implement friction anchors, position friction correction, disabled by default. Use colObj->setCollisionFlag(flag | CF_HAS_FRICTION_ANCHOR); See test/RobotClientAPI/SlopeFrictionMain.cpp. In URDF or SDF, add <friction_anchor/> in <contact> section of <link> to enable.
PhysicsServer: properly restore old activation state after releasing picked object
btMultiBodyConstraintSolver: disable flip/flop of contact/friction constraint solving by default (it breaks some internal flaky unit tests)
Added demos for rigid and multi body soft (compliant) contact.
Will also add simplified Hertz compliant contact, by dynamically modifying the ERP/CFM to mimic a non-linear spring.
Note that btManifoldPoint is growing too big, we need to implement proper contact constraints derived from btTypedConstraint.
CFM for contacts use world CFM value by default, and can override with custom CFM value using the
BT_CONTACT_FLAG_HAS_CONTACT_CFM stored in m_contactPointFlags.
Boolean m_lateralFrictionInitialized is replaced 'BT_CONTACT_FLAG_LATERAL_FRICTION_INITIALIZED' flag stored in int m_contactPointFlags in btManifoldPoint.
Enable successive over-relaxation parameter (SOR) for contacts. btMLCPSolver uses global CFM.
In one of the next commits, contact softness will be enabled btMultiBody contacts.
Also need to review use of CFM in btMLCPSolvers (only world CFM is used at the moment)
See http://www.youtube.com/watch?v=RV7sBAsKu4M and Bullet/Demos/RollingFrictionDemo
Fixes in FractureDemo (mouse picking constraint needs to be removed, otherwise constraint solver crashes/asserts)
warmstarting for contact points was broken, fix in btPersistentManifold
enable split impulse by default (at the cost of some performance)
add the option for zero-length friction (instead of recomputing friction directions using btPlaneSpace), use the solver mode flag SOLVER_ALLOW_ZERO_LENGTH_FRICTION_DIRECTIONS
precompute lateral friction directions (in btManifoldResult)
remove the mConstraintRow[3] from btManifoldPoint, it just took a lot of memory with no benefits: fixed it in btParallelConstraintSolver
+ improved friction warm starting
+ made constraint solver configuration more consistent (moved m_solverMode into btContactSolverInfo)
+ reset timing in CDTestFramework after initialization (SAP init destorts timings)
+ make it easier to change default sizes for stack allocator in btDefaultCollisionConfiguration
- copy user data over to child shape
- added applied impulse to btManifoldPoint
- add ContactProcessedCallback (needs test/demo)
- didn't copy over m_additionalDampingFactor into btRigidBody.
It leads to problems with certain compilers, when Bullet/src is located in a long pathname.
Keep include path starting with "LinearMath/, "BulletCollision/, or "BulletDynamics/
