CGAL-5.5

The CGAL Open Source Project is pleased to announce the release 5.5 of CGAL, the Computational Geometry Algorithms Library.

Besides fixes and general enhancement to existing packages, the following has changed since CGAL 5.4:

3D Alpha Wrapping (new package)

• This component takes a 3D triangle mesh, soup, or point set as input, and generates a valid (watertight, intersection-free, and combinatorially 2-manifold) surface triangle mesh that contains the input.
  The algorithm proceeds by shrink-wrapping and refining a 3D Delaunay triangulation, starting from a loose bounding box of the input.
  Two user-defined parameters, alpha and offset, offer control over the maximum size of cavities where the shrink-wrapping process can enter, and the tightness of the final surface mesh to the input, respectively. Once combined, these parameters provide a means to trade fidelity
  to the input for complexity of the output.

  See also the announcement page.

2D Straight Skeleton and Polygon Offsetting (breaking change)

• Fix the output of the function CGAL::create_exterior_skeleton_and_offset_polygons_with_holes_2()
  to not take into account the offset of the outer frame.
• Fix the computation of the exterior offset of a polygon with holes that was not computing the offset of the holes

3D Convex Hulls

• Added an overload of the function CGAL::convex_hull_3(), which writes the result in an indexed triangle set.

2D Polygons

• Add vertex, edge, and hole ranges.
• The concept GeneralPolygonWithHoles_2 now requires the nested type Polygon_2 instead of General_polygon_2.

2D Regularized Boolean Set-Operations

• The concept GeneralPolygonSetTraits_2 now requires the nested type Construct_polygon_with_holes_2 instead of Construct_general_polygon_with_holes_2.

Combinatorial Maps

• Removed old code deprecated in CGAL 4.9 and 4.10 (global functions, and information associated with darts).

2D Arrangements

• Fixed the intersect_2, compare_y_at_x_right, and compare_y_at_x_left function objects of the traits class template Arr_geodesic_arc_on_sphere_traits_2 that handles geodesic arcs on sphere and applied a small syntactical fix to the tracing traits.

Tetrahedral Mesh Generation

• Added the function remove_isolated_vertices() as a post-processing step for the tetrahedral mesh generation.

Polygon Mesh Processing

• Added the function CGAL::Polygon_mesh_processing::orient_triangle_soup_with_reference_triangle_soup(), which enables re-orienting the faces of a triangle soup based on the orientation of the nearest face in a reference triangle soup.
• Added the function CGAL::Polygon_mesh_processing::compatible_orientations(), which enables to retrieve the (in)compatibility of orientations of faces from different connected components.
• Added the function CGAL::Polygon_mesh_processing::tangential_relaxation(), which applies an area-based tangential mesh smoothing to the vertices of a surface triangle mesh.
• Added the named parameter visitor to the function triangulate_hole(), which enables to track progress with callbacks.
• Added more functions in the visitor of the corefinement based methods to track progress.

Surface Mesh Simplification

• Introduced four variations of the Garland-Heckbert simplification algorithm based on the probabilistic approach of Trettner and Kobbelt (Fast and Robust QEF Minimization using Probabilistic Quadrics): GarlandHeckbert_plane_policies, GarlandHeckbert_probabilistic_plane_policies, GarlandHeckbert_triangle_policies, and GarlandHeckbert_probabilistic_triangle_policies.
• The class GarlandHeckbert_policies has been deprecated, GarlandHeckbert_plane_policies replaces it.

Point Set Processing

• A new optional named parameter, min_points_per_cell has been added to grid_simplify_point_set(). By adding a minimal number of points in a cell such that a point is retained, one can also filter out low density areas and outliers: in the case of densely sampled point clouds, this yields better results than using grid simplification and then outlier removal, while being very vast. The default value is 1 to keep the previous behavior as default.

dD Spatial Searching

• Added the member function write_graphviz() to the class Kd_tree that writes the tree in a stream in the Graphviz format.

CGAL and the Boost Graph Library (BGL)

• Added the function invert_selection() in the class Face_filtered_graph, which toggles the selected status of a graph: selected faces are deselected, and unselected faces are selected.

CGAL-5.4.2

CGAL-5.4.2 is a bug-fix release.

See on Github the list of bugs that were solved since CGAL-5.4.1.

CGAL-5.4.1

CGAL-5.4.1 is a bug-fix release.

See on Github the list of bugs that were solved since CGAL-5.4.

CGAL-5.3.2

CGAL-5.3.2 is a bug-fix release.

