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Enable softness for btRigidBody contacts. This is implemented by some value (CFM, constraint force mixing) to the main diagonal of A.

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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)
This commit is contained in:
erwin coumans
2016-01-22 17:43:36 -08:00
parent 6bc3f94f52
commit 645a88176d
6 changed files with 40 additions and 42 deletions
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23
src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.cpp
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@@ -775,7 +775,11 @@ void btSequentialImpulseConstraintSolver::setupContactConstraint(btSolverConstra
//rel_pos1 = pos1 - bodyA->getWorldTransform().getOrigin();
//rel_pos2 = pos2 - bodyB->getWorldTransform().getOrigin();
relaxation = 1.f;
relaxation = infoGlobal.m_sor;
btScalar invTimeStep = btScalar(1)/infoGlobal.m_timeStep;
btScalar cfm = (cp.m_contactPointFlags&BT_CONTACT_FLAG_HAS_CONTACT_CFM)?cp.m_contactCFM:infoGlobal.m_globalCfm;
cfm *= invTimeStep;
btVector3 torqueAxis0 = rel_pos1.cross(cp.m_normalWorldOnB);
solverConstraint.m_angularComponentA = rb0 ? rb0->getInvInertiaTensorWorld()*torqueAxis0*rb0->getAngularFactor() : btVector3(0,0,0);
@@ -802,7 +806,7 @@ void btSequentialImpulseConstraintSolver::setupContactConstraint(btSolverConstra
}
#endif //COMPUTE_IMPULSE_DENOM
btScalar denom = relaxation/(denom0+denom1);
btScalar denom = relaxation/(denom0+denom1+cfm);
solverConstraint.m_jacDiagABInv = denom;
}
@@ -894,10 +898,11 @@ void btSequentialImpulseConstraintSolver::setupContactConstraint(btSolverConstra
{
positionalError = 0;
velocityError -= penetration / infoGlobal.m_timeStep;
velocityError -= penetration *invTimeStep;
} else
{
positionalError = -penetration * erp/infoGlobal.m_timeStep;
positionalError = -penetration * erp*invTimeStep;
}
btScalar penetrationImpulse = positionalError*solverConstraint.m_jacDiagABInv;
@@ -915,7 +920,7 @@ void btSequentialImpulseConstraintSolver::setupContactConstraint(btSolverConstra
solverConstraint.m_rhs = velocityImpulse;
solverConstraint.m_rhsPenetration = penetrationImpulse;
}
solverConstraint.m_cfm = 0.f;
solverConstraint.m_cfm = cfm*solverConstraint.m_jacDiagABInv;
solverConstraint.m_lowerLimit = 0;
solverConstraint.m_upperLimit = 1e10f;
}
@@ -1094,7 +1099,7 @@ void btSequentialImpulseConstraintSolver::convertContact(btPersistentManifold* m
///In that case, you can set the target relative motion in each friction direction (cp.m_contactMotion1 and cp.m_contactMotion2)
///this will give a conveyor belt effect
///
if (!(infoGlobal.m_solverMode & SOLVER_ENABLE_FRICTION_DIRECTION_CACHING) || !cp.m_lateralFrictionInitialized)
if (!(infoGlobal.m_solverMode & SOLVER_ENABLE_FRICTION_DIRECTION_CACHING) || !(cp.m_contactPointFlags&BT_CONTACT_FLAG_LATERAL_FRICTION_INITIALIZED))
{
cp.m_lateralFrictionDir1 = vel - cp.m_normalWorldOnB * rel_vel;
btScalar lat_rel_vel = cp.m_lateralFrictionDir1.length2();
@@ -1132,16 +1137,16 @@ void btSequentialImpulseConstraintSolver::convertContact(btPersistentManifold* m
if ((infoGlobal.m_solverMode & SOLVER_USE_2_FRICTION_DIRECTIONS) && (infoGlobal.m_solverMode & SOLVER_DISABLE_VELOCITY_DEPENDENT_FRICTION_DIRECTION))
{
cp.m_lateralFrictionInitialized = true;
cp.m_contactPointFlags|=BT_CONTACT_FLAG_LATERAL_FRICTION_INITIALIZED;
}
}
} else
{
addFrictionConstraint(cp.m_lateralFrictionDir1,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation,cp.m_contactMotion1, cp.m_contactCFM1);
addFrictionConstraint(cp.m_lateralFrictionDir1,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation,cp.m_contactMotion1, cp.m_frictionCFM);
if ((infoGlobal.m_solverMode & SOLVER_USE_2_FRICTION_DIRECTIONS))
addFrictionConstraint(cp.m_lateralFrictionDir2,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation, cp.m_contactMotion2, cp.m_contactCFM2);
addFrictionConstraint(cp.m_lateralFrictionDir2,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation, cp.m_contactMotion2, cp.m_frictionCFM);
}
setFrictionConstraintImpulse( solverConstraint, solverBodyIdA, solverBodyIdB, cp, infoGlobal);

