btSequentialImpulseConstraintSolver.cpp

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/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/

This software is provided 'as-is', without any express or implied warranty.
In no event will the authors be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose, 
including commercial applications, and to alter it and redistribute it freely, 
subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/

//#define COMPUTE_IMPULSE_DENOM 1
//It is not necessary (redundant) to refresh contact manifolds, this refresh has been moved to the collision algorithms.

#include "btSequentialImpulseConstraintSolver.h"
#include "BulletCollision/NarrowPhaseCollision/btPersistentManifold.h"
#include "BulletDynamics/Dynamics/btRigidBody.h"
#include "btContactConstraint.h"
#include "btSolve2LinearConstraint.h"
#include "btContactSolverInfo.h"
#include "LinearMath/btIDebugDraw.h"
#include "btJacobianEntry.h"
#include "LinearMath/btMinMax.h"
#include "BulletDynamics/ConstraintSolver/btTypedConstraint.h"
#include <new>
#include "LinearMath/btStackAlloc.h"
#include "LinearMath/btQuickprof.h"
#include "btSolverBody.h"
#include "btSolverConstraint.h"
#include "LinearMath/btAlignedObjectArray.h"
#include <string.h> //for memset

int     gNumSplitImpulseRecoveries = 0;

btSequentialImpulseConstraintSolver::btSequentialImpulseConstraintSolver()
:m_btSeed2(0)
{

}

btSequentialImpulseConstraintSolver::~btSequentialImpulseConstraintSolver()
{
}

#ifdef USE_SIMD
#include <emmintrin.h>
#define btVecSplat(x, e) _mm_shuffle_ps(x, x, _MM_SHUFFLE(e,e,e,e))
static inline __m128 btSimdDot3( __m128 vec0, __m128 vec1 )
{
    __m128 result = _mm_mul_ps( vec0, vec1);
    return _mm_add_ps( btVecSplat( result, 0 ), _mm_add_ps( btVecSplat( result, 1 ), btVecSplat( result, 2 ) ) );
}
#endif//USE_SIMD

// Project Gauss Seidel or the equivalent Sequential Impulse
void btSequentialImpulseConstraintSolver::resolveSingleConstraintRowGenericSIMD(btRigidBody& body1,btRigidBody& body2,const btSolverConstraint& c)
{
#ifdef USE_SIMD
    __m128 cpAppliedImp = _mm_set1_ps(c.m_appliedImpulse);
    __m128  lowerLimit1 = _mm_set1_ps(c.m_lowerLimit);
    __m128  upperLimit1 = _mm_set1_ps(c.m_upperLimit);
    __m128 deltaImpulse = _mm_sub_ps(_mm_set1_ps(c.m_rhs), _mm_mul_ps(_mm_set1_ps(c.m_appliedImpulse),_mm_set1_ps(c.m_cfm)));
    __m128 deltaVel1Dotn    =   _mm_add_ps(btSimdDot3(c.m_contactNormal.mVec128,body1.internalGetDeltaLinearVelocity().mVec128), btSimdDot3(c.m_relpos1CrossNormal.mVec128,body1.internalGetDeltaAngularVelocity().mVec128));
    __m128 deltaVel2Dotn    =   _mm_sub_ps(btSimdDot3(c.m_relpos2CrossNormal.mVec128,body2.internalGetDeltaAngularVelocity().mVec128),btSimdDot3((c.m_contactNormal).mVec128,body2.internalGetDeltaLinearVelocity().mVec128));
    deltaImpulse    =   _mm_sub_ps(deltaImpulse,_mm_mul_ps(deltaVel1Dotn,_mm_set1_ps(c.m_jacDiagABInv)));
    deltaImpulse    =   _mm_sub_ps(deltaImpulse,_mm_mul_ps(deltaVel2Dotn,_mm_set1_ps(c.m_jacDiagABInv)));
    btSimdScalar sum = _mm_add_ps(cpAppliedImp,deltaImpulse);
    btSimdScalar resultLowerLess,resultUpperLess;
    resultLowerLess = _mm_cmplt_ps(sum,lowerLimit1);
    resultUpperLess = _mm_cmplt_ps(sum,upperLimit1);
    __m128 lowMinApplied = _mm_sub_ps(lowerLimit1,cpAppliedImp);
    deltaImpulse = _mm_or_ps( _mm_and_ps(resultLowerLess, lowMinApplied), _mm_andnot_ps(resultLowerLess, deltaImpulse) );
    c.m_appliedImpulse = _mm_or_ps( _mm_and_ps(resultLowerLess, lowerLimit1), _mm_andnot_ps(resultLowerLess, sum) );
    __m128 upperMinApplied = _mm_sub_ps(upperLimit1,cpAppliedImp);
    deltaImpulse = _mm_or_ps( _mm_and_ps(resultUpperLess, deltaImpulse), _mm_andnot_ps(resultUpperLess, upperMinApplied) );
    c.m_appliedImpulse = _mm_or_ps( _mm_and_ps(resultUpperLess, c.m_appliedImpulse), _mm_andnot_ps(resultUpperLess, upperLimit1) );
    __m128  linearComponentA = _mm_mul_ps(c.m_contactNormal.mVec128,body1.internalGetInvMass().mVec128);
    __m128  linearComponentB = _mm_mul_ps((c.m_contactNormal).mVec128,body2.internalGetInvMass().mVec128);
    __m128 impulseMagnitude = deltaImpulse;
    body1.internalGetDeltaLinearVelocity().mVec128 = _mm_add_ps(body1.internalGetDeltaLinearVelocity().mVec128,_mm_mul_ps(linearComponentA,impulseMagnitude));
    body1.internalGetDeltaAngularVelocity().mVec128 = _mm_add_ps(body1.internalGetDeltaAngularVelocity().mVec128 ,_mm_mul_ps(c.m_angularComponentA.mVec128,impulseMagnitude));
    body2.internalGetDeltaLinearVelocity().mVec128 = _mm_sub_ps(body2.internalGetDeltaLinearVelocity().mVec128,_mm_mul_ps(linearComponentB,impulseMagnitude));
    body2.internalGetDeltaAngularVelocity().mVec128 = _mm_add_ps(body2.internalGetDeltaAngularVelocity().mVec128 ,_mm_mul_ps(c.m_angularComponentB.mVec128,impulseMagnitude));
#else
    resolveSingleConstraintRowGeneric(body1,body2,c);
#endif
}

// Project Gauss Seidel or the equivalent Sequential Impulse
 void btSequentialImpulseConstraintSolver::resolveSingleConstraintRowGeneric(btRigidBody& body1,btRigidBody& body2,const btSolverConstraint& c)
{
    btScalar deltaImpulse = c.m_rhs-btScalar(c.m_appliedImpulse)*c.m_cfm;
    const btScalar deltaVel1Dotn    =   c.m_contactNormal.dot(body1.internalGetDeltaLinearVelocity())   + c.m_relpos1CrossNormal.dot(body1.internalGetDeltaAngularVelocity());
    const btScalar deltaVel2Dotn    =   -c.m_contactNormal.dot(body2.internalGetDeltaLinearVelocity()) + c.m_relpos2CrossNormal.dot(body2.internalGetDeltaAngularVelocity());

