PortAudio - PortAudio is a cross platform, open-source, audio I/O library.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
OpenAL Soft - OpenAL Soft is an LGPL-licensed, cross-platform, software implementation of the OpenAL 3D audio API.
SketchUp - 3D for Everyone
JUCE - JUCE is a wide-ranging C++ class library for building rich cross-platform applications and plugins...
AC3D - AC3D is a 3D software for games, virtual reality and flight simulation, scientific, medical and general data visualisation, rapid prototypes of 3D designs, 3D printing, Google Earth, X-Plane, Second Life and more.