGraphSite_2. It also provides constructions for sites and several function object types for the predicates.

Has models
CGAL::Segment_Delaunay_graph_traits_2<K,MTag>
CGAL::Segment_Delaunay_graph_traits_without_intersections_2<K,MTag>
CGAL::Segment_Delaunay_graph_filtered_traits_2<CK,CM,EK,EM,FK,FM>
CGAL::Segment_Delaunay_graph_filtered_traits_without_intersections_2<CK,CM,EK,EM,FK,FM>
See also
SegmentDelaunayGraphSite_2
CGAL::Segment_Delaunay_graph_2<Gt,St,DS>
CGAL::Segment_Delaunay_graph_hierarchy_2<Gt,St,STag,DS>
CGAL::Segment_Delaunay_graph_traits_2<K,MTag>
CGAL::Segment_Delaunay_graph_traits_without_intersections_2<K,MTag>
CGAL::Segment_Delaunay_graph_filtered_traits_2<CK,CM,EK,EM,FK,FM>
CGAL::Segment_Delaunay_graph_filtered_traits_without_intersections_2<CK,CM,EK,EM,FK,FM>

Types

typedef unspecified_type Intersections_tag
 Indicates or not whether the intersecting segments are to be supported.
 
typedef unspecified_type Site_2
 A type for a site of the segment Delaunay graph.
 
typedef unspecified_type Point_2
 A type for a point.
 
typedef unspecified_type Line_2
 A type for a line.
 
typedef unspecified_type Ray_2
 A type for a ray.
 
typedef unspecified_type Segment_2
 A type for a segment.
 
typedef unspecified_type FT
 A type for the field number type of sites, points, etc...
 
typedef unspecified_type RT
 A type for the ring number type of sites, points, etc.
 
typedef unspecified_type Arrangement_type
 An enumeration type that indicates the type of the arrangement of two sites.
 
typedef unspecified_type Object_2
 A type representing different types of objects in two dimensions, namely: Point_2, Site_2, Line_2, Ray_2 and Segment_2.
 
typedef unspecified_type Assign_2
 Must provide template <class T> bool operator() ( T& t, Object_2 o) which assigns o to t if o was constructed from an object of type T.
 
typedef unspecified_type Construct_object_2
 Must provide template <class T> Object_2 operator()( T t) that constructs an object of type Object_2 that contains t and returns it.
 
typedef unspecified_type Construct_svd_vertex_2
 A constructor for a point of the segment Voronoi diagram equidistant from three sites.
 
typedef unspecified_type Compare_x_2
 A predicate object type.
 
typedef unspecified_type Compare_y_2
 A predicate object type.
 
typedef unspecified_type Less_x_2
 A predicate object type.
 
typedef unspecified_type Less_y_2
 A predicate object type.
 
typedef unspecified_type Orientation_2
 A predicate object type.
 
typedef unspecified_type Equal_2
 A predicate object type.
 
typedef unspecified_type Are_parallel_2
 A predicate object type.
 
typedef unspecified_type Oriented_side_of_bisector_2
 A predicate object type.
 
typedef unspecified_type Vertex_conflict_2
 A predicate object type.
 
typedef unspecified_type Finite_edge_interior_conflict_2
 A predicate object type.
 
typedef unspecified_type Infinite_edge_interior_conflict_2
 A predicate object type.
 
typedef unspecified_type Oriented_side_2
 A predicate object type.
 
typedef unspecified_type Arrangement_type_2
 A predicate object type.
 

Access to predicate objects

Compare_x_2 compare_x_2_object ()
 
Compare_y_2 compare_y_2_object ()
 
Less_x_2 less_x_2_object ()
 
Less_y_2 less_y_2_object ()
 
Orientation_2 orientation_2_object ()
 
Equal_2 equal_2_object ()
 
Are_parallel_2 are_parallel_2_object ()
 
Oriented_side_of_bisector_2 oriented_side_of_bisector_test_2_object ()
 
Vertex_conflict_2 vertex_conflict_2_object ()
 
Finite_edge_interior_conflict_2 finite_edge_interior_conflict_2_object ()
 
Infinite_edge_interior_conflict_2 infinite_edge_interior_conflict_2_object ()
 
Oriented_side_2 oriented_side_2_object ()
 
Arrangement_type_2 arrangement_type_2_object ()
 

Access to constructor objects

Construct_object_2 construct_object_2_object ()
 
Construct_svd_vertex_2 construct_svd_vertex_2_object ()
 

Access to other objects

Assign_2 assign_2_object ()
 

Member Typedef Documentation

◆ Are_parallel_2

A predicate object type.

