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CGAL 6.0 - 2D and 3D Linear Geometry Kernel
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#include <CGAL/Projection_traits_xy_3.h>
The class Projection_traits_xy_3 is an adapter to apply 2D algorithms to the projections of 3D data on the xy-plane.
CGAL provides also predefined geometric traits classes Projection_traits_yz_3<K> and Projection_traits_xz_3<K> to deal with projections on the zx- and the zy-plane, respectively.
| K | must be a model of Kernel. |
K is a model of Kernel providing exact constructions or if K is a CGAL::Filtered_kernel (such as for CGAL::Exact_predicates_inexact_constructions_kernel), this class automatically provides exact predicates.PolygonTraits_2 ConvexHullTraits_2 TriangulationTraits_2 DelaunayTriangulationTraits_2 ConstrainedTriangulationTraits_2 ConvexHullTraits_2 DelaunayMeshTraits_2 AnalyticWeightTraits_2 Barycentric_coordinates::BarycentricTraits_2 CGAL::Projection_traits_3 Types | |
| typedef Point_3< K > | Point_2 |
| typedef Segment_3< K > | Segment_2 |
| typedef Triangle_3< K > | Triangle_2 |
| typedef Line_3< K > | Line_2 |
Functors | |
The functors provided by this class are those listed in the concepts, except that it does not provide the type and constructors required to build the dual Voronoi diagram. The functors operate on the 2D projection of their arguments. They come with preconditions that projections of the arguments are non-degenerate, eg. a line segment does not project on a single point, two points do not project on the same point, etc. In the following, we specify the choice of the | |
| typedef unspecified_type | Intersect_2 |
| A construction object. | |
Creation | |
| Projection_traits_xy_3 () | |
| default constructor. | |
| Projection_traits_xy_3 (Projection_traits_xy_3 tr) | |
| Copy constructor. | |
| Projection_traits_xy_3 | operator= (Projection_traits_xy_3 tr) |
| Assignment operator. | |
| typedef unspecified_type CGAL::Projection_traits_xy_3< K >::Intersect_2 |
A construction object.
Provides the operator :
std::optional< std::variant<Point_2,Segment_2> > operator()(Segment_2 s1, Segment_2 s2); which returns a 3D object whose projection on the xy-plane is the intersection of the projections of s1 and s2. If non empty, the returned object is either a segment or a point. Its embedding in 3D is computed as the interpolation between s1 and s2, meaning that any point p of the returned object is the midpoint of segment p1p2 where p1 and p2 are the two points of s1 and s2 respectively, both projecting on p.
s1 and the projection of s2 are non-degenerate 2D segments.