CGAL 5.1.3  3D Fast Intersection and Distance Computation (AABB Tree)

#include <CGAL/AABB_tree.h>
Static data structure for efficient intersection and distance computations in 3D.
It builds a hierarchy of axisaligned bounding boxes (an AABB tree) from a set of 3D geometric objects, and can receive intersection and distance queries, provided that the corresponding predicates are implemented in the traits class AABBTraits. An instance of the class AABBTraits
is internally stored.
AABBTraits
AABBPrimitive
Public Member Functions  
AABBTraits::Primitive::Datum_reference  datum (Primitive &p) const 
Returns the datum (geometric object) represented p .  
Types  
typedef AABBTraits::FT  FT 
Number type returned by the distance queries.  
typedef AABBTraits::Point_3  Point 
Type of 3D point.  
typedef AABBTraits::Primitive  Primitive 
Type of input primitive.  
typedef Primitive::Id  Primitive_id 
Identifier for a primitive in the tree.  
typedef Primitives::size_type  size_type 
Unsigned integral size type.  
typedef AABBTraits::Bounding_box  Bounding_box 
Type of bounding box.  
typedef AABBTraits::Point_and_primitive_id  Point_and_primitive_id 
3D Point and Primitive Id type  
typedef AABBTraits::Object_and_primitive_id  Object_and_primitive_id 
template<typename Query >  
using  Intersection_and_primitive_id = AABBTraits::Intersection_and_primitive_id< Query > 
An alias to AABBTraits::Intersection_and_primitive_id<Query>  
Creation  
AABB_tree (const AABBTraits &traits=AABBTraits())  
constructs an empty tree, and initializes the internally stored traits class using traits . More...  
template<typename InputIterator , typename ... T>  
AABB_tree (InputIterator first, InputIterator beyond, T &&...)  
Builds the datastructure from a sequence of primitives. More...  
template<typename ... T>  
void  build (T &&...) 
triggers the (re)construction of the internal tree structure. More...  
Operations  
template<typename ConstPrimitiveIterator , typename ... T>  
void  rebuild (ConstPrimitiveIterator first, ConstPrimitiveIterator beyond, T &&...) 
is equivalent to calling clear() , insert(first,last,t...) , and build()  
template<typename InputIterator , typename ... T>  
void  insert (InputIterator first, InputIterator beyond, T &&...) 
adds a sequence of primitives to the set of primitives of the AABB tree. More...  
void  insert (const Primitive &p) 
adds a primitive to the set of primitives of the tree.  
~AABB_tree ()  
clears and destroys the tree.  
const AABBTraits &  traits () const 
returns a const reference to the internally stored traits class.  
void  clear () 
clears the tree and the search tree if it was constructed, and switches on the usage of the search tree to find the hint for the distance queries  
const Bounding_box  bbox () const 
returns the axisaligned bounding box of the whole tree. More...  
size_type  size () const 
returns the number of primitives in the tree.  
bool  empty () const 
returns true , iff the tree contains no primitive.  
Intersection Tests  
template<typename Query >  
bool  do_intersect (const Query &query) const 
returns true , iff the query intersects at least one of the input primitives. More...  
template<typename Query >  
size_type  number_of_intersected_primitives (const Query &query) const 
returns the number of primitives intersected by the query. More...  
template<typename Query , typename OutputIterator >  
OutputIterator  all_intersected_primitives (const Query &query, OutputIterator out) const 
puts in out the ids of all intersected primitives. More...  
template<typename Query >  
boost::optional< Primitive_id >  any_intersected_primitive (const Query &query) const 
returns the id of the intersected primitive that is encountered first in the tree traversal, iff the query intersects at least one of the input primitives. More...  
Intersections  
template<typename Query , typename OutputIterator >  
OutputIterator  all_intersections (const Query &query, OutputIterator out) const 
puts in out all intersections, as objects of Intersection_and_primitive_id<Query>::Type , between the query and the input data to the iterator. More...  
template<typename Query >  
boost::optional< typename Intersection_and_primitive_id< Query >::Type >  any_intersection (const Query &query) const 
returns if any the intersection that is encountered first in the tree traversal. More...  
template<typename Ray , typename SkipFunctor >  
boost::optional< typename Intersection_and_primitive_id< Ray >::Type >  first_intersection (const Ray &query, const SkipFunctor &skip) const 
returns the intersection and primitive id closest to the source point of the ray query. More...  
template<typename Ray , typename SkipFunctor >  
boost::optional< Primitive_id >  first_intersected_primitive (const Ray &query, const SkipFunctor &skip) const 
returns the primitive id closest to the source point of the ray query. More...  
Distance Queries  
FT  squared_distance (const Point &query) const 
returns the minimum squared distance between the query point and all input primitives. More...  
Point  closest_point (const Point &query) const 
returns the point in the union of all input primitives which is closest to the query. More...  
Point_and_primitive_id  closest_point_and_primitive (const Point &query) const 
returns a Point_and_primitive_id which realizes the smallest distance between the query point and all input primitives. More...  
