btSimulationIslandManager.cpp

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/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans  https://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.
*/
 
#include "LinearMath/btScalar.h"
#include "btSimulationIslandManager.h"
#include "BulletCollision/BroadphaseCollision/btDispatcher.h"
#include "BulletCollision/NarrowPhaseCollision/btPersistentManifold.h"
#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
#include "BulletCollision/CollisionDispatch/btCollisionWorld.h"
 
//#include <stdio.h>
#include "LinearMath/btQuickprof.h"
 
btSimulationIslandManager::btSimulationIslandManager() : m_splitIslands(true)
{
}
 
btSimulationIslandManager::~btSimulationIslandManager()
{
}
 
void btSimulationIslandManager::initUnionFind(int n)
{
        m_unionFind.reset(n);
}
 
void btSimulationIslandManager::findUnions(btDispatcher* /* dispatcher */, btCollisionWorld* colWorld)
{
        {
                btOverlappingPairCache* pairCachePtr = colWorld->getPairCache();
                const int numOverlappingPairs = pairCachePtr->getNumOverlappingPairs();
                if (numOverlappingPairs)
                {
                        btBroadphasePair* pairPtr = pairCachePtr->getOverlappingPairArrayPtr();
 
                        for (int i = 0; i < numOverlappingPairs; i++)
                        {
                                const btBroadphasePair& collisionPair = pairPtr[i];
                                btCollisionObject* colObj0 = (btCollisionObject*)collisionPair.m_pProxy0->m_clientObject;
                                btCollisionObject* colObj1 = (btCollisionObject*)collisionPair.m_pProxy1->m_clientObject;
 
                                if (((colObj0) && ((colObj0)->mergesSimulationIslands())) &&
                                        ((colObj1) && ((colObj1)->mergesSimulationIslands())))
                                {
                                        m_unionFind.unite((colObj0)->getIslandTag(),
                                                                          (colObj1)->getIslandTag());
                                }
                        }
                }
        }
}
 
#ifdef STATIC_SIMULATION_ISLAND_OPTIMIZATION
void btSimulationIslandManager::updateActivationState(btCollisionWorld* colWorld, btDispatcher* dispatcher)
{
        // put the index into m_controllers into m_tag
        int index = 0;
        {
                int i;
                for (i = 0; i < colWorld->getCollisionObjectArray().size(); i++)
                {
                        btCollisionObject* collisionObject = colWorld->getCollisionObjectArray()[i];
                        //Adding filtering here
                        if (!collisionObject->isStaticOrKinematicObject())
                        {
                                collisionObject->setIslandTag(index++);
                        }
                        collisionObject->setCompanionId(-1);
                        collisionObject->setHitFraction(btScalar(1.));
                }
        }
        // do the union find
 
        initUnionFind(index);
 
        findUnions(dispatcher, colWorld);
}
 
void btSimulationIslandManager::storeIslandActivationState(btCollisionWorld* colWorld)
{
        // put the islandId ('find' value) into m_tag
        {
                int index = 0;
                int i;
                for (i = 0; i < colWorld->getCollisionObjectArray().size(); i++)
                {
                        btCollisionObject* collisionObject = colWorld->getCollisionObjectArray()[i];
                        if (!collisionObject->isStaticOrKinematicObject())
                        {
                                collisionObject->setIslandTag(m_unionFind.find(index));
                                //Set the correct object offset in Collision Object Array
                                m_unionFind.getElement(index).m_sz = i;
                                collisionObject->setCompanionId(-1);
                                index++;
                        }
                        else
                        {
                                collisionObject->setIslandTag(-1);
                                collisionObject->setCompanionId(-2);
                        }
                }
        }
}
 
#else  //STATIC_SIMULATION_ISLAND_OPTIMIZATION
void btSimulationIslandManager::updateActivationState(btCollisionWorld* colWorld, btDispatcher* dispatcher)
{
        initUnionFind(int(colWorld->getCollisionObjectArray().size()));
 
