FreeCAD is a CAx RAD based on OpenCASCADE, Qt4, and Python. It features some key concepts like Macro recording, Workbenches, and the ability to run as a server. It's also platform-independent. It is is fully scriptable and designed to be easily extensible; only the core functionality is embedded into the core libraries, but all further functionality like support of triangle meshes, CAM, FEM, etc. is implemented in extension modules. Normally, such a module is divided into an 'App' part containing the data structures and algorithms and a 'GUI' containing the graphical representation of data structures, dialogs, workbenches, etc.
FreeSG is a portable, high-level 3D engine with an emphasis on generality. It is designed as a component to be integrated, as opposed to an application framework. Its goal is to support applications ranging from small 3D games running on portable consoles to large simulations that must be rendered photorealistically using fourth-generation graphics hardware.
GLgraph is an interactive OpenGL based function grapher for Linux written in Perl. It visualizes any mathematical function in 1, 2, or 3 unkowns (x,z,t) in a 2D, 3D, or 4D wireframe or solid surface. It creates an animation after one time period. GLgraph has a command line interface to input a function, to specify the minimum and maximum plotting bound, and more. It can be interactively controlled with the keyboard.
GNUSTEP Live CD contains a lot of software for GNUstep, a free implementation of the OPENSTEP framework (which is also directly used in Mac OS X as Cocoa). It includes excellent applications for RAD (GORM and ProjectCenter). The CD is available for i486, AMD64, Apple Mac PowerPC, and Sun UltraSPARC computers.
The GTO format's primary usage is storage of static geometric data. The types of data you might find in a GTO file are things like polygonal meshes, various types of subdivision surfaces, NURBS or UBS surfaces, coordinate systems, hierarchies of objects, material bindings, and even images. It is used by film, video, and game production companies to streamline the modeling, animation, rendering, and 3-D paint processes. The distribution includes source code for a RenderMan Procedural plug-in, four Maya plug-ins, a Houdini plug-in, a number of command line tools, a Wavefront .obj parser, and two Python modules for reading, writing, and editing GTO files.
The GNU Triangulated Surface Library (GTS) provides a set of useful functions to deal with 3D surfaces meshed with interconnected triangles. It features metric operations (area, volume, curvature, etc.), 2D Delaunay and constrained Delaunay triangulations, robust geometric predicates and set operations on surfaces (union, intersection, etc.), surface refinement and coarsening (multiresolution models), and bounding-boxes trees for collision/intersection detection.
Garbure is a collection of dedicated distributions. Each distribution provides carefully selected tools for a specific target domain, and is completed with examples and documentation. The set of distributions forms an entity, but each distribution works also on its own. All elements are arranged in the same way for each distribution.
Gmsh is an automatic 3D finite element grid generator with built-in CAD and post-processing facilities. Its design goal is to provide a simple meshing tool with parametric input and advanced visualization capabilities. It is built around four modules: geometry, mesh, solver, and post-processing. The specification of any input to these modules is done either interactively using the graphical user interface (based on FLTK and OpenGL) or in ASCII text files using Gmsh's own scripting language.