# CGAL 3.1 Released, Computational Geometry Algorithms Library

Andreas Fabri Andreas.Fabri at geometryfactory.com
Wed Dec 22 20:18:13 PST 2004

```We are pleased to announce the release 3.1 of CGAL, the Computational Geometry
Algorithms Library.

Besides improvements of existing packages this release offers
the following new algorithms and data structures.

o 2D Segment Voronoi Diagram

An incremental algorithm for Voronoi diagrams of segments in the plane
under the Euclidean metric. The Voronoi edges are arcs of straight lines
and parabolas. In case the input segments intersect, the Voronoi diagram
of their arrangement is computed.

o 2D Conforming Triangulations and Meshes

An implementation of Shewchuk's algorithm to construct conforming
triangulations and 2D meshes.

o 3D Boolean Operations on Nef Polyhedra

A data structure 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.
Also available are planar Nef polyhedra embedded on the sphere.

o dD Box Intersection Testing and Reporting

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

o 2D Snap Rounding

An algorithm for converting arbitrary-precision arrangements of segments
into a fixed-precision representation. An Iterated Snap Rounding algorithm
is also available in which each vertex is at least half the width of a
pixel away from any non-incident edge.

o 2D and Surface Function Interpolation

Several algorithms for scattered data interpolation from measures of a
function on a set of discrete data points.  The package further offers
functions for natural neighbor interpolation.

See http://www.cgal.org/releases_frame.html 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. The CGAL library contains:
o The Kernel providing basic geometric primitives such as points, vectors,
lines, predicates for testing things such as relative positions of points,
and operations such as intersections and distance calculation.
o The Basic Library, a collection of standard data structures and geometric
algorithms, such as convex hull, (Delaunay, Regular, Constrained)
triangulation, Voronoi diagrams, planar map, arrangements, polyhedron,
smallest enclosing sphere, multidimensional query structures...
o Interfaces to other packages, e.g. for visualization, and I/O, and
other support facilities.

(GNU Lesser General Public License v2.1).
The Basic Library is distributed under the terms of the QPL Open Source
If your intended usage does not meet the criteria of the
GeometryFactory (www.geometryfactory.com).

documentation, please visit the CGAL web page: http://www.cgal.org/

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