//  const btScalar delta_rel_vel    =   deltaVel1Dotn-deltaVel2Dotn;
    deltaImpulse    -=  deltaVel1Dotn*c.m_jacDiagABInv;
    deltaImpulse    -=  deltaVel2Dotn*c.m_jacDiagABInv;

    const btScalar sum = btScalar(c.m_appliedImpulse) + deltaImpulse;
    if (sum < c.m_lowerLimit)
    {
        deltaImpulse = c.m_lowerLimit-c.m_appliedImpulse;
        c.m_appliedImpulse = c.m_lowerLimit;
    }
    else if (sum > c.m_upperLimit) 
    {
        deltaImpulse = c.m_upperLimit-c.m_appliedImpulse;
        c.m_appliedImpulse = c.m_upperLimit;
    }
    else
    {
        c.m_appliedImpulse = sum;
    }
        body1.internalApplyImpulse(c.m_contactNormal*body1.internalGetInvMass(),c.m_angularComponentA,deltaImpulse);
        body2.internalApplyImpulse(-c.m_contactNormal*body2.internalGetInvMass(),c.m_angularComponentB,deltaImpulse);
}

 void btSequentialImpulseConstraintSolver::resolveSingleConstraintRowLowerLimitSIMD(btRigidBody& body1,btRigidBody& body2,const btSolverConstraint& c)
{
#ifdef USE_SIMD
    __m128 cpAppliedImp = _mm_set1_ps(c.m_appliedImpulse);
    __m128  lowerLimit1 = _mm_set1_ps(c.m_lowerLimit);
    __m128  upperLimit1 = _mm_set1_ps(c.m_upperLimit);
    __m128 deltaImpulse = _mm_sub_ps(_mm_set1_ps(c.m_rhs), _mm_mul_ps(_mm_set1_ps(c.m_appliedImpulse),_mm_set1_ps(c.m_cfm)));
    __m128 deltaVel1Dotn    =   _mm_add_ps(btSimdDot3(c.m_contactNormal.mVec128,body1.internalGetDeltaLinearVelocity().mVec128), btSimdDot3(c.m_relpos1CrossNormal.mVec128,body1.internalGetDeltaAngularVelocity().mVec128));
    __m128 deltaVel2Dotn    =   _mm_sub_ps(btSimdDot3(c.m_relpos2CrossNormal.mVec128,body2.internalGetDeltaAngularVelocity().mVec128),btSimdDot3((c.m_contactNormal).mVec128,body2.internalGetDeltaLinearVelocity().mVec128));
    deltaImpulse    =   _mm_sub_ps(deltaImpulse,_mm_mul_ps(deltaVel1Dotn,_mm_set1_ps(c.m_jacDiagABInv)));
    deltaImpulse    =   _mm_sub_ps(deltaImpulse,_mm_mul_ps(deltaVel2Dotn,_mm_set1_ps(c.m_jacDiagABInv)));
    btSimdScalar sum = _mm_add_ps(cpAppliedImp,deltaImpulse);
    btSimdScalar resultLowerLess,resultUpperLess;
    resultLowerLess = _mm_cmplt_ps(sum,lowerLimit1);
    resultUpperLess = _mm_cmplt_ps(sum,upperLimit1);
    __m128 lowMinApplied = _mm_sub_ps(lowerLimit1,cpAppliedImp);
    deltaImpulse = _mm_or_ps( _mm_and_ps(resultLowerLess, lowMinApplied), _mm_andnot_ps(resultLowerLess, deltaImpulse) );
    c.m_appliedImpulse = _mm_or_ps( _mm_and_ps(resultLowerLess, lowerLimit1), _mm_andnot_ps(resultLowerLess, sum) );
    __m128  linearComponentA = _mm_mul_ps(c.m_contactNormal.mVec128,body1.internalGetInvMass().mVec128);
    __m128  linearComponentB = _mm_mul_ps((c.m_contactNormal).mVec128,body2.internalGetInvMass().mVec128);
    __m128 impulseMagnitude = deltaImpulse;
    body1.internalGetDeltaLinearVelocity().mVec128 = _mm_add_ps(body1.internalGetDeltaLinearVelocity().mVec128,_mm_mul_ps(linearComponentA,impulseMagnitude));
    body1.internalGetDeltaAngularVelocity().mVec128 = _mm_add_ps(body1.internalGetDeltaAngularVelocity().mVec128 ,_mm_mul_ps(c.m_angularComponentA.mVec128,impulseMagnitude));
    body2.internalGetDeltaLinearVelocity().mVec128 = _mm_sub_ps(body2.internalGetDeltaLinearVelocity().mVec128,_mm_mul_ps(linearComponentB,impulseMagnitude));
    body2.internalGetDeltaAngularVelocity().mVec128 = _mm_add_ps(body2.internalGetDeltaAngularVelocity().mVec128 ,_mm_mul_ps(c.m_angularComponentB.mVec128,impulseMagnitude));
#else
    resolveSingleConstraintRowLowerLimit(body1,body2,c);
#endif
}

// Project Gauss Seidel or the equivalent Sequential Impulse
 void btSequentialImpulseConstraintSolver::resolveSingleConstraintRowLowerLimit(btRigidBody& body1,btRigidBody& body2,const btSolverConstraint& c)
{
    btScalar deltaImpulse = c.m_rhs-btScalar(c.m_appliedImpulse)*c.m_cfm;
    const btScalar deltaVel1Dotn    =   c.m_contactNormal.dot(body1.internalGetDeltaLinearVelocity())   + c.m_relpos1CrossNormal.dot(body1.internalGetDeltaAngularVelocity());
    const btScalar deltaVel2Dotn    =   -c.m_contactNormal.dot(body2.internalGetDeltaLinearVelocity()) + c.m_relpos2CrossNormal.dot(body2.internalGetDeltaAngularVelocity());

    deltaImpulse    -=  deltaVel1Dotn*c.m_jacDiagABInv;
    deltaImpulse    -=  deltaVel2Dotn*c.m_jacDiagABInv;
    const btScalar sum = btScalar(c.m_appliedImpulse) + deltaImpulse;
    if (sum < c.m_lowerLimit)
    {
        deltaImpulse = c.m_lowerLimit-c.m_appliedImpulse;
        c.m_appliedImpulse = c.m_lowerLimit;
    }
    else
    {
        c.m_appliedImpulse = sum;
    }
    body1.internalApplyImpulse(c.m_contactNormal*body1.internalGetInvMass(),c.m_angularComponentA,deltaImpulse);
    body2.internalApplyImpulse(-c.m_contactNormal*body2.internalGetInvMass(),c.m_angularComponentB,deltaImpulse);
}


void    btSequentialImpulseConstraintSolver::resolveSplitPenetrationImpulseCacheFriendly(
        btRigidBody& body1,
        btRigidBody& body2,
        const btSolverConstraint& c)
{
        if (c.m_rhsPenetration)
        {
            gNumSplitImpulseRecoveries++;
            btScalar deltaImpulse = c.m_rhsPenetration-btScalar(c.m_appliedPushImpulse)*c.m_cfm;
            const btScalar deltaVel1Dotn    =   c.m_contactNormal.dot(body1.internalGetPushVelocity())  + c.m_relpos1CrossNormal.dot(body1.internalGetTurnVelocity());
            const btScalar deltaVel2Dotn    =   -c.m_contactNormal.dot(body2.internalGetPushVelocity()) + c.m_relpos2CrossNormal.dot(body2.internalGetTurnVelocity());

            deltaImpulse    -=  deltaVel1Dotn*c.m_jacDiagABInv;
            deltaImpulse    -=  deltaVel2Dotn*c.m_jacDiagABInv;
            const btScalar sum = btScalar(c.m_appliedPushImpulse) + deltaImpulse;
            if (sum < c.m_lowerLimit)
            {
                deltaImpulse = c.m_lowerLimit-c.m_appliedPushImpulse;
                c.m_appliedPushImpulse = c.m_lowerLimit;
            }
            else
            {
                c.m_appliedPushImpulse = sum;
            }
            body1.internalApplyPushImpulse(c.m_contactNormal*body1.internalGetInvMass(),c.m_angularComponentA,deltaImpulse);
            body2.internalApplyPushImpulse(-c.m_contactNormal*body2.internalGetInvMass(),c.m_angularComponentB,deltaImpulse);
        }
}

 void btSequentialImpulseConstraintSolver::resolveSplitPenetrationSIMD(btRigidBody& body1,btRigidBody& body2,const btSolverConstraint& c)
{
#ifdef USE_SIMD
    if (!c.m_rhsPenetration)
        return;

    gNumSplitImpulseRecoveries++;