See on Github the list of bugs that were solved since CGAL-5.3.1.

CGAL-5.5-beta1

The CGAL Open Source Project is pleased to announce the release 5.5 Beta 1 of CGAL, the Computational Geometry Algorithms Library.

CGAL version 5.5 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 5.5 in July 2022.

Besides fixes and general enhancement to existing packages, the following has changed since CGAL 5.4:

3D Alpha Wrapping (new package)

• This component takes a 3D triangle mesh, soup, or point set as input, and generates a valid (watertight, intersection-free, and combinatorially 2-manifold) surface triangle mesh that contains the input.
  The algorithm proceeds by shrink-wrapping and refining a 3D Delaunay triangulation, starting from a loose bounding box of the input.
  Two user-defined parameters, alpha and offset, offer control over the maximum size of cavities where the shrink-wrapping process can enter, and the tightness of the final surface mesh to the input, respectively. Once combined, these parameters provide a means to trade fidelity
  to the input for complexity of the output.

  See also the announcement page.

3D Convex Hulls

• Added an overload of the function CGAL::convex_hull_3(), which writes the result in an indexed triangle set.

2D Polygons

• Add vertex, edge, and hole ranges.
• The concept GeneralPolygonWithHoles_2 now requires the nested type Polygon_2 instead of General_polygon_2.

2D Regularized Boolean Set-Operations

• The concept GeneralPolygonSetTraits_2 now requires the nested type Construct_polygon_with_holes_2 instead of Construct_general_polygon_with_holes_2.

Combinatorial Maps

• Removed old code deprecated in CGAL 4.9 and 4.10 (global functions, and information associated with darts).

2D Arrangements

• Fixed the intersect_2, compare_y_at_x_right, and compare_y_at_x_left function objects of the traits class template Arr_geodesic_arc_on_sphere_traits_2 that handles geodesic arcs on sphere and applied a small syntactical fix to the tracing traits.

Tetrahedral Mesh Generation

• Added the function remove_isolated_vertices() as a post-processing step for the tetrahedral mesh generation.

Polygon Mesh Processing

• Added the function CGAL::Polygon_mesh_processing::orient_triangle_soup_with_reference_triangle_soup(), which enables re-orienting the faces of a triangle soup based on the orientation of the nearest face in a reference triangle soup.
• Added the function CGAL::Polygon_mesh_processing::compatible_orientations(), which enables to retrieve the (in)compatibility of orientations of faces from different connected components.
• Added the function CGAL::Polygon_mesh_processing::tangential_relaxation(), which applies an area-based tangential mesh smoothing to the vertices of a surface triangle mesh.
• Added the named parameter visitor to the function triangulate_hole(), which enables to track progress with callbacks.
• Added more functions in the visitor of the corefinement based methods to track progress.

Surface Mesh Simplification

• Introduced four variations of the Garland-Heckbert simplification algorithm based on the probabilistic approach of Trettner and Kobbelt (Fast and Robust QEF Minimization using Probabilistic Quadrics): GarlandHeckbert_plane_policies, GarlandHeckbert_probabilistic_plane_policies, GarlandHeckbert_triangle_policies, and GarlandHeckbert_probabilistic_triangle_policies.
• The class GarlandHeckbert_policies has been deprecated, GarlandHeckbert_plane_policies replaces it.

Point Set Processing

• A new optional named parameter, min_points_per_cell has been added to grid_simplify_point_set(). By adding a minimal number of points in a cell such that a point is retained, one can also filter out low density areas and outliers: in the case of densely sampled point clouds, this yields better results than using grid simplification and then outlier removal, while being very vast. The default value is 1 to keep the previous behavior as default.

dD Spatial Searching

• Added the member function write_graphviz() to the class Kd_tree that writes the tree in a stream in the Graphviz format.

CGAL and the Boost Graph Library (BGL)

• Added the function invert_selection() in the class Face_filtered_graph, which toggles the selected status of a graph: selected faces are deselected, and unselected faces are selected.

CGAL-5.4

The CGAL Open Source Project is pleased to announce the release 5.4 of CGAL, the Computational Geometry Algorithms Library.

Besides fixes and general enhancement to existing packages, the following has changed since CGAL 5.3:

General changes

• Added the cmake target CGAL::CGAL_Basic_viewer to ease the compilation of programs using the basic viewer-based function CGAL::draw(). This target will define the macro and link with CGAL_Qt5 target when linked with it.

• The kernel providing exact constructions and exact predicates (CGAL::Exact_predicates_exact_constructions_kernel) is now thread-safe. See changes in 2D and 3D Linear Geometry Kernel for more details.

