Release notes of CGAL.

-------------------------------- Release 3.9 --------------------------------

Release date: Sep 2011

CGAL 3.9 offers the following improvements and new functionality :


* General

  - The class Root_of_2 is now deprecated. It is recommended to use the class
    Sqrt_extension instead.

  - The class Sqrt_extension is now used everywhere in CGAL where an algebraic
    number of degree 2 is needed. This change has been done in the
    Root_of_traits mechanism (indirectly packages 2D Circular kernel and 3D
    Spherical kernel) and the packages 2D Segment Delaunay Graphs and 2D
    Arrangements.

  - Various fixes in the manual.


* Combinatorial Maps (new package)

  - This package provides a new combinatorial data structure allowing to
    describe any orientable subdivided object whatever its dimension. It
    describes all cells of the subdivision and all the incidence and adjacency
    relations between these cells. For example it allows to describe a 3D
    object subdivided in vertices, edges, faces and volumes. This data
    structure can be seen as the generalization in dD of the haldedge data
    structure.


* 3D Convex Hull (major performance improvement)

  - The quickhull implementation of CGAL (CGAL::convex_hull_3) has been worked
    out to provide very better performances.

  - The function CGAL::convex_hull_3 no longer computes the plane equations of
    the facets of the output polyhedron. However an example is provided to show
    how to compute them easily.

  - A global function convex_hull_3_to_polyhedron_3 is now provided to extract
    the convex hull of a 3D points set from a triangulation of these points.


* dD Spatial Searching (major new feature added)

  - A traits-class and distance adapter that together with a point property
    map, allow to make nearest neighbor queries on keys instead of points have
    been added.

  - Few bug fixes in the documentation have revealed some inconsistencies that
    have been corrected. Two traits class concept are now documented
    (RangeSearchTraits and SearchTraits). Most other changes concerns only
    classes documented as advanced. One issue that user can encounter is due to
    an additional requirement on the nested class
    Construct_cartesian_const_iterator_d defined in the concept SearchTraits
    that must provide a nested type result_type.


* Spatial Sorting (major new feature added)

  - General dimension is now supported.

  - Hilbert sorting admits now two policies: splitting at median or at middle
    (see user manual).

  - Using a property map, sorting on keys instead of points is now easier


* dD Kernel

  - The d-dimensional kernel concept and models have been modified to
    additionally provide two new functors Less_coordinate_d and
    Point_dimension_d.


* 2D Arrangements

  - A new geometry-traits class that handles rational arcs, namely
    Arr_rational_function_traits_2, has been introduced. It replaced an old
    traits class, which handled the same family of curves, but it was less
    efficient. The new traits exploits CGAL algebraic kernels and polynomials,
    which were not available at the time the old traits class was developed.

  - A new geometry traits concept called ArrangementOpenBoundaryTraits_2 has
    been introduced. A model of this concept suports curves that approach the
    open boundary of an iso-rectangular area called parameter space, which can
    be unbounded or bounded. The general code of the package, however, supports
    only the unbounded parameter space. We intend to enhance the general code
    to support also bounded parameter spaces in a future release.

  - The deprecated member function is_at_infinity() of Arrangement_2::Vertex
    has been removed. It has been previously replaced new function
    is_at_open_boundary().

  - The tags in the geometry traits that indicate the type of boundary of the
    embedding surface were replaced by the following new tags:
             Left_side_category
             Bottom_side_category
             Top_side_category
             Right_side_category
    It is still possible not to indicate the tags at all. Default values are
    assumed. This however will produce warning messages, and should be avoided.


-------------------------------- Release 3.8 --------------------------------

Release date: April 2011

CGAL 3.8 offers the following improvements and new functionality :


* General

  - Boost version 1.39 at least is now required.

  - Initial support for the LLVM Clang compiler (prereleases of version 2.9).

  - Full support for the options -strict-ansi of the Intel Compiler 11, and -
    ansi of the GNU g++ compiler.

  - Adding a concept of ranges. In the following releases, it will be the way
    to provide a set of objects (vs. a couple of iterators).

  - Fix a memory leak in CORE polynomials.

  - Various fixes in the manual.


* 3D Mesh Generation (major new feature added)

  - Adding the possibility to handle sharp features: the 3D Mesh generation
    package now offers the possibility to get in the final mesh an accurate
    representation of 1-dimensional sharp features present in the description
    of the input domain.


* 2D Triangulations (major new feature added)

  - Add a way to efficiently insert a range of points with information into a
    2D Delaunay and regular triangulation.

  - Add member function mirror_edge taking an edge as parameter.

  - Fix an infinite loop in constrained triangulation.


* 3D Triangulations (major new feature added)

  - Add a way to efficiently insert a range of points with information into a
    3D Delaunay and regular triangulation.

  - Add a member function to remove a cluster of points from a Delaunay or
    regular triangulation.

  - function vertices_in_conflict is renamed vertices_on_conflict_zone_boundary
    for Delaunay and regular triangulation. Function
    vertices_inside_conflict_zone is added to regular triangulation.

  - Structural filtering is now internally used in locate function of Delaunay
    and regular triangulation. It improves average construction time by 20%.

  - Added demo.


* 3D Alpha Shapes (major new feature added)

  - The new class Fixed_alpha_shape_3 provides a robust and faster way to
    compute one alpha shape (with a fixed value of alpha).


* AABB tree

  - Adding the possibility to iteratively add primitives to an existing tree
    and to build it only when no further insertion is needed.


* 2D and 3D Kernel

  - Better handling of 2D points with elevation (3D points projected onto
    trivial planes). More general traits classes (Projection_traits_xy_3,
    Projection_traits_yz_3,Projection_traits_yz_3) are provided to work with
    triangulations, algorithms on polygons, alpha-shapes, convex hull
    algorithm... Usage of former equivalent traits classes in different
    packages is now deprecated.

  - Exact_predicates_exact_constructions_kernel now better use the static
    filters which leads to performance improvements.

  - Add an overload for the global function angle, taking three 3D points.

  - In the 2D and 3D kernel concept, the constant Boolean
    Has_filtered_predicates is now deprecated. It is now required to use
    Has_filtered_predicates_tag (being either Tag_true or Tag_false).

  - Compare_distance_2 and Compare_distance_3 provide additional operators for
    3 and 4 elements.

  - Add intersection test and intersection computation capabilities between an
    object of type Ray_3 and either an object of type Line_3, Segment_3 or
    Ray_3.

  - Improve intersection test performance between an object of type Bbox_3 and
    an object of type Plane_3 or Triangle_3 by avoiding arithmetic filter
    failures.


* 2D Envelope

  - Env_default_diagram_1 is deprecated, Envelope_diagram_1 should be used
    instead.


* 3D Envelope

  - A new demo program called L1_Voronoi_diagram_2 has been introduced. It
    demonstrates how 2D Voronoi diagrams of points under the L1 metric are
    constructed using lower envelopes.


* dD Kernel

  - Add functor Compute_coordinate_d to Kernel_d concept.


* Geometric Object Generators

  - CGAL::Random uses boost::rand48 instead of std::rand.

  - Adding to CGAL::Random a way to generate random integers.

  - Adding generators for dD points.


* Algebraic Foundations

  - Algebraic_structure_traits now provides an Inverse functor for Fields.
    There is also a new global function inverse.


* Bounding Volumes

  - dD Min sphere of spheres has a new traits class for the min sphere of
    points.


* Triangulated Surface Mesh Simplification

  - The priority queue internally used to prioritize edge simplifications is no
    longer a relaxed heap but a binomial heap. This fix guarantees that all
    edges satisfying a simplification criteria are removed (if possible).


* 3D Boolean Operations on Nef Polyhedra

  - Allow construction of a 3D nef polyhedron from a 3D polyhedron with
    normals.


* 2D Arrangements

  - Fix a bug in the method insert_at_vertices of the Arrangement_2 class.

  - Fix several bugs in the traits class Arr_Bezier_curve_traits_2 for
    arrangement of Bezier curves.


* 2D Minkowski Sums

  - A bug in the convolution method was fixed.


-------------------------------- Release 3.7 --------------------------------

Release date: October 2010

CGAL 3.7 offers the following improvements and new functionality :


* General

  - The configuration of CGAL libraries now requires CMake>=2.6.

  - Changes in the set of supported platforms:

      - GNU g++ 4.5 supported (with or without the compilation option -
        std=c++0x).

      - Initial support for the option -strict-ansi of the Intel Compiler 11.
        The CGAL libraries compile with that option, and most CGAL headers have
        been fixed. The packages "3D Boolean Operations on Nef Polyhedra"
        (Nef_3), "Convex Decomposition of Polyhedra" (Convex_decomposition_3),
        and "3D Minkowski Sum of Polyhedra" (Minkowski_sum_3) are known to
        still fail to compile with that compiler flag.

      - The Microsoft Windows Visual C++ compiler 2010 (VC10), that was
        experimentally supported by CGAL-3.6.1, is now fully supported. Note
        that CMake>=2.8.2 is required for that support.

      - The Microsoft Windows Visual C++ compiler 2005 (VC8) is no longer
        supported by the CGAL project since CGAL-3.7.

      - With Microsoft Windows Visual C++ (VC9 and VC10), the optional
        dependencies Gmp, Mpfr, Blas, Lapack, Taucs no longer use Boost-style
        name mangling. Only one variant is now provided by the CGAL Windows
        installer (release, with dynamic runtime).


  - Some demos now require a version of Qt4 >= 4.3.

  - CGAL_PDB is no longer provided with CGAL. An alternative solution for
    people interested in reading PDB files is to use ESBTL (http://
    esbtl.sourceforge.net/).

  - Fix issues of the CGAL wrappers around the CORE library, on 64 bits
    platforms.


* Arithmetic and Algebra

  - New models Algebraic_kernel_d_1 and Algebraic_kernel_d_2 for the
    corresponding concepts. They provide generic support for various
    coefficient types


* Arrangements

  - A new model Arr_algebraic_segment_traits_2 of ArrangementTraits_2 that
    supports algebraic curves of arbitrary degree in the plane


* 2D Triangulations

  - The Delaunay and regular 2D triangulations now use a symbolic perturbation
    to choose a particular triangulation in co-circular cases.

  - The return type of the template member function insert(It beg, It end),
    taking an iterator range of points, has been changed from int to std::
    ptrdiff_t.

  - Classes Triangulation_euclidean_traits_xy_3,
    Triangulation_euclidean_traits_yz_3 and Triangulation_euclidean_traits_xz_3
    are now model of the concept ConstrainedTriangulationTraits_2. They can be
    used with and without intersection of constraints.

  - 2D Delaunay and basic triangulations now provide vertex relocation by the
    mean of these two new methods: move and move_if_no_collision. The methods
    are also available for the hierarchy (Triangulation_hierarchy_2).


