source: code/archive/tutorial/src/external/bullet/BulletCollision/CollisionDispatch/btCompoundCollisionAlgorithm.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 "BulletCollision/CollisionDispatch/btCompoundCollisionAlgorithm.h"
#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
#include "BulletCollision/CollisionShapes/btCompoundShape.h"
#include "BulletCollision/BroadphaseCollision/btDbvt.h"
#include "LinearMath/btIDebugDraw.h"
#include "LinearMath/btAabbUtil2.h"
#include "btManifoldResult.h"

btCompoundCollisionAlgorithm::btCompoundCollisionAlgorithm( const btCollisionAlgorithmConstructionInfo& ci,btCollisionObject* body0,btCollisionObject* body1,bool isSwapped)
:btActivatingCollisionAlgorithm(ci,body0,body1),
m_isSwapped(isSwapped),
m_sharedManifold(ci.m_manifold)
{
        m_ownsManifold = false;

        btCollisionObject* colObj = m_isSwapped? body1 : body0;
        btAssert (colObj->getCollisionShape()->isCompound());
        
        btCompoundShape* compoundShape = static_cast<btCompoundShape*>(colObj->getCollisionShape());
        m_compoundShapeRevision = compoundShape->getUpdateRevision();
        
        preallocateChildAlgorithms(body0,body1);
}

void    btCompoundCollisionAlgorithm::preallocateChildAlgorithms(btCollisionObject* body0,btCollisionObject* body1)
{
        btCollisionObject* colObj = m_isSwapped? body1 : body0;
        btCollisionObject* otherObj = m_isSwapped? body0 : body1;
        btAssert (colObj->getCollisionShape()->isCompound());
        
        btCompoundShape* compoundShape = static_cast<btCompoundShape*>(colObj->getCollisionShape());

        int numChildren = compoundShape->getNumChildShapes();
        int i;
        
        m_childCollisionAlgorithms.resize(numChildren);
        for (i=0;i<numChildren;i++)
        {
                if (compoundShape->getDynamicAabbTree())
                {
                        m_childCollisionAlgorithms[i] = 0;
                } else
                {
                        btCollisionShape* tmpShape = colObj->getCollisionShape();
                        btCollisionShape* childShape = compoundShape->getChildShape(i);
                        colObj->internalSetTemporaryCollisionShape( childShape );
                        m_childCollisionAlgorithms[i] = m_dispatcher->findAlgorithm(colObj,otherObj,m_sharedManifold);
                        colObj->internalSetTemporaryCollisionShape( tmpShape );
                }
        }
}

void    btCompoundCollisionAlgorithm::removeChildAlgorithms()
{
        int numChildren = m_childCollisionAlgorithms.size();
        int i;
        for (i=0;i<numChildren;i++)
        {
                if (m_childCollisionAlgorithms[i])
                {
                        m_childCollisionAlgorithms[i]->~btCollisionAlgorithm();
                        m_dispatcher->freeCollisionAlgorithm(m_childCollisionAlgorithms[i]);
                }
        }
}

btCompoundCollisionAlgorithm::~btCompoundCollisionAlgorithm()
{
        removeChildAlgorithms();
}




struct  btCompoundLeafCallback : btDbvt::ICollide
{

public:

        btCollisionObject* m_compoundColObj;
        btCollisionObject* m_otherObj;
        btDispatcher* m_dispatcher;
        const btDispatcherInfo& m_dispatchInfo;
        btManifoldResult*       m_resultOut;
        btCollisionAlgorithm**  m_childCollisionAlgorithms;
        btPersistentManifold*   m_sharedManifold;




        btCompoundLeafCallback (btCollisionObject* compoundObj,btCollisionObject* otherObj,btDispatcher* dispatcher,const btDispatcherInfo& dispatchInfo,btManifoldResult*      resultOut,btCollisionAlgorithm**        childCollisionAlgorithms,btPersistentManifold*  sharedManifold)
                :m_compoundColObj(compoundObj),m_otherObj(otherObj),m_dispatcher(dispatcher),m_dispatchInfo(dispatchInfo),m_resultOut(resultOut),
                m_childCollisionAlgorithms(childCollisionAlgorithms),
                m_sharedManifold(sharedManifold)
        {

        }


        void    ProcessChildShape(btCollisionShape* childShape,int index)
        {
                
                btCompoundShape* compoundShape = static_cast<btCompoundShape*>(m_compoundColObj->getCollisionShape());


                //backup
                btTransform     orgTrans = m_compoundColObj->getWorldTransform();
                btTransform     orgInterpolationTrans = m_compoundColObj->getInterpolationWorldTransform();
                const btTransform& childTrans = compoundShape->getChildTransform(index);
                btTransform     newChildWorldTrans = orgTrans*childTrans ;