    __m128 cpAppliedImp = _mm_set1_ps(c.m_appliedPushImpulse);
    __m128  lowerLimit1 = _mm_set1_ps(c.m_lowerLimit);
    __m128  upperLimit1 = _mm_set1_ps(c.m_upperLimit);
    __m128 deltaImpulse = _mm_sub_ps(_mm_set1_ps(c.m_rhsPenetration), _mm_mul_ps(_mm_set1_ps(c.m_appliedPushImpulse),_mm_set1_ps(c.m_cfm)));
    __m128 deltaVel1Dotn    =   _mm_add_ps(btSimdDot3(c.m_contactNormal.mVec128,body1.internalGetPushVelocity().mVec128), btSimdDot3(c.m_relpos1CrossNormal.mVec128,body1.internalGetTurnVelocity().mVec128));
    __m128 deltaVel2Dotn    =   _mm_sub_ps(btSimdDot3(c.m_relpos2CrossNormal.mVec128,body2.internalGetTurnVelocity().mVec128),btSimdDot3((c.m_contactNormal).mVec128,body2.internalGetPushVelocity().mVec128));
    deltaImpulse    =   _mm_sub_ps(deltaImpulse,_mm_mul_ps(deltaVel1Dotn,_mm_set1_ps(c.m_jacDiagABInv)));
    deltaImpulse    =   _mm_sub_ps(deltaImpulse,_mm_mul_ps(deltaVel2Dotn,_mm_set1_ps(c.m_jacDiagABInv)));
    btSimdScalar sum = _mm_add_ps(cpAppliedImp,deltaImpulse);
    btSimdScalar resultLowerLess,resultUpperLess;
    resultLowerLess = _mm_cmplt_ps(sum,lowerLimit1);
    resultUpperLess = _mm_cmplt_ps(sum,upperLimit1);
    __m128 lowMinApplied = _mm_sub_ps(lowerLimit1,cpAppliedImp);
    deltaImpulse = _mm_or_ps( _mm_and_ps(resultLowerLess, lowMinApplied), _mm_andnot_ps(resultLowerLess, deltaImpulse) );
    c.m_appliedImpulse = _mm_or_ps( _mm_and_ps(resultLowerLess, lowerLimit1), _mm_andnot_ps(resultLowerLess, sum) );
    __m128  linearComponentA = _mm_mul_ps(c.m_contactNormal.mVec128,body1.internalGetInvMass().mVec128);
    __m128  linearComponentB = _mm_mul_ps((c.m_contactNormal).mVec128,body2.internalGetInvMass().mVec128);
    __m128 impulseMagnitude = deltaImpulse;
    body1.internalGetPushVelocity().mVec128 = _mm_add_ps(body1.internalGetPushVelocity().mVec128,_mm_mul_ps(linearComponentA,impulseMagnitude));
    body1.internalGetTurnVelocity().mVec128 = _mm_add_ps(body1.internalGetTurnVelocity().mVec128 ,_mm_mul_ps(c.m_angularComponentA.mVec128,impulseMagnitude));
    body2.internalGetPushVelocity().mVec128 = _mm_sub_ps(body2.internalGetPushVelocity().mVec128,_mm_mul_ps(linearComponentB,impulseMagnitude));
    body2.internalGetTurnVelocity().mVec128 = _mm_add_ps(body2.internalGetTurnVelocity().mVec128 ,_mm_mul_ps(c.m_angularComponentB.mVec128,impulseMagnitude));
#else
    resolveSplitPenetrationImpulseCacheFriendly(body1,body2,c);
#endif
}



unsigned long btSequentialImpulseConstraintSolver::btRand2()
{
    m_btSeed2 = (1664525L*m_btSeed2 + 1013904223L) & 0xffffffff;
    return m_btSeed2;
}



//See ODE: adam's all-int straightforward(?) dRandInt (0..n-1)
int btSequentialImpulseConstraintSolver::btRandInt2 (int n)
{
    // seems good; xor-fold and modulus
    const unsigned long un = static_cast<unsigned long>(n);
    unsigned long r = btRand2();

    // note: probably more aggressive than it needs to be -- might be
    //       able to get away without one or two of the innermost branches.
    if (un <= 0x00010000UL) {
        r ^= (r >> 16);
        if (un <= 0x00000100UL) {
            r ^= (r >> 8);
            if (un <= 0x00000010UL) {
                r ^= (r >> 4);
                if (un <= 0x00000004UL) {
                    r ^= (r >> 2);
                    if (un <= 0x00000002UL) {
                        r ^= (r >> 1);
                    }
                }
            }
        }
    }

    return (int) (r % un);
}


#if 0
void    btSequentialImpulseConstraintSolver::initSolverBody(btSolverBody* solverBody, btCollisionObject* collisionObject)
{
    btRigidBody* rb = collisionObject? btRigidBody::upcast(collisionObject) : 0;

    solverBody->internalGetDeltaLinearVelocity().setValue(0.f,0.f,0.f);
    solverBody->internalGetDeltaAngularVelocity().setValue(0.f,0.f,0.f);
    solverBody->internalGetPushVelocity().setValue(0.f,0.f,0.f);
    solverBody->internalGetTurnVelocity().setValue(0.f,0.f,0.f);

    if (rb)
    {
        solverBody->internalGetInvMass() = btVector3(rb->getInvMass(),rb->getInvMass(),rb->getInvMass())*rb->getLinearFactor();
        solverBody->m_originalBody = rb;
        solverBody->m_angularFactor = rb->getAngularFactor();
    } else
    {
        solverBody->internalGetInvMass().setValue(0,0,0);
        solverBody->m_originalBody = 0;
        solverBody->m_angularFactor.setValue(1,1,1);
    }
}
#endif





btScalar btSequentialImpulseConstraintSolver::restitutionCurve(btScalar rel_vel, btScalar restitution)
{
    btScalar rest = restitution * -rel_vel;
    return rest;
}



void    applyAnisotropicFriction(btCollisionObject* colObj,btVector3& frictionDirection);
void    applyAnisotropicFriction(btCollisionObject* colObj,btVector3& frictionDirection)
{
    if (colObj && colObj->hasAnisotropicFriction())
    {
        // transform to local coordinates
        btVector3 loc_lateral = frictionDirection * colObj->getWorldTransform().getBasis();
        const btVector3& friction_scaling = colObj->getAnisotropicFriction();
        //apply anisotropic friction
        loc_lateral *= friction_scaling;
        // ... and transform it back to global coordinates
        frictionDirection = colObj->getWorldTransform().getBasis() * loc_lateral;
    }
}


void btSequentialImpulseConstraintSolver::setupFrictionConstraint(btSolverConstraint& solverConstraint, const btVector3& normalAxis,btRigidBody* solverBodyA,btRigidBody* solverBodyB,btManifoldPoint& cp,const btVector3& rel_pos1,const btVector3& rel_pos2,btCollisionObject* colObj0,btCollisionObject* colObj1, btScalar relaxation, btScalar desiredVelocity, btScalar cfmSlip)
{


    btRigidBody* body0=btRigidBody::upcast(colObj0);
    btRigidBody* body1=btRigidBody::upcast(colObj1);

    solverConstraint.m_contactNormal = normalAxis;

    solverConstraint.m_solverBodyA = body0 ? body0 : &getFixedBody();
    solverConstraint.m_solverBodyB = body1 ? body1 : &getFixedBody();

    solverConstraint.m_friction = cp.m_combinedFriction;
    solverConstraint.m_originalContactPoint = 0;

    solverConstraint.m_appliedImpulse = 0.f;
    solverConstraint.m_appliedPushImpulse = 0.f;