Accelerating the Distance Queries  
In the following paragraphs, we discuss details of the implementation of the distance queries. We explain the internal use of hints, how the user can pass his own hints to the tree, and how the user can influence the construction of the secondary data structure used for accelerating distance queries. Internally, the distance queries algorithms are initialized with some hint, which has the same type as the return type of the query, and this value is refined along a traversal of the tree, until it is optimal, that is to say until it realizes the shortest distance to the primitives. In particular, the exact specification of these internal algorithms is that they minimize the distance to the object composed of the union of the primitives and the hint. It follows that
This second observation is reasonable, in the sense that providing a hint to the algorithm means claiming that this hint belongs to the union of the primitives. These considerations about the hints being exactly on the primitives or not are important: in the case where the set of primitives is a triangle soup, and if some of the primitives are large, one may want to provide a much better hint than a vertex of the triangle soup could be. It could be, for example, the barycenter of one of the triangles. But, except with the use of a kernel with exact constructions, one cannot easily construct points other than the vertices, that lie exactly on a triangle soup. Hence, providing a good hint sometimes means not being able to provide it exactly on the primitives. In rare occasions, this hint can be returned as the closest point. In order to accelerate distance queries significantly, the AABB tree builds an internal KDtree containing a set of potential hints. This KDtree provides very good hints that allow the algorithms to run much faster than when  
bool  accelerate_distance_queries () 
constructs the internal search tree from a point set taken on the internal primitives returns true iff successful memory allocation  
void  do_not_accelerate_distance_queries () 
turns off the usage of the internal search tree and clears it if it was already constructed.  
template<typename ConstPointIterator >  
bool  accelerate_distance_queries (ConstPointIterator first, ConstPointIterator beyond) 
constructs an internal KDtree containing the specified point set, to be used as the set of potential hints for accelerating the distance queries. More...  
FT  squared_distance (const Point &query, const Point &hint) const 
returns the minimum squared distance between the query point and all input primitives. More...  
Point  closest_point (const Point &query, const Point &hint) const 
returns the point in the union of all input primitives which is closest to the query. More...  
Point_and_primitive_id  closest_point_and_primitive (const Point &query, const Point_and_primitive_id &hint) const 
returns a Point_and_primitive_id which realizes the smallest distance between the query point and all input primitives. More...  
typedef AABBTraits::Object_and_primitive_id CGAL::AABB_tree< AABBTraits >::Object_and_primitive_id 
CGAL::AABB_tree< AABBTraits >::AABB_tree  (  const AABBTraits &  traits = AABBTraits()  ) 
constructs an empty tree, and initializes the internally stored traits class using traits
.
CGAL::AABB_tree< AABBTraits >::AABB_tree  (  InputIterator  first, 
InputIterator  beyond,  
T &&  ...  
) 
Builds the datastructure from a sequence of primitives.
first  iterator over first primitive to insert 
beyond  pasttheend iterator 
constructs an empty tree followed by a call to insert(first,last,t...)
. The tree stays empty if the memory allocation is not successful.
bool CGAL::AABB_tree< AABBTraits >::accelerate_distance_queries  (  ConstPointIterator  first, 
ConstPointIterator  beyond  
) 
constructs an internal KDtree containing the specified point set, to be used as the set of potential hints for accelerating the distance queries.
Note that the search tree built in this function will not be invalidated by the insertion of a new primitive, and an explicit call to accelerate_distance_queries()
is needed to update the search tree.
ConstPointIterator  is an iterator with value type Point_and_primitive_id . 
OutputIterator CGAL::AABB_tree< Tr >::all_intersected_primitives  (  const Query &  query, 
OutputIterator  out  
)  const 
puts in out
the ids of all intersected primitives.
This function does not compute the intersection points and is hence faster than the function all_intersections()
function below.
Query  must be a type for which Do_intersect operators are defined in the traits class AABBTraits . 
OutputIterator CGAL::AABB_tree< Tr >::all_intersections  (  const Query &  query, 
OutputIterator  out  
)  const 
puts in out
all intersections, as objects of Intersection_and_primitive_id<Query>::Type
, between the query and the input data to the iterator.
Query  must be a type for which Do_intersect and Intersection operators are defined in the traits class AABBTraits . 
boost::optional<Primitive_id> CGAL::AABB_tree< AABBTraits >::any_intersected_primitive  (  const Query &  query  )  const 
returns the id of the intersected primitive that is encountered first in the tree traversal, iff the query intersects at least one of the input primitives.
No particular order is guaranteed over the tree traversal, such that, e.g, the primitive returned is not necessarily the closest from the source point of a ray query.
Query  must be a type for which Do_intersect operators are defined in the traits class AABBTraits . 
boost::optional< typename Intersection_and_primitive_id<Query>::Type > CGAL::AABB_tree< AABBTraits >::any_intersection  (  const Query &  query  )  const 
returns if any the intersection that is encountered first in the tree traversal.