                //perform an AABB check first
                btVector3 aabbMin0,aabbMax0,aabbMin1,aabbMax1;
                childShape->getAabb(newChildWorldTrans,aabbMin0,aabbMax0);
                m_otherObj->getCollisionShape()->getAabb(m_otherObj->getWorldTransform(),aabbMin1,aabbMax1);

                if (TestAabbAgainstAabb2(aabbMin0,aabbMax0,aabbMin1,aabbMax1))
                {

                        m_compoundColObj->setWorldTransform( newChildWorldTrans);
                        m_compoundColObj->setInterpolationWorldTransform(newChildWorldTrans);

                        //the contactpoint is still projected back using the original inverted worldtrans
                        btCollisionShape* tmpShape = m_compoundColObj->getCollisionShape();
                        m_compoundColObj->internalSetTemporaryCollisionShape( childShape );

                        if (!m_childCollisionAlgorithms[index])
                                m_childCollisionAlgorithms[index] = m_dispatcher->findAlgorithm(m_compoundColObj,m_otherObj,m_sharedManifold);

                        m_childCollisionAlgorithms[index]->processCollision(m_compoundColObj,m_otherObj,m_dispatchInfo,m_resultOut);
                        if (m_dispatchInfo.m_debugDraw && (m_dispatchInfo.m_debugDraw->getDebugMode() & btIDebugDraw::DBG_DrawAabb))
                        {
                                btVector3 worldAabbMin,worldAabbMax;
                                m_dispatchInfo.m_debugDraw->drawAabb(aabbMin0,aabbMax0,btVector3(1,1,1));
                                m_dispatchInfo.m_debugDraw->drawAabb(aabbMin1,aabbMax1,btVector3(1,1,1));
                        }
                        
                        //revert back transform
                        m_compoundColObj->internalSetTemporaryCollisionShape( tmpShape);
                        m_compoundColObj->setWorldTransform(  orgTrans );
                        m_compoundColObj->setInterpolationWorldTransform(orgInterpolationTrans);
                }
        }
        void            Process(const btDbvtNode* leaf)
        {
                int index = leaf->dataAsInt;

                btCompoundShape* compoundShape = static_cast<btCompoundShape*>(m_compoundColObj->getCollisionShape());
                btCollisionShape* childShape = compoundShape->getChildShape(index);
                if (m_dispatchInfo.m_debugDraw && (m_dispatchInfo.m_debugDraw->getDebugMode() & btIDebugDraw::DBG_DrawAabb))
                {
                        btVector3 worldAabbMin,worldAabbMax;
                        btTransform     orgTrans = m_compoundColObj->getWorldTransform();
                        btTransformAabb(leaf->volume.Mins(),leaf->volume.Maxs(),0.,orgTrans,worldAabbMin,worldAabbMax);
                        m_dispatchInfo.m_debugDraw->drawAabb(worldAabbMin,worldAabbMax,btVector3(1,0,0));
                }
                ProcessChildShape(childShape,index);

        }
};






void btCompoundCollisionAlgorithm::processCollision (btCollisionObject* body0,btCollisionObject* body1,const btDispatcherInfo& dispatchInfo,btManifoldResult* resultOut)
{
        btCollisionObject* colObj = m_isSwapped? body1 : body0;
        btCollisionObject* otherObj = m_isSwapped? body0 : body1;

        

        btAssert (colObj->getCollisionShape()->isCompound());
        btCompoundShape* compoundShape = static_cast<btCompoundShape*>(colObj->getCollisionShape());

        ///btCompoundShape might have changed:
        ////make sure the internal child collision algorithm caches are still valid
        if (compoundShape->getUpdateRevision() != m_compoundShapeRevision)
        {
                ///clear and update all
                removeChildAlgorithms();
                
                preallocateChildAlgorithms(body0,body1);
        }


        btDbvt* tree = compoundShape->getDynamicAabbTree();
        //use a dynamic aabb tree to cull potential child-overlaps
        btCompoundLeafCallback  callback(colObj,otherObj,m_dispatcher,dispatchInfo,resultOut,&m_childCollisionAlgorithms[0],m_sharedManifold);

