btMultiBodyConstraint.cpp

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#include "btMultiBodyConstraint.h"
#include "BulletDynamics/Dynamics/btRigidBody.h"
#include "btMultiBodyPoint2Point.h"                             //for testing (BTMBP2PCONSTRAINT_BLOCK_ANGULAR_MOTION_TEST macro)



btMultiBodyConstraint::btMultiBodyConstraint(btMultiBody* bodyA,btMultiBody* bodyB,int linkA, int linkB, int numRows, bool isUnilateral)
        :m_bodyA(bodyA),
        m_bodyB(bodyB),
        m_linkA(linkA),
        m_linkB(linkB),
        m_numRows(numRows),
        m_jacSizeA(0),
        m_jacSizeBoth(0),
        m_isUnilateral(isUnilateral),
        m_numDofsFinalized(-1),
        m_maxAppliedImpulse(100)
{

}

void btMultiBodyConstraint::updateJacobianSizes()
{
    if(m_bodyA)
        {
                m_jacSizeA = (6 + m_bodyA->getNumDofs());
        }

        if(m_bodyB)
        {
                m_jacSizeBoth = m_jacSizeA + 6 + m_bodyB->getNumDofs();
        }
        else
                m_jacSizeBoth = m_jacSizeA;
}

void btMultiBodyConstraint::allocateJacobiansMultiDof()
{
        updateJacobianSizes();

        m_posOffset = ((1 + m_jacSizeBoth)*m_numRows);
        m_data.resize((2 + m_jacSizeBoth) * m_numRows);
}

btMultiBodyConstraint::~btMultiBodyConstraint()
{
}

void    btMultiBodyConstraint::applyDeltaVee(btMultiBodyJacobianData& data, btScalar* delta_vee, btScalar impulse, int velocityIndex, int ndof)
{
        for (int i = 0; i < ndof; ++i)
                data.m_deltaVelocities[velocityIndex+i] += delta_vee[i] * impulse;
}

btScalar btMultiBodyConstraint::fillMultiBodyConstraint(        btMultiBodySolverConstraint& solverConstraint,
                                                        btMultiBodyJacobianData& data,
                                                        btScalar* jacOrgA, btScalar* jacOrgB,
                                                        const btVector3& constraintNormalAng,
                                                        const btVector3& constraintNormalLin,
                                                        const btVector3& posAworld, const btVector3& posBworld,
                                                        btScalar posError,
                                                        const btContactSolverInfo& infoGlobal,
                                                        btScalar lowerLimit, btScalar upperLimit,
                                                        bool angConstraint,
                                                        btScalar relaxation,
                                                        bool isFriction, btScalar desiredVelocity, btScalar cfmSlip)
{
    solverConstraint.m_multiBodyA = m_bodyA;
    solverConstraint.m_multiBodyB = m_bodyB;
    solverConstraint.m_linkA = m_linkA;
    solverConstraint.m_linkB = m_linkB;
    
    btMultiBody* multiBodyA = solverConstraint.m_multiBodyA;
    btMultiBody* multiBodyB = solverConstraint.m_multiBodyB;
    
    btSolverBody* bodyA = multiBodyA ? 0 : &data.m_solverBodyPool->at(solverConstraint.m_solverBodyIdA);
    btSolverBody* bodyB = multiBodyB ? 0 : &data.m_solverBodyPool->at(solverConstraint.m_solverBodyIdB);
    
    btRigidBody* rb0 = multiBodyA ? 0 : bodyA->m_originalBody;
    btRigidBody* rb1 = multiBodyB ? 0 : bodyB->m_originalBody;
    
    btVector3 rel_pos1, rel_pos2;                               //these two used to be inited to posAworld and posBworld (respectively) but it does not seem necessary
    if (bodyA)
        rel_pos1 = posAworld - bodyA->getWorldTransform().getOrigin();
    if (bodyB)
        rel_pos2 = posBworld - bodyB->getWorldTransform().getOrigin();
    
    if (multiBodyA)
    {
        if (solverConstraint.m_linkA<0)
        {
            rel_pos1 = posAworld - multiBodyA->getBasePos();
        } else
        {
            rel_pos1 = posAworld - multiBodyA->getLink(solverConstraint.m_linkA).m_cachedWorldTransform.getOrigin();
        }
        
        const int ndofA  = multiBodyA->getNumDofs() + 6;
        
        solverConstraint.m_deltaVelAindex = multiBodyA->getCompanionId();
        
        if (solverConstraint.m_deltaVelAindex <0)
        {
            solverConstraint.m_deltaVelAindex = data.m_deltaVelocities.size();
            multiBodyA->setCompanionId(solverConstraint.m_deltaVelAindex);
            data.m_deltaVelocities.resize(data.m_deltaVelocities.size()+ndofA);
        } else
        {
            btAssert(data.m_deltaVelocities.size() >= solverConstraint.m_deltaVelAindex+ndofA);
        }
        
