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

## Changelog

### Supported platforms

- Microsoft Visual C++, version 7.
- SunPro 5.3 (with patch 111685-05) on Solaris
- g++ 3.1 on Linux and Solaris

### General

- Bugs in the following packages have been fixed: 3D Convex hull, 2D Polygon partition, simple polygon generator.
- Tttempts have been made to assure compatability with the upcoming LEDA release that introduces the leda namespace.

### Kernels

`Point_d`

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

### 2D Polygon Partitioning

- Traits requirements for optimal partitioning have been changed slightly.

### 2D Sweep line (new package)

- 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->`

.

- Iterators and circulators are convertible to handles
automatically, no need to call

### 2D Search structures

- Additional range search operations taking a predicate functor have been added.

### Planar Maps and Arrangements

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

### 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.

### 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.

#### Plateform specific issues

- 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.