FlightGear Flight Simulator: free open-source multiplatform flight sim
3D Engine c++
Open Source Solid Modeling CAD
Interactive 3D Layout Viewer for GDSII
DirectX 8 to OpenGL wrapper for legacy apps and portability
GLScene Engine for Delphi & C++Builder VCL Windows 32/64
LDraw™ editor for LEGO® style digital building instructions.
C++ Frontend for the RenderMan Interface
High-efficiency minimalist C++ wrapper for OpenGL 4.3
A simple 3D framework in C++
Support for legacy OpenGL in core profiles
C++ header-only library that simulates GLSL math