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btMinkowskiPenetrationDepthSolver.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 "btMinkowskiPenetrationDepthSolver.h"
#include "BulletCollision/NarrowPhaseCollision/btSubSimplexConvexCast.h"
#include "BulletCollision/NarrowPhaseCollision/btVoronoiSimplexSolver.h"
#include "BulletCollision/NarrowPhaseCollision/btGjkPairDetector.h"
#include "BulletCollision/CollisionShapes/btConvexShape.h"




#define NUM_UNITSPHERE_POINTS 42
static btVector3  sPenetrationDirections[NUM_UNITSPHERE_POINTS+MAX_PREFERRED_PENETRATION_DIRECTIONS*2] = 
{
btVector3(btScalar(0.000000) , btScalar(-0.000000),btScalar(-1.000000)),
btVector3(btScalar(0.723608) , btScalar(-0.525725),btScalar(-0.447219)),
btVector3(btScalar(-0.276388) , btScalar(-0.850649),btScalar(-0.447219)),
btVector3(btScalar(-0.894426) , btScalar(-0.000000),btScalar(-0.447216)),
btVector3(btScalar(-0.276388) , btScalar(0.850649),btScalar(-0.447220)),
btVector3(btScalar(0.723608) , btScalar(0.525725),btScalar(-0.447219)),
btVector3(btScalar(0.276388) , btScalar(-0.850649),btScalar(0.447220)),
btVector3(btScalar(-0.723608) , btScalar(-0.525725),btScalar(0.447219)),
btVector3(btScalar(-0.723608) , btScalar(0.525725),btScalar(0.447219)),
btVector3(btScalar(0.276388) , btScalar(0.850649),btScalar(0.447219)),
btVector3(btScalar(0.894426) , btScalar(0.000000),btScalar(0.447216)),
btVector3(btScalar(-0.000000) , btScalar(0.000000),btScalar(1.000000)),
btVector3(btScalar(0.425323) , btScalar(-0.309011),btScalar(-0.850654)),
btVector3(btScalar(-0.162456) , btScalar(-0.499995),btScalar(-0.850654)),
btVector3(btScalar(0.262869) , btScalar(-0.809012),btScalar(-0.525738)),
btVector3(btScalar(0.425323) , btScalar(0.309011),btScalar(-0.850654)),
btVector3(btScalar(0.850648) , btScalar(-0.000000),btScalar(-0.525736)),
btVector3(btScalar(-0.525730) , btScalar(-0.000000),btScalar(-0.850652)),
btVector3(btScalar(-0.688190) , btScalar(-0.499997),btScalar(-0.525736)),
btVector3(btScalar(-0.162456) , btScalar(0.499995),btScalar(-0.850654)),
btVector3(btScalar(-0.688190) , btScalar(0.499997),btScalar(-0.525736)),
btVector3(btScalar(0.262869) , btScalar(0.809012),btScalar(-0.525738)),
btVector3(btScalar(0.951058) , btScalar(0.309013),btScalar(0.000000)),
btVector3(btScalar(0.951058) , btScalar(-0.309013),btScalar(0.000000)),
btVector3(btScalar(0.587786) , btScalar(-0.809017),btScalar(0.000000)),
btVector3(btScalar(0.000000) , btScalar(-1.000000),btScalar(0.000000)),
btVector3(btScalar(-0.587786) , btScalar(-0.809017),btScalar(0.000000)),
btVector3(btScalar(-0.951058) , btScalar(-0.309013),btScalar(-0.000000)),
btVector3(btScalar(-0.951058) , btScalar(0.309013),btScalar(-0.000000)),
btVector3(btScalar(-0.587786) , btScalar(0.809017),btScalar(-0.000000)),
btVector3(btScalar(-0.000000) , btScalar(1.000000),btScalar(-0.000000)),
btVector3(btScalar(0.587786) , btScalar(0.809017),btScalar(-0.000000)),
btVector3(btScalar(0.688190) , btScalar(-0.499997),btScalar(0.525736)),
btVector3(btScalar(-0.262869) , btScalar(-0.809012),btScalar(0.525738)),
btVector3(btScalar(-0.850648) , btScalar(0.000000),btScalar(0.525736)),
btVector3(btScalar(-0.262869) , btScalar(0.809012),btScalar(0.525738)),
btVector3(btScalar(0.688190) , btScalar(0.499997),btScalar(0.525736)),
btVector3(btScalar(0.525730) , btScalar(0.000000),btScalar(0.850652)),
btVector3(btScalar(0.162456) , btScalar(-0.499995),btScalar(0.850654)),
btVector3(btScalar(-0.425323) , btScalar(-0.309011),btScalar(0.850654)),
btVector3(btScalar(-0.425323) , btScalar(0.309011),btScalar(0.850654)),
btVector3(btScalar(0.162456) , btScalar(0.499995),btScalar(0.850654))
};


