CGAL users discussion list

[Laurent Rineau <>]

The CGAL Open Source Project is pleased to announce the release
6.0 Beta 1 of CGAL, the Computational Geometry Algorithms Library.

CGAL version 6.0 Beta 1 is a public testing release. It should provide a
solid ground to report bugs that need to be tackled before the release
of the final version of CGAL 6.0 in July 2024.

Besides fixes and general enhancement to existing packages, the
following has changed since CGAL 5.6:

General Changes

-   CGAL 6.0 is the first release of CGAL that requires a C++ compiler
    with the support of C++17 or later. The new list of supported
    compilers is:
    -   Visual C++ 15.9, 16.10, 17.0 (from Visual Studio 2017, 2019
        and 2022) or later
    -   Gnu g++ 11.4.0 or later (on Linux or macOS)
    -   LLVM Clang version 15.0.7 or later (on Linux)
    -   Apple Clang compiler versions 10.0.1, 12.0.5, and 15.0.0 (on
        macOS)
-   The minimal supported version of Boost is now 1.72.0.
-   The CGAL Core library is no longer based on GMP, but on
    Boost.Multiprecision. Either GMP backend or Boost backend can be
    used.
-   All demos are now based on Qt6.
-   Breaking change: The CMake file UseCGAL.cmake has been removed from
    CGAL. Usages of the CMake variables ${CGAL_USE_FILE} and
    ${CGAL_LIBRARIES} must be replaced by a link to the imported target
    CGAL::CGAL, for example:
    target_link_library(your_target PRIVATE CGAL::CGAL).

Kinetic Space Partition (new package)

-   This package implements kinetic space partition: based on a set of
    planar input shapes, the bounding box of the input data is split
    into convex volumes. The complexity of the partition can be adjusted
    with a single parameter.

Kinetic Surface Reconstruction (new package)

-   The package implements a piece-wise planar surface reconstruction
    pipeline from point clouds combining methods from the Shape
    Detection, Shape Regularization and Kinetic Shape Partition packages
    and graph-cut to reconstruct surfaces from point clouds.

Basic Viewer (new package)

-   The basic viewer package provides interactive visualization for most
    CGAL packages, such as 2D Arrangements, 2D Regularized Boolean
    Set-Operations, Linear Cell Complex, 3D Boolean Operations on Nef
    Polyhedra, 2D Periodic Triangulations, 3D Point Set, 2D Polygons, 3D
    Polyhedral Surface, 2D Straight Skeleton and Polygon Offsetting,
    Surface Mesh, 2D Triangulations, 3D Triangulations, 2D Voronoi
    Diagrams, and more. The most simple use case of the basic viewer is
    the call of the global CGAL::draw() function. There is one such
    draw() function for each CGAL package that has a basic viewer. Such
    a call opens an interactive window showing the given model and
    allowing to navigate in the scene, show or hide some specific cells,
    show the interior of the model if any, etc. The Basic_viewer is
    based on Qt6.

Polygon Repair (new package)

-   This package provides algorithms to repair 2D polygons, polygons
    with holes, and multipolygons with holes, by selecting faces of the
    arrangement of the input using the odd-even heuristic.

2D and 3D Linear Geometry Kernel

-   Breaking change: Replaced all instances of boost::variant with
    std::variant in the intersection functions.
-   Breaking change: Replaced all instances of boost::optional with
    std::optional in the intersection functions.

3D Polyhedral Surface

-   The demo of this package, also known as “Polyhedron Demo” has been
    renamed “CGAL Lab” and moved to its own package (“Lab”).

2D and 3D Fast Intersection and Distance Computation (AABB Tree)

-   The AABB tree can now be used with 2D or 3D primitives:
    -   The concepts AABBGeomTraits and AABBRayIntersectionGeomTraits
        have been replaced by AABBGeomTraits_3 and by
        AABBRayIntersectionGeomTraits_3, respectively.
    -   The concepts AABBGeomTraits_2 and
        AABBRayIntersectionGeomTraits_2 have been introduced, as the 2D
        counterparts.
    -   The class CGAL::AABB_traits is deprecated and replaced by
        CGAL::AABB_traits_3.
    -   The class CGAL::AABB_traits_2 is introduced as the 2D
        counterpart.
    -   The class CGAL::AABB_segment_primitive has been deprecated and
        replaced by the class CGAL::AABB_segment_primitive_3.
    -   The class CGAL::AABB_triangle_primitive has been deprecated and
        replaced by the class CGAL::AABB_triangle_primitive_3.
    -   The following 2D primitive classes have been added:
        CGAL::AABB_segment_primitive_2,
        CGAL::AABB_polyline_segment_primitive_2,
        CGAL::AABB_triangle_primitive_2,
        CGAL::AABB_indexed_triangle_primitive_2.
-   Breaking change: The concept AABBTraits now refines the concept
    SearchTraits.
-   Breaking change: Replaced all instances of boost::optional with
    std::optional.