    {
        btVector3 ftorqueAxis1 = rel_pos1.cross(solverConstraint.m_contactNormal);
        solverConstraint.m_relpos1CrossNormal = ftorqueAxis1;
        solverConstraint.m_angularComponentA = body0 ? body0->getInvInertiaTensorWorld()*ftorqueAxis1*body0->getAngularFactor() : btVector3(0,0,0);
    }
    {
        btVector3 ftorqueAxis1 = rel_pos2.cross(-solverConstraint.m_contactNormal);
        solverConstraint.m_relpos2CrossNormal = ftorqueAxis1;
        solverConstraint.m_angularComponentB = body1 ? body1->getInvInertiaTensorWorld()*ftorqueAxis1*body1->getAngularFactor() : btVector3(0,0,0);
    }

#ifdef COMPUTE_IMPULSE_DENOM
    btScalar denom0 = rb0->computeImpulseDenominator(pos1,solverConstraint.m_contactNormal);
    btScalar denom1 = rb1->computeImpulseDenominator(pos2,solverConstraint.m_contactNormal);
#else
    btVector3 vec;
    btScalar denom0 = 0.f;
    btScalar denom1 = 0.f;
    if (body0)
    {
        vec = ( solverConstraint.m_angularComponentA).cross(rel_pos1);
        denom0 = body0->getInvMass() + normalAxis.dot(vec);
    }
    if (body1)
    {
        vec = ( -solverConstraint.m_angularComponentB).cross(rel_pos2);
        denom1 = body1->getInvMass() + normalAxis.dot(vec);
    }


#endif //COMPUTE_IMPULSE_DENOM
    btScalar denom = relaxation/(denom0+denom1);
    solverConstraint.m_jacDiagABInv = denom;

#ifdef _USE_JACOBIAN
    solverConstraint.m_jac =  btJacobianEntry (
        rel_pos1,rel_pos2,solverConstraint.m_contactNormal,
        body0->getInvInertiaDiagLocal(),
        body0->getInvMass(),
        body1->getInvInertiaDiagLocal(),
        body1->getInvMass());
#endif //_USE_JACOBIAN


    {
        btScalar rel_vel;
        btScalar vel1Dotn = solverConstraint.m_contactNormal.dot(body0?body0->getLinearVelocity():btVector3(0,0,0)) 
            + solverConstraint.m_relpos1CrossNormal.dot(body0?body0->getAngularVelocity():btVector3(0,0,0));
        btScalar vel2Dotn = -solverConstraint.m_contactNormal.dot(body1?body1->getLinearVelocity():btVector3(0,0,0)) 
            + solverConstraint.m_relpos2CrossNormal.dot(body1?body1->getAngularVelocity():btVector3(0,0,0));

        rel_vel = vel1Dotn+vel2Dotn;

//      btScalar positionalError = 0.f;

        btSimdScalar velocityError =  desiredVelocity - rel_vel;
        btSimdScalar    velocityImpulse = velocityError * btSimdScalar(solverConstraint.m_jacDiagABInv);
        solverConstraint.m_rhs = velocityImpulse;
        solverConstraint.m_cfm = cfmSlip;
        solverConstraint.m_lowerLimit = 0;
        solverConstraint.m_upperLimit = 1e10f;
    }
}



btSolverConstraint& btSequentialImpulseConstraintSolver::addFrictionConstraint(const btVector3& normalAxis,btRigidBody* solverBodyA,btRigidBody* solverBodyB,int frictionIndex,btManifoldPoint& cp,const btVector3& rel_pos1,const btVector3& rel_pos2,btCollisionObject* colObj0,btCollisionObject* colObj1, btScalar relaxation, btScalar desiredVelocity, btScalar cfmSlip)
{
    btSolverConstraint& solverConstraint = m_tmpSolverContactFrictionConstraintPool.expandNonInitializing();
    solverConstraint.m_frictionIndex = frictionIndex;
    setupFrictionConstraint(solverConstraint, normalAxis, solverBodyA, solverBodyB, cp, rel_pos1, rel_pos2, 
                            colObj0, colObj1, relaxation, desiredVelocity, cfmSlip);
    return solverConstraint;
}

int btSequentialImpulseConstraintSolver::getOrInitSolverBody(btCollisionObject& body)
{
#if 0
    int solverBodyIdA = -1;

    if (body.getCompanionId() >= 0)
    {
        //body has already been converted
        solverBodyIdA = body.getCompanionId();
    } else
    {
        btRigidBody* rb = btRigidBody::upcast(&body);
        if (rb && rb->getInvMass())
        {
            solverBodyIdA = m_tmpSolverBodyPool.size();
            btSolverBody& solverBody = m_tmpSolverBodyPool.expand();
            initSolverBody(&solverBody,&body);
            body.setCompanionId(solverBodyIdA);
        } else
        {
            return 0;//assume first one is a fixed solver body
        }
    }
    return solverBodyIdA;
#endif
    return 0;
}
#include <stdio.h>


void btSequentialImpulseConstraintSolver::setupContactConstraint(btSolverConstraint& solverConstraint, 
                                                                 btCollisionObject* colObj0, btCollisionObject* colObj1,
                                                                 btManifoldPoint& cp, const btContactSolverInfo& infoGlobal,
                                                                 btVector3& vel, btScalar& rel_vel, btScalar& relaxation,
                                                                 btVector3& rel_pos1, btVector3& rel_pos2)
{
            btRigidBody* rb0 = btRigidBody::upcast(colObj0);
            btRigidBody* rb1 = btRigidBody::upcast(colObj1);

            const btVector3& pos1 = cp.getPositionWorldOnA();
            const btVector3& pos2 = cp.getPositionWorldOnB();

//          btVector3 rel_pos1 = pos1 - colObj0->getWorldTransform().getOrigin(); 
//          btVector3 rel_pos2 = pos2 - colObj1->getWorldTransform().getOrigin();
            rel_pos1 = pos1 - colObj0->getWorldTransform().getOrigin(); 
            rel_pos2 = pos2 - colObj1->getWorldTransform().getOrigin();

            relaxation = 1.f;

            btVector3 torqueAxis0 = rel_pos1.cross(cp.m_normalWorldOnB);
            solverConstraint.m_angularComponentA = rb0 ? rb0->getInvInertiaTensorWorld()*torqueAxis0*rb0->getAngularFactor() : btVector3(0,0,0);
            btVector3 torqueAxis1 = rel_pos2.cross(cp.m_normalWorldOnB);        
            solverConstraint.m_angularComponentB = rb1 ? rb1->getInvInertiaTensorWorld()*-torqueAxis1*rb1->getAngularFactor() : btVector3(0,0,0);

                {
#ifdef COMPUTE_IMPULSE_DENOM
                    btScalar denom0 = rb0->computeImpulseDenominator(pos1,cp.m_normalWorldOnB);
                    btScalar denom1 = rb1->computeImpulseDenominator(pos2,cp.m_normalWorldOnB);
#else                           
                    btVector3 vec;
                    btScalar denom0 = 0.f;
                    btScalar denom1 = 0.f;
                    if (rb0)
                    {
                        vec = ( solverConstraint.m_angularComponentA).cross(rel_pos1);
                        denom0 = rb0->getInvMass() + cp.m_normalWorldOnB.dot(vec);
                    }
                    if (rb1)
                    {
                        vec = ( -solverConstraint.m_angularComponentB).cross(rel_pos2);
                        denom1 = rb1->getInvMass() + cp.m_normalWorldOnB.dot(vec);
                    }
#endif //COMPUTE_IMPULSE_DENOM      

                    btScalar denom = relaxation/(denom0+denom1);
                    solverConstraint.m_jacDiagABInv = denom;
                }

                solverConstraint.m_contactNormal = cp.m_normalWorldOnB;
                solverConstraint.m_relpos1CrossNormal = rel_pos1.cross(cp.m_normalWorldOnB);
                solverConstraint.m_relpos2CrossNormal = rel_pos2.cross(-cp.m_normalWorldOnB);




            btVector3 vel1 = rb0 ? rb0->getVelocityInLocalPoint(rel_pos1) : btVector3(0,0,0);
            btVector3 vel2 = rb1 ? rb1->getVelocityInLocalPoint(rel_pos2) : btVector3(0,0,0);
            vel  = vel1 - vel2;
            rel_vel = cp.m_normalWorldOnB.dot(vel);

