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expose pybullet changeDynamics(spinningFriction=..., rollingFriction=..., restitution=...)

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Bullet C-API b3ChangeDynamicsInfoSetSpinningFriction/RollingFriction/Resitution
b3PhysicsParamSetRestitutionVelocityThreshold, / pybullet.setPhysicsEngineParameter restitutionVelocityThreshold:
if the velocity is below this threshhold, the restitution is zero (this prevents energy buildup at near-resting state)
pybullet restitution.py example.
This commit is contained in:
Erwin Coumans
2017-05-26 18:14:38 -07:00
parent 8c6d4a4c85
commit b645963879
12 changed files with 317 additions and 51 deletions
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2
src/BulletDynamics/ConstraintSolver/btContactSolverInfo.h
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@@ -62,6 +62,7 @@ struct btContactSolverInfoData
btScalar m_maxGyroscopicForce;
btScalar m_singleAxisRollingFrictionThreshold;
btScalar m_leastSquaresResidualThreshold;
btScalar m_restitutionVelocityThreshold;
};
@@ -97,6 +98,7 @@ struct btContactSolverInfo : public btContactSolverInfoData
m_maxGyroscopicForce = 100.f; ///it is only used for 'explicit' version of gyroscopic force
m_singleAxisRollingFrictionThreshold = 1e30f;///if the velocity is above this threshold, it will use a single constraint row (axis), otherwise 3 rows.
m_leastSquaresResidualThreshold = 0.f;
m_restitutionVelocityThreshold = 0.2f;//if the relative velocity is below this threshold, there is zero restitution
}
};

8
src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.cpp
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@@ -506,8 +506,12 @@ void btSequentialImpulseConstraintSolver::initSolverBody(btSolverBody* solverBod
btScalar btSequentialImpulseConstraintSolver::restitutionCurve(btScalar rel_vel, btScalar restitution)
btScalar btSequentialImpulseConstraintSolver::restitutionCurve(btScalar rel_vel, btScalar restitution, btScalar velocityThreshold)
{
//printf("rel_vel =%f\n", rel_vel);
if (btFabs(rel_vel)<velocityThreshold)
return 0.;
btScalar rest = restitution * -rel_vel;
return rest;
}
@@ -947,7 +951,7 @@ void btSequentialImpulseConstraintSolver::setupContactConstraint(btSolverConstra
solverConstraint.m_friction = cp.m_combinedFriction;
restitution = restitutionCurve(rel_vel, cp.m_combinedRestitution);
restitution = restitutionCurve(rel_vel, cp.m_combinedRestitution, infoGlobal.m_restitutionVelocityThreshold);
if (restitution <= btScalar(0.))
{
restitution = 0.f;

2
src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.h
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@@ -86,7 +86,7 @@ protected:
unsigned long m_btSeed2;
btScalar restitutionCurve(btScalar rel_vel, btScalar restitution);
btScalar restitutionCurve(btScalar rel_vel, btScalar restitution, btScalar velocityThreshold);
virtual void convertContacts(btPersistentManifold** manifoldPtr, int numManifolds, const btContactSolverInfo& infoGlobal);