8
src/BulletDynamics/Featherstone/btMultiBodyConstraintSolver.cpp
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@@ -685,7 +685,7 @@ void btMultiBodyConstraintSolver::convertMultiBodyContact(btPersistentManifold*
///In that case, you can set the target relative motion in each friction direction (cp.m_contactMotion1 and cp.m_contactMotion2)
///this will give a conveyor belt effect
///
if (!(infoGlobal.m_solverMode & SOLVER_ENABLE_FRICTION_DIRECTION_CACHING) || !cp.m_lateralFrictionInitialized)
if (!(infoGlobal.m_solverMode & SOLVER_ENABLE_FRICTION_DIRECTION_CACHING) || !(cp.m_contactPointFlags&BT_CONTACT_FLAG_LATERAL_FRICTION_INITIALIZED))
{/*
cp.m_lateralFrictionDir1 = vel - cp.m_normalWorldOnB * rel_vel;
btScalar lat_rel_vel = cp.m_lateralFrictionDir1.length2();
@@ -724,16 +724,16 @@ void btMultiBodyConstraintSolver::convertMultiBodyContact(btPersistentManifold*
if ((infoGlobal.m_solverMode & SOLVER_USE_2_FRICTION_DIRECTIONS) && (infoGlobal.m_solverMode & SOLVER_DISABLE_VELOCITY_DEPENDENT_FRICTION_DIRECTION))
{
cp.m_lateralFrictionInitialized = true;
cp.m_contactPointFlags|=BT_CONTACT_FLAG_LATERAL_FRICTION_INITIALIZED;
}
}
} else
{
addMultiBodyFrictionConstraint(cp.m_lateralFrictionDir1,manifold,frictionIndex,cp,colObj0,colObj1, relaxation,infoGlobal,cp.m_contactMotion1, cp.m_contactCFM1);
addMultiBodyFrictionConstraint(cp.m_lateralFrictionDir1,manifold,frictionIndex,cp,colObj0,colObj1, relaxation,infoGlobal,cp.m_contactMotion1, cp.m_frictionCFM);
if ((infoGlobal.m_solverMode & SOLVER_USE_2_FRICTION_DIRECTIONS))
addMultiBodyFrictionConstraint(cp.m_lateralFrictionDir2,manifold,frictionIndex,cp,colObj0,colObj1, relaxation, infoGlobal,cp.m_contactMotion2, cp.m_contactCFM2);
addMultiBodyFrictionConstraint(cp.m_lateralFrictionDir2,manifold,frictionIndex,cp,colObj0,colObj1, relaxation, infoGlobal,cp.m_contactMotion2, cp.m_frictionCFM);
//setMultiBodyFrictionConstraintImpulse( solverConstraint, solverBodyIdA, solverBodyIdB, cp, infoGlobal);
//todo:

7
src/BulletDynamics/MLCPSolvers/btMLCPSolver.cpp
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@@ -22,8 +22,7 @@ subject to the following restrictions:
btMLCPSolver::btMLCPSolver( btMLCPSolverInterface* solver)
:m_solver(solver),
m_fallback(0),
m_cfm(0.000001)//0.0000001
m_fallback(0)
{
}
@@ -436,7 +435,7 @@ void btMLCPSolver::createMLCPFast(const btContactSolverInfo& infoGlobal)
// add cfm to the diagonal of m_A
for ( int i=0; i<m_A.rows(); ++i)
{
m_A.setElem(i,i,m_A(i,i)+ m_cfm / infoGlobal.m_timeStep);
m_A.setElem(i,i,m_A(i,i)+ infoGlobal.m_globalCfm/ infoGlobal.m_timeStep);
}
}
@@ -564,7 +563,7 @@ void btMLCPSolver::createMLCP(const btContactSolverInfo& infoGlobal)
// add cfm to the diagonal of m_A
for ( int i=0; i<m_A.rows(); ++i)
{
m_A.setElem(i,i,m_A(i,i)+ m_cfm / infoGlobal.m_timeStep);
m_A.setElem(i,i,m_A(i,i)+ infoGlobal.m_globalCfm / infoGlobal.m_timeStep);
}
}

10
src/BulletDynamics/MLCPSolvers/btMLCPSolver.h
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@@ -42,7 +42,6 @@ protected:
btAlignedObjectArray<btSolverConstraint*> m_allConstraintPtrArray;
btMLCPSolverInterface* m_solver;
int m_fallback;
btScalar m_cfm;
virtual btScalar solveGroupCacheFriendlySetup(btCollisionObject** bodies, int numBodies, btPersistentManifold** manifoldPtr, int numManifolds,btTypedConstraint** constraints,int numConstraints,const btContactSolverInfo& infoGlobal,btIDebugDraw* debugDrawer);
virtual btScalar solveGroupCacheFriendlyIterations(btCollisionObject** bodies ,int numBodies,btPersistentManifold** manifoldPtr, int numManifolds,btTypedConstraint** constraints,int numConstraints,const btContactSolverInfo& infoGlobal,btIDebugDraw* debugDrawer);
@@ -73,15 +72,6 @@ public:
m_fallback = num;
}
btScalar getCfm() const
{
return m_cfm;
}
void setCfm(btScalar cfm)
{
m_cfm = cfm;
}
virtual btConstraintSolverType getSolverType() const
{
return BT_MLCP_SOLVER;