Important changes:

• Debian snapshot package creation.
• LC_ALL is set to POSIX in all executables to avoid problems with locale-dependent floating-point conventions.

Important changes:

• Switched to darcs for version control (the CVS tree is obsolete).

• For constrained Delaunay, closest face for glib >= 2.4 did not use planar distance.
• Several fixes for gts_delaunay_add_constraint.
• Fix for degenerate case in isotetra_bcl().
• Fix for comments not being fully ignored by GtsFile.

• delaunay and happrox are installed.
• Fast triangle-box intersection test by Tomas Akenine-Moller.
• New function gts_triangle_interpolate_height().
• binary STL files work on win32.

New features/important changes include:

• Autodetection and support for glib >= 2.4 (but glib >= 1.2.8 is still supported): glib >= 2.0 and < 2.4 is not supported (send me patches!).
• pkgconfig preliminary support.
• Mingwin support.
• Changes to the interface of gts_graph_read().

• Constrained Delaunay Triangulation guess selection.
• Boolean operations: Now uses SOS for segment/triangle intersections.

New features includes:

• gts2dxf and gts2stl filters.
• New GtsColorVertex class.
• "Dual" isosurface calculation by Tim F.
• New "happrox" algorithm to approximate terrain models.
• New GtsMatrix implementation (quaternions) by Wayne Gramlich and Michael Loehr.
• Attributes inheritance when computing intersections.

• Major changes to inner loops triangulation for boolean operations.
• Compilation on SGI Altix
• Fixed gts.def generation for Windows support.
• Cygwin support.

New features includes:

• Sphere tessellation by Jerome Benoit.

As well as a number of bug and compilation fixes.

I consider this new release to be a major step forward with a new very robust implementation of boolean operations as well as several very interesting contributions from other people: marching tetrahedra for isosurface extraction (Gert Wollny) and differential geometry operators (Ray Jones) in particular. Thanks to all people who contributed, reported bugs etc... A summary of the most significant changes follows:

Boolean operations have been almost entirely rewritten and now use a Simulation of Simplicity (SoS) technique to deal with degenerate cases. This should fix most of the problems encountered when dealing with "simple" geometric objects (i.e. cube/cube intersections with coplanar faces etc...) Almost all the test cases in the test suite (including significant tests submitted by users) now pass. Difficult test cases like an object intersecting with a simplified version of itself (created using coarsen for example) work fine despite the huge number of degenerate cases (coincident and nearly coincident edges, faces, vertices).

There is still a caveat however for intersections which creates multiple closed loops contained within one another (note that this was not a problem in the previous version). This needs to be fixed at some point.

Another problem is that the surfaces resulting from a boolean operation while guaranteed to be topologically consistent may contain degenerate edges/faces which will prevent them from being used in a subsequent boolean operation. The degenerate entities need first to be eliminated (through edge/face collapse).

The gts_point_is_inside_surface() function has been rewritten using SoS.

A new stl2gts tool provides conversion between STL (stereolithography) format and GTS format.

Ray Jones has added new functions to compute gaussian curvature, principal curvature directions etc...

The gts_file_close() function call has been replaced by a gts_file_destroy() function which does not close the file. This is better left to the caller. Your application might need a slight modification there.

The whole automake/autoconf stuff has been upgraded to use version 1.6.3 of automake.

Gert Wollny has added a marching tetrahedra isosurface construction technique which should avoid topological defects in isosurfaces (created by inconsistencies inherent to the marching cube technique).

In this version, all the input functions are using a new structure (GtsFile) which fixes the problem of reporting syntax errors when reading input files. A detailed message describing the location (line, column) and the type of error can now be easily set. All the read() methods of the library classes now use this mechanism which gives far clearer error reporting.

This comes at a cost however and a number of input functions (gts_surface_read() etc...) have changed interface. Using the examples/ it should be easy to port your code though.

Other significant changes include:

• New gts_surface_refine() syntax: allows for more generic cost functions.
• New gtscheck executable: checks for topologically incorrect surfaces using in particular the new function gts_surface_is_self_intersecting(). You should use this program before trying to do any boolean operations with your surfaces.
• src/: gts.h, partition.c: Bisection algorithms now takes an extra "imbalance" argument which allows some control over the weight balancing of the partition.
• src/cdt.c: Checks for degenerate triangles when looking for root of the search (thanks to Mashuda Glencross for reporting this problem).
• tools/gtstemplate: for generation of a template used to create new object classes.

Configuration and compilation have been cleaned and updated. Now builds both shared and static libraries.

A new "gts-config" script allows simpler use of the library (a la glib), together with a gts.m4 macro definition for your own autoconf usage.

A number of new features have been added:

• Configurable out-of-core simplification framework for surfaces larger than the main memory.
• Conforming constrained Delaunay triangulation and Delaunay refinement by addition of Steiner points.
• Simple implementation of FIFOs (First-In First-out queues).
• New graph objects and operations on graphs. In particular efficient graph partitioning routines.
• "Stabbing" functions have been added to bounding box trees, which now allows for efficient testing whether a point lies inside or outside a surface.

A number of bug fixes and improvements have also been added:

• More generic object methods for surfaces.
• Easily definable inheritance of face attributes (in particular for boolean operations).
• Bug fixes for boolean operations.
• The srf2oogl converter has been renamed to gts2oogl and an "isolines" functionality was added.

I finally found the time to clean up all the stuff I wanted. Much has happened since 0.3.0. A new object structure inspired by GTK allows to use classical inheritance mechanisms and virtual functions. As a consequence the object hierarchy has been restructured and now uses points, vertices, segments, edges, triangles, faces and surfaces.

The Delaunay triangulation has been entirely re-written and is now fully-dynamic (insertion or deletion of vertices). The constrained Delaunay triangulation is semi-dynamic (insertion of vertices and constraints).

Boolean operations between surfaces have also been re-written and are more robust (and also benefit from a much more robust implementation of the Delaunay triangulation).

Surface coarsening routines have been improved both in term of a more generic interface and in order to avoid artefacts such as folds in the simplified surface.

An interesting new extension is the implementation of progressive surfaces which allow dynamic real-time continuous level-of-detail representation of a surface. Progressive transmission of surfaces is also possible. The first building blocks for a hierarchical surface extension have been written. This will allow for dynamic view-dependent simplification of surfaces.

The floating-point control interface necessary for robust geometric predicates has been cleaned and GTS should now build on any (touch wood) UNIX-based machine.

Preliminary support has been added for win32 compilation using Microsoft C.

I am glad to announce that version 0.3.0 of GTS is available for download. New features include isosurface computation from 3D functions and the "memoryless simplification" algorithm of Lindstrom and Turk for mesh decimation (in the bibliography). The new screenshots and manual should give you an idea of what this is about. More to come soon.

The main API change you will have to deal with is that GTS now uses GSList instead of GList everywhere. It allows to save something like 30% of memory usage for a typical surface.

A few examples of how to use GTS are now included with the distribution.

This section "News" is up and running! A new section "Bibliography" is also available. This is a collection of articles with links relevant to the design of GTS.