text: /*==================================================================================
      Copyright (c) 2008, binaryzebra
      All rights reserved.
  
      Redistribution and use in source and binary forms, with or without
      modification, are permitted provided that the following conditions are met:
  
      * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
      * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
      * Neither the name of the binaryzebra nor the
      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.
  
      THIS SOFTWARE IS PROVIDED BY THE binaryzebra AND CONTRIBUTORS "AS IS" AND
      ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
      WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
      DISCLAIMED. IN NO EVENT SHALL binaryzebra BE LIABLE FOR ANY
      DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
      (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
      LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
      ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
      (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
      SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  =====================================================================================*/
  
  /*
  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 "btPoint2PointConstraint.h"
  #include "BulletDynamics/Dynamics/btRigidBody.h"
  #include <new>
  
  btPoint2PointConstraint::btPoint2PointConstraint(btRigidBody& rbA, btRigidBody& rbB, const btVector3& pivotInA, const btVector3& pivotInB)
      : btTypedConstraint(POINT2POINT_CONSTRAINT_TYPE, rbA, rbB)
      , m_pivotInA(pivotInA)
      , m_pivotInB(pivotInB)
      , m_flags(0)
      , m_useSolveConstraintObsolete(false)
  {
  }
  
  btPoint2PointConstraint::btPoint2PointConstraint(btRigidBody& rbA, const btVector3& pivotInA)
      : btTypedConstraint(POINT2POINT_CONSTRAINT_TYPE, rbA)
      , m_pivotInA(pivotInA)
      , m_pivotInB(rbA.getCenterOfMassTransform()(pivotInA))
      , m_flags(0)
      , m_useSolveConstraintObsolete(false)
  {
  }
  
  void btPoint2PointConstraint::buildJacobian()
  {
      ///we need it for both methods
      {
          m_appliedImpulse = btScalar(0.);
  
          btVector3 normal(0, 0, 0);
  
          for (int i = 0; i < 3; i++)
          {
              normal[i] = 1;
              new (&m_jac[i]) btJacobianEntry(
              m_rbA.getCenterOfMassTransform().getBasis().transpose(),
              m_rbB.getCenterOfMassTransform().getBasis().transpose(),
              m_rbA.getCenterOfMassTransform() * m_pivotInA - m_rbA.getCenterOfMassPosition(),
              m_rbB.getCenterOfMassTransform() * m_pivotInB - m_rbB.getCenterOfMassPosition(),
              normal,
              m_rbA.getInvInertiaDiagLocal(),
              m_rbA.getInvMass(),
              m_rbB.getInvInertiaDiagLocal(),
              m_rbB.getInvMass());
              normal[i] = 0;
          }
      }
  }
  
  void btPoint2PointConstraint::getInfo1(btConstraintInfo1* info)
  {
      getInfo1NonVirtual(info);
  }
  
  void btPoint2PointConstraint::getInfo1NonVirtual(btConstraintInfo1* info)
  {
      if (m_useSolveConstraintObsolete)
      {
          info->m_numConstraintRows = 0;
          info->nub = 0;
      }
      else
      {
          info->m_numConstraintRows = 3;
          info->nub = 3;
      }
  }
  
  void btPoint2PointConstraint::getInfo2(btConstraintInfo2* info)
  {
      getInfo2NonVirtual(info, m_rbA.getCenterOfMassTransform(), m_rbB.getCenterOfMassTransform());
  }
  
  void btPoint2PointConstraint::getInfo2NonVirtual(btConstraintInfo2* info, const btTransform& body0_trans, const btTransform& body1_trans)
  {
      btAssert(!m_useSolveConstraintObsolete);
  
      //retrieve matrices
  
      // anchor points in global coordinates with respect to body PORs.
  