                btScalar penetration = cp.getDistance()+infoGlobal.m_linearSlop;


                solverConstraint.m_friction = cp.m_combinedFriction;

                btScalar restitution = 0.f;
                
                if (cp.m_lifeTime>infoGlobal.m_restingContactRestitutionThreshold)
                {
                    restitution = 0.f;
                } else
                {
                    restitution =  restitutionCurve(rel_vel, cp.m_combinedRestitution);
                    if (restitution <= btScalar(0.))
                    {
                        restitution = 0.f;
                    };
                }


                if (infoGlobal.m_solverMode & SOLVER_USE_WARMSTARTING)
                {
                    solverConstraint.m_appliedImpulse = cp.m_appliedImpulse * infoGlobal.m_warmstartingFactor;
                    if (rb0)
                        rb0->internalApplyImpulse(solverConstraint.m_contactNormal*rb0->getInvMass()*rb0->getLinearFactor(),solverConstraint.m_angularComponentA,solverConstraint.m_appliedImpulse);
                    if (rb1)
                        rb1->internalApplyImpulse(solverConstraint.m_contactNormal*rb1->getInvMass()*rb1->getLinearFactor(),-solverConstraint.m_angularComponentB,-(btScalar)solverConstraint.m_appliedImpulse);
                } else
                {
                    solverConstraint.m_appliedImpulse = 0.f;
                }

                solverConstraint.m_appliedPushImpulse = 0.f;

                {
                    btScalar rel_vel;
                    btScalar vel1Dotn = solverConstraint.m_contactNormal.dot(rb0?rb0->getLinearVelocity():btVector3(0,0,0)) 
                        + solverConstraint.m_relpos1CrossNormal.dot(rb0?rb0->getAngularVelocity():btVector3(0,0,0));
                    btScalar vel2Dotn = -solverConstraint.m_contactNormal.dot(rb1?rb1->getLinearVelocity():btVector3(0,0,0)) 
                        + solverConstraint.m_relpos2CrossNormal.dot(rb1?rb1->getAngularVelocity():btVector3(0,0,0));

                    rel_vel = vel1Dotn+vel2Dotn;

                    btScalar positionalError = 0.f;
                    btScalar    velocityError = restitution - rel_vel;// * damping;

                    if (penetration>0)
                    {
                        positionalError = 0;
                        velocityError -= penetration / infoGlobal.m_timeStep;
                    } else
                    {
                        positionalError = -penetration * infoGlobal.m_erp/infoGlobal.m_timeStep;
                    }

                    btScalar  penetrationImpulse = positionalError*solverConstraint.m_jacDiagABInv;
                    btScalar velocityImpulse = velocityError *solverConstraint.m_jacDiagABInv;
                    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 = 0;
                    solverConstraint.m_upperLimit = 1e10f;
                }




}



void btSequentialImpulseConstraintSolver::setFrictionConstraintImpulse( btSolverConstraint& solverConstraint, 
                                                                        btRigidBody* rb0, btRigidBody* rb1, 
                                                                 btManifoldPoint& cp, const btContactSolverInfo& infoGlobal)
{
                    if (infoGlobal.m_solverMode & SOLVER_USE_FRICTION_WARMSTARTING)
                    {
                        {
                            btSolverConstraint& frictionConstraint1 = m_tmpSolverContactFrictionConstraintPool[solverConstraint.m_frictionIndex];
                            if (infoGlobal.m_solverMode & SOLVER_USE_WARMSTARTING)
                            {
                                frictionConstraint1.m_appliedImpulse = cp.m_appliedImpulseLateral1 * infoGlobal.m_warmstartingFactor;
                                if (rb0)
                                    rb0->internalApplyImpulse(frictionConstraint1.m_contactNormal*rb0->getInvMass()*rb0->getLinearFactor(),frictionConstraint1.m_angularComponentA,frictionConstraint1.m_appliedImpulse);
                                if (rb1)
                                    rb1->internalApplyImpulse(frictionConstraint1.m_contactNormal*rb1->getInvMass()*rb1->getLinearFactor(),-frictionConstraint1.m_angularComponentB,-(btScalar)frictionConstraint1.m_appliedImpulse);
                            } else
                            {
                                frictionConstraint1.m_appliedImpulse = 0.f;
                            }
                        }

                        if ((infoGlobal.m_solverMode & SOLVER_USE_2_FRICTION_DIRECTIONS))
                        {
                            btSolverConstraint& frictionConstraint2 = m_tmpSolverContactFrictionConstraintPool[solverConstraint.m_frictionIndex+1];
                            if (infoGlobal.m_solverMode & SOLVER_USE_WARMSTARTING)
                            {
                                frictionConstraint2.m_appliedImpulse = cp.m_appliedImpulseLateral2 * infoGlobal.m_warmstartingFactor;
                                if (rb0)
                                    rb0->internalApplyImpulse(frictionConstraint2.m_contactNormal*rb0->getInvMass(),frictionConstraint2.m_angularComponentA,frictionConstraint2.m_appliedImpulse);
                                if (rb1)
                                    rb1->internalApplyImpulse(frictionConstraint2.m_contactNormal*rb1->getInvMass(),-frictionConstraint2.m_angularComponentB,-(btScalar)frictionConstraint2.m_appliedImpulse);
                            } else
                            {
                                frictionConstraint2.m_appliedImpulse = 0.f;
                            }
                        }
                    } else
                    {
                        btSolverConstraint& frictionConstraint1 = m_tmpSolverContactFrictionConstraintPool[solverConstraint.m_frictionIndex];
                        frictionConstraint1.m_appliedImpulse = 0.f;
                        if ((infoGlobal.m_solverMode & SOLVER_USE_2_FRICTION_DIRECTIONS))
                        {
                            btSolverConstraint& frictionConstraint2 = m_tmpSolverContactFrictionConstraintPool[solverConstraint.m_frictionIndex+1];
                            frictionConstraint2.m_appliedImpulse = 0.f;
                        }
                    }
}




void    btSequentialImpulseConstraintSolver::convertContact(btPersistentManifold* manifold,const btContactSolverInfo& infoGlobal)
{
    btCollisionObject* colObj0=0,*colObj1=0;

    colObj0 = (btCollisionObject*)manifold->getBody0();
    colObj1 = (btCollisionObject*)manifold->getBody1();


    btRigidBody* solverBodyA = btRigidBody::upcast(colObj0);
    btRigidBody* solverBodyB = btRigidBody::upcast(colObj1);

    if ((!solverBodyA || !solverBodyA->getInvMass()) && (!solverBodyB || !solverBodyB->getInvMass()))
        return;

    for (int j=0;j<manifold->getNumContacts();j++)
    {

        btManifoldPoint& cp = manifold->getContactPoint(j);

        if (cp.getDistance() <= manifold->getContactProcessingThreshold())
        {
            btVector3 rel_pos1;
            btVector3 rel_pos2;
            btScalar relaxation;
            btScalar rel_vel;
            btVector3 vel;

            int frictionIndex = m_tmpSolverContactConstraintPool.size();
            btSolverConstraint& solverConstraint = m_tmpSolverContactConstraintPool.expandNonInitializing();
            btRigidBody* rb0 = btRigidBody::upcast(colObj0);
            btRigidBody* rb1 = btRigidBody::upcast(colObj1);
            solverConstraint.m_solverBodyA = rb0? rb0 : &getFixedBody();
            solverConstraint.m_solverBodyB = rb1? rb1 : &getFixedBody();
            solverConstraint.m_originalContactPoint = &cp;

            setupContactConstraint(solverConstraint, colObj0, colObj1, cp, infoGlobal, vel, rel_vel, relaxation, rel_pos1, rel_pos2);