* 3D Triangulations

  - The return type of the template member function insert(It beg, It end),
    taking an iterator range of points, has been changed from int to std::
    ptrdiff_t.

  - 3D Delaunay triangulations now provide vertex relocation by the mean of
    these two new methods: move and move_if_no_collision. This works in both
    Compact_policy and Fast_policy.


* 2D and 3D Alpha Shapes

  - The type int in the API has been changed to std::size_t so that CGAL can
    deal with large data sets (64 bit addresses).


* 2D Mesh Generation

  - The execution of the 2D mesh generator is now deterministic (same at each
    run).


* 3D Mesh Generation

  - The efficiency of the 3D mesh generator has been improved (the number of
    calls to the oracle per inserted vertex has globally decrease). This is
    achieved through a slight change of the mesh generator strategy which
    implies that a surface component that is not detected at the surface mesher
    level will never be discovered by chance, owing to the refinement of some
    tetrahedra, as it could happen before. Please note that defining the macro
    CGAL_MESH_3_USE_OLD_SURFACE_RESTRICTED_DELAUNAY_UPDATE switches back to the
    old behavior.

  - A demo program is now available.


* Surface Reconstruction from Point Sets

  - Improved performance and minor bug fix.


* 2D Range and Neighbor Search

  - The type int in the API has been changed to std::size_t so that CGAL can
    deal with large data sets (64 bit addresses).


-------------------------------- Release 3.6.1 --------------------------------

Release date: June 2010

This is a bug fix release. The following has been changed since CGAL-3.6:


* General

  - Fix compilation errors with recent Boost versions (since 1.40).

  - Initial support for the Microsoft Visual C++ compiler 10.0 (MSVC 2010). For
    that support, CMake>=2.8.2 is required. Note also that the compiler option
    "/bigobj" is necessary to compile some CGAL programs with MSVC 2010.


* Polynomial

  - Fix compilation errors with the Microsoft Visual C++ compiler and the Intel
    C++ compiler.


* Polyhedron

  - Fix a compilation errors in demo/Polyhedron/:

  - issue with the location of qglobal.h of Qt4 on MacOS X,

  - missing texture.cpp, if TAUCS is used,

  - Fix the location of built plugins of demo/Polyhedron/, when CGAL is
    configured with WITH_demos=ON


* 3D Periodic Triangulations

  - Fixed bug in the triangulation hierarchy for periodic triangulations.


* 2D Mesh Generation

  - Fix a bug that lead to precondition violation.

  - Improve the user manual about the member function is_in_domain() of the
    Face type.

  - The 2D meshing process is now deterministic (sorting of bad faces no longer
    relies on pointers comparisons).


* 3D Mesh Generation

  - Fix a linking errors (duplicate symbols) when <CGAL/refine_mesh_3.h> is
    included in different compilation units.


* Spatial Searching

  - Fix a bug in <CGAL/Orthogonal_k_neighbor_search.h> when several nearest
    neighbors are at the same distance from the query point.


* IO Streams

  - Fix a bug in <CGAL/IO/VRML_2_ostream.h> that generated VRML 2 files with an
    invalid syntax for IndexedFaceSet nodes.


* Triangulation_2

  - Add missing Compare_distance_2 functor in trait classes
    Triangulation_euclidean_traits_xy_3 Triangulation_euclidean_traits_yz_3 and
    Triangulation_euclidean_traits_xz_3. This was preventing calling member
    function nearest_vertex of Delaunay_triangulation_2 instantiated with one
    of these traits.


-------------------------------- Release 3.6 --------------------------------

Release date: March 2010

CGAL 3.6 offers the following improvements and new functionality :


* General

  - Boost version 1.34.1 at least is now required.


* Arithmetic and Algebra

 ** Algebraic Kernel (new package)

  - This new package is targeted to provide black-box implementations of state-
    of-the-art algorithms to determine, compare and approximate real roots of
    univariate polynomials and bivariate polynomial systems. It includes models
    of the univariate algebraic kernel concept, based on the library RS.


 ** Number Types

  - Two new arbitrary fixed-precision floating-point number types have been
    added: the scalar type Gmpfr and the interval type Gmpfi, based on the MPFR
    and MPFI libraries respectively.


* Geometry Kernels

 ** 2D and 3D Geometry Kernel

  - Add new do_intersect() and intersection() overloads:

      - do_intersect(Bbox_3, Bbox_3/Line_3/Ray_3/Segment_3)

      - intersection(Triangle_3, Line_3/Ray_3/Segment_3)



* Polygons

 ** 2D Regularized Boolean Set-Operations

  - Fixed General_polygon_set_2::arrangement() to return the proper type of
    object.


* Arrangement

 ** 2D Arrangements

  - Fixed passing a (const) traits object to the constructor of Arrangement_2.

  - Introduced Arrangement_2::fictitious_face(), which returns the fictitious
    face in case of an unbounded arrangement.

  - Fixed a bug in Bezier-curve handling.

  - Added (back) iterator, number_of_holes(), holes_begin(), and holes_end() to
    the default DCEL for backward compatibility.

  - Added (simple) versions of the free overlay() function. It employs the
    default overlay-traits, which practically does nothing.


* Polyhedron

  - Fix a compilation errors in demo/Polyhedron/:

      - issue with the location of qglobal.h of Qt4 on MacOS X,

      - missing texture.cpp, if TAUCS is used,


  - Fix the location of built plugins of demo/Polyhedron/, when CGAL is
    configured with WITH_demos=ON

  - Fix a bug in test_facet function of the incremental builder: the function
    did not test if while a new facet makes a vertex manifold, no other facet
    incident to that vertex breaks the manifold property.


* Triangulations and Delaunay Triangulations

 ** 2D/3D Regular Triangulations

  - Weighted_point now has a constructor from Cartesian coordinates.


 ** 3D Triangulations

  - Regular_triangulation_3 : semi-static floating-point filters are now used
    in its predicates, which can speed up its construction by a factor of about
    3 when Exact_predicates_inexact_constructions_kernel is used.

  - The class Regular_triangulation_filtered_traits_3 is deprecated, the class
    Regular_triangulation_euclidean_traits_3 must be used instead. The
    predicates of that traits will be filtered if the kernel given as template
    parameter of that traits is itself a filtered kernel.

  - Triangulation_hierarchy_3 is now deprecated, and replaced by a simpler
    CGAL::Fast_location policy template parameter of Delaunay_triangulation_3.

  - The old version of remove() (enabled with CGAL_DELAUNAY_3_OLD_REMOVE) has
    been deleted.


 ** 3D Periodic Triangulations

  - New demo: 3D periodic Lloyd algorithm.

  - New functionality for Voronoi diagrams: dual of an edge and of a vertex,
    volume and centroid of the dual of a vertex.

  - The package can now be used with the 3D Alpha Shapes package to compute
    periodic alpha shapes.


 ** 3D Alpha shapes

  - The class Weighted_alpha_shape_euclidean_traits_3 is deprecated, the class
    Regular_triangulation_euclidean_traits_3 must be used instead.

  - The package can now be used together with the 3D Periodic Triangulation
    package to compute periodic alpha shapes.


 ** 2D/3D Triangulations, 2D Segment Delaunay Graph, 2D Apollonius Graph, and
3D Periodic Triangulations

  - The constructor and insert function taking ranges now produce structures
    whose iterator orders is now deterministic (same at each run).


* Mesh Generation

 ** 2D Mesh Generation

  - The 2D mesh generator can now be used with a constrained Delaunay
    triangulation with constraints hierarchy
    (Constrained_triangulation_plus_2).

  - In some cases (refinement of a constrained edge that is on the convex
    hull), the 2D mesh generator from CGAL-3.4 and CGAL-3.5 could create
    invalid triangulations. This bug is now fixed.


 ** 3D Mesh Generation

  - The mesh generator has been enriched with an optimization phase to provide
    3D meshes with well shaped tetrahedra (and in particular no slivers). The
    optimization phase involves four different optimization processes: two
    global optimization processes (ODT and Lloyd), a perturber and an exuder.
    Each of these processes can be activated or not, and tuned to the users
    needs and to available computer resources.


* Support library

 ** CGAL ipelets

  - Add support for version 7 of Ipe.


-------------------------------- Release 3.5.1 --------------------------------

Release date: December 2009

This is a bug fix release.


* Documentation

  - Fixes in the documentation (the online documentation of CGAL-3.5 is now
    based on CGAL-3.5.1).

  - Fixes to the bibliographic references.


* Windows installer

  - The Windows installer of CGAL-3.5.1 fixes an issue with downloading of
    precompiled binaries of the external library TAUCS.


* Bug fixes in the following CGAL packages

 ** AABB tree

  - Fix a linker issue in do_intersect(Bbox_3,Bbox_3).

  - Fix compilation issue in do_intersect(Bbox_3,Ray_3) when using the
    parameters in this order.


 ** 3D Mesh Generation

  - Fix a bug in initial points construction of a polyhedral surface.


-------------------------------- Release 3.5 --------------------------------

Release date: October 2009

CGAL releases will now be published about every six months. As a transition
release, CGAL-3.5 has been developed during 9 months from the release CGAL-3.4.

Version 3.5 differs from version 3.4 in the platforms that are supported and in
functionality. There have also been a number of bug fixes for this release.


* General

  - Additional supported platforms:

      - GNU g++ 4.4 supported.

      - Intel Compiler 11 supported on Linux


  - Fixed ABI incompatibilities when mixing CGAL and Boost Program Options on
    Windows/Visual C++ (the compilation flag -D_SECURE_SCL=0 is not longer use
    in Debug mode).


* Geometry Kernels

 ** 3D Spherical Geometry Kernel

  - Add functionalities to manipulate circles, circular arcs and points that
    belong to the same sphere.


* Polygons

 ** 2D Regularized Boolean Set-Operations

  - The polygon validation operations were enhanced and their interface was
    improved. They are now offered as free functions and applied properly.


 ** 2D Straight Skeleton and Polygon Offsetting

  - Updated the manual to document the new partial skeletons feature (already
    in the code since 3.4)


* Arrangements

 ** 2D Arrangements

  - The member function is_at_infinity() of Arrangement_2::Vertex was replaced
    by the new function is_at_open_boundary(). The former is deprecated. While
    still supported in version 3.5, It will not be supported in future
    releases. The member functions boundary_type_in_x() and boundary_type_in_y
    () were permanently replaced by the functions parameter_space_in_x() and
    parameter_space_in_y(), respectively. The 2 new functions return an
    enumeration of a new type, namely Arr_parameter_space.

  - The tags in the geometry traits that indicate the type of boundary of the
    embedding surface were replaced by the following new tags:
    Arr_left_side_tag Arr_bottom_side_tag Arr_top_side_tag Arr_right_side_tag
    In addition, the code was change, and now it is possible not to indicate
    the tags at all. Default values are assumed. This however will produce
    warning messages, and should be avoided.