      // set jacobian
      info->m_J1linearAxis[0] = 1;
      info->m_J1linearAxis[info->rowskip + 1] = 1;
      info->m_J1linearAxis[2 * info->rowskip + 2] = 1;
  
      btVector3 a1 = body0_trans.getBasis() * getPivotInA();
      {
          btVector3* angular0 = (btVector3*)(info->m_J1angularAxis);
          btVector3* angular1 = (btVector3*)(info->m_J1angularAxis + info->rowskip);
          btVector3* angular2 = (btVector3*)(info->m_J1angularAxis + 2 * info->rowskip);
          btVector3 a1neg = -a1;
          a1neg.getSkewSymmetricMatrix(angular0, angular1, angular2);
      }
  
      /*info->m_J2linearAxis[0] = -1;
      info->m_J2linearAxis[s+1] = -1;
      info->m_J2linearAxis[2*s+2] = -1;
  	*/
  
      btVector3 a2 = body1_trans.getBasis() * getPivotInB();
  
      {
          btVector3 a2n = -a2;
          btVector3* angular0 = (btVector3*)(info->m_J2angularAxis);
          btVector3* angular1 = (btVector3*)(info->m_J2angularAxis + info->rowskip);
          btVector3* angular2 = (btVector3*)(info->m_J2angularAxis + 2 * info->rowskip);
          a2.getSkewSymmetricMatrix(angular0, angular1, angular2);
      }
  
      // set right hand side
      btScalar currERP = (m_flags & BT_P2P_FLAGS_ERP) ? m_erp : info->erp;
      btScalar k = info->fps * currERP;
      int j;
      for (j = 0; j < 3; j++)
      {
          info->m_constraintError[j * info->rowskip] = k * (a2[j] + body1_trans.getOrigin()[j] - a1[j] - body0_trans.getOrigin()[j]);
          //printf("info->m_constraintError[%d]=%f\n",j,info->m_constraintError[j]);
      }
      if (m_flags & BT_P2P_FLAGS_CFM)
      {
          for (j = 0; j < 3; j++)
          {
              info->cfm[j * info->rowskip] = m_cfm;
          }
      }
  
      btScalar impulseClamp = m_setting.m_impulseClamp; //
      for (j = 0; j < 3; j++)
      {
          if (m_setting.m_impulseClamp > 0)
          {
              info->m_lowerLimit[j * info->rowskip] = -impulseClamp;
              info->m_upperLimit[j * info->rowskip] = impulseClamp;
          }
      }
      info->m_damping = m_setting.m_damping;
  }
  
  void btPoint2PointConstraint::updateRHS(btScalar timeStep)
  {
      (void)timeStep;
  }
  
  ///override the default global value of a parameter (such as ERP or CFM), optionally provide the axis (0..5).
  ///If no axis is provided, it uses the default axis for this constraint.
  void btPoint2PointConstraint::setParam(int num, btScalar value, int axis)
  {
      if (axis != -1)
      {
          btAssertConstrParams(0);
      }
      else
      {
          switch (num)
          {
          case BT_CONSTRAINT_ERP:
          case BT_CONSTRAINT_STOP_ERP:
              m_erp = value;
              m_flags |= BT_P2P_FLAGS_ERP;
              break;
          case BT_CONSTRAINT_CFM:
          case BT_CONSTRAINT_STOP_CFM:
              m_cfm = value;
              m_flags |= BT_P2P_FLAGS_CFM;
              break;
          default:
              btAssertConstrParams(0);
          }
      }
  }
  
  ///return the local value of parameter
  btScalar btPoint2PointConstraint::getParam(int num, int axis) const
  {
      btScalar retVal(SIMD_INFINITY);
      if (axis != -1)
      {
          btAssertConstrParams(0);
      }
      else
      {
          switch (num)
          {
          case BT_CONSTRAINT_ERP:
          case BT_CONSTRAINT_STOP_ERP:
              btAssertConstrParams(m_flags & BT_P2P_FLAGS_ERP);
              retVal = m_erp;
              break;
          case BT_CONSTRAINT_CFM:
          case BT_CONSTRAINT_STOP_CFM:
              btAssertConstrParams(m_flags & BT_P2P_FLAGS_CFM);
              retVal = m_cfm;
              break;
          default:
              btAssertConstrParams(0);
          }
      }
      return retVal;
  }
  