text: /*
  Bullet Continuous Collision Detection and Physics Library
  Copyright (c) 2013 Erwin Coumans  http://bulletphysics.org
  
  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.
  */
  
  ///This file was written by Erwin Coumans
  
  #include "btMultiBodyPoint2Point.h"
  #include "btMultiBodyLinkCollider.h"
  #include "bullet/BulletDynamics/Dynamics/btRigidBody.h"
  
  btMultiBodyPoint2Point::btMultiBodyPoint2Point(btMultiBody* body, int link, btRigidBody* bodyB, const btVector3& pivotInA, const btVector3& pivotInB)
  	:btMultiBodyConstraint(body,0,link,-1,3,false),
  	m_rigidBodyA(0),
  	m_rigidBodyB(bodyB),
  	m_pivotInA(pivotInA),
  	m_pivotInB(pivotInB)
  {
  }
  
  btMultiBodyPoint2Point::btMultiBodyPoint2Point(btMultiBody* bodyA, int linkA, btMultiBody* bodyB, int linkB, const btVector3& pivotInA, const btVector3& pivotInB)
  	:btMultiBodyConstraint(bodyA,bodyB,linkA,linkB,3,false),
  	m_rigidBodyA(0),
  	m_rigidBodyB(0),
  	m_pivotInA(pivotInA),
  	m_pivotInB(pivotInB)
  {
  }
  
  
  btMultiBodyPoint2Point::~btMultiBodyPoint2Point()
  {
  }
  
  
  int btMultiBodyPoint2Point::getIslandIdA() const
  {
  	if (m_rigidBodyA)
  		return m_rigidBodyA->getIslandTag();
  
  	if (m_bodyA)
  	{
  		btMultiBodyLinkCollider* col = m_bodyA->getBaseCollider();
  		if (col)
  			return col->getIslandTag();
  		for (int i=0;i<m_bodyA->getNumLinks();i++)
  		{
  			if (m_bodyA->getLink(i).m_collider)
  				return m_bodyA->getLink(i).m_collider->getIslandTag();
  		}
  	}
  	return -1;
  }
  
  int btMultiBodyPoint2Point::getIslandIdB() const
  {
  	if (m_rigidBodyB)
  		return m_rigidBodyB->getIslandTag();
  	if (m_bodyB)
  	{
  		btMultiBodyLinkCollider* col = m_bodyB->getBaseCollider();
  		if (col)
  			return col->getIslandTag();
  
  		for (int i=0;i<m_bodyB->getNumLinks();i++)
  		{
  			col = m_bodyB->getLink(i).m_collider;
  			if (col)
  				return col->getIslandTag();
  		}
  	}
  	return -1;
  }
  
  
  
  void btMultiBodyPoint2Point::createConstraintRows(btMultiBodyConstraintArray& constraintRows,
  		btMultiBodyJacobianData& data,
  		const btContactSolverInfo& infoGlobal)
  {
  
  //	int i=1;
  	for (int i=0;i<3;i++)
  	{
  
  		btMultiBodySolverConstraint& constraintRow = constraintRows.expandNonInitializing();
  
  		constraintRow.m_solverBodyIdA = data.m_fixedBodyId;
  		constraintRow.m_solverBodyIdB = data.m_fixedBodyId;
  		
  
  		btVector3 contactNormalOnB(0,0,0);
  		contactNormalOnB[i] = -1;
  
  		btScalar penetration = 0;
  
  		 // Convert local points back to world
  		btVector3 pivotAworld = m_pivotInA;
  		if (m_rigidBodyA)
  		{
  			
  			constraintRow.m_solverBodyIdA = m_rigidBodyA->getCompanionId();
  			pivotAworld = m_rigidBodyA->getCenterOfMassTransform()*m_pivotInA;
  		} else
  		{
  			if (m_bodyA)
  				pivotAworld = m_bodyA->localPosToWorld(m_linkA, m_pivotInA);
  		}
  		btVector3 pivotBworld = m_pivotInB;
  		if (m_rigidBodyB)
  		{
  			constraintRow.m_solverBodyIdB = m_rigidBodyB->getCompanionId();
  			pivotBworld = m_rigidBodyB->getCenterOfMassTransform()*m_pivotInB;
  		} else
  		{
  			if (m_bodyB)
  				pivotBworld = m_bodyB->localPosToWorld(m_linkB, m_pivotInB);
  			
  		}
  		btScalar position = (pivotAworld-pivotBworld).dot(contactNormalOnB);
  		btScalar relaxation = 1.f;
  		fillMultiBodyConstraintMixed(constraintRow, data,
  																 contactNormalOnB,
  																 pivotAworld, pivotBworld, 
  																 position,
  																 infoGlobal,
  																 relaxation,
  																 false);
  		constraintRow.m_lowerLimit = -m_maxAppliedImpulse;
  		constraintRow.m_upperLimit = m_maxAppliedImpulse;
  
  	}
  }
  