  - All operations of the geometry traits-class were made 'const'. This change
    was reflected in the code of this package and all other packages that are
    based on it. Traits classes that maintain state, should declare the data
    members that store the state as mutable.


 ** Envelopes of Surfaces in 3D

  - A few bugs in the code that computes envelopes were fixed, in particular in
    the code that computes the envelopes of planes.


* Triangulations and Delaunay Triangulations

 ** 3D Periodic Triangulations (new package)

  - This package allows to build and handle triangulations of point sets in the
    three dimensional flat torus. Triangulations are built incrementally and
    can be modified by insertion or removal of vertices. They offer point
    location facilities.


* Mesh Generation

 ** Surface Reconstruction from Point Sets (new package)

  - This CGAL package implements an implicit surface reconstruction method:
    Poisson Surface Reconstruction. The input is an unorganized point set with
    oriented normals.


 ** 3D Mesh Generation (new package)

  - This package generates 3 dimensional meshes. It computes isotropic
    simplicial meshes for domains or multidomains provided that a domain
    descriptor, able to answer queries from a few different types on the
    domain, is given. In the current version, Mesh_3 generate meshes for domain
    described through implicit functional, 3D images or polyhedral boundaries.
    The output is a 3D mesh of the domain volume and conformal surface meshes
    for all the boundary and subdividing surfaces.


* Geometry Processing

 ** Triangulated Surface Mesh Simplification

  - BREAKING API change in the passing of the visitor object.

  - Fixed a bug in the link_condition test

  - Added a geometric test to avoid folding of facets

  - Fixed a bug in the handling of overflow in the LindstromTurk computations

  - Updated the manual to account for the new visitor interface


 ** Point Set Processing (new package)

  - This packages implements a set of algorithms for analysis, processing, and
    normal estimation and orientation of point sets.


* Spatial Searching and Sorting

 ** AABB tree (new package)

  - This package implements a hierarchy of axis-aligned bounding boxes (a AABB
    tree) for efficient intersection and distance computations between 3D
    queries and sets of input 3D geometric objects.


* Support Library

 ** CGAL_ipelets (new package):

  - Object that eases the writing of Ipe's plugins that use CGAL. Plugins for
    CGAL main 2D algorithm are provided as demo.


-------------------------------- Release 3.4 --------------------------------

Release date: January 2009

Version 3.4 differs from version 3.3.1 in the platforms that are supported and
in functionality. There have also been a number of bug fixes for this release.


* General

  - GNU g++ 4.3 supported. Support for g++ 3.3 is dropped.

  - Visual 9 supported. Support for Visual 7 is dropped.

  - Boost version 1.33 at least is now required.

  - CGAL now depends on Boost.Threads, which implies to link against a compiled
    part of Boost.

  - The new macro CGAL_NO_DEPRECATED_CODE can be defined to disable deprecated
    code, helping users discover if they rely on code that may be removed in
    subsequent releases.

  - Assertion behaviour: It is not possible anymore to set the CONTINUE mode
    for assertion failures. Functions that allow to change the assertion
    behaviour are now declared in <CGAL/assertions_behaviour.h>.

  - Qt3 based demos are still there but the documentation has been removed as
    the CGAL::Qt_Widget will be deprecated.

  - Qt4 based demos use the Qt GraphicsView framework and the libQGLViewer.


* Installation

  - install_cgal has been replaced by CMake.


* Polynomial (new package)

  - This package introduces a concept Polynomial_d, a concept for multivariate
    polynomials in d variables.


* Modular Arithmetic (new package)

  - This package provides arithmetic over finite fields.


* Number Types

  - the counter Interval_nt::number_of_failures() has been removed, replaced by
    a profiling counter enabled with CGAL_PROFILE.

  - Fix of a bug in CORE/Expr.h; as a consequence, the arrangement demo works
    properly when handling arrangements of conics, for example, when defining
    an arc with 5 points.


* 3D Spherical Geometry Kernel (new package)

  - This package is an extension of the linear CGAL Kernel. It offers
    functionalities on spheres, circles, circular arcs and line segments in the
    3D space.


* Linear Kernel

  - We recommend that you use the object_cast() function instead of assign() to
    extract an object from a CGAL::Object, for efficiency reasons.

  - The Kernel archetypes provided by the 2D/3D linear kernel have been
    removed.

  - The deprecated linear kernel functors Construct_supporting_line_2 and
    Construct_supporting_line_3 have been removed.

  - Ambiant_dimension and Feature_dimenison have been added to retrieve the
    potentially compile-time dimension of a space or of an object.

  - barycenter() functions have been added.

  - The geometric object Circle_3 as well as predicates and constructions have
    been added to the kernel

  - The missing intersection/do_intersect between Line_3 and Line_3 has been
    added as well.


* 3D Triangulations

  - Removed the deprecated functions Cell:mirror_index() and Cell::
    mirror_vertex().

  - Derecursification of two functions that in some cases lead to stack
    overflows


* 3D Nef Polyhedron

  - n-ary union/intersection

  - intersection with halfspace under standard kernel

  - constructor for polylines


* CGAL and the Qt4 GraphicsView (new package)

  - 2D CGAL Kernel objects and many data structures have can be rendered in a
    QGraphicsView


* STL Extensions:

  - The functor adaptors for argument binding and composition (bind_*, compose,
    compose_shared, swap_*, negate, along with the helper functions set_arity_*
    and Arity class and Arity_tag typedefs) which were provided by <CGAL/
    functional.h> have been removed. Please use the better boost::bind mecanism
    instead. The concept AdaptableFunctor has been changed accordingly such
    that only a nested result_type is required.

  - The accessory classes Twotuple, Threetuple, Fourtuple and Sixtuple are also
    deprecated (use CGAL::array instead).

  - CGAL::Triple and CGAL::Quadruple are in the process of being replaced by
    boost::tuple. As a first step, we strongly recommend that you replace the
    direct access to the data members (.first, .second, .third, .fourth), by
    the get<i>() member function; and replace the make_triple and
    make_quadruple maker functions by make_tuple.
    This way, in a further release, we will be able to switch to boost::tuple
    more easily.

  - The class CGAL::Uncertain<> has been documented. It is typically used to
    report uncertain results for predicates using interval arithmetic, and
    other filtering techniques.


* 2D Arrangements

  - Changed the name of the arrangement package from Arrangement_2 to
    Arrangement_on_surface_2 to reflect the potential capabilities of the
    package to construct and maintain arrangements induced by curves embedded
    on two dimensional surfaces in three space. Most of these capabilities will
    become available only in future releases though.

  - Enhanced the geometry traits concept to handle arrangements embedded on
    surfaces. Each geometry-traits class must now define the
    'Boundary_category' tag.

  - Fixed a bug in Arr_polyline_traits_2.h, where the operator that compares
    two curves failed to evaluate the correct result (true) when the curves are
    different, but their graphs are identical.

  - Permanently removed IO/Arr_postscript_file_stream.h and IO/
    Polyline_2_postscript_file_stream.h, as they depend on obsolete features
    and LEDA.

  - Fixed several bugs in the arrangement demo and enhanced it. e.g., fixed
    background color change, allowed vertex coloring , enabled "smart" color
    selection, etc.

  - Enhanced the arrangement demo with new features, such as allowing the
    abortion of the merge function (de-select), updated the how-to description,
    etc.

  - Replace the functions CGAL::insert_curve(), CGAL::insert_curves(), CGAL::
    insert_x_monotone_curve(), and CGAL::insert_x_monotone_curves() with a
    single overloaded function CGAL::insert(). The former 4 functions are now
    deprecated, and may no longer be supported in future releases.


* Envelopes of Surfaces in 3D

  - Fixed a bug in the computation of the envelope of unbounded planes caused
    by multiple removals of vertices at infinity.


* 2D Regularized Boolean Set-Operations

  - Fixed a bug in connect_holes() that caused failures when connecting holes
    touching the outer boundary.

  - Fixed the concept GeneralPolygonSetTraits_2. Introduced two new concepts
    GpsTraitsGeneralPolygon_2 and GpsTraitsGeneralPolygonWithHoles_2. Fixed the
    definition of the two nested required types Polygon_2 and
    Polygon_with_holes_2 of the GeneralPolygonSetTraits_2 concept. They must
    model now the two new concepts above.

  - Added a default template parameter to 'General_polygon_set_2' to allow
    users to pass their specialized DCEL used to instantiate the underlying
    arrangement.

  - Enhanced the BOP demo to use multiple windows.


* 2D Minkowski Sums

  - Fixed a few bugs in the approximate offset function, making it robust to
    highly degenerate inputs.

  - Fixed a bug in the exact Minkowski sum computation when processing
    degenerate inputs that induce overlapping of contiguous segments in the
    convolution cycles.

  - Optimized the approximate offset function (reduced time consumption up to a
    factor of 2 in some cases).

  - Added functionality to compute the offset (or to approximate the offset) of
    a Polygon_with_holes_2 (and not just of a Polygon_2).

  - Added the functionality to compute (or to approximate) the inner offset of
    a polygon.


-------------------------------- Release 3.3.1 --------------------------------

Release date: August 2007

This is a bug fix release.


* General

  - Intel C++ 9 was wrongly recognized as unsupported by install_cgal.

  - Added autolink (for Visual C++) for the CGALImageIO and CGALPDB libraries.

  - Fixed bug in Memory_sizer when using more than 4GB of memory (64bit).


* Number Types

  - Fixed bug in FPU rounding mode macros (affected only the alpha
    architecture).

  - Fixed bug in MP_Float constructor from double for some particular values.

  - Fixed bug in to_double(Lazy_exact_nt) sometimes returning NaN.


* Kernel

  - Fixed forgotten derivation in Circular_kernel_2::Has_on_2

  - Added some missing functions in Bbox_3 compared to Bbox_2.


* Skin Surface Meshing

  - The new Skin Surface Meshing package had been forgotten in the list of
    changes and the release announcement of CGAL 3.3: This package allows to
    build a triangular mesh of a skin surface. Skin surfaces are used for
    modeling large molecules in biological computing.


* Arrangements

  - Fixed a bug in the Arrangement_2 package in dual arrangement representation
    for Boost graphs when reporting all halfedges of a face.

  - Fixed a bug in the Arrangement sweep-line when using a specific polyline
    configuration.

  - Fixed bug in Arrangement_2 in walk along a line point location for
    unbounded curves.

  - Fixed bug in aggregated insertion to Arrangement_2.

  - Fixed bug in Arrangment_2 class when inserting an unbounded curve from an
    existing vertex.

  - Fixed bug when dealing with a degenerate conic arc in Arr_conic_traits_2 of
    the Arrangment package, meaning a line segment which is part of a
    degenerate parabola/hyperbola.