        // put the index into m_controllers into m_tag
        {
                int index = 0;
                int i;
                for (i = 0; i < colWorld->getCollisionObjectArray().size(); i++)
                {
                        btCollisionObject* collisionObject = colWorld->getCollisionObjectArray()[i];
                        collisionObject->setIslandTag(index);
                        collisionObject->setCompanionId(-1);
                        collisionObject->setHitFraction(btScalar(1.));
                        index++;
                }
        }
        // do the union find
 
        findUnions(dispatcher, colWorld);
}
 
void btSimulationIslandManager::storeIslandActivationState(btCollisionWorld* colWorld)
{
        // put the islandId ('find' value) into m_tag
        {
                int index = 0;
                int i;
                for (i = 0; i < colWorld->getCollisionObjectArray().size(); i++)
                {
                        btCollisionObject* collisionObject = colWorld->getCollisionObjectArray()[i];
                        if (!collisionObject->isStaticOrKinematicObject())
                        {
                                collisionObject->setIslandTag(m_unionFind.find(index));
                                collisionObject->setCompanionId(-1);
                        }
                        else
                        {
                                collisionObject->setIslandTag(-1);
                                collisionObject->setCompanionId(-2);
                        }
                        index++;
                }
        }
}
 
#endif  //STATIC_SIMULATION_ISLAND_OPTIMIZATION
 
inline int getIslandId(const btPersistentManifold* lhs)
{
        int islandId;
        const btCollisionObject* rcolObj0 = static_cast<const btCollisionObject*>(lhs->getBody0());
        const btCollisionObject* rcolObj1 = static_cast<const btCollisionObject*>(lhs->getBody1());
        islandId = rcolObj0->getIslandTag() >= 0 ? rcolObj0->getIslandTag() : rcolObj1->getIslandTag();
        return islandId;
}
 
class btPersistentManifoldSortPredicate
{
public:
        SIMD_FORCE_INLINE bool operator()(const btPersistentManifold* lhs, const btPersistentManifold* rhs) const
        {
                return getIslandId(lhs) < getIslandId(rhs);
        }
};
 
class btPersistentManifoldSortPredicateDeterministic
{
public:
        SIMD_FORCE_INLINE bool operator()(const btPersistentManifold* lhs, const btPersistentManifold* rhs) const
        {
                return (
                        (getIslandId(lhs) < getIslandId(rhs)) || ((getIslandId(lhs) == getIslandId(rhs)) && lhs->getBody0()->getBroadphaseHandle()->m_uniqueId < rhs->getBody0()->getBroadphaseHandle()->m_uniqueId) || ((getIslandId(lhs) == getIslandId(rhs)) && (lhs->getBody0()->getBroadphaseHandle()->m_uniqueId == rhs->getBody0()->getBroadphaseHandle()->m_uniqueId) && (lhs->getBody1()->getBroadphaseHandle()->m_uniqueId < rhs->getBody1()->getBroadphaseHandle()->m_uniqueId)));
        }
};
 
void btSimulationIslandManager::buildIslands(btDispatcher* dispatcher, btCollisionWorld* collisionWorld)
{
        BT_PROFILE("islandUnionFindAndQuickSort");
 
        btCollisionObjectArray& collisionObjects = collisionWorld->getCollisionObjectArray();
 
        m_islandmanifold.resize(0);
 
        //we are going to sort the unionfind array, and store the element id in the size
        //afterwards, we clean unionfind, to make sure no-one uses it anymore
 
        getUnionFind().sortIslands();
        int numElem = getUnionFind().getNumElements();
 
        int endIslandIndex = 1;
        int startIslandIndex;
 
        //update the sleeping state for bodies, if all are sleeping
        for (startIslandIndex = 0; startIslandIndex < numElem; startIslandIndex = endIslandIndex)
        {
                int islandId = getUnionFind().getElement(startIslandIndex).m_id;
                for (endIslandIndex = startIslandIndex + 1; (endIslandIndex < numElem) && (getUnionFind().getElement(endIslandIndex).m_id == islandId); endIslandIndex++)
                {
                }
 
                //int numSleeping = 0;
 
                bool allSleeping = true;
 
                int idx;
                for (idx = startIslandIndex; idx < endIslandIndex; idx++)
                {
                        int i = getUnionFind().getElement(idx).m_sz;
 