Must provide bool operator()(Site_2 s1, Site_2 s2), which determines is the segments represented by the sites s1 and s2 are parallel.

Precondition
s1 and s2 must be segments.

◆ Arrangement_type

An enumeration type that indicates the type of the arrangement of two sites.

The possible values are DISJOINT, IDENTICAL, CROSSING, TOUCHING_1, TOUCHING_2, TOUCHING_11, TOUCHING_12, TOUCHING_21, TOUCHING_22, OVERLAPPING_11, OVERLAPPING_12, OVERLAPPING_21, OVERLAPPING_22, INTERIOR, INTERIOR_1, INTERIOR_2, TOUCHING_11_INTERIOR_1, TOUCHING_11_INTERIOR_2, TOUCHING_12_INTERIOR_1, TOUCHING_12_INTERIOR_2, TOUCHING_21_INTERIOR_1, TOUCHING_21_INTERIOR_2, TOUCHING_22_INTERIOR_1, TOUCHING_22_INTERIOR_2. A detailed description of the meaning of these values is shown the end of the reference manual for this concept.

◆ Arrangement_type_2

A predicate object type.

Must provide Arrangement_type operator()(Site_2 s1, Site_2 s2) that returns the type of the arrangement of the two sites s1 and s2.

◆ Assign_2

Must provide template <class T> bool operator() ( T& t, Object_2 o) which assigns o to t if o was constructed from an object of type T.

Returns true, if the assignment was possible.

◆ Compare_x_2

A predicate object type.

Must provide Comparison_result operator()(Site_2 s1, Site_2 s2), which compares the \( x\)-coordinates of the points represented by the sites s1 and s2.

Precondition
s1 and s2 must be points.

◆ Compare_y_2

A predicate object type.

Must provide Comparison_result operator()(Site_2 s1, Site_2 s2), which compares the \( y\)-coordinates of the points represented by the sites s1 and s2.

Precondition
s1 and s2 must be points.

◆ Construct_svd_vertex_2

A constructor for a point of the segment Voronoi diagram equidistant from three sites.

Must provide Point_2 operator()(Site_2 s1, Site_2 s2, Site_2 s3), which constructs a point equidistant from the sites s1, s2 and s3.

◆ Equal_2

A predicate object type.

Must provide bool operator()(Site_2 s1, Site_2 s2), which determines is the points represented by the sites s1 and s2 are identical.

Precondition
s1 and s2 must be points.

◆ Finite_edge_interior_conflict_2

A predicate object type.

Must provide bool operator()(Site_2 s1, Site_2 s2, Site_2 s3, Site_2 s4, Site_2 q, Sign sgn). The sites s1, s2, s3 and s4 define a Voronoi edge that lies on the bisector of s1 and s2 and has as endpoints the Voronoi vertices defined by the triplets s1, s2, s3 and s1, s4 and s2. The sign sgn is the common sign of the distance of the site q from the Voronoi circle of the triplets s1, s2, s3 and s1, s4 and s2. In case that sgn is equal to NEGATIVE, the predicate returns true if and only if the entire Voronoi edge is in conflict with q. If sgn is equal to POSITIVE or ZERO, the predicate returns false if and only if q is not in conflict with the Voronoi edge.

Precondition
the Voronoi vertices of s1, s2, s3, and s1, s4, s2 must exist.

Must also provide bool operator()(Site_2 s1, Site_2 s2, Site_2 s3, Site_2 q, Sign sgn). The sites s1, s2, s3 and the site at infinity \( s_\infty\) define a Voronoi edge that lies on the bisector of s1 and s2 and has as endpoints the Voronoi vertices \( v_{123}\) and \( v_{1\infty{2}}\) defined by the triplets s1, s2, s3 and s1, \( s_\infty\) and s2 (the second vertex is actually at infinity). The sign sgn is the common sign of the distance of the site q from the two Voronoi circles centered at the Voronoi vertices \( v_{123}\) and \( v_{1\infty{2}}\). In case that sgn is NEGATIVE, the predicate returns true if and only if the entire Voronoi edge is in conflict with q. If sgn is POSITIVE or ZERO, the predicate returns false if and only if q is not in conflict with the Voronoi edge.

Precondition
the Voronoi vertex \( v_{123}\) of s1, s2, s3 must exist.

