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Solve2LinearConstraint.cpp

/*
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.
*/



#include "Solve2LinearConstraint.h"

#include "Dynamics/RigidBody.h"
#include "SimdVector3.h"
#include "JacobianEntry.h"


void Solve2LinearConstraint::resolveUnilateralPairConstraint(
                                                                           RigidBody* body1,
            RigidBody* body2,

                                    const SimdMatrix3x3& world2A,
                                    const SimdMatrix3x3& world2B,
                                    
                                    const SimdVector3& invInertiaADiag,
                                    const SimdScalar invMassA,
                                    const SimdVector3& linvelA,const SimdVector3& angvelA,
                                    const SimdVector3& rel_posA1,
                                    const SimdVector3& invInertiaBDiag,
                                    const SimdScalar invMassB,
                                    const SimdVector3& linvelB,const SimdVector3& angvelB,
                                    const SimdVector3& rel_posA2,

                                SimdScalar depthA, const SimdVector3& normalA, 
                                const SimdVector3& rel_posB1,const SimdVector3& rel_posB2,
                                SimdScalar depthB, const SimdVector3& normalB, 
                                SimdScalar& imp0,SimdScalar& imp1)
{

      imp0 = 0.f;
      imp1 = 0.f;

      SimdScalar len = fabs(normalA.length())-1.f;
      if (fabs(len) >= SIMD_EPSILON)
            return;

      ASSERT(len < SIMD_EPSILON);


      //this jacobian entry could be re-used for all iterations
      JacobianEntry jacA(world2A,world2B,rel_posA1,rel_posA2,normalA,invInertiaADiag,invMassA,
            invInertiaBDiag,invMassB);
      JacobianEntry jacB(world2A,world2B,rel_posB1,rel_posB2,normalB,invInertiaADiag,invMassA,
            invInertiaBDiag,invMassB);
      
      //const SimdScalar vel0 = jacA.getRelativeVelocity(linvelA,angvelA,linvelB,angvelB);
      //const SimdScalar vel1 = jacB.getRelativeVelocity(linvelA,angvelA,linvelB,angvelB);

      const SimdScalar vel0 = normalA.dot(body1->getVelocityInLocalPoint(rel_posA1)-body2->getVelocityInLocalPoint(rel_posA1));
      const SimdScalar vel1 = normalB.dot(body1->getVelocityInLocalPoint(rel_posB1)-body2->getVelocityInLocalPoint(rel_posB1));

//    SimdScalar penetrationImpulse = (depth*contactTau*timeCorrection)  * massTerm;//jacDiagABInv
      SimdScalar massTerm = 1.f / (invMassA + invMassB);


      // calculate rhs (or error) terms
      const SimdScalar dv0 = depthA  * m_tau * massTerm - vel0 * m_damping;
      const SimdScalar dv1 = depthB  * m_tau * massTerm - vel1 * m_damping;


      // dC/dv * dv = -C
      
      // jacobian * impulse = -error
      //

      //impulse = jacobianInverse * -error

      // inverting 2x2 symmetric system (offdiagonal are equal!)
      // 


      SimdScalar nonDiag = jacA.getNonDiagonal(jacB,invMassA,invMassB);
      SimdScalar  invDet = 1.0f / (jacA.getDiagonal() * jacB.getDiagonal() - nonDiag * nonDiag );
      
      //imp0 = dv0 * jacA.getDiagonal() * invDet + dv1 * -nonDiag * invDet;
      //imp1 = dv1 * jacB.getDiagonal() * invDet + dv0 * - nonDiag * invDet;

      imp0 = dv0 * jacA.getDiagonal() * invDet + dv1 * -nonDiag * invDet;
      imp1 = dv1 * jacB.getDiagonal() * invDet + dv0 * - nonDiag * invDet;

      //[a b]                                                 [d -c]
      //[c d] inverse = (1 / determinant) * [-b a] where determinant is (ad - bc)

      //[jA nD] * [imp0] = [dv0]
      //[nD jB]   [imp1]   [dv1]

}



void Solve2LinearConstraint::resolveBilateralPairConstraint(
                                    RigidBody* body1,
                                    RigidBody* body2,
                                    const SimdMatrix3x3& world2A,
                                    const SimdMatrix3x3& world2B,
                                    
                                    const SimdVector3& invInertiaADiag,
                                    const SimdScalar invMassA,
                                    const SimdVector3& linvelA,const SimdVector3& angvelA,
                                    const SimdVector3& rel_posA1,
                                    const SimdVector3& invInertiaBDiag,
                                    const SimdScalar invMassB,
                                    const SimdVector3& linvelB,const SimdVector3& angvelB,
                                    const SimdVector3& rel_posA2,