  - Fixed bug in the Bezier traits-class: properly handle line segments.
    properly handle comparison near a vertical tangency.


* 2D Polygon

  - Fixed bug in degenerate case of Polygon_2::is_convex() for equal points.


* 2D Triangulations

  - Fixed bug in Regular_triangulation_2.


* 3D Triangulations

  - Added a circumcenter() function in the default Cell type parameter
    Triangulation_ds_cell_base_3, so that the .dual() member function of
    Delaunay still work as before, without requiring the explicit use of
    Triangulation_cell_base.

  - Added missing operator->() to Facet_circulator.


* Interpolation

  - Fixed bug in Interpolation 3D about the normalization coefficient
    initialization.


* 3D Boolean Operations on Nef Polyhedra

  - Fixed bug in construction of Nef_polyhedron_3 from off-file. Now, always
    the inner volume is selected.

  - Fixed bug in conversion from Nef_polyhedron_3 to Polyhedron_3. Polyhedron_3
    was not cleared at the beginning.

  - Fixed bug in Nef_polyhedron_3 in update of indexes for construction of
    external structure.


* Third Party Libraries Shipped with CGAL

  - TAUCS supports now 64 bits platforms.

  - CAUTION: Since version 3.3.1, CGAL is no longer compatible with the
    official release of TAUCS (currently 2.2). Make sure to use the version
    modified by the CGAL project and available from the download section of
    http://www.cgal.org.


-------------------------------- Release 3.3 --------------------------------

Release date: May 2007

Version 3.3 differs from version 3.2.1 in the platforms that are supported and
in functionality. There have also been a number of bug fixes for this release.

Additional supported platforms

  - GNU g++ 4.1 and 4.2

  - Intel C++ compiler 9

  - Microsoft Visual C++ compiler 8.0


The following platforms are no longer supported:

  - Intel 8


CGAL now supports Visual C++ "Checked iterators" as well as the debug mode of
GNU g++'s STL (-D_GLIBCXX_DEBUG).

CGAL now works around the preprocessor macros 'min' and 'max' defined in
<windows.h> which were clashing with min/max functions.


* Installation

  - On Windows the libraries built in Developer Studio now have names which
    encode the compiler version, the runtime and whether it was built in
    release or debug mode. The libraries to link against are chosen with linker
    pragmas in header files.

  - On all platforms but Windows shared and static versions of the libraries
    are generated


* Manuals

  - The Package Overview page now also hosts the precompiled demos.


* Algebraic Foundations

  - Algebraic Foundations (new package)
    This package defines what algebra means for CGAL, in terms of concepts,
    classes and functions. The main features are: (i) explicit concepts for
    interoperability of types (ii) separation between algebraic types (not
    necessarily embeddable into the reals), and number types (embeddable into
    the reals).

  - Number Types
    Fixed_precision_nt and Filtered_exact number types have been removed.



* Kernels

  - 2D Circular Kernel
    Efficiency improved through geometric filtering of predicates, introduced
    with the filtered kernel Filtered_bbox_circular_kernel_2<.>, and also
    chosen for the predefined kernel Exact_circular_kernel_2.

  - Linear Kernel
    Exact_predicates_exact_constructions_kernel memory and run-time
    improvements through usage of lazy geometric constructions instead of lazy
    arithmetic.



* Data Structures and Algorithms

  - Surface Mesh Simplification (new package)
    This package provides a mesh simplification framework using edge collapse
    operations, and provides the Turk/Lindstrom simplification algorithm.

  - Skin Surface Meshing (new package)
    This package allows to build a triangular mesh of a skin surface. Skin
    surfaces are used for modeling large molecules in biological computing. The
    surface is defined by a set of balls, representing the atoms of the
    molecule, and a shrink factor that determines the size of the smooth
    patches gluing the balls together.

  - Estimation of Local Differential Properties (new package)
    This package allows to compute local differential quantities of a surface
    from a point sample

  - Approximation of Ridges and Umbilics on Triangulated Surface Meshes (new
    package)
    This package enables the approximation of differential features on
    triangulated surface meshes. Such curvature related features are lines:
    ridges or crests, and points: umbilics.

  - Envelopes of Curves in 2D (new package)
    This package contains two sets of functions that construct the lower and
    upper envelope diagram for a given range of bounded or unbounded curves.

  - Envelopes of Surfaces in 3D (new package)
    This package contains two sets of functions that construct the lower and
    upper envelope diagram for a given range of bounded or unbounded surfaces.
    The envelope diagram is realized as a 2D arrangement.

  - Minkowski Sums in 2D (new package)
    This package contains functions for computing planar Minkowski sums of two
    closed polygons, and for a polygon and a disc (an operation also known as
    offsetting or dilating a polygon). The package also contains an efficient
    approximation algorithm for the offset computation, which provides a
    guaranteed approximation bound while significantly expediting the running
    times w.r.t. the exact computation procedure.

  - Surface Mesh Parametrization
    Added Jacobi and SSOR preconditioners to OpenNL solver, which makes it much
    faster and more stable.

  - 2D Arrangements

      - Added support for unbounded curves.

      - Added a traits class that supports bounded and unbounded linear
        objects, namely lines, rays and line segments.

      - Added traits classes that handle circular arcs based on the circular
        kernel.

      - Added a traits class that supports Bezier curves.

      - Enhanced the traits class that supports rational functions to handle
        unbounded (as well as bounded) arcs

      - Added a free function called decompose() that produces the symbolic
        vertical decomposition of a given arrangement, performing a batched
        vertical ray-shooting query from all arrangement vertices.

      - Fixed a memory leak in the sweep-line code.

      - Fixed a bug in computing the minor axis of non-degenerate hyperbolas.


  - Boolean Set Operations

      - Added the DCEL as a default template parameter to the
        General_polygon_set_2 and Polygon_set_2 classes. This allows users to
        extend the DCEL of the underlying arrangement.

      - Added a function template called connect_holes() that connects the
        holes in a given polygon with holes, turning it into a sequence of
        points, where the holes are connceted to the outer boundary using zero-
        width passages.

      - Added a non-const function member to General_polygon_set_2 that obtains
        the underlying arrangement.


  - 2D and 3D Triangulations

      - The constructors and insert member functions which take an iterator
        range perform spatial sorting in order to speed up the insertion.


  - Optimal Distances

      - Polytope_distance_d: has support for homogeneous points; bugfix in fast
        exact version.


  - Bounding Volumes

      - Min_annulus_d has support for homogeneous points; bugfix in fast exact
        version.




* Support Library

  - CGAL and the Boost Graph Library (BGL) (new package)
    This package provides the glue layer for several CGAL data structures such
    that they become models of the BGL graph concept.

  - Spatial Sorting (new package)
    This package allows to sort points and other objects along a Hilbert curve
    which can improve the performance of algorithms like triangulations. It is
    used by the constructors of the triangulation package which have an
    iterator range of points as argument.

  - Linear and Quadratic Programming Solver (new package)
    This package contains algorithms for minimizing linear and convex quadratic
    functions over polyhedral domains, described by linear equations and
    inequalities.


-------------------------------- Release 3.2.1 --------------------------------

Release date: July 2006

This is a bug fix release


* Number Types

  - Fix MP_Float constructor which crashed for some values.


* Kernel

  - Rename Bool to avoid a clash with a macro in X11 headers.


* Arrangement

  - Derived the Arr_segment_traits_2 Arrangement_2 traits class from the
    parameterized Kernel. This allows the use of this traits class in an
    extended range of applications that require kernel objects and operations
    on these objects beyond the ones required by the Arrangement_2 class
    itself.

  - Fixed a compilation bug in the code that handles overlay of arrangements
    instantiated with different DCEL classes.

  - Fixed a couple of bugs in the implementation of the Trapezoidal RIC point-
    location strategy


* Triangulation, Alpha Shapes

  - Qualify calls to filter_iterator with "CGAL::" to avoid overload
    ambiguities with Boost's filter_iterator.


* Surface Mesher

  - Fixed a bug in iterators of the class template
    Surface_mesh_complex_2_in_triangulation_3


* Surface Mesh Parametrisation

  - Updated the precompiled taucs lib


* Kinetic Data Structures

  - Fixed problems caused by old versions of gcc being confused by operator!
    and operator int()

  - Added point removal support to the Active_objects_vector


-------------------------------- Release 3.2 --------------------------------

Release date: May 2006

Version 3.2 differs from version 3.1 in the platforms that are supported and in
functionality. There have also been a number of bug fixes for this release.

The following platforms are no longer supported:

  - SunPro CC versions 5.4 and 5.5 on Solaris

  - SGI Mips Pro


For Visual C++ the installation scripts choose the multi-threaded dynamically
linked runtime (/MD). Before it was the single-threaded static runtime (/ML).


* Installation

  - The install tool tries to find third party libraries at "standard"
    locations.

  - Installers for Apple, Windows, and rpms.


* Manuals

  - User and Reference manual pages of a package are in the same chapter


* Kernels

  - 2D Circular Kernel (new package)
    This package is an extension of the linear CGAL Kernel. It offers
    functionalities on circles, circular arcs and line segments in the plane.



* Data Structures and Algorithms

  - 2D Regularized Boolean Set-Operations (new package)
    This package consists of the implementation of Boolean set-operations on
    point sets bounded by weakly x-monotone curves in 2-dimensional Euclidean
    space. In particular, it contains the implementation of regularized Boolean
    set-operations, intersection predicates, and point containment predicates.

  - 2D Straight Skeleton and Polygon Offsetting (new package)
    This package implements an algorithm to construct a halfedge data structure
    representing the straight skeleton in the interior of 2D polygons with
    holes and an algorithm to construct inward offset polygons at any offset
    distance given a straight skeleton.

  - 2D Voronoi Diagram Adaptor (new package)
    This package provides an adaptor that adapts a 2-dimensional triangulated
    Delaunay graph to the corresponding Voronoi diagram, represented as a
    doubly connected edge list (DCEL) data structure. The adaptor has the
    ability to automatically eliminate, in a consistent manner, degenerate
    features of the Voronoi diagram, that are artifacts of the requirement that
    Delaunay graphs should be triangulated even in degenerate configurations.
    Depending on the type of operations that the underlying Delaunay graph
    supports, the adaptor allows for the incremental or dynamic construction of
    Voronoi diagrams and can support point location queries.

  - 3D Surface Mesher (new package)
    This package provides functions to generate surface meshes that interpolate
    smooth surfaces. The meshing algorithm is based on Delaunay refinement and
    provides some guarantees on the resulting mesh: the user is able to control
    the size and shape of the mesh elements and the accuracy of the surface
    approximation. There is no restriction on the topology and number of
    components of input surfaces. The surface mesher may also be used for non
    smooth surfaces but without guarantee.
    Currently, implementations are provided for implicit surfaces described as
    the zero level set of some function and surfaces described as a gray level
    set in a three-dimensional image.


