OpenCSG is a library that does image-based CSG rendering using OpenGL. CSG is short for "constructive solid geometry" and represents a modeling technique for composing shapes with 3D-primitives which are combined using volumetric boolean operations. Image-based CSG rendering means rendering CSG shapes without calculating their surface in object-space. Instead, the image of a CSG shape is composed directly in the frame-buffer of the graphics hardware by rather sophisticated stenciling and z-buffer operations.
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.
Kobldes makes it possible for the designer to model building information and uses POV-Ray for visualization. It is also programmed using the POV-Ray screen description language (SDL). The goal of is to create a fully functioning building information modeling and management tool for designing buildings. It currently allows the designer to accomplish basic tasks with building components such as building levels and spaces in the process of solving design problems. In the near future, it will compute and make available information about the building such as sizes/volumes (such as an area for painting in a particular room), requirement checks (e.g. spatial conformance), and Property checks (e.g. calculating the solar savings factor).