Smoothed Particle Hydrodynamics (SPH) fluids preview, thanks to Rama Hoetzlein for contributing this under the ZLib license! See Bullet/Extras/sph. The SPH fluids will be integrated into Bullet with two-way interaction, similar to cloth/soft body simulation.
GPU physics kernels preview, in preparation for Bullet 3.x. Right now mainly CPU version, you can enable CUDA version manually. The OpenCL version is available in a separate branch. See Bullet/Demos/Gpu2/3dDemo
2D physics demo, with 2D and 3D object interaction, see Bullet/Demos/Box2dDemo
New constraints: btHinge2Constraint,btUniversalConstraint,btGeneric6DofSpringConstraint, thanks to Roman Ponomarev
Use ALT+Left/Middle/Right Mouse button+mouse motion for Maya-style camera navigation
Re-enabled split impulse constraint solver option, to avoid adding momentum due to penetration recovery (includes SIMD support)
Removed first argument 'localInertiaTensor, from btMultiSphereShape. Update your code by remove the first argument: it calculates its local inertia from its aabb now.
Increased performance by disabling motion state synchronization for static/inactive objects.
Use btDiscreteDynamicsWorld::setSynchronizeAllMotionStates(true); for backwards compatiblity.
Improvements in Soft Body simulation: added tetrahedral volumetric demos, allow for per-triangle/per-tetrahedron collision (pass 0 in generateClusters), increased stability for cluster collision, improved performance of bending constraint generation.
Added pre-tick callback option, called at the start of each internal simulation substep.
Added optimized capsule-capsule collider, useful for ragdolls.
many bug fixes
Thanks everyone for the contributions and patches and other feedback!
Remaining open issues will be addressed in upcoming versions.