  - 3D Surface Subdivision Methods (new package)
    Subdivision methods recursively refine a control mesh and generate points
    approximating the limit surface. This package consists of four popular
    subdivision methods and their refinement hosts. Supported subdivision
    methods include Catmull-Clark, Loop, Doo-Sabin and sqrt(3) subdivisions.
    Their respective refinement hosts are PQQ, PTQ, DQQ and sqrt(3)
    refinements. Variations of those methods can be easily extended by
    substituting the geometry computation of the refinement host.

  - Planar Parameterization of Triangulated Surface Meshes (new package)
    Parameterizing a surface amounts to finding a one-to-one mapping from a
    suitable domain to the surface. In this package, we focus on triangulated
    surfaces that are homeomorphic to a disk and on piecewise linear mappings
    into a planar domain. This package implements some of the state-of-the-art
    surface mesh parameterization methods, such as least squares conformal
    maps, discrete conformal map, discrete authalic parameterization, Floater
    mean value coordinates or Tutte barycentric mapping.

  - Principal Component Analysis (new package)
    This package provides functions to compute global informations on the shape
    of a set of 2D or 3D objects such as points. It provides the computation of
    axis-aligned bounding boxes, centroids of point sets, barycenters of
    weighted point sets, as well as linear least squares fitting for point sets
    in 2D, and point sets as well as triangle sets in 3D.

  - 2D Placement of Streamlines (new package)
    Visualizing vector fields is important for many application domains. A good
    way to do it is to generate streamlines that describe the flow behaviour.
    This package implements the "Farthest Point Seeding" algorithm for placing
    streamlines in 2D vector fields. It generates a list of streamlines
    corresponding to an input flow using a specified separating distance. The
    algorithm uses a Delaunay triangulation to model objects and adress
    different queries, and relies on choosing the centers of the biggest empty
    circles to start the integration of the streamlines.

  - Kinetic Data Structures (new package)
    Kinetic data structures allow combinatorial structures to be maintained as
    the primitives move. The package provides implementations of kinetic data
    structures for Delaunay triangulations in two and three dimensions, sorting
    of points in one dimension and regular triangulations in three dimensions.
    The package supports exact or inexact operations on primitives which move
    along polynomial trajectories.

  - Kinetic Framework (new package)
    Kinetic data structures allow combinatorial geometric structures to be
    maintained as the primitives move. The package provides a framework to ease
    implementing and debugging kinetic data structures. The package supports
    exact or inexact operations on primitives which move along polynomial
    trajectories.

  - Smallest Enclosing Ellipsoid (new package)
    This algorithm is new in the chapter Geometric Optimisation.

  - 2D Arrangement (major revision)
    This package can be used to construct, maintain, alter, and display
    arrangements in the plane. Once an arrangement is constructed, the package
    can be used to obtain results of various queries on the arrangement, such
    as point location. The package also includes generic implementations of two
    algorithmic frameworks, that are, computing the zone of an arrangement, and
    line-sweeping the plane, the arrangements is embedded on.
    Arrangements and arrangement components can also be extended to store
    additional data. An important extension stores the construction history of
    the arrangement, such that it is possible to obtain the originating curve
    of an arrangement subcurve.


  - Geometric Optimisation (major revision)
    The underlying QP solver which is the foundation for several algorithms in
    the Geometric Optimisation chapter has been completely rewritten.

  - 3D Triangulation (new functionality)
    Regular_triangulation_3 now offers vertex removal.



-------------------------------- Release 3.1 --------------------------------

Release date: December 2004

Version 3.1 differs from version 3.0 in the platforms that are supported and in
functionality. There have also been a number of bug fixes for this release.

Additional supported platforms:

  - MS Visual C++, version 7.3. and 8.0

  - Intel 8.0

  - SunPro CC versions 5.4 and 5.5 on Solaris

  - GNU g++ versions 3.4 on Linux, Solaris, Irix, cygwin, FreeBSD, and MacOS X

  - Darwin (MacOS X) and IA64/Linux support.


The following platforms are no longer supported:

  - MS Visual C++, version 7.0


The following functionality has been added or changed:



* All

  - The CORE 1.7 library for exact real arithmetic.

  - Updated GMP to 4.1.3.

  - Added Mpfr a library for multiple-precision floating-point computations
    with exact rounding.

  - Added Boost 1.32.0 (only include files).


* Installation

  - new option --disable-shared to omit building libCGAL.so.


* Manuals

  - Merged all major manuals in one multi-part manual, which provides now
    cross-links between the CGAL Kernel, the CGAL Basic Library, and the CGAL
    Support Library HTML manuals.

  - Improved layout.


* Kernels

  - Improved efficiency of filtered kernels.

  - More predicates and constructions.


* Basic Library

  - 2D Segment Voronoi Diagram (new package)
    A data structure for Voronoi diagrams of segments in the plane under the
    Euclidean metric. The Voronoi edges are arcs of straight lines and
    parabolas. The algorithm provided in this package is incremental.

  - 2D Conforming Triangulations and Meshes (new package)
    An implementation of Shewchuk's algorithm to construct conforming
    triangulations and 2D meshes.

  - 3D Boolean Operations on Nef Polyhedra (new package)
    A new class (Nef_polyhedron_3) representing 3D Nef polyhedra, a boundary
    representation for cell-complexes bounded by halfspaces that supports
    boolean operations and topological operations in full generality including
    unbounded cells, mixed dimensional cells (e.g., isolated vertices and
    antennas). Nef polyhedra distinguish between open and closed sets and can
    represent non-manifold geometry.

  - 2D and Surface Function Interpolation (new package)
    This package implements different methods for scattered data interpolation:
    Given measures of a function on a set of discrete data points, the task is
    to interpolate this function on an arbitrary query point. The package
    further offers functions for natural neighbor interpolation.

  - Planar Nef polyhedra embedded on the sphere (new package)
    A new class (Nef_polyhedron_S2) designed and supported mainly to represent
    sphere neighborhoods around vertices of the three- dimensional Nef
    polyhedra.

  - Box_intersection_d (new package)
    A new efficient algorithm for finding all intersecting pairs for large
    numbers of iso-oriented boxes, i.e., typically these will be bounding boxes
    of more complicated geometries. Useful for (self-) intersection tests of
    surfaces etc.

  - 2D Snap Rounding (new package)
    Snap Rounding is a well known method for converting arbitrary-precision
    arrangements of segments into a fixed-precision representation. In the
    study of robust geometric computing, it can be classified as a finite
    precision approximation technique. Iterated Snap Roundingis a modification
    of Snap Rounding in which each vertex is at least half-the-width-of-a-pixel
    away from any non-incident edge. This package supports both methods.

  - 3D Triangulations

      - Triangulation_3: added operator==(),removed push_back() and
        copy_triangulation().

      - Delaunay_3 : added nearest_vertex(), move_point(), vertices_in_conflict
        ().

      - Regular_3 : added filtered traits class, and nearest_power_vertex().


  - Planar_map and Arrangement_2

      - The interface of the two traits functions that compute the intersection
        of two given curves changed. The functions
        nearest_intersection_to_right() and nearest_intersection_to_left()
        return an object of type CGAL::Object that represents either an empty
        intersection, a point, or an overlapping subcurve.

      - Requirements to define two binary tags were added to the traits concept
        of the Planar_map as follows: Has_left_category - indicates whether the
        functions curves_compare_y_at_x_left() and nearest_intersection_to_left
        () are implemented in the traits model. Has_reflect_category -
        indicates whether the functions point_reflect_in_x_and_y() and
        curve_reflect_in_x_and_y() are implemented in the traits model. They
        can be used as an alternative to the two function in the previous item.

      - A new constructor of the Segment_cached_2 type that represents a
        segment in the Arr_segment_cached_traits_2 traits class was introduced.
        The new constructor accepts the segment endpoints as well as the
        coefficients of the underlying line.

      - A new version of the conic-arc traits, based on CORE version 1.7 was
        introduced. This new traits class makes use of CORE's rootOf() operator
        to compute the intersection points in the arrangement, making its code
        much simpler and more elegant than the previous version. In addition,
        new constructors for conic arcs are provided. The new traits class
        usually performs about 30% faster than the version included in CGAL 3.0

      - The traits class that handles continuous piecewise linear curves,
        namely Arr_polyline_traits_2, was rewritten. The new class is
        parametrized with a traits class that handles segments, say
        Segment_traits. The polyline curve defined within the
        Arr_polyline_traits_2 class is implemented as a vector of segments of
        type Segment_traits::Curve_2.

      - A meta traits class, namely Arr_curve_data_traits_2, that extends the
        curve type of the planar-map with arbitrary additional data was
        introduced. It should be instantiated with a regular traits-class and a
        class that contains all extraneous data associated with a curve.

      - The class that represents the trapezoidal-decomposition point location
        strategy was renamed to Pm_trapezoid_ric_point_location.

      - The Arrangement demo was rewritten. It covers many more features, has a
        much better graphical user interface, and comes with online
        documentation.

      - Few bugs in the sweep-line module related to overlapping vertical
        segments were fixed. This module is used by the aggregate insert method
        that inserts a collection of curves at once.


  - Triangulation_2

      - added a filtered trait class in the regular triangulation

      - added split and join operations in the triangulation data structure
        class


  - Alpha_shapes_3

      - major changes in the implementation of the class Alpha_shapes_3.

      - New implementation results in a true GENERAL mode allowing null and
        negative alpha-values. It also fixed the edges classification bug and
        introduces a classification of vertices.


  - Min_ellipse_2

      - made access to approximate double representation public

      - fixed bugs in conversion to double representation

      - added is_circle() method

      - minor performance improvements


  - Min_sphere_of_spheres_d:

      - The models Min_sphere_of_spheres_d_traits_2<K,FT,UseSqrt,Algorithm>,
        Min_sphere_of_spheres_d_traits_3<K,FT,UseSqrt,Algorithm>, and
        Min_sphere_of_spheres_d_traits_d<K,FT,Dim,UseSqrt,Algorithm> of concept
        MinSphereOfSpheresTraits now represent a sphere as a std::
        pair<Point,Radius> (and not any more as a CGAL::
        Weighted_point<Point,Weight>)

      - Internal code cleanup; in particular, implementation details don't
        pollute the namespace CGAL anymore


  - Polyhedron_3

      - New Tutorial on CGAL Polyhedron for Subdivision Algorithms with
        interactive demo viewer in source code available.

      - Added example program for efficient self-intersection test. - Added
        small helper functions, such as vertex_degree, facet_degree, edge_flip,
        and is_closed.


  - Apollonius Graph (Voronoi of Circles)

      - Reduced memory requirements by approximately a factor of two.



-------------------------------- Release 3.0.1 --------------------------------

Release date: February 2004

This is a bug-fix release. No new features have been added in 3.0.1. Here is
the list of bug-fixes.