        //determine jacobian of this 1D constraint in terms of multibodyA's degrees of freedom
        //resize..
        solverConstraint.m_jacAindex = data.m_jacobians.size();
        data.m_jacobians.resize(data.m_jacobians.size()+ndofA);
        //copy/determine
        if(jacOrgA)
        {
            for (int i=0;i<ndofA;i++)
                data.m_jacobians[solverConstraint.m_jacAindex+i] = jacOrgA[i];
        }
        else
        {
            btScalar* jac1=&data.m_jacobians[solverConstraint.m_jacAindex];
            //multiBodyA->fillContactJacobianMultiDof(solverConstraint.m_linkA, posAworld, constraintNormalLin, jac1, data.scratch_r, data.scratch_v, data.scratch_m);
            multiBodyA->fillConstraintJacobianMultiDof(solverConstraint.m_linkA, posAworld, constraintNormalAng, constraintNormalLin, jac1, data.scratch_r, data.scratch_v, data.scratch_m);
        }
        
        //determine the velocity response of multibodyA to reaction impulses of this constraint (i.e. A[i,i] for i=1,...n_con: multibody's inverse inertia with respect to this 1D constraint)
        //resize..
        data.m_deltaVelocitiesUnitImpulse.resize(data.m_deltaVelocitiesUnitImpulse.size()+ndofA);               //=> each constraint row has the constrained tree dofs allocated in m_deltaVelocitiesUnitImpulse
        btAssert(data.m_jacobians.size() == data.m_deltaVelocitiesUnitImpulse.size());
        btScalar* delta = &data.m_deltaVelocitiesUnitImpulse[solverConstraint.m_jacAindex];
        //determine..
        multiBodyA->calcAccelerationDeltasMultiDof(&data.m_jacobians[solverConstraint.m_jacAindex],delta,data.scratch_r, data.scratch_v);
        
        btVector3 torqueAxis0;
        if (angConstraint) {
            torqueAxis0 = constraintNormalAng;
        }
        else {
            torqueAxis0 = rel_pos1.cross(constraintNormalLin);
            
        }
        solverConstraint.m_relpos1CrossNormal = torqueAxis0;
        solverConstraint.m_contactNormal1 = constraintNormalLin;
    }
    else //if(rb0)
    {
        btVector3 torqueAxis0;
        if (angConstraint) {
            torqueAxis0 = constraintNormalAng;
        }
        else {
            torqueAxis0 = rel_pos1.cross(constraintNormalLin);
        }
        solverConstraint.m_angularComponentA = rb0 ? rb0->getInvInertiaTensorWorld()*torqueAxis0*rb0->getAngularFactor() : btVector3(0,0,0);
        solverConstraint.m_relpos1CrossNormal = torqueAxis0;
        solverConstraint.m_contactNormal1 = constraintNormalLin;
    }
    
    if (multiBodyB)
    {
        if (solverConstraint.m_linkB<0)
        {
            rel_pos2 = posBworld - multiBodyB->getBasePos();
        } else
        {
            rel_pos2 = posBworld - multiBodyB->getLink(solverConstraint.m_linkB).m_cachedWorldTransform.getOrigin();
        }
        
        const int ndofB  = multiBodyB->getNumDofs() + 6;
        
        solverConstraint.m_deltaVelBindex = multiBodyB->getCompanionId();
        if (solverConstraint.m_deltaVelBindex <0)
        {
            solverConstraint.m_deltaVelBindex = data.m_deltaVelocities.size();
            multiBodyB->setCompanionId(solverConstraint.m_deltaVelBindex);
            data.m_deltaVelocities.resize(data.m_deltaVelocities.size()+ndofB);
        }
        
        //determine jacobian of this 1D constraint in terms of multibodyB's degrees of freedom
        //resize..
        solverConstraint.m_jacBindex = data.m_jacobians.size();
        data.m_jacobians.resize(data.m_jacobians.size()+ndofB);
        //copy/determine..
        if(jacOrgB)
        {
            for (int i=0;i<ndofB;i++)
                data.m_jacobians[solverConstraint.m_jacBindex+i] = jacOrgB[i];
        }
        else
        {
            //multiBodyB->fillContactJacobianMultiDof(solverConstraint.m_linkB, posBworld, -constraintNormalLin, &data.m_jacobians[solverConstraint.m_jacBindex], data.scratch_r, data.scratch_v, data.scratch_m);
            multiBodyB->fillConstraintJacobianMultiDof(solverConstraint.m_linkB, posBworld, -constraintNormalAng, -constraintNormalLin, &data.m_jacobians[solverConstraint.m_jacBindex], data.scratch_r, data.scratch_v, data.scratch_m);
        }
        
