Very little besides the Doxygen: http://bulletphysics.org/Bullet/BulletFull/
Good luck.
Bullet is written in C++, and exposes only a C++ API.
A C API has been somewhat considered: bulletphysics/bullet3#130
- http://stackoverflow.com/questions/6004381/ideas-for-physics-for-rolling-dice
- http://stackoverflow.com/questions/1034253/are-there-any-decent-physics-engines-for-android
TODO: efficient compared to say, Box2D?
- official example classified under experiments in the example browser https://github.com/bulletphysics/bullet3/blob/2.83/examples/Planar2D/Planar2D.cpp
- http://gamedev.stackexchange.com/questions/6130/is-it-worth-it-to-use-bullet-for-2d-physics-instead-of-box2d-for-the-sake-of-lea
- 2D demo https://www.youtube.com/watch?v=CsPgMmgsU7E
Library creator worked at:
- Havok
- Sony
- AMD (on Bullet)
- Google (on Bullet)