* Polyhedral Surface

  - Fixed wrong include files for output support. Added example.


* Planar_map

  - Fixed the so called "Walk-along-a-line" point-location strategy to
    correctly handle a degenerate case.


* 2D Triangulation

  - added missing figure in html doc

  - in Line_face_circulator_2.h:
    Fixed changes made to support handles with a typedef to iterator. The fix
    concerns operator== and !=.


* Alpha_shapes_3

  - fixed classify member function for edges.


* Number types

  - Lazy_exact_nt:

      - added the possibility to select the relative precision of to_double()
        (by default 1e-5). This should fix reports that some circumcenters
        computations have poor coordinates, e.g. nan).

      - when exact computation is triggered, the interval is recomputed, this
        should speed up some kinds of computations.


  - to_interval(Quotient<MP_Float>): avoid spurious overflows.


* Kernel

  - missing acknowledgment in the manual and minor clarification of
    intersection() documentation.


-------------------------------- Release 3.0 --------------------------------

Release date: October 2003

Version 3.0 differs from version 2.4 in the platforms that are supported and in
functionality. There have also been a number of bug fixes for this release.

The license has been changed to either the LGPL (GNU Lesser General Public
License v2.1) or the QPL (Q Public License v1.0) depending on each package. So
CGAL remains free of use for you, if your usage meets the criteria of these
licenses, otherwise, a commercial license has to be purchased from
GeometryFactory.

Additional supported platforms:

  - MS Visual C++, version 7.1.

  - SunPro CC versions 5.4 and 5.5 on Solaris

  - GNU g++ versions 3.2 and 3.3 on Linux, Solaris, Irix, cygwin, and FreeBSD.

  - MipsPRO CC 7.30 and 7.40 with both the n32 and n64 ABIs.


The following platforms are no longer supported:

  - MS Visual C++, version 6.

  - GNU g++ 2.95.2 (2.95.3 is still supported)

  - Kai C++ and Borland C++, all versions


The following functionality has been added or changed:

All

  - The CORE library for exact computations is now distributed as part of CGAL
    as well.



* Kernels

  - 3 typedefs have been added to ease the choice of a robust and fast kernel:

      - Exact_predicates_inexact_constructions_kernel

      - Exact_predicates_exact_constructions_kernel

      - Exact_predicates_exact_constructions_kernel_with_sqrt


  - Progress has been made towards the complete adaptability and extensibility
    of our kernels.

  - New faster Triangle_3 intersection test routines.
    (see Erratum)

  - Added a Kernel concept archetype to check that generic algorithms don't use
    more functionality than they should.

  - A few more miscellaneous functions.


* Basic Library

  - 2D Apollonius Graph (new package)
    Algorithms for computing the Apollonius graph in two dimensions. The
    Apollonius graph is the dual of the Apollonius diagram, also known as the
    additively weighted Voronoi diagram. The latter can be thought of as the
    Voronoi diagram of a set of circles under the Euclidean metric, and it is a
    generalization of the standard Voronoi diagram for points. The algorithms
    provided are dynamic.

  - dD Min Sphere of Spheres (new package)
    Algorithms to compute the smallest enclosing sphere of a given set of
    spheres in Rd. The package provides an algorithm with maximal expected
    running time O(2O(d) n) and a fast and robust heuristic (for dimension less
    than 30).

  - Spatial Searching (new package)
    Provides exact and approximate distance browsing in a set of points in d-
    dimensional space using implementations of algorithms supporting:

      - both nearest and furthest neighbor searching

      - both exact and approximate searching

      - (approximate) range searching

      - (approximate) k-nearest and k-furthest neighbor searching

      - (approximate) incremental nearest and incremental furthest neighbor
        searching

      - query items representing points and spatial objects.


  - Kd-tree
    this package is deprecated, its documentation is removed. It is replaced by
    the Spatial Searching package.

  - Largest_empty_rectangle_2
    Given a set of points P in the plane, the class
    Largest_empty_iso_rectangle_2 is a data structure that maintains an iso-
    rectangle with the largest area among all iso-rectangles that are inside a
    given iso-rectangle bounding box, and that do not contain any point of the
    point set P.

  - 2D Triangulation and 3D Triangulation

      - The classes Triangulation_data_structure_2 (and 3), which implements
        the data structure for 2D triangulation class, now makes use of CGAL::
        Compact_container (see Support Library section below).

      - The triangulation classes use a Rebind mecanism to provide the full
        flexibility on Vertex and Face base classes. This means that it is
        possible for the user to derive its own Face of Vertex base class,
        adding a functionality that makes use of types defined by the
        triangulation data structure like Face_handle or Vertex_handle.

      - New classes Triangulation_vertex_base_with_info_2 (and 3) and
        Triangulation_face_base_with_info_2 (and 3) to make easier the
        customisation of base classes in most cases.


  - 2D Triangulation

      - Regular triangulation provides an easy access to hidden points.

      - The Triangulation_hierarchy_2, which provide an efficient location data
        structure, can now be used with any 2D triangulation class plugged in
        (including Regular triangulations).


  - 3D Triangulation

      - faster vertex removal function in Delaunay_triangulation_3.

      - Delaunay_triangulation_3 is now independent of the order of insertions
        of the points (in case of degenerate cosphericity).

      - Regular_triangulation_3 now hides vertices (and updates itself) when
        inserting a coinciding point with greater weight. This required a new
        predicate.

      - deprecated functions: copy_triangulation(), push_back(),
        set_number_of_vertices().

      - Triangulation_3 now gives non-const access to the data structure.


  - Interval Skip List (new package)
    An interval skip list is a data strucure for finding all intervals that
    contain a point, and for stabbing queries, that is for answering the
    question whether a given point is contained in an interval or not.

  - Planar Maps and Arrangements
    The changes concern mainly the traits classes.
       1. New traits hierarchy and interface: The set of requirements was made
          sound and complete. A couple of requirements were eliminated, few
          others were redefined, and some were renamed. A hierarchy of three
          traits classes for the Planar_map_2, Planar_map_with_intersections_2,
          and Arrangement_2 types was established to include only the necessary
          requirements at each level. It was determined that for the aggregate
          insertion- operation based on a sweep-line algorithm only a subset of
          the requirements is needed. Preconditions were added where
          appropriate to tighten the requirements further.
          The following functions have been renamed:

            - point_is_same() renamed to point_equal()

            - curve_is_same() renamed to curve_equal()

            - curve_is_in_x_range() renamed to point_in_x_range()

            - curve_compare_at_x() renamed to curves_compare_y_at_x()
              Furthermore, a precondition has been added that the reference
              point is in the x-range of both curves.

            - curve_compare_at_x_right() renamed to
              curves_compare_y_at_x_to_right(). Furthermore, a precondition has
              been added that both curves are equal at the reference point and
              defined to its right.

            - curve_compare_at_x_left() renamed to
              curves_compare_y_at_x_to_left(). Furthermore, a precondition has
              been added that both curves are equal at the reference point and
              defined to its right.

            - curve_get_point_status() renamed to curve_compare_y_at_x().
              Furthermore, a precondition has been added that the point is in
              the x-range of the curve. Consequently, the function now returns
              a Comparison_result (instead of a special enum).

            - make_x_monotone() renamed to curve_make_x_monotone() See more
              details below.

            - curve_flip() renamed to curve_opposite()

          The following functions have been removed:

            - curve_is_between_cw()

            - point_to_left()

            - point_to_right()

            - is_x_monotone()

            - point_reflect_in_x_and_y()

            - curve_reflect_in_x_and_y()

            - do_intersect_to_right()

            - do_intersect_to_left()

          Most functions, are required by the PlanarMapTraits_2 concept, except
          for the make_x_monotone(), nearest_intersection_to_right(),
          nearest_intersection_to_left(), curves_overlap() and curve_opposite
          (). PlanarMapWithIntersectionsTraits_2 requires all these functions,
          except curve_opposite(), needed only by the ArrangementTraits_2
          concept.

          Furthermore, the two functions curve_compare_at_x_left() and
          nearest_intersection_to_left() can be omitted, if the two functions
          point_reflect_in_x() and curve_reflect_in_x() are implemented.
          Reflection can be avoided, if the two _left functions are supplied.

       2. The type X_curve_2 of the PlanarMapWithIntersectionsTraits_2 concept
          was renamed to X_monotone_curve_2, and the distinction between this
          type and the Curve_2 type was made firm. The method is_x_monotone()
          of the PlanarMapWithIntersectionsTraits_2 concept was removed. The
          related method curve_make_x_monotone() is now called for each input
          curve of type Curve_2 when curves are inserted into a
          Planar_map_with_intersections_2 to subdivide the input curve into x-
          monotone sub-curves (and in case the curve is already x-monotone,
          this function is responsible for casting it to an x-monotone curve).
       3. New and improved traits classes:
       4. Conic traits - Arr_conic_traits_2 Support finite segments of
          ellipses, hyperbolas and parabolas, as well as line segments. The
          traits require an exact real number- type, such as leda_real or
          CORE::Expr.
       5. Segment cached traits - Arr_segment_cached_traits_2 This class uses
          an improved representation for segments that helps avoiding cascaded
          computations, thus achieving faster running times. To work properly,
          an exact rational number-type should be used.
       6. Polyline traits - Arr_polyline_traits_2 The polyline traits class has
          been reimplemented to work in a more efficient, generic manner. The
          new class replaces the obsolete Arr_polyline_traits class. It is
          parameterized with a segment traits class.
       7. Hyperbola and segment traits - Arr_hyper_segment_traits_2 Supports
          line segments and segments of canonical hyperbolas. This is the type
          of curves that arise when projecting segments in three-space
          rotationally around a line onto a plane containing the line. Such
          projections are often useful in CAD/CAM problems.
       8. Removed old traits class:

            - The models of the PlanarMapWithIntersectionsTraits_2 concept
              below became obsolete, as the new conic traits, namely
              Arr_conic_traits_2, supports the same functionality and is much
              more efficient.

                - Arr_circles_real_traits

                - Arr_segment_circle_traits


            - The segment traits class and the new polyline traits class were
              reimplemented using standard CGAL-kernel calls. This essentially
              eliminated the corresponding leda traits classes, namely:

                - Pm_leda_segment_traits_2

                - Arr_leda_segment_traits_2

                - Arr_leda_polyline_traits

              With the use of the Leda_rat_kernel new external package the same
              functionality can be achieved with less overhead and more
              efficiency.

       9. Sweep Line

            - The Sweep_line_2 package was reimplemented. As a consequence it
              is much more efficient, its traits is tighter (namely neither the
              two _left nor the reflection functions are required), and its
              interface has changed a bit.
                 1. The following global functions have been removed:

                      - sweep_to_produce_subcurves_2()

                      - sweep_to_produce_points_2()

                      - sweep_to_construct_planar_map_2()

                    Instead, the public methods of the Sweep_line_2 class
                    listed below were introduced:

                      - get_subcurves() - Given a container of curves, this
                        function returns a list of curves that are created by
                        intersecting the input curves.