2D Arrangements

-   Breaking change: Replaced all instances of boost::variant with
    std::variant.
-   Breaking change: The type of the result of point location queries
    has been changed to std::variant. Support for the old macro
    CGAL_ARR_POINT_LOCATION_VERSION has been removed.
-   Breaking change: Eliminated the error-prone C-type casting that was
    used to define observers. In general, backward compatibility was
    maintained; however, the class template CGAL::Arr_observer has been
    replaced by an alias template. (The class CGAL::Arr_observer was
    renamed to CGAL::Aos_observer).
-   Introduced Arr_dcel, which essentially replaces the former
    CGAL::Arr_default_dcel. Backward compatibility was maintained by the
    introduction of the alias template CGAL::Arr_default_dcel.
    CGAL::Arr_dcel, as opposed to the former CGAL::Arr_default_dcel is
    templated (in addition to the geometry traits) by Vertex, Halfedge,
    and Face template parameters, and they have default type values. All
    this enables the layered extension of DCEL records.
-   Fixed a bug in the zone construction code applied to arrangements of
    geodesic arcs on a sphere, when inserting an arc that lies on the
    identification curve.
-   Introduced a new interactive program that demonstrates 2D
    arrangements embedded on the sphere called earth. The program (i)
    reads a database of all administrative boundaries of the countries
    in the world, (ii) displays the globe with all countries and land
    covered by water (which is land not covered by countries) on a
    window, and (ii) enables interaction with the user.

3D Envelopes

-   Breaking change: Construct_projected_boundary_2 in EnvelopeTraits_3
    now uses std::variant instead of CGAL::Object.
-   Passed the base class of CGAL::Env_plane_traits_3 as a template
    parameter with a default value (being the 2D arrangement linear
    traits). Similarly, passed the base class of
    CGAL::Env_triangle_traits_3 as a template parameter with a default
    value (being the 2D arrangement segment traits).

Combinatorial Maps and Generalized Maps

-   Added the function insert_cell_1_between_two_cells_2() to the
    GenericMap concept, which enables users to insert an edge between
    two different faces in order to create faces with holes.

-   Added new meshing criterion edge_distance, an upper bound for the
    distance from the edge to the 1D feature.

-   Breaking change: the concept MeshEdgeCriteria_3 was modified to
    include the new meshing criterion edge_distance.

Quadtrees, Octrees, and Orthtrees

-   Breaking change:
    -   Node splitting behavior and per-node data are now customizable
        via the Traits class.
    -   Nodes are now stored as a property map, with properties of each
        node accessed by index.
    -   Nearest neighbors functions only work for Orthtrees which
        provide the necessary functionality.

CGAL and the Boost Graph Library (BGL)

-   Added the function CGAL::remove_all_elements(), which removes
    vertices, halfedges, and faces without collecting garbage and
    without removing properties.
-   Dynamic property maps can now have a default value.
-   The class CGAL::Face_filtered_graph now supports patch IDs of any
    type and not just faces_size_type. The only requirement is that the
    type is hashable.

Polygon Mesh Processing

-   Added the function
    CGAL::Polygon_mesh_processing::autorefine_triangle_soup(), which can
    be used to refine a soup of triangles such that no pair of triangles
    intersects in their interiors. Also added, the function
    CGAL::Polygon_mesh_processing::autorefine() operating directly on a
    triangle mesh and updating it using the aforementioned function on a
    triangle soup.
-   Added the class CGAL::Corefinement::Non_manifold_output_visitor,
    which can be used in corefinement based functions to deal with
    non-manifold outputs.
-   Added the option to use a variable sizing field for
    CGAL::Polygon_mesh_processing::isotropic_remeshing(), and a sizing
    function based on a measure of local curvature for adaptive
    remeshing.
-   Added the function
    CGAL::Polygon_mesh_processing::interpolated_corrected_curvatures()
    which can be used to compute the mean and Gaussian curvatures, as
    well as the principal curvature and directions.
-   Added the function
    CGAL::Polygon_mesh_processing::refine_mesh_at_isolevel() which can
    be used to refine a polygon mesh along an isocurve.
-   Added the function CGAL::Polygon_mesh_processing::add_bbox(), which
    enables adding a tight or extended, triangulated or not, bounding
    box to a face graph.