bool btMinkowskiPenetrationDepthSolver::calcPenDepth(btSimplexSolverInterface& simplexSolver,
                                                                           const btConvexShape* convexA,const btConvexShape* convexB,
                                                                           const btTransform& transA,const btTransform& transB,
                                                                           btVector3& v, btPoint3& pa, btPoint3& pb,
                                                                           class btIDebugDraw* debugDraw,btStackAlloc* stackAlloc
                                                                           )
{

      (void)stackAlloc;
      (void)v;
      

      struct btIntermediateResult : public btDiscreteCollisionDetectorInterface::Result
      {

            btIntermediateResult():m_hasResult(false)
            {
            }
            
            btVector3 m_normalOnBInWorld;
            btVector3 m_pointInWorld;
            btScalar m_depth;
            bool  m_hasResult;

            virtual void setShapeIdentifiers(int partId0,int index0,    int partId1,int index1)
            {
                  (void)partId0;
                  (void)index0;
                  (void)partId1;
                  (void)index1;
            }
            void addContactPoint(const btVector3& normalOnBInWorld,const btVector3& pointInWorld,btScalar depth)
            {
                  m_normalOnBInWorld = normalOnBInWorld;
                  m_pointInWorld = pointInWorld;
                  m_depth = depth;
                  m_hasResult = true;
            }
      };

      //just take fixed number of orientation, and sample the penetration depth in that direction
      btScalar minProj = btScalar(1e30);
      btVector3 minNorm(btScalar(0.), btScalar(0.), btScalar(0.));
      btVector3 minA,minB;
      btVector3 seperatingAxisInA,seperatingAxisInB;
      btVector3 pInA,qInB,pWorld,qWorld,w;

#define USE_BATCHED_SUPPORT 1
#ifdef USE_BATCHED_SUPPORT

      btVector3   supportVerticesABatch[NUM_UNITSPHERE_POINTS+MAX_PREFERRED_PENETRATION_DIRECTIONS*2];
      btVector3   supportVerticesBBatch[NUM_UNITSPHERE_POINTS+MAX_PREFERRED_PENETRATION_DIRECTIONS*2];
      btVector3   seperatingAxisInABatch[NUM_UNITSPHERE_POINTS+MAX_PREFERRED_PENETRATION_DIRECTIONS*2];
      btVector3   seperatingAxisInBBatch[NUM_UNITSPHERE_POINTS+MAX_PREFERRED_PENETRATION_DIRECTIONS*2];
      int i;

      int numSampleDirections = NUM_UNITSPHERE_POINTS;

      for (i=0;i<numSampleDirections;i++)
      {
            const btVector3& norm = sPenetrationDirections[i];
            seperatingAxisInABatch[i] =  (-norm) * transA.getBasis() ;
            seperatingAxisInBBatch[i] =  norm   * transB.getBasis() ;
      }

      {
            int numPDA = convexA->getNumPreferredPenetrationDirections();
            if (numPDA)
            {
                  for (int i=0;i<numPDA;i++)
                  {
                        btVector3 norm;
                        convexA->getPreferredPenetrationDirection(i,norm);
                        norm  = transA.getBasis() * norm;
                        sPenetrationDirections[numSampleDirections] = norm;
                        seperatingAxisInABatch[numSampleDirections] = (-norm) * transA.getBasis();
                        seperatingAxisInBBatch[numSampleDirections] = norm * transB.getBasis();
                        numSampleDirections++;
                  }
            }
      }

      {
            int numPDB = convexB->getNumPreferredPenetrationDirections();
            if (numPDB)
            {
                  for (int i=0;i<numPDB;i++)
                  {
                        btVector3 norm;
                        convexB->getPreferredPenetrationDirection(i,norm);
                        norm  = transB.getBasis() * norm;
                        sPenetrationDirections[numSampleDirections] = norm;
                        seperatingAxisInABatch[numSampleDirections] = (-norm) * transA.getBasis();
                        seperatingAxisInBBatch[numSampleDirections] = norm * transB.getBasis();
                        numSampleDirections++;
                  }
            }
      }



      convexA->batchedUnitVectorGetSupportingVertexWithoutMargin(seperatingAxisInABatch,supportVerticesABatch,numSampleDirections);
      convexB->batchedUnitVectorGetSupportingVertexWithoutMargin(seperatingAxisInBBatch,supportVerticesBBatch,numSampleDirections);