No particular order is guaranteed over the tree traversal, e.g, the primitive returned is not necessarily the closest from the query.
Query  must be a type for which Do_intersect and Intersection operators are defined in the traits class AABBTraits . 
const Bounding_box CGAL::AABB_tree< AABBTraits >::bbox  (  )  const 
returns the axisaligned bounding box of the whole tree.
!empty()
void CGAL::AABB_tree< AABBTraits >::build  (  T &&  ...  ) 
triggers the (re)construction of the internal tree structure.
The internal tree structure is automatically invalidated by the insertion of any primitives after one or more calls to insert()
. This procedure is called implicitly at the first call to a query member function. An explicit call to build()
must be made to ensure that the next call to a query function will not trigger the construction of the data structure. A call to AABBTraits::set_shared_data(t...)
is made using the internally stored traits. This procedure has a complexity of \(O(n log(n))\), where \(n\) is the number of primitives of the tree.
AABB_tree< Tr >::Point CGAL::AABB_tree< Tr >::closest_point  (  const Point &  query  )  const 
returns the point in the union of all input primitives which is closest to the query.
In case there are several closest points, one arbitrarily chosen closest point is returned.
!empty()
AABB_tree< Tr >::Point CGAL::AABB_tree< Tr >::closest_point  (  const Point &  query, 
const Point &  hint  
)  const 
returns the point in the union of all input primitives which is closest to the query.
In case there are several closest points, one arbitrarily chosen closest point is returned. The internal KDtree is not used.
!empty()
AABB_tree< Tr >::Point_and_primitive_id CGAL::AABB_tree< Tr >::closest_point_and_primitive  (  const Point &  query  )  const 
returns a Point_and_primitive_id
which realizes the smallest distance between the query point and all input primitives.
!empty()
AABB_tree< Tr >::Point_and_primitive_id CGAL::AABB_tree< Tr >::closest_point_and_primitive  (  const Point &  query, 
const Point_and_primitive_id &  hint  
)  const 
returns a Point_and_primitive_id
which realizes the smallest distance between the query point and all input primitives.
The internal KDtree is not used.
!empty()
bool CGAL::AABB_tree< Tr >::do_intersect  (  const Query &  query  )  const 
returns true
, iff the query intersects at least one of the input primitives.
Query  must be a type for which Do_intersect operators are defined in the traits class AABBTraits . 
boost::optional<Primitive_id> CGAL::AABB_tree< AABBTraits >::first_intersected_primitive  (  const Ray &  query, 
const SkipFunctor &  skip  
)  const 
returns the primitive id closest to the source point of the ray query.
Ray  must be the same as AABBTraits::Ray_3 and do_intersect predicates and intersections for it must be defined. 
Skip  a functor with an operator bool operator()(const Primitive_id& id) const that returns true in order to skip the primitive. Defaults to a functor that always returns false . 
AABBTraits
must be a model of AABBRayIntersectionTraits
to call this member function.
boost::optional< typename Intersection_and_primitive_id<Ray>::Type > CGAL::AABB_tree< AABBTraits >::first_intersection  (  const Ray &  query, 
const SkipFunctor &  skip  
)  const 
returns the intersection and primitive id closest to the source point of the ray query.
Ray  must be the same as AABBTraits::Ray_3 and do_intersect predicates and intersections for it must be defined. 
Skip  a functor with an operator bool operator()(const Primitive_id& id) const that returns true in order to skip the primitive. Defaults to a functor that always returns false . 
skip
might be given some primitives that are not intersected by query
because the intersection test is done after the skip test. Also note that the order the primitives are given to skip
is not necessarily the intersection order with query
.AABBTraits
must be a model of AABBRayIntersectionTraits
to call this member function.
void CGAL::AABB_tree< AABBTraits >::insert  (  InputIterator  first, 
InputIterator  beyond,  
T &&  ...  
) 
adds a sequence of primitives to the set of primitives of the AABB tree.
InputIterator
is any iterator and the parameter pack T
contains any types such that Primitive
has a constructor with the following signature: Primitive(InputIterator, T...)
. If Primitive
is a model of the concept AABBPrimitiveWithSharedData
, a call to AABBTraits::set_shared_data(t...)
is made using the internally stored traits.
size_type CGAL::AABB_tree< AABBTraits >::number_of_intersected_primitives  (  const Query &  query  )  const 
returns the number of primitives intersected by the query.
Query  must be a type for which Do_intersect operators are defined in the traits class AABBTraits . 
AABB_tree< Tr >::FT CGAL::AABB_tree< Tr >::squared_distance  (  const Point &  query  )  const 
returns the minimum squared distance between the query point and all input primitives.
!empty()
AABB_tree< Tr >::FT CGAL::AABB_tree< Tr >::squared_distance  (  const Point &  query, 
const Point &  hint  
)  const 
returns the minimum squared distance between the query point and all input primitives.
The internal KDtree is not used.
!empty()