Ayam is a free 3D modelling environment for the RenderMan interface. It features good RIB export, CSG (all RenderMan primitives supported), and NURBS modelling. Features instancing, arbitrary number of modeling views, object clipboard, independent property clipboard, n-level undo, console, and Tree-View with Drag-and-Drop support.
BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, and image and signal-processing tools.
The Nebula Device is a free multiplatform game engine currently running under Linux and Windows. It uses OpenGL and/or Direct3D for rendering and Tcl/Tk for scripting. Living C++ objects can be browsed and manipulated at runtime from the builtin console, or remotedly from a minimal terminal based console app. A powerful channel animation system allows any floating point attribute to be animated, and specialized animator classes allow things like realtime bone animation with weighted vertex skin.
The Virtual Rendering System is a computer graphics software library for constructing interactive 3D applications. It provides a large collection of 3D rendering components which facilitate implementing 3D graphics applications and experimenting with 3D graphics and imaging algorithms. It is implemented as a C++ library. Applications can incorporate VRS as C++ library based on the C++ API. In addition, it provides a complete Tcl/Tk binding of the C++ API, called iVRS.
VMD (Visual Molecular Dynamics) is designed for the visualization and analysis of biological systems such as proteins, nucleic acids, lipid bilayer assemblies, etc. It may be used to view more general molecules, as VMD can read standard Protein Data Bank (PDB) files and display the contained structure. VMD provides a wide variety of methods for rendering and coloring a molecule: simple points and lines, CPK spheres and cylinders, licorice bonds, backbone tubes and ribbons, cartoon drawings, and others. VMD can be used to animate and analyze the trajectory of a molecular dynamics (MD) simulation. In particular, VMD can act as a graphical front end for an external MD program by displaying and animating a molecule undergoing simulation on a remote computer. VMD uses OpenGL and OpenGL Programmable Shading Language for high performance rendering of large structures.
World Foundry is a 3D level game engine and asset production pathway with over 170,000 lines of code. It was originaly created as a commercial product, but is now being released under the GPL. The engine was designed from the beginning to be cross platform, and ran on Windows (DirectX, GL), and the Sony Playstation. The production pathway ran on Windows, and extended 3DStudio Max to be our level editor. The engine is currently being ported to Linux (it runs, but needs work), with plans to port the production pathway as well. Developers are wanted to help with this effort.