                                SimdScalar depthA, const SimdVector3& normalA, 
                                const SimdVector3& rel_posB1,const SimdVector3& rel_posB2,
                                SimdScalar depthB, const SimdVector3& normalB, 
                                SimdScalar& imp0,SimdScalar& imp1)
{

      imp0 = 0.f;
      imp1 = 0.f;

      SimdScalar len = fabs(normalA.length())-1.f;
      if (fabs(len) >= SIMD_EPSILON)
            return;

      ASSERT(len < SIMD_EPSILON);


      //this jacobian entry could be re-used for all iterations
      JacobianEntry jacA(world2A,world2B,rel_posA1,rel_posA2,normalA,invInertiaADiag,invMassA,
            invInertiaBDiag,invMassB);
      JacobianEntry jacB(world2A,world2B,rel_posB1,rel_posB2,normalB,invInertiaADiag,invMassA,
            invInertiaBDiag,invMassB);
      
      //const SimdScalar vel0 = jacA.getRelativeVelocity(linvelA,angvelA,linvelB,angvelB);
      //const SimdScalar vel1 = jacB.getRelativeVelocity(linvelA,angvelA,linvelB,angvelB);

      const SimdScalar vel0 = normalA.dot(body1->getVelocityInLocalPoint(rel_posA1)-body2->getVelocityInLocalPoint(rel_posA1));
      const SimdScalar vel1 = normalB.dot(body1->getVelocityInLocalPoint(rel_posB1)-body2->getVelocityInLocalPoint(rel_posB1));

      // calculate rhs (or error) terms
      const SimdScalar dv0 = depthA  * m_tau - vel0 * m_damping;
      const SimdScalar dv1 = depthB  * m_tau - vel1 * m_damping;

      // dC/dv * dv = -C
      
      // jacobian * impulse = -error
      //

      //impulse = jacobianInverse * -error

      // inverting 2x2 symmetric system (offdiagonal are equal!)
      // 


      SimdScalar nonDiag = jacA.getNonDiagonal(jacB,invMassA,invMassB);
      SimdScalar  invDet = 1.0f / (jacA.getDiagonal() * jacB.getDiagonal() - nonDiag * nonDiag );
      
      //imp0 = dv0 * jacA.getDiagonal() * invDet + dv1 * -nonDiag * invDet;
      //imp1 = dv1 * jacB.getDiagonal() * invDet + dv0 * - nonDiag * invDet;

      imp0 = dv0 * jacA.getDiagonal() * invDet + dv1 * -nonDiag * invDet;
      imp1 = dv1 * jacB.getDiagonal() * invDet + dv0 * - nonDiag * invDet;

      //[a b]                                                 [d -c]
      //[c d] inverse = (1 / determinant) * [-b a] where determinant is (ad - bc)

      //[jA nD] * [imp0] = [dv0]
      //[nD jB]   [imp1]   [dv1]

      if ( imp0 > 0.0f)
      {
            if ( imp1 > 0.0f )
            {
                  //both positive
            }
            else
            {
                  imp1 = 0.f;

                  // now imp0>0 imp1<0
                  imp0 = dv0 / jacA.getDiagonal();
                  if ( imp0 > 0.0f )
                  {
                  } else
                  {
                        imp0 = 0.f;
                  }
            }
      }
      else
      {
            imp0 = 0.f;

            imp1 = dv1 / jacB.getDiagonal();
            if ( imp1 <= 0.0f )
            {
                  imp1 = 0.f;
                  // now imp0>0 imp1<0
                  imp0 = dv0 / jacA.getDiagonal();
                  if ( imp0 > 0.0f )
                  {
                  } else
                  {
                        imp0 = 0.f;
                  }
            } else
            {
            }
      }
}



void Solve2LinearConstraint::resolveAngularConstraint(      const SimdMatrix3x3& invInertiaAWS,
                                                                  const SimdScalar invMassA,
                                                                  const SimdVector3& linvelA,const SimdVector3& angvelA,
                                                                  const SimdVector3& rel_posA1,
                                                                  const SimdMatrix3x3& invInertiaBWS,
                                                                  const SimdScalar invMassB,
                                                                  const SimdVector3& linvelB,const SimdVector3& angvelB,
                                                                  const SimdVector3& rel_posA2,

                                                                  SimdScalar depthA, const SimdVector3& normalA, 
                                                                  const SimdVector3& rel_posB1,const SimdVector3& rel_posB2,
                                                                  SimdScalar depthB, const SimdVector3& normalB, 
                                                                  SimdScalar& imp0,SimdScalar& imp1)
{

}


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