                      - get_intersection_points() - Given a range of curves,
                        this function returns a list of points that are the
                        intersection points of the curves.

                      - get_intersecting_curves() - Given a range of curves,
                        this function returns an iterator to the beginning of a
                        range that contains the list of curves for each
                        intersection point between any two curves in the
                        specified range.

                 2. It is possible to construct a planar map with intersections
                    (or an arrangement) by inserting a range of curves into an
                    empty map. This will invoke the sweep-line process to
                    construct the map more efficiently.

            - New interface functions to the Planar_map_with_intersections_2
              class. The Planar_map_with_intersections_2 class maintains a
              planar map of input curves that possibly intersect each other and
              are not necessarily x-monotone. If an input curve, or a set of
              input curves, are known to be x-monotone and pairwise disjoint,
              the new functions below can be used to insert them into the map
              efficiently.


  - Polyhedral Surface

      - The old design that was deprecated since CGAL 2.3 has been removed.

      - Class Polyhedron_incremental_builder_3:

          - Renamed local enum ABSOLUTE to ABSOLUTE_INDEXING, and RELATIVE to
            RELATIVE_INDEXING to avoid conflicts with similarly named macros of
            another library.

          - Changed member functions add_vertex(), begin_facet(), and end_facet
            () to return useful handles.

          - Added test_facet() to check facets for validity before adding them.

          - Added vertex( size_t i) to return Vertex_handle for index i.



  - Halfedge Data Structure

      - The old design that was deprecated since CGAL 2.3 has been removed.



* Support Library

  - New container class Compact_container, which (roughly) provides the
    flexibility of std::list, with the memory compactness of std::vector.

  - Geomview_stream: added a function gv.draw_triangles(InputIterator begin,
    InputIterator end) which draws a set of triangles much more quickly than
    one by one.

  - Number types:

      - number types are now required to provide a function: std::pair<double,
        double> to_interval(const NT &amp;).

      - number types are now required to provide mixed operators with "int".

      - CLN support removed.

      - faster square() for MP_Float.

      - added Gmp_q.


  - Qt_widget:

      - New classes:

          - Qt_help_window: provides a simple way to show some helpful
            information about a demo as an HTML page.

          - Qt_widget_history: provides basic functionality to manipulate
            intervals of Qt_widget class. The current visible area of Qt_widget
            is mapped to an interval. Each interval could be stored in the
            Qt_widget_history object. So you can use this object to navigate in
            history. It is mostly used by Qt_widget_standard_toolbar.


      - Changes:

          - Qt_widget_standard_toolbar: is derived from QToolBar class, so pay
            attention to modify your code, if you used this class. Some public
            methods were introduced to control the history object that the
            toolbar use to navigate.

          - the icons are now part of libCGALQt.


      - Deprecated members of Qt_widget:

          - add_to_history(), clear_history(), back(), forth(): use forward(),
            back() and clear_history() of the Qt_widget_standard_toolbar
            instead.

          - custom_redraw(): use redraw_on_back() and redraw_on_front()
            instead.


      - Optimizations: the output operators of the following classes have been
        optimized:

          - CGAL::Segment_2 (now tests for intersection with the drawing area)

          - CGAL::Triangle_2 (now tests for intersection with the drawing area)

          - CGAL::Triangulation_2 (is optimized for faster display on zooming)




* Erratum in the Kernel manual

  - Intersection test routines
    The documentation of CGAL::do_intersect should mention, for the 3D case:
    Also, in three-dimensional space Type1 can be

      - either Plane_3<Kernel>

      - or Triangle_3<Kernel>

    and Type2 any of

      - Plane_3<Kernel>

      - Line_3<Kernel>

      - Ray_3<Kernel>

      - Segment_3<Kernel>

      - Triangle_3<Kernel>


    In the same way, for Kernel::DoIntersect_3:
    for all pairs Type1 and Type2, where the type Type1 is

      - either Kernel::Plane_3

      - or Kernel::Triangle_3

    and Type2 can be any of the following:

      - Kernel::Plane_3

      - Kernel::Line_3

      - Kernel::Ray_3

      - Kernel::Segment_3

      - Kernel::Triangle_3


    Philippe Guigue (INRIA Sophia-Antipolis) should be mentioned as one of the
    authors.



-------------------------------- Release 2.4 --------------------------------

Release date: May 2002

Version 2.4 differs from version 2.3 in the platforms that are supported and in
functionality. There have also been a number of bug fixes for this release.

Additional supported platforms:

  - Microsoft Visual C++, version 7.

  - SunPro 5.3 (with patch 111685-05) on Solaris

  - g++ 3.1 on Linux and Solaris


The following functionality has been added or changed:



* Kernels

  - Point_d has been removed from the 2D and 3D kernels. This type is now
    available from the d-dimensional kernel only.


* Basic Library

  - 2D Polygon Partitioning
    Traits requirements for optimal partitioning have been changed slightly.


  - 2D Sweep line
    A new package that implements a sweep-line algorithm to compute
    arrangements of curves for different families of curves, which are not
    necessarily line segments (e.g., it also works for circular arcs). The
    resulting output can be the list of vertex points, the resulting subcurves
    or a planar map.


  - Planar Maps and Arrangements

      - New quicker insertion functions of Planar_map_2 for cases where more
        precomputed information is available regarding the position of the
        inserted curve in the map.

      - New query function for planar maps that determines whether a given
        point is within a given face of the planar map.

      - New iterator over edges of planar maps in addition to the existing
        iterator over halfedges.

      - New copy constructor and assignment operator for arrangements.




  - Polyhedral Surface

      - new design introduced with release 2.3 now supported by VC7 compiler

      - Extended functionality of Polyhedron_incremental_builder: absolute
        indexing allows one to add new surfaces to existing ones.




  - 2D Triangulation

      - There is a new triangulation data structure replacing the two previous
        ones. This new data structure is coherent with the 3d triangulation
        data structure and offer the advantages of both previous ones. Backward
        compatibility is ensured and this change is transparent for the user of
        triangulation classes.

      - Constrained and Delaunay constrained triangulations are now able to
        handle intersecting input constraints. The behavior of constrained
        triangulations with repect to intersection of input constraints can be
        customized using an intersection tag.

      - A new class Constrained_triangulation_plus offers a constrained
        hierarchy on top of a constrained triangulations. This additionnal data
        structure describes the subdivision of the original constraints into
        edges of the triangulations.




  - 3D Triangulation

      - Running time improved by a better and more compact management of memory
        allocation

      - Various improvements and small functionalities added:

          - Triangulation_3<GT,Tds>::triangle() returns a triangle oriented
            towards the outside of the cell c for facet (c,i)

          - New function insert(Point, Locate_type, Cell_handle, int, int)
            which avoids the location step.

          - New function to get access to cells in conflict in a Delaunay
            insertion : find_conflicts() and insert_in_hole()

          - New function TDS::delete_cells(begin, end).

          - New functions : degree(v), reorient(), remove_decrease_dimension(),
            remove_from_simplex().


      - Changes of interface:

          - vertices and cells are the same for the triangulation data
            structure and the geometric triangulation

          - the triangulation data structure uses Vertex_handle (resp
            Cell_handle) instead of Vertex* (resp Cell*).

          - incident_cells() and incident_vertices() are templated by output
            iterators

          - changes in the iterators and circulators interface:

              - Iterators and circulators are convertible to handles
                automatically, no need to call "->handle()" anymore.

              - Vertex_iterator split into All_vertices_iterator and
                Finite_vertices_iterator (and similar for cells...).

              - TDS::Edge/Facet iterators now support operator->.






  - 2D Search structures
    Additional range search operations taking a predicate functor have been
    added


* Support Library

  - Qt_widget

      - We have added a new class for visualization of 2D CGAL objects. It is
        derived from Trolltech's Qt class QWidget and privdes a used to scale
        and pan.

      - Some demos were developed for the following packages: 2D Alpha shapes,
        2D Convex Hull, Largest empty 2D rectangle, Maximum k-gon, Minimum
        ellipse, Minimum 2D quadrilateral, 2D polygon partitioning 2D regular
        and constrained triangulation.

      - Tutorials are available to help users get used to Qt_widget




  - Timer
    Fixed Timer class (for user process time) to have no wrap-around anymore on
    Posix-compliant systems.

The following functionality is no longer supported:

  - Planar maps of infinite curves (the so-called planar map bounding-box).


Bugs in the following packages have been fixed: 3D Convex hull, 2D Polygon
partition, simple polygon generator

Also attempts have been made to assure compatability with the upcoming LEDA
release that introduces the leda namespace.


* Known problems

  - 2D Nef Polyhedra contains a memory leak. Memory problems are also the
    likely cause of occasional run-time errors on some platforms.

  - The d-dimensional convex hull computation produces run-time errors on some
    platforms because of memory management bugs.

  - The new Halfedge Data Structure design introduced with release 2.3 does not
    work on VC6. See the release notes in the manual for more information.

  - The following deficiencies relate to planar maps, planar maps of
    intersecting curves (pmwx), arrangements and sweep line.

      - On KCC, Borland and SunPro we guarantee neither compilation nor correct
        execution for all of the packages above.

      - On VC6 and VC7 we guarantee neither compilation nor correct execution
        of the sweep line package.

      - On CC (on Irix 6.5) the trapezoidal decomposition point location
        strategy is problematic when used with planar maps, pmwx, or
        arrangements (mind that this is the default for planar maps).

      - On CC (on Irix 6.5) sweep line with polyline traits does not compile
        (mind that the so-called leda polyline traits does compile).

      - On g++ (on Irix 6.5) the segment-circle (Arr_segment_circle_traits_2)
        traits does not compile for either of the above packages.



-------------------------------- Release 2.3 --------------------------------

Release date: August 2001

Version 2.3 differs from version 2.2 in the platforms that are supported and in
functionality.

Additional supported platform:

  - Gnu g++ 3.0 on Solaris and Linux


The following functionality has been added:



* Kernels

  - The 2D and 3D kernels now serve as models of the new kernel concept
    described in the recent paper, "An Adaptable and Extensible Geometry
    Kernel" by Susan Hert, Micheal Hoffmann, Lutz Kettner, Sylvain Pion, and
    Michael Seel to be presented at WAE 2001 (and soon available as a technical
    report). This new kernel is completely compatible with the previous design
    but is more flexible in that it allows geometric predicates as well as
    objects to be easily exchanged and adapted individually to users' needs.

  - A new kernel called Simple_homogeneous is available. It is equivalent to
    Homogeneous but without reference-counted objects.