                        btCollisionObject* colObj0 = collisionObjects[i];
                        if ((colObj0->getIslandTag() != islandId) && (colObj0->getIslandTag() != -1))
                        {
                                //                              printf("error in island management\n");
                        }
 
            btAssert((colObj0->getIslandTag() == islandId) || (colObj0->getIslandTag() == -1));
                        if (colObj0->getIslandTag() == islandId)
                        {
                                if (colObj0->getActivationState() == ACTIVE_TAG ||
                                        colObj0->getActivationState() == DISABLE_DEACTIVATION)
                                {
                                        allSleeping = false;
                                        break;
                                }
                        }
                }
 
                if (allSleeping)
                {
                        int idx;
                        for (idx = startIslandIndex; idx < endIslandIndex; idx++)
                        {
                                int i = getUnionFind().getElement(idx).m_sz;
                                btCollisionObject* colObj0 = collisionObjects[i];
                                if ((colObj0->getIslandTag() != islandId) && (colObj0->getIslandTag() != -1))
                                {
                                        //                                      printf("error in island management\n");
                                }
 
                btAssert((colObj0->getIslandTag() == islandId) || (colObj0->getIslandTag() == -1));
 
                                if (colObj0->getIslandTag() == islandId)
                                {
                                        colObj0->setActivationState(ISLAND_SLEEPING);
                                }
                        }
                }
                else
                {
                        int idx;
                        for (idx = startIslandIndex; idx < endIslandIndex; idx++)
                        {
                                int i = getUnionFind().getElement(idx).m_sz;
 
                                btCollisionObject* colObj0 = collisionObjects[i];
                                if ((colObj0->getIslandTag() != islandId) && (colObj0->getIslandTag() != -1))
                                {
                                        //                                      printf("error in island management\n");
                                }
 
                 btAssert((colObj0->getIslandTag() == islandId) || (colObj0->getIslandTag() == -1));
 
 
                                if (colObj0->getIslandTag() == islandId)
                                {
                                        if (colObj0->getActivationState() == ISLAND_SLEEPING)
                                        {
                                                colObj0->setActivationState(WANTS_DEACTIVATION);
                                                colObj0->setDeactivationTime(0.f);
                                        }
                                }
                        }
                }
        }
 
        int i;
        int maxNumManifolds = dispatcher->getNumManifolds();
 
        //#define SPLIT_ISLANDS 1
        //#ifdef SPLIT_ISLANDS
 
        //#endif //SPLIT_ISLANDS
 
        for (i = 0; i < maxNumManifolds; i++)
        {
                btPersistentManifold* manifold = dispatcher->getManifoldByIndexInternal(i);
                if (collisionWorld->getDispatchInfo().m_deterministicOverlappingPairs)
                {
                        if (manifold->getNumContacts() == 0)
                                continue;
                }
 
                const btCollisionObject* colObj0 = static_cast<const btCollisionObject*>(manifold->getBody0());
                const btCollisionObject* colObj1 = static_cast<const btCollisionObject*>(manifold->getBody1());
 
                if (((colObj0) && colObj0->getActivationState() != ISLAND_SLEEPING) ||
                        ((colObj1) && colObj1->getActivationState() != ISLAND_SLEEPING))
                {
                        //kinematic objects don't merge islands, but wake up all connected objects
                        if (colObj0->isKinematicObject() && colObj0->getActivationState() != ISLAND_SLEEPING)
                        {
                                if (colObj0->hasContactResponse())
                                        colObj1->activate();
                        }
                        if (colObj1->isKinematicObject() && colObj1->getActivationState() != ISLAND_SLEEPING)
                        {
                                if (colObj1->hasContactResponse())
                                        colObj0->activate();
                        }
                        if (m_splitIslands)
                        {
                                //filtering for response
                                if (dispatcher->needsResponse(colObj0, colObj1))
                                        m_islandmanifold.push_back(manifold);
                        }
                }
        }
}
 
 
void btSimulationIslandManager::buildAndProcessIslands(btDispatcher* dispatcher, btCollisionWorld* collisionWorld, IslandCallback* callback)
{
        buildIslands(dispatcher, collisionWorld);
    processIslands(dispatcher, collisionWorld, callback);
}
 
void btSimulationIslandManager::processIslands(btDispatcher* dispatcher, btCollisionWorld* collisionWorld, IslandCallback* callback)
{
    btCollisionObjectArray& collisionObjects = collisionWorld->getCollisionObjectArray();
        int endIslandIndex = 1;
        int startIslandIndex;
        int numElem = getUnionFind().getNumElements();
 
