Appleseed – open-source physically-based rendering engine
2015 Interview with the lead developer: <a href="http://blenderdiplom.com/en/interviews/607-interview-francois-beaune-on-appleseed-renderer.html" rel="nofollow">http://blenderdiplom.com/en/interviews/607-interview-francoi...</a><p>Seems like it's in around the same place, although the plugins are getting better and the renderer is starting to support complex scene features (not quite there yet).<p>Overall though there are 100's of ray-tracers and scene renderers (seemingly all in C++), so it's not clear if it has any compelling advantages.