  - A new kernel called Filtered_kernel is available that allows one to build
    kernel traits classes that use exact and efficient predicates.

  - There are two classes, Cartesian_converter and Homogeneous_converter that
    allows one to convert objects between different Cartesian and homogeneous
    kernels, respectively.

  - A new d-dimensional kernel, Kernel_d is available. It provides diverse
    kernel objects, predicates and constructions in d dimensions with two
    representations based on the kernel families Cartesean_d and Homogeneous_d


* Basic Library
Almost all packages in the basic library have been adapted to the new kernel
design to realize the flexibility this design makes possible. In several
packages, this means that the traits class requirements have changed to conform
to the function objects offered in the kernels so the kernels themselves can be
used as traits classes in many instances.


  - 2D Convex Hull
    The traits requirements have changed slightly to bring them in line with
    the CGAL kernels.

  - 3D Convex Hull

      - The function convex_hull_3 now uses a new implementation of the
        quickhull algorithm and no longer requires LEDA.

      - A new convex_hull_incremental_3 function based on the new d-dimensional
        convex hull class is available for comparison purposes.



  - Convex_hull_d, Delaunay_d
    Two new application classes offering the calculation of d-dimensional
    convex hulls and delaunay triangulations


  - Polygons and Polygon Operations

      - The traits class requirements have been changed.

      - The simplicity test has a completely new implementation.

      - Properties like convexity, simplicity and area can now be cached by
        polygons. You need to set a flag to select this behaviour.





  - Planar Nef Polyhedra
    A new class (Nef_polyhedron_2) representing planar Nef polyhedra =
    rectilinearly bounded points sets that are the result of binary and
    topological operations starting from halfplanes.


  - A new package offering functions to partition planar polygons into convex
    and y-monotone pieces is available.


  - Planar Maps and Arrangements

      - A new class Planar_map_with_intersections_2<Planar_map> for planar maps
        of possibly intersecting, possibly non-x-monotone, possibly overlapping
        curves (like Arrangement_2 but without the hierarchy tree).

      - I/O utilities for planar maps and arrangements for textual and
        graphical streams. (It is possible to save and later reload built
        planar maps or arrangements.)

      - New arrangement traits class for line segments and circular arcs
        (Arr_segment_circle_traits<NT>).

      - New faster traits for polylines specialized for using the LEDA rational
        kernel (Arr_leda_polylines_traits). The LEDA traits for segments was
        also made faster.

      - A new point location strategy (Pm_simple_point_location<Planar_map>).




  - Halfedge Data Structure

    The halfedge data structure has been completely revised. The new design is
    more in line with the STL naming scheme and it provides a safe and coherent
    type system throughout the whole design (no void* pointers anymore), which
    allows for better extendibility. A user can add new incidences in the mesh
    easily. The new design also uses standard allocators with a new template
    parameter that has a suitable default.

    The old design is still available, but its use is deprecated, see the
    manual of deprecated packages for its documentation. Reported bugs in
    copying the halfedge data structure (and therefore also polyhedral
    surfaces) have been fixed in both designs. Copying a list-based
    representation is now based on hash maps instead of std::map and is
    therefore considerably faster.


  - Polyhedral Surface

    The polyhedral surface has been rewritten to work with the new halfedge
    data structure design. The user level interface of the CGAL::Polyhedron_3
    class is almost backwards compatible with the previous class. The
    exceptions are the template parameter list, everything that relies on the
    flexibility of the underlying halfedge data structure, such as a self-
    written facet class, and that the distinction between supported normals and
    supported planes has been removed. Only planes are supported. See the
    manuals for suggestions how to handle normals instead of planes.

    More example programs are provided with polyhedral surfaces, for example,
    one about Euler operator and one computing a subdivision surface given a
    control mesh as input.

    The old design is still available for backwards compatibility and to
    support older compiler, such as MSVC++6.0. For the polyhedral surface, old
    and new design cannot be used simultaneously (they have identical include
    file names and class names). The include files select automatically the old
    design for MSVC++6.0 and the new design otherwise. This automatism can be
    overwritten by defining appropriate macros before the include files. The
    old design is selected with the CGAL_USE_POLYHEDRON_DESIGN_ONE macro. The
    new design is selected with the CGAL_USE_POLYHEDRON_DESIGN_TWO macro.


  - 2D Triangulation

      - The geometric traits class requirements have been changed to conform to
        the new CGAL kernels. CGAL kernel classes can be used as traits classes
        for all 2D triangulations except for regular triangulations.

      - Additionnal functionality:

          - dual method for regular triangulations (to build a power diagram)

          - unified names and signatures for various "find_conflicts()" member
            functions in Delaunay and constrained Delaunay triangulation.

          - As an alternative to the simple insert() member function, insertion
            of points in those triangulation can be performed using the
            combination of find_conflicts() and star_hole() which eventually
            allows the user to keep track of deleted faces.


      - More demos and examples



  - 3D Triangulation

      - Major improvements

          - A new class Triangulation_hierarchy_3 that allows a faster point
            location, and thus construction of the Delaunay triangulation

          - A new method for removing a vertex from a Delaunay triangulation
            that solves all degenerate cases

          - Running time of the usual location and insertion methods improved


      - A bit more functionality, such as

          - New geomview output

          - dual methods in Delaunay triangulations to draw the Voronoi diagram


      - More demos and examples

      - Changes in interface

          - Traits classes requirements have been modified

          - The kernel can be used directly as a traits class (except for
            regular triangulation)

          - insert methods in Triangulation_data_structure have a new interface




  - A new class (Alpha_shapes_3) that computes Alpha shapes of point sets in 3D
    is available.


  - The traits requirements for matrix search and minimum quadrilaterals have
    been changed to bring them in line with the CGAL kernels.


  - Point_set_2

      - now independent of LEDA; based on the CGAL Delaunay triangulation

      - traits class requirements adapted to new kernel concept.

      - function template versions of the provided query operations are
        available



* Support Library

  - Number types:

      - Lazy_exact_nt<NT> is a new number type wrapper to speed up exact number
        types.

      - MP_Float is a new multiprecision floating point number type. It can do
        exact additions, subtractions and multiplications over floating point
        values.


  - In_place_list has a new third template parameter (with a suitable default)
    for an STL-compliant allocator.

  - Unique_hash_map is a new support class.

  - Union_find is a new support class.

  - Geomview_stream :

      - Geomview version 1.8.1 is now required.

      - no need to have a ~/.geomview file anymore.

      - new output operators for triangulations.

      - new output operators for Ray_2, Line_2, Ray_3, Line_3, Sphere_3.

      - various new manipulators.


  - Window stream In cooperation with Algorithmic Solutions, GmBH (distributors
    of the LEDA library), we can now offer a visualization package downloadable
    in binary form that supports visualization on a ported version of the LEDA
    window lib.


-------------------------------- Release 2.2 --------------------------------

Release date: October 2000

Version 2.2 differs from version 2.1 in the platforms that are supported and in
functionality.

Additional supported platforms:

  - the KAI compiler (4.0) on Solaris 5.8

  - Borland C++ (5.5)


The following functionality has been added:

  - There is a new, non-reference-counted kernel, Simple_cartesian. Because
    reference counting is not used, and thus coordinates are stored within a
    class, debugging is easier using this kernel. This kernel can also be
    faster in some cases than the reference-counted Cartesian kernel.

  - New optimisation algorithms

      - Min_annulus_d - Algorithm for computing the smallest enclosing annulus
        of points in arbitrary dimension

      - Polytope_distance_d - Algorithm for computing the (squared) distance
        between two convex polytopes in arbitrary dimension

      - Width_3 - Algorithm for computing the (squared) width of points sets in
        three dimensions


  - 2D Triangulations

      - There are now two triangulation data structures available in CGAL. The
        new one uses a list to store the faces and allows one to represent two-
        dimensional triangulations embedded in three spaces as well as planar
        triangulations.

      - The triangulation hierarchy which allows fast location query is now
        available.


  - Inifinite objects can now be included in planar maps.

  - Removal as well as insertions of vertices for 3D Delaunay triangulations is
    now possible.

  - A generator for ``random'' simple polygons is now available.

  - In directory demo/Robustness, programs that demonstrate typical robustness
    problems in geometric computing are presented along with the solutions to
    these problems that CGAL provides.


The following functionality has been removed:

  - The binary operations on polygons (union, intersection ...) have been
    removed. Those operations were not documented in the previous release
    (2.1). Arrangements can often be used as a substitute.



-------------------------------- Release 2.1 --------------------------------

Release date: January 2000

Version 2.1 differs from version 2.0 in the platforms that are supported and in
functionality.

Supported platforms:

  - the newest gnu compiler (2.95.2) on Sun, SGI, Linux and Windows.

  - the Microsoft Visual C++ compiler, version 6.

  - the mips CC compiler version 7.3 under Irix.

Support for the old g++ compiler (2.8) and for mips CC 7.2 has been dropped.

The following functionality has been added:

  - Alpha shapes and weighted alpha shapes in 2D. Alpha shapes are a
    generalization of the convex hull of a point set.

  - Arrangements in 2D. Arrangements are related to and based on planar maps.
    The major difference between the two is that curves are allowed to
    intersect in the case of arrangements.

  - Extensions to triangulations in 2D. Constrained triangulations are now
    dynamic: they support insertions of new constraint as well as removal of
    existing constraints. There are also constrained Delaunay triangulations.

  - Triangulations in 3D were added, both Delaunay triangulations and regular
    triangulations.

  - Min_quadrilateral optimisations have been added. These are algorithms to
    compute the minimum enclosing rectangle/parallelogram (arbitrary
    orientation) and the minimum enclosing strip of a convex point set.

  - 2d Point_set is a package for 2d range search operations, Delaunay
    triangulation, nearest neighbor queries. This package works only if LEDA is
    installed.

  - Support for GeoWin visualization library. This also depends on LEDA.

  - Support for using the CLN number type together with CGAL.



-------------------------------- Release 2.0 --------------------------------

Release date: June 1999

The main difference from release 1.2 is the introduction of namespaces -
- namespace std for code from the standard library and namespace CGAL for the
CGAL library.


-------------------------------- Release 1.2 --------------------------------

Release date: January 1999

Additions to release 1.1 include:


  - topological map

  - planar map overlay

  - regular and constrained triangulations


-------------------------------- Release 1.1 --------------------------------

Release date: July 1998

Additions to release 1.0 include:

  - 3D intersections

  - kD points

  - 3D convex hull

  - kD smallest enclosing sphere



-------------------------------- Release 1.0 --------------------------------

Release date: April 1998

Additions to release 0.9 include:

  - Polyhedral surfaces

  - Halfedge Data Structure

  - Planar maps



-------------------------------- Release 0.9 --------------------------------

Release date: June 1997

Initial (beta) release of the CGAL library.