2D Triangulations

-   Breaking change: the concept TriangulationTraits_2 now requires an
    additional functor Compare_xy_2.

3D Triangulations

-   Added three member functions vertices() to the class
    CGAL::Triangulation_3. Each of them returns an array containing the
    vertices of the given triangulation simplex.

dD Triangulations

-   Breaking change: CGAL::TDS_full_cell_mirror_storage_policy is now
    unsupported in dimension larger than 127.
-   Breaking change: Inserting multiple unweighted points in the same
    position now keeps the first one, instead of switching to the
    latest. This only affects custom point types where not all points in
    the same position are equivalent.

Tetrahedral Remeshing

-   Added a sizing field as new parameter of
    CGAL::tetrahedral_isotropic_remeshing(), which can be used to
    perform non-uniform and adaptive remeshing.
-   Breaking change: The template parameters of
    CGAL::Tetrahedral_remeshing::Remeshing_cell_base_3 have been
    modified, reverting changes introduced in CGAL 5.6.
-   Breaking change: The vertex base of
    CGAL::Tetrahedral_remeshing::Remeshing_vertex_base_3 must now be a
    model of the concept SimplicialMeshVertexBase_3 (and not only
    TriangulationVertexBase_3).

3D Simplicial Mesh Data Structure

-   Breaking change: The template parameters of
    CGAL::Simplicial_mesh_cell_base_3 have been modified to enable
    passing a geometric traits and a custom cell base class.

3D Mesh Generation

-   Breaking change: Removed the concept TriangleAccessor, the template
    parameter TriangleAccessor, as well as the class Triangle_accessor.
    These were no longer used for several releases.
-   Breaking change: Removed the class templates
    CGAL::Gray_image_mesh_domain_3, CGAL::Implicit_mesh_domain_3, and
    CGAL::Labeled_image_mesh_domain_3, which were deprecated since
    CGAL-4.13.

3D Surface Mesh Generation

-   This package is deprecated and the package 3D Mesh Generation should
    be used instead.

Surface Mesh Parameterization

-   Breaking change: The method
    CGAL::Surface_mesh_parameterization::LSCM_parameterizer_3 now
    requires the Eigen library.
-   Breaking change: CGAL no longer ships its own version of OpenNL.

Surface Mesh

-   Breaking change: The return type of
    CGAL::Surface_mesh::property_map() has been changed to
    std::optional.

3D Point Set

-   Breaking change: The return type of
    CGAL::Point_set_3::property_map() has been changed to std::optional.

Shape Detection

-   Breaking change: Replaced all instances of boost::shared_ptr with
    std::shared_ptr.

2D Straight Skeleton and Polygon Offsetting

-   Breaking change: Replaced all instances of boost::shared_ptr with
    std::shared_ptr.
-   Breaking change: Replaced all instances of boost::optional with
    std::optional.


See https://www.cgal.org/2024/06/21/cgal60-beta1/ for a
complete list of changes.


The CGAL project is a collaborative effort to develop a robust,
easy-to-use, and efficient C++ software library of geometric data
structures and algorithms, like
- triangulations (2D constrained triangulations, Delaunay triangulations
  and periodic triangulations in 2D and 3D),
- Voronoi diagrams (for 2D and 3D points, 2D additively weighted
  Voronoi diagrams, and segment Voronoi diagrams),
- Boolean operations on polygons and polyhedra,
- regularized Boolean operations on polygons with curved arcs
- arrangements of curves,
- mesh generation (2D, 3D and surface mesh generation,
  surface mesh subdivision and parametrization),
- alpha shapes (in 2D and 3D),
- convex hull algorithms (in 2D, 3D and dD),
- operations on polygons (straight skeleton and offset polygon),
- search structures (kd trees for nearest neighbor search, and
  range and segment trees),
- interpolation (natural neighbor interpolation and placement of
  streamlines),
- optimization algorithms (smallest enclosing sphere of points or
  spheres, smallest enclosing ellipsoid of points, principal
  component analysis).




Some modules are distributed under the terms of the LGPL Open Source
license (GNU Lesser General Public License v3 or later versions).
Most modules are distributed under the terms of the GPL Open Source
license (GNU General Public License v3 or later versions).
If your intended usage does not meet the criteria of the
aforementioned licenses, a commercial license can be purchased from
GeometryFactory (https://www.geometryfactory.com/).


For further information and for downloading the library and its
documentation, please visit the CGAL web site: https://www.cgal.org/

-- 
Laurent Rineau, PhD
R&D Engineer at GeometryFactory           http://www.geometryfactory.com/
Release Manager of the CGAL Project       http://www.cgal.org/