//          const btVector3& pos1 = cp.getPositionWorldOnA();
//          const btVector3& pos2 = cp.getPositionWorldOnB();


            solverConstraint.m_frictionIndex = m_tmpSolverContactFrictionConstraintPool.size();

            if (!(infoGlobal.m_solverMode & SOLVER_ENABLE_FRICTION_DIRECTION_CACHING) || !cp.m_lateralFrictionInitialized)
            {
                cp.m_lateralFrictionDir1 = vel - cp.m_normalWorldOnB * rel_vel;
                btScalar lat_rel_vel = cp.m_lateralFrictionDir1.length2();
                if (!(infoGlobal.m_solverMode & SOLVER_DISABLE_VELOCITY_DEPENDENT_FRICTION_DIRECTION) && lat_rel_vel > SIMD_EPSILON)
                {
                    cp.m_lateralFrictionDir1 /= btSqrt(lat_rel_vel);
                    if((infoGlobal.m_solverMode & SOLVER_USE_2_FRICTION_DIRECTIONS))
                    {
                        cp.m_lateralFrictionDir2 = cp.m_lateralFrictionDir1.cross(cp.m_normalWorldOnB);
                        cp.m_lateralFrictionDir2.normalize();//??
                        applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir2);
                        applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir2);
                        addFrictionConstraint(cp.m_lateralFrictionDir2,solverBodyA,solverBodyB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
                    }

                    applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir1);
                    applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir1);
                    addFrictionConstraint(cp.m_lateralFrictionDir1,solverBodyA,solverBodyB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
                    cp.m_lateralFrictionInitialized = true;
                } else
                {
                    //re-calculate friction direction every frame, todo: check if this is really needed
                    btPlaneSpace1(cp.m_normalWorldOnB,cp.m_lateralFrictionDir1,cp.m_lateralFrictionDir2);
                    if ((infoGlobal.m_solverMode & SOLVER_USE_2_FRICTION_DIRECTIONS))
                    {
                        applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir2);
                        applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir2);
                        addFrictionConstraint(cp.m_lateralFrictionDir2,solverBodyA,solverBodyB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
                    }

                    applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir1);
                    applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir1);
                    addFrictionConstraint(cp.m_lateralFrictionDir1,solverBodyA,solverBodyB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);

                    cp.m_lateralFrictionInitialized = true;
                }

            } else
            {
                addFrictionConstraint(cp.m_lateralFrictionDir1,solverBodyA,solverBodyB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation,cp.m_contactMotion1, cp.m_contactCFM1);
                if ((infoGlobal.m_solverMode & SOLVER_USE_2_FRICTION_DIRECTIONS))
                    addFrictionConstraint(cp.m_lateralFrictionDir2,solverBodyA,solverBodyB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation, cp.m_contactMotion2, cp.m_contactCFM2);
            }
            
            setFrictionConstraintImpulse( solverConstraint, rb0, rb1, cp, infoGlobal);

        }
    }
}


btScalar btSequentialImpulseConstraintSolver::solveGroupCacheFriendlySetup(btCollisionObject** bodies, int numBodies, btPersistentManifold** manifoldPtr, int numManifolds,btTypedConstraint** constraints,int numConstraints,const btContactSolverInfo& infoGlobal,btIDebugDraw* debugDrawer,btStackAlloc* stackAlloc)
{
    BT_PROFILE("solveGroupCacheFriendlySetup");
    (void)stackAlloc;
    (void)debugDrawer;


    if (!(numConstraints + numManifolds))
    {
        //      printf("empty\n");
        return 0.f;
    }

    if (infoGlobal.m_splitImpulse)
    {
        for (int i = 0; i < numBodies; i++)
        {
            btRigidBody* body = btRigidBody::upcast(bodies[i]);
            if (body)
            {   
                body->internalGetDeltaLinearVelocity().setZero();
                body->internalGetDeltaAngularVelocity().setZero();
                body->internalGetPushVelocity().setZero();
                body->internalGetTurnVelocity().setZero();
            }
        }
    }
    else
    {
        for (int i = 0; i < numBodies; i++)
        {
            btRigidBody* body = btRigidBody::upcast(bodies[i]);
            if (body)
            {   
                body->internalGetDeltaLinearVelocity().setZero();
                body->internalGetDeltaAngularVelocity().setZero();
            }
        }
    }

    if (1)
    {
        int j;
        for (j=0;j<numConstraints;j++)
        {
            btTypedConstraint* constraint = constraints[j];
            constraint->buildJacobian();
        }
    }
    //btRigidBody* rb0=0,*rb1=0;

    //if (1)
    {
        {

            int totalNumRows = 0;
            int i;
            
            m_tmpConstraintSizesPool.resize(numConstraints);
            //calculate the total number of contraint rows
            for (i=0;i<numConstraints;i++)
            {
                btTypedConstraint::btConstraintInfo1& info1 = m_tmpConstraintSizesPool[i];
                constraints[i]->getInfo1(&info1);
                totalNumRows += info1.m_numConstraintRows;
            }
            m_tmpSolverNonContactConstraintPool.resize(totalNumRows);

            
            int currentRow = 0;

            for (i=0;i<numConstraints;i++)
            {
                const btTypedConstraint::btConstraintInfo1& info1 = m_tmpConstraintSizesPool[i];
                
                if (info1.m_numConstraintRows)
                {
                    btAssert(currentRow<totalNumRows);

                    btSolverConstraint* currentConstraintRow = &m_tmpSolverNonContactConstraintPool[currentRow];
                    btTypedConstraint* constraint = constraints[i];



                    btRigidBody& rbA = constraint->getRigidBodyA();
                    btRigidBody& rbB = constraint->getRigidBodyB();

                    
                    int j;
                    for ( j=0;j<info1.m_numConstraintRows;j++)
                    {
                        memset(&currentConstraintRow[j],0,sizeof(btSolverConstraint));
                        currentConstraintRow[j].m_lowerLimit = -FLT_MAX;
                        currentConstraintRow[j].m_upperLimit = FLT_MAX;
                        currentConstraintRow[j].m_appliedImpulse = 0.f;
                        currentConstraintRow[j].m_appliedPushImpulse = 0.f;
                        currentConstraintRow[j].m_solverBodyA = &rbA;
                        currentConstraintRow[j].m_solverBodyB = &rbB;
                    }

                    rbA.internalGetDeltaLinearVelocity().setValue(0.f,0.f,0.f);
                    rbA.internalGetDeltaAngularVelocity().setValue(0.f,0.f,0.f);
                    rbB.internalGetDeltaLinearVelocity().setValue(0.f,0.f,0.f);
                    rbB.internalGetDeltaAngularVelocity().setValue(0.f,0.f,0.f);



                    btTypedConstraint::btConstraintInfo2 info2;
                    info2.fps = 1.f/infoGlobal.m_timeStep;
                    info2.erp = infoGlobal.m_erp;
                    info2.m_J1linearAxis = currentConstraintRow->m_contactNormal;
                    info2.m_J1angularAxis = currentConstraintRow->m_relpos1CrossNormal;
                    info2.m_J2linearAxis = 0;
                    info2.m_J2angularAxis = currentConstraintRow->m_relpos2CrossNormal;
                    info2.rowskip = sizeof(btSolverConstraint)/sizeof(btScalar);//check this
                    btAssert(info2.rowskip*sizeof(btScalar)== sizeof(btSolverConstraint));
                    info2.m_constraintError = &currentConstraintRow->m_rhs;
                    currentConstraintRow->m_cfm = infoGlobal.m_globalCfm;
                    info2.m_damping = infoGlobal.m_damping;
                    info2.cfm = &currentConstraintRow->m_cfm;
                    info2.m_lowerLimit = &currentConstraintRow->m_lowerLimit;
                    info2.m_upperLimit = &currentConstraintRow->m_upperLimit;
                    info2.m_numIterations = infoGlobal.m_numIterations;
                    constraints[i]->getInfo2(&info2);

                    for ( j=0;j<info1.m_numConstraintRows;j++)
                    {
                        btSolverConstraint& solverConstraint = currentConstraintRow[j];
                        solverConstraint.m_originalContactPoint = constraint;