• The class Geomview_stream and all the dependent features have been removed from CGAL. Those features were actually no longer supported since CGAL-5.3 but it was not properly announced.

Shape Regularization (new package)

• This package enables to regularize a set of segments and open or closed contours in 2D and a set of planes in 3D such that all input objects are rotated and aligned with respect to the user-specified conditions. In addition, it provides a global regularization framework that can be adjusted for the user needs and any type of geometric objects.

Weights (new package)

• This package provides a simple and unified interface to different types of weights. In particular, it groups all weights into three category: analytic weights including all basic weights which can be computed analytically for a query point with respect to its local neighbors in 2D and 3D; barycentric weights, including all weights which can be computed for a query point with respect to the vertices of a planar polygon; and weighting regions, including all weights which are used to balance other weights.

2D Generalized Barycentric Coordinates (major changes)

• Breaking change: The headers Segment_coordinates_2.h and Triangle_coordinates_2.h are renamed to segment_coordinates_2.h and triangle_coordinates_2.h.
• The classes Segment_coordinates_2 and Triangle_coordinates_2 are deprecated. The free functions compute_segment_coordinates_2() and compute_triangle_coordinates_2() are deprecated as well. Instead, the free functions segment_coordinates_2() and triangle_coordinates_2() should be used.
• The enums Query_point_location and Type_of_algorithm are deprecated. Instead, the enum Computation_policy_2 should be used.
• The classes Wachspress_2, Discrete_harmonic_2, Mean_value_2, and Generalized_barycentric_coordinates_2 are deprecated. As consequence, the concept BarycentricCoordinates_2 is deprecated as well. Instead, the classes Wachspress_coordinates_2, Discrete_harmonic_coordinates_2, and Mean_value_coordinates_2 should be used.
• Added the class Harmonic_coordinates_2 to compute approximate harmonic coordinates in 2D. These coordinates satisfy all properties of barycentric coordinates inside any simple polygon.
• Added a new concept DiscretizedDomain_2 and a model of this concept called Delaunay_domain_2, which is based on the Mesh 2 package. A model of this concept is required to use Harmonic_coordinates_2.
• Added free functions to compute Wachspress, discrete harmonic, and mean value coordinates.
• All free functions and classes are now using ranges and property maps.

2D and 3D Linear Geometry Kernel

• Most operations on CGAL::Exact_predicates_exact_constructions_kernel objects are now thread-safe if CGAL::Exact_rational is mpq_class (from GMPXX), boost::multiprecision::mpq_rational or CGAL::Quotient<CGAL::MP_Float>. The objects are not atomic though, so the usual restrictions on avoiding race conditions apply. For users who do not use threads, this can be disabled with CGAL_HAS_NO_THREADS.

• Added documentation for the class Projection_traits_3, which enables the use of 2D algorithms on the projections of 3D data onto an arbitrary plane.

• Added construct_centroid_2_object() and compute_determinant_2_object() in Projection_traits_xy_3, Projection_traits_xz_3, and Projection_traits_yz_3 classes.

• Added the functor NonZeroCoordinateIndex_3 to the concept Kernel with int operator()(Vector_3) which returns the index of any coordinate of the vector different from zero, or -1.

dD Kernel

• Most operations on Epeck_d objects are now thread-safe, see 2D and 3D Linear Geometry Kernel for details.

2D Arrangements

• Breaking Change: The traits function objects Compare_x_at_limit_2 and Compare_x_near_limit_2 are renamed to Compare_x_on_boundary_2 and Compare_x_near_boundary_2, respectively.

• A new hierarchy of traits concepts has been introduced. It captures all the valid combinations of boundary conditions for the 4 boundary sides of the parameter space. The 4 boundaries are Bottom, Top, Left, and Right. Each boundary side can be either contracted, identified, close, open, or oblivious. Not all possible combinations are valid. If one side is identified then the other must be as well. Two adjacent sides cannot be contracted.

• A new geometric traits, Arr_geodesic_arc_on_sphere_traits_2 has been introduced. It handles arcs of great circles embedded on the unit sphere.

2D Regularized Boolean Set-Operations

• Added an extra parameter (UsePolylines) to all free functions ( [`complement()...

CGAL-5.4-beta1

The CGAL Open Source Project is pleased to announce the release 5.4 Beta 1 of CGAL, the Computational Geometry Algorithms Library.

CGAL version 5.4 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 5.4 in January 2022.