        //determine velocity response of multibodyB to reaction impulses of this constraint (i.e. A[i,i] for i=1,...n_con: multibody's inverse inertia with respect to this 1D constraint)
        //resize..
        data.m_deltaVelocitiesUnitImpulse.resize(data.m_deltaVelocitiesUnitImpulse.size()+ndofB);
        btAssert(data.m_jacobians.size() == data.m_deltaVelocitiesUnitImpulse.size());
        btScalar* delta = &data.m_deltaVelocitiesUnitImpulse[solverConstraint.m_jacBindex];
        //determine..
        multiBodyB->calcAccelerationDeltasMultiDof(&data.m_jacobians[solverConstraint.m_jacBindex],delta,data.scratch_r, data.scratch_v);
        
        btVector3 torqueAxis1;
        if (angConstraint) {
            torqueAxis1 = constraintNormalAng;
        }
        else {
            torqueAxis1 = rel_pos2.cross(constraintNormalLin);
        }
        solverConstraint.m_relpos2CrossNormal = -torqueAxis1;
        solverConstraint.m_contactNormal2 = -constraintNormalLin;
    }
    else //if(rb1)
    {
        btVector3 torqueAxis1;
        if (angConstraint) {
            torqueAxis1 = constraintNormalAng;
        }
        else {
            torqueAxis1 = rel_pos2.cross(constraintNormalLin);
        }
        solverConstraint.m_angularComponentB = rb1 ? rb1->getInvInertiaTensorWorld()*-torqueAxis1*rb1->getAngularFactor() : btVector3(0,0,0);
        solverConstraint.m_relpos2CrossNormal = -torqueAxis1;
        solverConstraint.m_contactNormal2 = -constraintNormalLin;
    }
    {
        
        btVector3 vec;
        btScalar denom0 = 0.f;
        btScalar denom1 = 0.f;
        btScalar* jacB = 0;
        btScalar* jacA = 0;
        btScalar* deltaVelA = 0;
        btScalar* deltaVelB = 0;
        int ndofA  = 0;
        //determine the "effective mass" of the constrained multibodyA with respect to this 1D constraint (i.e. 1/A[i,i])
        if (multiBodyA)
        {
            ndofA = multiBodyA->getNumDofs() + 6;
            jacA = &data.m_jacobians[solverConstraint.m_jacAindex];
            deltaVelA = &data.m_deltaVelocitiesUnitImpulse[solverConstraint.m_jacAindex];
            for (int i = 0; i < ndofA; ++i)
            {
                btScalar j = jacA[i] ;
                btScalar l = deltaVelA[i];
                denom0 += j*l;
            }
        }
        else if(rb0)
        {
            vec = ( solverConstraint.m_angularComponentA).cross(rel_pos1);
            if (angConstraint) {
                                denom0 = constraintNormalAng.dot(solverConstraint.m_angularComponentA);
            }
            else {
                denom0 = rb0->getInvMass() + constraintNormalLin.dot(vec);
            }
        }
        //
        if (multiBodyB)
        {
            const int ndofB = multiBodyB->getNumDofs() + 6;
            jacB = &data.m_jacobians[solverConstraint.m_jacBindex];
            deltaVelB = &data.m_deltaVelocitiesUnitImpulse[solverConstraint.m_jacBindex];
            for (int i = 0; i < ndofB; ++i)
            {
                btScalar j = jacB[i] ;
                btScalar l = deltaVelB[i];
                denom1 += j*l;
            }
            
        }
        else if(rb1)
        {
            vec = ( -solverConstraint.m_angularComponentB).cross(rel_pos2);
            if (angConstraint) {
                                denom1 = constraintNormalAng.dot(-solverConstraint.m_angularComponentB);
            }
            else {
                denom1 = rb1->getInvMass() + constraintNormalLin.dot(vec);
            }
        }
        
        //
        btScalar d = denom0+denom1;
        if (d>SIMD_EPSILON)
        {
            solverConstraint.m_jacDiagABInv = relaxation/(d);
        }
        else
        {
            //disable the constraint row to handle singularity/redundant constraint
            solverConstraint.m_jacDiagABInv  = 0.f;
        }
    }
    