                        {
                            const btVector3& ftorqueAxis1 = solverConstraint.m_relpos1CrossNormal;
                            solverConstraint.m_angularComponentA = constraint->getRigidBodyA().getInvInertiaTensorWorld()*ftorqueAxis1*constraint->getRigidBodyA().getAngularFactor();
                        }
                        {
                            const btVector3& ftorqueAxis2 = solverConstraint.m_relpos2CrossNormal;
                            solverConstraint.m_angularComponentB = constraint->getRigidBodyB().getInvInertiaTensorWorld()*ftorqueAxis2*constraint->getRigidBodyB().getAngularFactor();
                        }

                        {
                            btVector3 iMJlA = solverConstraint.m_contactNormal*rbA.getInvMass();
                            btVector3 iMJaA = rbA.getInvInertiaTensorWorld()*solverConstraint.m_relpos1CrossNormal;
                            btVector3 iMJlB = solverConstraint.m_contactNormal*rbB.getInvMass();//sign of normal?
                            btVector3 iMJaB = rbB.getInvInertiaTensorWorld()*solverConstraint.m_relpos2CrossNormal;

                            btScalar sum = iMJlA.dot(solverConstraint.m_contactNormal);
                            sum += iMJaA.dot(solverConstraint.m_relpos1CrossNormal);
                            sum += iMJlB.dot(solverConstraint.m_contactNormal);
                            sum += iMJaB.dot(solverConstraint.m_relpos2CrossNormal);

                            solverConstraint.m_jacDiagABInv = btScalar(1.)/sum;
                        }


                        {
                            btScalar rel_vel;
                            btScalar vel1Dotn = solverConstraint.m_contactNormal.dot(rbA.getLinearVelocity()) + solverConstraint.m_relpos1CrossNormal.dot(rbA.getAngularVelocity());
                            btScalar vel2Dotn = -solverConstraint.m_contactNormal.dot(rbB.getLinearVelocity()) + solverConstraint.m_relpos2CrossNormal.dot(rbB.getAngularVelocity());

                            rel_vel = vel1Dotn+vel2Dotn;

                            btScalar restitution = 0.f;
                            btScalar positionalError = solverConstraint.m_rhs;//already filled in by getConstraintInfo2
                            btScalar    velocityError = restitution - rel_vel * info2.m_damping;
                            btScalar    penetrationImpulse = positionalError*solverConstraint.m_jacDiagABInv;
                            btScalar    velocityImpulse = velocityError *solverConstraint.m_jacDiagABInv;
                            solverConstraint.m_rhs = penetrationImpulse+velocityImpulse;
                            solverConstraint.m_appliedImpulse = 0.f;

                        }
                    }
                }
                currentRow+=m_tmpConstraintSizesPool[i].m_numConstraintRows;
            }
        }

        {
            int i;
            btPersistentManifold* manifold = 0;
//          btCollisionObject* colObj0=0,*colObj1=0;


            for (i=0;i<numManifolds;i++)
            {
                manifold = manifoldPtr[i];
                convertContact(manifold,infoGlobal);
            }
        }
    }

    btContactSolverInfo info = infoGlobal;



    int numConstraintPool = m_tmpSolverContactConstraintPool.size();
    int numFrictionPool = m_tmpSolverContactFrictionConstraintPool.size();

    m_orderTmpConstraintPool.resize(numConstraintPool);
    m_orderFrictionConstraintPool.resize(numFrictionPool);
    {
        int i;
        for (i=0;i<numConstraintPool;i++)
        {
            m_orderTmpConstraintPool[i] = i;
        }
        for (i=0;i<numFrictionPool;i++)
        {
            m_orderFrictionConstraintPool[i] = i;
        }
    }

    return 0.f;

}

btScalar btSequentialImpulseConstraintSolver::solveSingleIteration(int iteration, btCollisionObject** /*bodies */,int /*numBodies*/,btPersistentManifold** /*manifoldPtr*/, int /*numManifolds*/,btTypedConstraint** constraints,int numConstraints,const btContactSolverInfo& infoGlobal,btIDebugDraw* /*debugDrawer*/,btStackAlloc* /*stackAlloc*/)
{

    int numConstraintPool = m_tmpSolverContactConstraintPool.size();
    int numFrictionPool = m_tmpSolverContactFrictionConstraintPool.size();

    int j;

    if (infoGlobal.m_solverMode & SOLVER_RANDMIZE_ORDER)
    {
        if ((iteration & 7) == 0) {
            for (j=0; j<numConstraintPool; ++j) {
                int tmp = m_orderTmpConstraintPool[j];
                int swapi = btRandInt2(j+1);
                m_orderTmpConstraintPool[j] = m_orderTmpConstraintPool[swapi];
                m_orderTmpConstraintPool[swapi] = tmp;
            }

            for (j=0; j<numFrictionPool; ++j) {
                int tmp = m_orderFrictionConstraintPool[j];
                int swapi = btRandInt2(j+1);
                m_orderFrictionConstraintPool[j] = m_orderFrictionConstraintPool[swapi];
                m_orderFrictionConstraintPool[swapi] = tmp;
            }
        }
    }

    if (infoGlobal.m_solverMode & SOLVER_SIMD)
    {
        for (j=0;j<m_tmpSolverNonContactConstraintPool.size();j++)
        {
            btSolverConstraint& constraint = m_tmpSolverNonContactConstraintPool[j];
            resolveSingleConstraintRowGenericSIMD(*constraint.m_solverBodyA,*constraint.m_solverBodyB,constraint);
        }

        for (j=0;j<numConstraints;j++)
        {
            constraints[j]->solveConstraintObsolete(constraints[j]->getRigidBodyA(),constraints[j]->getRigidBodyB(),infoGlobal.m_timeStep);
        }

        int numPoolConstraints = m_tmpSolverContactConstraintPool.size();
        for (j=0;j<numPoolConstraints;j++)
        {
            const btSolverConstraint& solveManifold = m_tmpSolverContactConstraintPool[m_orderTmpConstraintPool[j]];
            resolveSingleConstraintRowLowerLimitSIMD(*solveManifold.m_solverBodyA,*solveManifold.m_solverBodyB,solveManifold);

        }
        int numFrictionPoolConstraints = m_tmpSolverContactFrictionConstraintPool.size();
        for (j=0;j<numFrictionPoolConstraints;j++)
        {
            btSolverConstraint& solveManifold = m_tmpSolverContactFrictionConstraintPool[m_orderFrictionConstraintPool[j]];
            btScalar totalImpulse = m_tmpSolverContactConstraintPool[solveManifold.m_frictionIndex].m_appliedImpulse;

            if (totalImpulse>btScalar(0))
            {
                solveManifold.m_lowerLimit = -(solveManifold.m_friction*totalImpulse);
                solveManifold.m_upperLimit = solveManifold.m_friction*totalImpulse;

                resolveSingleConstraintRowGenericSIMD(*solveManifold.m_solverBodyA, *solveManifold.m_solverBodyB,solveManifold);
            }
        }
    } else
    {

        for (j=0;j<m_tmpSolverNonContactConstraintPool.size();j++)
        {
            btSolverConstraint& constraint = m_tmpSolverNonContactConstraintPool[j];
            resolveSingleConstraintRowGeneric(*constraint.m_solverBodyA,*constraint.m_solverBodyB,constraint);
        }