Besides fixes and general enhancement to existing packages, the following has changed since CGAL 5.3:

General changes

• Added the cmake target CGAL::CGAL_Basic_viewer to ease the compilation of programs using the basic viewer-based function CGAL::draw(). This target will define the macro and link with CGAL_Qt5 target when linked with it.

• The kernel providing exact constructions and exact predicates (CGAL::Exact_predicates_exact_constructions_kernel) is now thread-safe. See changes in 2D and 3D Linear Geometry Kernel for more details.

Shape Regularization (new package)

• This package enables to regularize a set of segments and open or closed contours in 2D and a set of planes in 3D such that all input objects are rotated and aligned with respect to the user-specified conditions. In addition, it provides a global regularization framework that can be adjusted for the user needs and any type of geometric objects.

Weights (new package)

• This package provides a simple and unified interface to different types of weights. In particular, it groups all weights into three category: analytic weights including all basic weights which can be computed analytically for a query point with respect to its local neighbors in 2D and 3D; barycentric weights, including all weights which can be computed for a query point with respect to the vertices of a planar polygon; and weighting regions, including all weights which are used to balance other weights.

2D Generalized Barycentric Coordinates (major changes)

• Breaking change: The headers Segment_coordinates_2.h and Triangle_coordinates_2.h are renamed to segment_coordinates_2.h and triangle_coordinates_2.h.
• The classes Segment_coordinates_2 and Triangle_coordinates_2 are deprecated. The free functions compute_segment_coordinates_2() and compute_triangle_coordinates_2() are deprecated as well. Instead, the free functions segment_coordinates_2() and triangle_coordinates_2() should be used.
• The enums Query_point_location and Type_of_algorithm are deprecated. Instead, the enum Computation_policy_2 should be used.
• The classes Wachspress_2, Discrete_harmonic_2, Mean_value_2, and Generalized_barycentric_coordinates_2 are deprecated. As consequence, the concept BarycentricCoordinates_2 is deprecated as well. Instead, the classes Wachspress_coordinates_2, Discrete_harmonic_coordinates_2, and Mean_value_coordinates_2 should be used.
• Added the class Harmonic_coordinates_2 to compute approximate harmonic coordinates in 2D. These coordinates satisfy all properties of barycentric coordinates inside any simple polygon.
• Added a new concept DiscretizedDomain_2 and a model of this concept called Delaunay_domain_2, which is based on the Mesh 2 package. A model of this concept is required to use Harmonic_coordinates_2.
• Added free functions to compute Wachspress, discrete harmonic, and mean value coordinates.
• All free functions and classes are now using ranges and property maps.

2D and 3D Linear Geometry Kernel

• Most operations on CGAL::Exact_predicates_exact_constructions_kernel objects are now thread-safe if CGAL::Exact_rational is mpq_class (from GMPXX), boost::multiprecision::mpq_rational or CGAL::Quotient<CGAL::MP_Float>. The objects are not atomic though, so the usual restrictions on avoiding race conditions apply. For users who do not use threads, this can be disabled with CGAL_HAS_NO_THREADS.

• Added documentation for the class Projection_traits_3, which enables the use of 2D algorithms on the projections of 3D data onto an arbitrary plane.

• Added construct_centroid_2_object() and compute_determinant_2_object() in Projection_traits_xy_3, Projection_traits_xz_3, and Projection_traits_yz_3 classes.

• Added the functor NonZeroCoordinateIndex_3 to the concept Kernel with int operator()(Vector_3) which returns the index of any coordinate of the vector different from zero, or -1.

dD Kernel

• Most operations on Epeck_d objects are now thread-safe, see 2D and 3D Linear Geometry Kernel for details.

2D Arrangements

• Breaking Change: The traits function objects Compare_x_at_limit_2 and Compare_x_near_limit_2 are renamed to Compare_x_on_boundary_2 and Compare_x_near_boundary_2, respectively.

• A new hierarchy of traits concepts has been introduced. It captures all the valid combinations of boundary conditions for the 4 boundary sides of the parameter space. The 4 boundaries are Bottom, Top, Left, and Right. Each boundary side can be either contracted, identified, close, open, or oblivious. Not all possible combinations are valid. If one side is identified then the other must be as well. Two adjacent sides cannot be contracted.

• A new geometric traits, Arr_geodesic_arc_on_sphere_traits_2 has been introduced. It handles arcs of great circles embedded on the unit sphere.

2D Regularized Boolean Set-Operations

• Added an extra parameter (UsePolylines) to all free functions ( [`comp...

CGAL-5.3.1

CGAL-5.3.1 is a bug-fix release.

