OGRE, Object-oriented Graphics Rendering Engine, an open source MIT licensed 3D renderer just released version 1.12 after almost a year in development. The release is heavily focused on internal rearchitecting for future development.
Key features from the 1.12 release:
#includedirective supported for GLSL shaders
PF_DEPTHsupport for shadows with the RTSS and the Terrain component
- RTSS 3.0: vastly improved internal API and refactored shader library
- Per pixel-shading on D3D11/ GL3+/ GLES2 by default (via RTSS)
- The GL3+ RenderSystem is now used for rendering the reference Test images
- More precise timings for built-in profiler and support for external profiling via Remotery
- unified API for fixed-function pipeline and shaders
- NEON intrinsics for OptimizedMath on ARM (Android)
- Stable Material library (Media/) that you can reference in your projects
- the MSVC SDK now also includes the Python and Java components
- support for loading 1.7 style terrains (aka “terrain.cfg”)
You can learn more about the release in the New and Noteworthy document available here. Additionally the source code for OGRE is available here on GitHub. The book mentioned in the video below that covers OGRE for game engine development is Game Engine Architecture.