        for (j=0;j<numConstraints;j++)
        {
            constraints[j]->solveConstraintObsolete(constraints[j]->getRigidBodyA(),constraints[j]->getRigidBodyB(),infoGlobal.m_timeStep);
        }
        int numPoolConstraints = m_tmpSolverContactConstraintPool.size();
        for (j=0;j<numPoolConstraints;j++)
        {
            const btSolverConstraint& solveManifold = m_tmpSolverContactConstraintPool[m_orderTmpConstraintPool[j]];
            resolveSingleConstraintRowLowerLimit(*solveManifold.m_solverBodyA,*solveManifold.m_solverBodyB,solveManifold);
        }
        int numFrictionPoolConstraints = m_tmpSolverContactFrictionConstraintPool.size();
        for (j=0;j<numFrictionPoolConstraints;j++)
        {
            btSolverConstraint& solveManifold = m_tmpSolverContactFrictionConstraintPool[m_orderFrictionConstraintPool[j]];
            btScalar totalImpulse = m_tmpSolverContactConstraintPool[solveManifold.m_frictionIndex].m_appliedImpulse;

            if (totalImpulse>btScalar(0))
            {
                solveManifold.m_lowerLimit = -(solveManifold.m_friction*totalImpulse);
                solveManifold.m_upperLimit = solveManifold.m_friction*totalImpulse;

                resolveSingleConstraintRowGeneric(*solveManifold.m_solverBodyA,*solveManifold.m_solverBodyB,solveManifold);
            }
        }
    }
    return 0.f;
}


void btSequentialImpulseConstraintSolver::solveGroupCacheFriendlySplitImpulseIterations(btCollisionObject** bodies,int numBodies,btPersistentManifold** manifoldPtr, int numManifolds,btTypedConstraint** constraints,int numConstraints,const btContactSolverInfo& infoGlobal,btIDebugDraw* debugDrawer,btStackAlloc* stackAlloc)
{
    int iteration;
    if (infoGlobal.m_splitImpulse)
    {
        if (infoGlobal.m_solverMode & SOLVER_SIMD)
        {
            for ( iteration = 0;iteration<infoGlobal.m_numIterations;iteration++)
            {
                {
                    int numPoolConstraints = m_tmpSolverContactConstraintPool.size();
                    int j;
                    for (j=0;j<numPoolConstraints;j++)
                    {
                        const btSolverConstraint& solveManifold = m_tmpSolverContactConstraintPool[m_orderTmpConstraintPool[j]];

                        resolveSplitPenetrationSIMD(*solveManifold.m_solverBodyA,*solveManifold.m_solverBodyB,solveManifold);
                    }
                }
            }
        }
        else
        {
            for ( iteration = 0;iteration<infoGlobal.m_numIterations;iteration++)
            {
                {
                    int numPoolConstraints = m_tmpSolverContactConstraintPool.size();
                    int j;
                    for (j=0;j<numPoolConstraints;j++)
                    {
                        const btSolverConstraint& solveManifold = m_tmpSolverContactConstraintPool[m_orderTmpConstraintPool[j]];

                        resolveSplitPenetrationImpulseCacheFriendly(*solveManifold.m_solverBodyA,*solveManifold.m_solverBodyB,solveManifold);
                    }
                }
            }
        }
    }
}

btScalar btSequentialImpulseConstraintSolver::solveGroupCacheFriendlyIterations(btCollisionObject** bodies ,int numBodies,btPersistentManifold** manifoldPtr, int numManifolds,btTypedConstraint** constraints,int numConstraints,const btContactSolverInfo& infoGlobal,btIDebugDraw* debugDrawer,btStackAlloc* stackAlloc)
{
    BT_PROFILE("solveGroupCacheFriendlyIterations");

    
    //should traverse the contacts random order...
    int iteration;
    {
        for ( iteration = 0;iteration<infoGlobal.m_numIterations;iteration++)
        {           
            solveSingleIteration(iteration, bodies ,numBodies,manifoldPtr, numManifolds,constraints,numConstraints,infoGlobal,debugDrawer,stackAlloc);
        }
        
        solveGroupCacheFriendlySplitImpulseIterations(bodies ,numBodies,manifoldPtr, numManifolds,constraints,numConstraints,infoGlobal,debugDrawer,stackAlloc);
    }
    return 0.f;
}

btScalar btSequentialImpulseConstraintSolver::solveGroupCacheFriendlyFinish(btCollisionObject** bodies ,int numBodies,btPersistentManifold** /*manifoldPtr*/, int /*numManifolds*/,btTypedConstraint** /*constraints*/,int /* numConstraints*/,const btContactSolverInfo& infoGlobal,btIDebugDraw* /*debugDrawer*/,btStackAlloc* /*stackAlloc*/)
{
    int numPoolConstraints = m_tmpSolverContactConstraintPool.size();
    int i,j;

    for (j=0;j<numPoolConstraints;j++)
    {

        const btSolverConstraint& solveManifold = m_tmpSolverContactConstraintPool[j];
        btManifoldPoint* pt = (btManifoldPoint*) solveManifold.m_originalContactPoint;
        btAssert(pt);
        pt->m_appliedImpulse = solveManifold.m_appliedImpulse;
        if (infoGlobal.m_solverMode & SOLVER_USE_FRICTION_WARMSTARTING)
        {
            pt->m_appliedImpulseLateral1 = m_tmpSolverContactFrictionConstraintPool[solveManifold.m_frictionIndex].m_appliedImpulse;
            pt->m_appliedImpulseLateral2 = m_tmpSolverContactFrictionConstraintPool[solveManifold.m_frictionIndex+1].m_appliedImpulse;
        }

        //do a callback here?
    }

    numPoolConstraints = m_tmpSolverNonContactConstraintPool.size();
    for (j=0;j<numPoolConstraints;j++)
    {
        const btSolverConstraint& solverConstr = m_tmpSolverNonContactConstraintPool[j];
        btTypedConstraint* constr = (btTypedConstraint*)solverConstr.m_originalContactPoint;
        btScalar sum = constr->internalGetAppliedImpulse();
        sum += solverConstr.m_appliedImpulse;
        constr->internalSetAppliedImpulse(sum);
    }


    if (infoGlobal.m_splitImpulse)
    {       
        for ( i=0;i<numBodies;i++)
        {
            btRigidBody* body = btRigidBody::upcast(bodies[i]);
            if (body)
                body->internalWritebackVelocity(infoGlobal.m_timeStep);
        }
    } else
    {
        for ( i=0;i<numBodies;i++)
        {
            btRigidBody* body = btRigidBody::upcast(bodies[i]);
            if (body)
                body->internalWritebackVelocity();
        }
    }


    m_tmpSolverContactConstraintPool.resize(0);
    m_tmpSolverNonContactConstraintPool.resize(0);
    m_tmpSolverContactFrictionConstraintPool.resize(0);

    return 0.f;
}



btScalar btSequentialImpulseConstraintSolver::solveGroup(btCollisionObject** bodies,int numBodies,btPersistentManifold** manifoldPtr, int numManifolds,btTypedConstraint** constraints,int numConstraints,const btContactSolverInfo& infoGlobal,btIDebugDraw* debugDrawer,btStackAlloc* stackAlloc,btDispatcher* /*dispatcher*/)
{

    BT_PROFILE("solveGroup");
    //you need to provide at least some bodies
    btAssert(bodies);
    btAssert(numBodies);

    solveGroupCacheFriendlySetup( bodies, numBodies, manifoldPtr,  numManifolds,constraints, numConstraints,infoGlobal,debugDrawer, stackAlloc);

    solveGroupCacheFriendlyIterations(bodies, numBodies, manifoldPtr,  numManifolds,constraints, numConstraints,infoGlobal,debugDrawer, stackAlloc);

    solveGroupCacheFriendlyFinish(bodies, numBodies, manifoldPtr,  numManifolds,constraints, numConstraints,infoGlobal,debugDrawer, stackAlloc);
    
    return 0.f;
}

void    btSequentialImpulseConstraintSolver::reset()
{
    m_btSeed2 = 0;
}

btRigidBody& btSequentialImpulseConstraintSolver::getFixedBody()
{
    static btRigidBody s_fixed(0, 0,0);
    s_fixed.setMassProps(btScalar(0.),btVector3(btScalar(0.),btScalar(0.),btScalar(0.)));
    return s_fixed;
}