        ///we need to refresh all contact manifolds
        ///note that we should actually recursively traverse all children, btCompoundShape can nested more then 1 level deep
        ///so we should add a 'refreshManifolds' in the btCollisionAlgorithm
        {
                int i;
                btManifoldArray manifoldArray;
                for (i=0;i<m_childCollisionAlgorithms.size();i++)
                {
                        if (m_childCollisionAlgorithms[i])
                        {
                                m_childCollisionAlgorithms[i]->getAllContactManifolds(manifoldArray);
                                for (int m=0;m<manifoldArray.size();m++)
                                {
                                        if (manifoldArray[m]->getNumContacts())
                                        {
                                                resultOut->setPersistentManifold(manifoldArray[m]);
                                                resultOut->refreshContactPoints();
                                                resultOut->setPersistentManifold(0);//??necessary?
                                        }
                                }
                                manifoldArray.clear();
                        }
                }
        }

        if (tree)
        {

                btVector3 localAabbMin,localAabbMax;
                btTransform otherInCompoundSpace;
                otherInCompoundSpace = colObj->getWorldTransform().inverse() * otherObj->getWorldTransform();
                otherObj->getCollisionShape()->getAabb(otherInCompoundSpace,localAabbMin,localAabbMax);

                const ATTRIBUTE_ALIGNED16(btDbvtVolume) bounds=btDbvtVolume::FromMM(localAabbMin,localAabbMax);
                //process all children, that overlap with  the given AABB bounds
                tree->collideTV(tree->m_root,bounds,callback);

        } else
        {
                //iterate over all children, perform an AABB check inside ProcessChildShape
                int numChildren = m_childCollisionAlgorithms.size();
                int i;
                for (i=0;i<numChildren;i++)
                {
                        callback.ProcessChildShape(compoundShape->getChildShape(i),i);
                }
        }

        {
                                //iterate over all children, perform an AABB check inside ProcessChildShape
                int numChildren = m_childCollisionAlgorithms.size();
                int i;
                btManifoldArray manifoldArray;

                for (i=0;i<numChildren;i++)
                {
                        if (m_childCollisionAlgorithms[i])
                        {
                                btCollisionShape* childShape = compoundShape->getChildShape(i);
                        //if not longer overlapping, remove the algorithm
                                btTransform     orgTrans = colObj->getWorldTransform();
                                btTransform     orgInterpolationTrans = colObj->getInterpolationWorldTransform();
                                const btTransform& childTrans = compoundShape->getChildTransform(i);
                                btTransform     newChildWorldTrans = orgTrans*childTrans ;

                                //perform an AABB check first
                                btVector3 aabbMin0,aabbMax0,aabbMin1,aabbMax1;
                                childShape->getAabb(newChildWorldTrans,aabbMin0,aabbMax0);
                                otherObj->getCollisionShape()->getAabb(otherObj->getWorldTransform(),aabbMin1,aabbMax1);

                                if (!TestAabbAgainstAabb2(aabbMin0,aabbMax0,aabbMin1,aabbMax1))
                                {
                                        m_childCollisionAlgorithms[i]->~btCollisionAlgorithm();
                                        m_dispatcher->freeCollisionAlgorithm(m_childCollisionAlgorithms[i]);
                                        m_childCollisionAlgorithms[i] = 0;
                                }

                        }
                        
                }

                

        }
}

btScalar        btCompoundCollisionAlgorithm::calculateTimeOfImpact(btCollisionObject* body0,btCollisionObject* body1,const btDispatcherInfo& dispatchInfo,btManifoldResult* resultOut)
{

        btCollisionObject* colObj = m_isSwapped? body1 : body0;
        btCollisionObject* otherObj = m_isSwapped? body0 : body1;

        btAssert (colObj->getCollisionShape()->isCompound());
        
        btCompoundShape* compoundShape = static_cast<btCompoundShape*>(colObj->getCollisionShape());

        //We will use the OptimizedBVH, AABB tree to cull potential child-overlaps
        //If both proxies are Compound, we will deal with that directly, by performing sequential/parallel tree traversals
        //given Proxy0 and Proxy1, if both have a tree, Tree0 and Tree1, this means:
        //determine overlapping nodes of Proxy1 using Proxy0 AABB against Tree1
        //then use each overlapping node AABB against Tree0
        //and vise versa.

        btScalar hitFraction = btScalar(1.);

        int numChildren = m_childCollisionAlgorithms.size();
        int i;
        for (i=0;i<numChildren;i++)
        {
                //temporarily exchange parent btCollisionShape with childShape, and recurse
                btCollisionShape* childShape = compoundShape->getChildShape(i);

                //backup
                btTransform     orgTrans = colObj->getWorldTransform();
        
                const btTransform& childTrans = compoundShape->getChildTransform(i);
                //btTransform   newChildWorldTrans = orgTrans*childTrans ;
                colObj->setWorldTransform( orgTrans*childTrans );

                btCollisionShape* tmpShape = colObj->getCollisionShape();
                colObj->internalSetTemporaryCollisionShape( childShape );
                btScalar frac = m_childCollisionAlgorithms[i]->calculateTimeOfImpact(colObj,otherObj,dispatchInfo,resultOut);
                if (frac<hitFraction)
                {
                        hitFraction = frac;
                }
                //revert back
                colObj->internalSetTemporaryCollisionShape( tmpShape);
                colObj->setWorldTransform( orgTrans);
        }
        return hitFraction;

}