        BT_PROFILE("processIslands");
 
        if (!m_splitIslands)
        {
                btPersistentManifold** manifold = dispatcher->getInternalManifoldPointer();
                int maxNumManifolds = dispatcher->getNumManifolds();
                callback->processIsland(&collisionObjects[0], collisionObjects.size(), manifold, maxNumManifolds, -1);
        }
        else
        {
                // Sort manifolds, based on islands
                // Sort the vector using predicate and std::sort
                //std::sort(islandmanifold.begin(), islandmanifold.end(), btPersistentManifoldSortPredicate);
 
                int numManifolds = int(m_islandmanifold.size());
 
                //tried a radix sort, but quicksort/heapsort seems still faster
                //@todo rewrite island management
                //btPersistentManifoldSortPredicateDeterministic sorts contact manifolds based on islandid,
                //but also based on object0 unique id and object1 unique id
                if (collisionWorld->getDispatchInfo().m_deterministicOverlappingPairs)
                {
                        m_islandmanifold.quickSort(btPersistentManifoldSortPredicateDeterministic());
                }
                else
                {
                        m_islandmanifold.quickSort(btPersistentManifoldSortPredicate());
                }
 
                //m_islandmanifold.heapSort(btPersistentManifoldSortPredicate());
 
                //now process all active islands (sets of manifolds for now)
 
                int startManifoldIndex = 0;
                int endManifoldIndex = 1;
 
                //int islandId;
 
                //      printf("Start Islands\n");
 
                //traverse the simulation islands, and call the solver, unless all objects are sleeping/deactivated
                for (startIslandIndex = 0; startIslandIndex < numElem; startIslandIndex = endIslandIndex)
                {
                        int islandId = getUnionFind().getElement(startIslandIndex).m_id;
 
                        bool islandSleeping = true;
 
                        for (endIslandIndex = startIslandIndex; (endIslandIndex < numElem) && (getUnionFind().getElement(endIslandIndex).m_id == islandId); endIslandIndex++)
                        {
                                int i = getUnionFind().getElement(endIslandIndex).m_sz;
                                btCollisionObject* colObj0 = collisionObjects[i];
                                m_islandBodies.push_back(colObj0);
                                if (colObj0->isActive())
                                        islandSleeping = false;
                        }
 
                        //find the accompanying contact manifold for this islandId
                        int numIslandManifolds = 0;
                        btPersistentManifold** startManifold = 0;
 
                        if (startManifoldIndex < numManifolds)
                        {
                                int curIslandId = getIslandId(m_islandmanifold[startManifoldIndex]);
                                if (curIslandId == islandId)
                                {
                                        startManifold = &m_islandmanifold[startManifoldIndex];
 
                                        for (endManifoldIndex = startManifoldIndex + 1; (endManifoldIndex < numManifolds) && (islandId == getIslandId(m_islandmanifold[endManifoldIndex])); endManifoldIndex++)
                                        {
                                        }
                                        numIslandManifolds = endManifoldIndex - startManifoldIndex;
                                }
                        }
 
                        if (!islandSleeping)
                        {
                                callback->processIsland(&m_islandBodies[0], m_islandBodies.size(), startManifold, numIslandManifolds, islandId);
                                //                      printf("Island callback of size:%d bodies, %d manifolds\n",islandBodies.size(),numIslandManifolds);
                        }
 
                        if (numIslandManifolds)
                        {
                                startManifoldIndex = endManifoldIndex;
                        }
 
                        m_islandBodies.resize(0);
                }
        }  // else if(!splitIslands)
}