Add a virtual createConstraintRows method, to easier experiment with different kinds of btMultiBodyConstraint
This commit is contained in:
erwin.coumans
@@ -4,15 +4,16 @@
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#include "btMultiBodyLinkCollider.h"
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#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
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btMultiBodyJointLimitConstraint::btMultiBodyJointLimitConstraint(btMultiBody* body, int link, btScalar lower, btScalar upper)
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:btMultiBodyConstraint(body,body,link,link,2,true),
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m_lowerBound(lower),
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m_upperBound(upper)
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{
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// the jacobians never change, so may as well
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// the data.m_jacobians never change, so may as well
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// initialize them here
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// note: we rely on the fact that jacobians are
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// note: we rely on the fact that data.m_jacobians are
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// always initialized to zero by the Constraint ctor
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// row 0: the lower bound
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@@ -35,9 +36,12 @@ int btMultiBodyJointLimitConstraint::getIslandIdB() const
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return m_bodyB->getLinkCollider(0)->getIslandTag();
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}
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void btMultiBodyJointLimitConstraint::update()
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void btMultiBodyJointLimitConstraint::createConstraintRows(btMultiBodyConstraintArray& constraintRows,
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btMultiBodyJacobianData& data,
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const btContactSolverInfo& infoGlobal)
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{
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// only positions need to be updated -- jacobians and force
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// only positions need to be updated -- data.m_jacobians and force
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// directions were set in the ctor and never change.
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// row 0: the lower bound
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@@ -45,4 +49,249 @@ void btMultiBodyJointLimitConstraint::update()
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// row 1: the upper bound
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setPosition(1, m_upperBound - m_bodyA->getJointPos(m_linkA));
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}
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for (int row=0;row<getNumRows();row++)
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{
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btMultiBodySolverConstraint& constraintRow = constraintRows.expandNonInitializing();
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constraintRow.m_multiBodyA = m_bodyA;
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constraintRow.m_multiBodyB = m_bodyB;
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btScalar penetration = getPosition(row);
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fillConstraintRow(constraintRow,data,jacobianA(row),jacobianB(row),penetration,0,0,infoGlobal);
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}
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}
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void btMultiBodyJointLimitConstraint::fillConstraintRow(btMultiBodySolverConstraint& constraintRow,
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btMultiBodyJacobianData& data,
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btScalar* jacOrgA,btScalar* jacOrgB,
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btScalar penetration,btScalar combinedFrictionCoeff, btScalar combinedRestitutionCoeff,
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const btContactSolverInfo& infoGlobal)
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{
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btMultiBody* multiBodyA = constraintRow.m_multiBodyA;
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btMultiBody* multiBodyB = constraintRow.m_multiBodyB;
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if (multiBodyA)
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{
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const int ndofA = multiBodyA->getNumLinks() + 6;
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constraintRow.m_deltaVelAindex = multiBodyA->getCompanionId();
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if (constraintRow.m_deltaVelAindex <0)
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{
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constraintRow.m_deltaVelAindex = data.m_deltaVelocities.size();
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multiBodyA->setCompanionId(constraintRow.m_deltaVelAindex);
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data.m_deltaVelocities.resize(data.m_deltaVelocities.size()+ndofA);
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} else
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{
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btAssert(data.m_deltaVelocities.size() >= constraintRow.m_deltaVelAindex+ndofA);
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}
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constraintRow.m_jacAindex = data.m_jacobians.size();
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data.m_jacobians.resize(data.m_jacobians.size()+ndofA);
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data.m_deltaVelocitiesUnitImpulse.resize(data.m_deltaVelocitiesUnitImpulse.size()+ndofA);
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btAssert(data.m_jacobians.size() == data.m_deltaVelocitiesUnitImpulse.size());
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for (int i=0;i<ndofA;i++)
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data.m_jacobians[constraintRow.m_jacAindex+i] = jacOrgA[i];
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float* delta = &data.m_deltaVelocitiesUnitImpulse[constraintRow.m_jacAindex];
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multiBodyA->calcAccelerationDeltas(&data.m_jacobians[constraintRow.m_jacAindex],delta,data.scratch_r, data.scratch_v);
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}
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if (multiBodyB)
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{
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const int ndofB = multiBodyB->getNumLinks() + 6;
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constraintRow.m_deltaVelBindex = multiBodyB->getCompanionId();
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if (constraintRow.m_deltaVelBindex <0)
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{
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constraintRow.m_deltaVelBindex = data.m_deltaVelocities.size();
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multiBodyB->setCompanionId(constraintRow.m_deltaVelBindex);
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data.m_deltaVelocities.resize(data.m_deltaVelocities.size()+ndofB);
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}
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constraintRow.m_jacBindex = data.m_jacobians.size();
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data.m_jacobians.resize(data.m_jacobians.size()+ndofB);
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for (int i=0;i<ndofB;i++)
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data.m_jacobians[constraintRow.m_jacBindex+i] = jacOrgB[i];
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data.m_deltaVelocitiesUnitImpulse.resize(data.m_deltaVelocitiesUnitImpulse.size()+ndofB);
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btAssert(data.m_jacobians.size() == data.m_deltaVelocitiesUnitImpulse.size());
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multiBodyB->calcAccelerationDeltas(&data.m_jacobians[constraintRow.m_jacBindex],&data.m_deltaVelocitiesUnitImpulse[constraintRow.m_jacBindex],data.scratch_r, data.scratch_v);
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}
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{
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btVector3 vec;
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btScalar denom0 = 0.f;
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btScalar denom1 = 0.f;
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btScalar* jacB = 0;
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btScalar* jacA = 0;
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btScalar* lambdaA =0;
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btScalar* lambdaB =0;
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int ndofA = 0;
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if (multiBodyA)
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{
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ndofA = multiBodyA->getNumLinks() + 6;
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jacA = &data.m_jacobians[constraintRow.m_jacAindex];
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lambdaA = &data.m_deltaVelocitiesUnitImpulse[constraintRow.m_jacAindex];