See on Github the list of bugs that were solved since CGAL-5.3.

CGAL-5.2.4

CGAL-5.2.4 is a bug-fix release.

See on Github the list of bugs that were solved since CGAL-5.2.3.

CGAL-5.3

The CGAL Open Source Project is pleased to announce the release 5.3 of CGAL, the Computational Geometry Algorithms Library.

Besides fixes and general enhancement to existing packages, the following has changed since CGAL 5.2:

General changes

• The support for the compiled version of CGAL is dropped. Only the header-only version is supported.

• On Windows, the type used for Exact_rational, in Epick and indirectly (through Lazy_exact_nt)
  Epeck may now be boost::multiprecision::mpq_rational, as has been the case on other platforms
  for several releases. This depends on various options and is added to a list that includes
  mpq_class, CGAL::Gmpq, leda_rational and CGAL::Quotient<CGAL::MP_Float>.

Quadtrees, Octrees, and Orthtrees (new package)

• This package implements a tree data structure in which each node encloses a hypercubic section
  of space and each non-leave node has hypercubic children whose edge lengths are half its edge length.
  Such a data structure is known as a quadtree in 2D, an octree in 3D, and is generalized
  as an "orthtree" in higher dimensions.

Triangulations on the Sphere (new package)

• This package enables the construction and manipulation of Delaunay triangulations on the 2-sphere.
  Triangulations are built incrementally and can be modified by insertion or removal of vertices.
  Point location querying and primitives to build the dual Voronoi diagram are provided.

File Input / Output

• Point set, polygon soup, and polygon mesh file I/O functions have been harmonized and documented:
  • Point set I/O functions can be found in the packages Point_set_processing_3, and Point_set_3.
  • Polygon mesh I/O functions can be found in the package BGL.
  • Polygon soup I/O can be found in the package Stream_support.

A comprehensive list of the supported file formats is available in the Stream_support package here; inversely, the following page can be used to find out which CGAL data structures can be used given a specific file format.

Requirements

• The CMake minimal version is now 3.14.
• The GNU compiler g++ versions 6 and 7 are no longer tested. Only version 8.3 or later are supported

2D and 3D Linear Geometry Kernel

• Added is_translation(), is_scaling(), is_reflection(), and is_rotation() to the classes
  Aff_transformation_2
  and Aff_transformation_3,
  which enable determining if the transformations use a specialized representation internally.

2D Regularized Boolean Set-Operations

• Added documentation for the free functions oriented_side(const Point_2& p, ....)
  that accept a point and a polygon.
• Documentation has been improved across the whole package.

Polygon Mesh Processing

• Added the class CGAL::Polyhedral_envelope,
  providing a way to quickly check if a primitive (point, segment, or triangle)
  is within a polyhedral envelope around a set of triangles. It is based on the work of
  Bolun Wang, Teseo Schneider, Yixin Hu, Marco Attene, and Daniele Panozzo.
  "Exact and efficient polyhedral envelope containment check." (ACM Trans. Graph., 39-4, July 2020).
• Added more functions in the visitor of the corefinement based methods
  to track all edge creations.

Surface Mesh Topology

• Added the function CGAL::Surface_mesh_topology::Curves_on_surface_topology::is_homotopic_to_simple_cycle(),
  which can be used to determine whehter a closed path on a surface mesh can be continously
  transformed to a cycle without self intersection.

Surface Mesh Simplification

• Added a filtering mechanism so that costly tests get only applied to the next candidate for the edge collapse.
• Added the class Polyhedral_envelope_filter,
  which enables to perform mesh simplification inside a polyhedral envelope of the input mesh.

2D Polyline Simplification

• When polylines have common subsequences of vertices, these subsequences may now be simplifified simultaneously.

dD Triangulations

• Added the function insert_if_in_star()
  to the class CGAL::Regular_triangulation,
  which enables users to insert a point p in a regular triangulation on the condition that p
  appears post-insertion in the star of a user-specified, existing vertex.

2D and 3D Alpha Shapes

• Breaking change: The following deprecated classes have been removed: Alpha_shape_euclidean_traits_2,
  Weighted_alpha_shape_euclidean_traits_2, Alpha_shape_euclidean_traits_3, and
  Weighted_alpha_shape_euclidean_traits_3. All CGAL kernel can be used directly as models
  of the concepts of the 2D and 3D Alpha Shape packages.

Classification

• Breaking change: the support for TensorFlow has been dropped; the
  classifier CGAL::TensorFlow::Neural_network_classifier has been removed.