aka ogre v2 - scene-oriented, flexible 3D C++ engine
FlightGear Flight Simulator: free open-source multiplatform flight sim
Open Source Solid Modeling CAD
crossplatform multithreaded object-oriented render and audio engine
LDraw™ editor for LEGO® style digital building instructions.
3D Without Boundaries
Realtime raytracer using SIMD on ARM, MIPS, PPC and x86
Scanning Probe Microscopy Controller and Data Visualization Software
Cross Platform Professional Procedural Terrain Generation & Texturing
Vivid is a modern C++ 3D engine using OpenGL4+
Vivid Engine 2 is an open source 3D Engine coded using C# and C++.
3D game engine for C and C++
A small library to create SDL 2 - OpenGL applications.
Pear3DEngine is a modern and modular 3D development framework
A 3D rendering / entity engine