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for (int i = 0; i < ndofA; ++i)
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{
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float j = jacA[i] ;
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float l =lambdaA[i];
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denom0 += j*l;
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}
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}
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if (multiBodyB)
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{
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const int ndofB = multiBodyB->getNumLinks() + 6;
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jacB = &data.m_jacobians[constraintRow.m_jacBindex];
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lambdaB = &data.m_deltaVelocitiesUnitImpulse[constraintRow.m_jacBindex];
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for (int i = 0; i < ndofB; ++i)
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{
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float j = jacB[i] ;
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float l =lambdaB[i];
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denom1 += j*l;
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}
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}
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if (multiBodyA && (multiBodyA==multiBodyB))
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{
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// ndof1 == ndof2 in this case
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for (int i = 0; i < ndofA; ++i)
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{
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denom1 += jacB[i] * lambdaA[i];
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denom1 += jacA[i] * lambdaB[i];
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}
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}
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float d = denom0+denom1;
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if (btFabs(d)>SIMD_EPSILON)
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{
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constraintRow.m_jacDiagABInv = 1.f/(d);
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} else
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{
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constraintRow.m_jacDiagABInv = 1.f;
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}
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}
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//compute rhs and remaining constraintRow fields
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btScalar rel_vel = 0.f;
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int ndofA = 0;
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int ndofB = 0;
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{
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btVector3 vel1,vel2;
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if (multiBodyA)
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{
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ndofA = multiBodyA->getNumLinks() + 6;
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btScalar* jacA = &data.m_jacobians[constraintRow.m_jacAindex];
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for (int i = 0; i < ndofA ; ++i)
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rel_vel += multiBodyA->getVelocityVector()[i] * jacA[i];
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}
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if (multiBodyB)
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{
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ndofB = multiBodyB->getNumLinks() + 6;
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btScalar* jacB = &data.m_jacobians[constraintRow.m_jacBindex];
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for (int i = 0; i < ndofB ; ++i)
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rel_vel += multiBodyB->getVelocityVector()[i] * jacB[i];
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}
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constraintRow.m_friction = combinedFrictionCoeff;
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}
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/*
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///warm starting (or zero if disabled)
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if (infoGlobal.m_solverMode & SOLVER_USE_WARMSTARTING)
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{
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constraintRow.m_appliedImpulse = isFriction ? 0 : cp.m_appliedImpulse * infoGlobal.m_warmstartingFactor;
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if (constraintRow.m_appliedImpulse)
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{
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if (multiBodyA)
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{
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btScalar impulse = constraintRow.m_appliedImpulse;
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btScalar* deltaV = &data.m_deltaVelocitiesUnitImpulse[constraintRow.m_jacAindex];
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multiBodyA->applyDeltaVee(deltaV,impulse);
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applyDeltaVee(deltaV,impulse,constraintRow.m_deltaVelAindex,ndofA);
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}
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if (multiBodyB)
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{
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btScalar impulse = constraintRow.m_appliedImpulse;
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btScalar* deltaV = &data.m_deltaVelocitiesUnitImpulse[constraintRow.m_jacBindex];
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multiBodyB->applyDeltaVee(deltaV,impulse);
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applyDeltaVee(deltaV,impulse,constraintRow.m_deltaVelBindex,ndofB);
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}
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}
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}
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else
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*/
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{
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constraintRow.m_appliedImpulse = 0.f;
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}
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constraintRow.m_appliedPushImpulse = 0.f;
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{
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float desiredVelocity = -0.3;
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btScalar positionalError = 0.f;
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btScalar velocityError = - rel_vel;// * damping;
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btScalar erp = infoGlobal.m_erp2;
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if (!infoGlobal.m_splitImpulse || (penetration > infoGlobal.m_splitImpulsePenetrationThreshold))
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{
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erp = infoGlobal.m_erp;
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}
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if (penetration>0)
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{
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positionalError = 0;
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velocityError = -penetration / infoGlobal.m_timeStep;
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} else
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{
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positionalError = -penetration * erp/infoGlobal.m_timeStep;
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}
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btScalar penetrationImpulse = positionalError*constraintRow.m_jacDiagABInv;
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btScalar velocityImpulse = velocityError *constraintRow.m_jacDiagABInv;
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if (!infoGlobal.m_splitImpulse || (penetration > infoGlobal.m_splitImpulsePenetrationThreshold))
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{
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//combine position and velocity into rhs
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constraintRow.m_rhs = penetrationImpulse+velocityImpulse;
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constraintRow.m_rhsPenetration = 0.f;
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} else
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{
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//split position and velocity into rhs and m_rhsPenetration
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constraintRow.m_rhs = velocityImpulse;
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constraintRow.m_rhsPenetration = penetrationImpulse;
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}
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constraintRow.m_cfm = 0.f;
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constraintRow.m_lowerLimit = 0;
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constraintRow.m_upperLimit = 1e10f;
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}
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}
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