    
    //compute rhs and remaining solverConstraint fields
    btScalar penetration = isFriction? 0 : posError;
    
    btScalar rel_vel = 0.f;
    int ndofA  = 0;
    int ndofB  = 0;
    {
        btVector3 vel1,vel2;
        if (multiBodyA)
        {
            ndofA = multiBodyA->getNumDofs() + 6;
            btScalar* jacA = &data.m_jacobians[solverConstraint.m_jacAindex];
            for (int i = 0; i < ndofA ; ++i)
                rel_vel += multiBodyA->getVelocityVector()[i] * jacA[i];
        }
        else if(rb0)
        {
                        rel_vel += rb0->getLinearVelocity().dot(solverConstraint.m_contactNormal1);
                        rel_vel += rb0->getAngularVelocity().dot(solverConstraint.m_relpos1CrossNormal);
        }
        if (multiBodyB)
        {
            ndofB = multiBodyB->getNumDofs() + 6;
            btScalar* jacB = &data.m_jacobians[solverConstraint.m_jacBindex];
            for (int i = 0; i < ndofB ; ++i)
                rel_vel += multiBodyB->getVelocityVector()[i] * jacB[i];
            
        }
        else if(rb1)
        {
                        rel_vel += rb1->getLinearVelocity().dot(solverConstraint.m_contactNormal2);
                        rel_vel += rb1->getAngularVelocity().dot(solverConstraint.m_relpos2CrossNormal);
        }
        
        solverConstraint.m_friction = 0.f;//cp.m_combinedFriction;
    }
    
    
    /*
     if (infoGlobal.m_solverMode & SOLVER_USE_WARMSTARTING)
     {
     solverConstraint.m_appliedImpulse = isFriction ? 0 : cp.m_appliedImpulse * infoGlobal.m_warmstartingFactor;
     
     if (solverConstraint.m_appliedImpulse)
     {
     if (multiBodyA)
     {
     btScalar impulse = solverConstraint.m_appliedImpulse;
     btScalar* deltaV = &data.m_deltaVelocitiesUnitImpulse[solverConstraint.m_jacAindex];
     multiBodyA->applyDeltaVee(deltaV,impulse);
     applyDeltaVee(data,deltaV,impulse,solverConstraint.m_deltaVelAindex,ndofA);
     } else
     {
     if (rb0)
                                        bodyA->internalApplyImpulse(solverConstraint.m_contactNormal1*bodyA->internalGetInvMass()*rb0->getLinearFactor(),solverConstraint.m_angularComponentA,solverConstraint.m_appliedImpulse);
     }
     if (multiBodyB)
     {
     btScalar impulse = solverConstraint.m_appliedImpulse;
     btScalar* deltaV = &data.m_deltaVelocitiesUnitImpulse[solverConstraint.m_jacBindex];
     multiBodyB->applyDeltaVee(deltaV,impulse);
     applyDeltaVee(data,deltaV,impulse,solverConstraint.m_deltaVelBindex,ndofB);
     } else
     {
     if (rb1)
                                        bodyB->internalApplyImpulse(-solverConstraint.m_contactNormal2*bodyB->internalGetInvMass()*rb1->getLinearFactor(),-solverConstraint.m_angularComponentB,-(btScalar)solverConstraint.m_appliedImpulse);
     }
     }
     } else
     */
    
    solverConstraint.m_appliedImpulse = 0.f;
    solverConstraint.m_appliedPushImpulse = 0.f;
    
    {
        
        btScalar positionalError = 0.f;
        btScalar        velocityError = desiredVelocity - rel_vel;// * damping;
        
        
        btScalar erp = infoGlobal.m_erp2;
                
                //split impulse is not implemented yet for btMultiBody*
                //if (!infoGlobal.m_splitImpulse || (penetration > infoGlobal.m_splitImpulsePenetrationThreshold))
        {
            erp = infoGlobal.m_erp;
        }
        
        positionalError = -penetration * erp/infoGlobal.m_timeStep;
        
        btScalar  penetrationImpulse = positionalError*solverConstraint.m_jacDiagABInv;
        btScalar velocityImpulse = velocityError *solverConstraint.m_jacDiagABInv;
        
                //split impulse is not implemented yet for btMultiBody*

      //  if (!infoGlobal.m_splitImpulse || (penetration > infoGlobal.m_splitImpulsePenetrationThreshold))
        {
            //combine position and velocity into rhs
            solverConstraint.m_rhs = penetrationImpulse+velocityImpulse;
            solverConstraint.m_rhsPenetration = 0.f;
            
        } 
                /*else
        {
            //split position and velocity into rhs and m_rhsPenetration
            solverConstraint.m_rhs = velocityImpulse;
            solverConstraint.m_rhsPenetration = penetrationImpulse;
        }
        */

        solverConstraint.m_cfm = 0.f;
        solverConstraint.m_lowerLimit = lowerLimit;
        solverConstraint.m_upperLimit = upperLimit;
    }
    
    return rel_vel;
    
}