      for (i=0;i<numSampleDirections;i++)
      {
            const btVector3& norm = sPenetrationDirections[i];
            seperatingAxisInA = seperatingAxisInABatch[i];
            seperatingAxisInB = seperatingAxisInBBatch[i];

            pInA = supportVerticesABatch[i];
            qInB = supportVerticesBBatch[i];

            pWorld = transA(pInA);  
            qWorld = transB(qInB);
            w     = qWorld - pWorld;
            btScalar delta = norm.dot(w);
            //find smallest delta
            if (delta < minProj)
            {
                  minProj = delta;
                  minNorm = norm;
                  minA = pWorld;
                  minB = qWorld;
            }
      }     
#else

      int numSampleDirections = NUM_UNITSPHERE_POINTS;

      {
            int numPDA = convexA->getNumPreferredPenetrationDirections();
            if (numPDA)
            {
                  for (int i=0;i<numPDA;i++)
                  {
                        btVector3 norm;
                        convexA->getPreferredPenetrationDirection(i,norm);
                        norm  = transA.getBasis() * norm;
                        sPenetrationDirections[numSampleDirections] = norm;
                        numSampleDirections++;
                  }
            }
      }

      {
            int numPDB = convexB->getNumPreferredPenetrationDirections();
            if (numPDB)
            {
                  for (int i=0;i<numPDB;i++)
                  {
                        btVector3 norm;
                        convexB->getPreferredPenetrationDirection(i,norm);
                        norm  = transB.getBasis() * norm;
                        sPenetrationDirections[numSampleDirections] = norm;
                        numSampleDirections++;
                  }
            }
      }

      for (int i=0;i<numSampleDirections;i++)
      {
            const btVector3& norm = sPenetrationDirections[i];
            seperatingAxisInA = (-norm)* transA.getBasis();
            seperatingAxisInB = norm* transB.getBasis();
            pInA = convexA->localGetSupportingVertexWithoutMargin(seperatingAxisInA);
            qInB = convexB->localGetSupportingVertexWithoutMargin(seperatingAxisInB);
            pWorld = transA(pInA);  
            qWorld = transB(qInB);
            w     = qWorld - pWorld;
            btScalar delta = norm.dot(w);
            //find smallest delta
            if (delta < minProj)
            {
                  minProj = delta;
                  minNorm = norm;
                  minA = pWorld;
                  minB = qWorld;
            }
      }
#endif //USE_BATCHED_SUPPORT

      //add the margins

      minA += minNorm*convexA->getMargin();
      minB -= minNorm*convexB->getMargin();
      //no penetration
      if (minProj < btScalar(0.))
            return false;

      minProj += (convexA->getMargin() + convexB->getMargin());





//#define DEBUG_DRAW 1
#ifdef DEBUG_DRAW
      if (debugDraw)
      {
            btVector3 color(0,1,0);
            debugDraw->drawLine(minA,minB,color);
            color = btVector3 (1,1,1);
            btVector3 vec = minB-minA;
            btScalar prj2 = minNorm.dot(vec);
            debugDraw->drawLine(minA,minA+(minNorm*minProj),color);

      }
#endif //DEBUG_DRAW

      

      btGjkPairDetector gjkdet(convexA,convexB,&simplexSolver,0);

      btScalar offsetDist = minProj;
      btVector3 offset = minNorm * offsetDist;
      


      btGjkPairDetector::ClosestPointInput input;
            
      btVector3 newOrg = transA.getOrigin() + offset;

      btTransform displacedTrans = transA;
      displacedTrans.setOrigin(newOrg);

      input.m_transformA = displacedTrans;
      input.m_transformB = transB;
      input.m_maximumDistanceSquared = btScalar(1e30);//minProj;
      
      btIntermediateResult res;
      gjkdet.getClosestPoints(input,res,debugDraw);

      btScalar correctedMinNorm = minProj - res.m_depth;


      //the penetration depth is over-estimated, relax it
      btScalar penetration_relaxation= btScalar(1.);
      minNorm*=penetration_relaxation;

      if (res.m_hasResult)
      {

            pa = res.m_pointInWorld - minNorm * correctedMinNorm;
            pb = res.m_pointInWorld;
            
#ifdef DEBUG_DRAW
            if (debugDraw)
            {
                  btVector3 color(1,0,0);
                  debugDraw->drawLine(pa,pb,color);
            }
#endif//DEBUG_DRAW


      }
      return res.m_hasResult;
}




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