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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"

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

      btCollisionObject* colObj = m_isSwapped? body1 : body0;
      btCollisionObject* otherObj = m_isSwapped? body0 : body1;
      assert (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] = ci.m_dispatcher1->findAlgorithm(colObj,otherObj,m_sharedManifold);
                  colObj->internalSetTemporaryCollisionShape( tmpShape );
            }
      }
}


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




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;

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

      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);


      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;

      assert (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;

}



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