Must finally provide bool operator()(Site_2 s1, Site_2 s2, Site_2 q, Sign sgn). The sites s1, s2 and the site at infinity \( s_\infty\) define a Voronoi edge that lies on the bisector of \( v_{12\infty}\) and \( v_{1\infty{}2}\) s1 and s2 and has as endpoints the Voronoi vertices defined by the triplets s1, s2, \( s_\infty\) and s1, \( s_\infty\) and s2 (both vertices are actually at infinity). The sign sgn denotes the common sign of the distance of the site q from the Voronoi circles centered at \( v_{12\infty}\) and \( v_{1\infty{}2}\). If sgn is NEGATIVE, the predicate returns true if and only if the entire Voronoi edge is in conflict with q. If POSITIVE or ZERO is false, the predicate returns false if and only if q is not in conflict with the Voronoi edge.

◆ Infinite_edge_interior_conflict_2

A predicate object type.

Must provide bool operator()(Site_2 s1, Site_2 s2, Site_2 s3, Site_2 q, Sign sgn). The sites \( s_\infty\), s1, s2 and s3 define a Voronoi edge that lies on the bisector of \( s_\infty\) and s1 and has as endpoints the Voronoi vertices \( v_{\infty{}12}\) and \( v_{\infty{}31}\) defined by the triplets \( s_\infty\), s1, s2 and \( s_\infty\), s3 and s1. The sign sgn is the common sign of the distances of q from the Voronoi circles centered at the vertices \( v_{\infty{}12}\) and \( v_{\infty{}31}\). If sgn is NEGATIVE, the predicate returns true if and only if the entire Voronoi edge is in conflict with q. If sgn is POSITIVE or ZERO, the predicate returns false if and only if q is not in conflict with the Voronoi edge.

◆ Intersections_tag

Indicates or not whether the intersecting segments are to be supported.

The tag must either be CGAL::Tag_true or CGAL::Tag_false.

◆ Less_x_2

A predicate object type.

Must provide bool operator()(Point_2 p1, Point_2 p2), which returns true if p1.x() < p2.x().

◆ Less_y_2

A predicate object type.

Must provide bool operator()(Point_2 p1, Point_2 p2), which returns true if p1.y() < p2.y().

◆ Line_2

A type for a line.

Only required if the segment Delaunay graph is inserted in a stream.

◆ Orientation_2

A predicate object type.

Must provide Orientation operator()(Site_2 s1, Site_2 s2, Site_2 s3), which performs the usual orientation test for three points. s1, s2 and s3.

Precondition
the sites s1, s2 and s3 must be points.

◆ Oriented_side_2

A predicate object type.

Must provide Oriented_side operator()(Site_1 s1, Site_2 s2, Site_2 s3, Site_2 s, Site_2 p). Determines the oriented side of the line \( \ell\) that contains the point site p, where \( \ell\) is the line that passes through the Voronoi vertex of the sites s1, s2, s3 and is perpendicular to the segment site s.

Precondition
s must be a segment and p must be a point.

◆ Oriented_side_of_bisector_2

A predicate object type.

Must provide Oriented_side operator()(Site_2 s1, Site_2 s2, Point_2 p), which returns the oriented side of the bisector of s1 and s2 that contains p. Returns ON_POSITIVE_SIDE if p lies in the half-space of s1 (i.e., p is closer to s1 than s2); returns ON_NEGATIVE_SIDE if p lies in the half-space of s2; returns ON_ORIENTED_BOUNDARY if p lies on the bisector of s1 and s2.

◆ Ray_2

A type for a ray.

Only required if the segment Delaunay graph is inserted in a stream.

◆ Segment_2

A type for a segment.

Only required if if the segment Delaunay graph is inserted in a stream.

◆ Site_2

A type for a site of the segment Delaunay graph.

Must be a model of the concept SegmentDelaunayGraphSite_2.

◆ Vertex_conflict_2

A predicate object type.

Must provide Sign operator()(Site_2 s1, Site_2 s2, Site_2 s3, Site_2 q), which returns the sign of the distance of q from the Voronoi circle of s1, s2, s3 (the Voronoi circle of three sites s1, s2, s3 is a circle co-tangent to all three sites, that touches them in that order as we walk on its circumference in the counter-clockwise sense).

Precondition
the Voronoi circle of s1, s2, s3 must exist.

Must also provide Sign operator()(Site_2 s1, Site_2 s2, Site_2 q), which returns the sign of the distance of q from the bitangent line of s1, s2 (a degenerate Voronoi circle, with its center at infinity).