Glide for UNIX
- A project to support 3Dfx Glide API on Posix OS.
- http://www.alasir.com/software/glide/

3DGPL
- A Portable Library which provides basic set of tools for writing 3D applications.
- http://www.gamers.org/dEngine/rsc/

OpenSG
- A portable C++ scene graph library for 3D graphics applications. Its main distinguishing features are extensive support for multi-threading, reflectivity and good extensibility. [Open source, LGPL]
- http://opensg.vrsource.org/trac

OpenNPAR
- Provides a unifying framework for the creation of Non-Photorealistic Animation and Rendering. Images, videos, publications and demos available.
- http://isgwww.cs.uni-magdeburg.de/research/opennpar/

The Lightfeather 3D Engine
- A free and open source 3D library for MacOS X, Windows and Linux.[zlib/libpng]
- http://lf.mmdevel.de/

VCG Library
- A portable C++ templated library for efficient manipulation, processing and displaying with OpenGL of triangle and tetrahedral meshes.
- http://vcg.sourceforge.net/

Gino
- A suite of libraries for the development of 3D graphics applications. Available for Delphi, VB, Fortran, C++ and .NET.
- http://www.gino-graphics.com/

Gizmo 3D
- A software development kit that can be used in a variety of demanding application development projects.
- http://www.gizmosdk.com/

Obsisian
- A currently unsupported open source 3D virtual world for Linux and OpenGL.
- http://old.zog.net.au/computers/obsidian/

GNU 3DKit - Free Software Foundation (FSF)
- Provides several frameworks to render 3D graphics in a GNUstep environment. Its main purpose is to render any kind of 3D graphics in real-time on commodity hardware, using an optimised scene graph architecture.
- http://www.gnu.org/software/gnu3dkit/gnu3dkit.html

OGRE 3D
- A 3D library for OpenGL and/or Direct3D. [Open source, LGPL]
- http://www.ogre3d.org/

Velocity 3D
- Source code for an entirely software 3D-engine and a DirectX 3D-engine, along with screen shots, downloads and documentation.
- http://www.razorforce.co.uk/dev/

Expression 3D Toolkit
- A free Object Oriented 3D toolkit. It is written in C++/STL. It has support for interactive 3D graphics using OpenGL and non-interactive sphere tracing.
- http://www.kotterink.com/expression/

PLIB Home Page
- A set of libraries that are designed to help developers of interactive 3D applications such as games.
- http://plib.sourceforge.net/

Quesa
- A free (LGPL-ed) and open source, high level 3D graphics library which offers binary and source level compatibility with Apple's QuickDraw 3D API.
- http://quesa.designcommunity.com/

Virtools
- Tools for the development of 3D graphics, primarily for use with development of online applications.
- http://www.virtools.com/