# CGAL 3.3 Released, Computational Geometry Algorithms Library

The CGAL Open Source Project is pleased to announce the release 3.3 of CGAL, the Computational Geometry Algorithms Library.

Besides improvements of existing packages this release offers the following new algorithms and data structures.
o Surface Mesh Simplification
This package provides a mesh simplification framework using edge collapse operations, and provides the Turk/Lindstrom simplification algorithm.
o Estimation of Local Differential Properties
This package allows to compute local differential quantities of a surface from a point sample.
o Approximation of Ridges and Umbilics on Triangulated Surface Meshes
This package enables the approximation of differential features on triangulated surface meshes. Such curvature related features are lines: ridges or crests, and points: umbilics.
o Envelopes of Curves in 2D
This package contains two sets of functions that construct the lower and upper envelope diagram for a given range of bounded or unbounded curves.
o Envelopes of Surfaces in 3D
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.
o Minkowski Sums in 2D
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.
o CGAL and the Boost Graph Library
This package provides the glue layer for several CGAL data structures such that they become models of the BGL graph concept.
o Spatial Sorting
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.
o Linear and Quadratic Programming Solver
This package contains algorithms for minimizing linear and convex quadratic functions over polyhedral domains, described by linear equations and inequalities.
See http://www.cgal.org/releases.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, like - triangulations (2D constrained triangulations and Delaunay 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 algorithms (2D Delaunay mesh generation and 3D surface mesh generation, surface mesh subdivision and parameterization), - alpha shapes, - 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), - optimisation algorithms (smallest enclosing sphere of points or spheres, smallest enclosing ellipsoid of points, principal component analysis), - kinetic data structures