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GjkPairDetector.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 "GjkPairDetector.h"
#include "CollisionShapes/ConvexShape.h"
#include "NarrowPhaseCollision/SimplexSolverInterface.h"
#include "NarrowPhaseCollision/ConvexPenetrationDepthSolver.h"

static const SimdScalar rel_error = SimdScalar(1.0e-5);
SimdScalar rel_error2 = rel_error * rel_error;
float maxdist2 = 1.e30f;
#include <stdio.h>


int gGjkMaxIter=1000;
bool gIrregularCatch = true;

GjkPairDetector::GjkPairDetector(ConvexShape* objectA,ConvexShape* objectB,SimplexSolverInterface* simplexSolver,ConvexPenetrationDepthSolver*  penetrationDepthSolver)
:m_cachedSeparatingAxis(0.f,0.f,1.f),
m_penetrationDepthSolver(penetrationDepthSolver),
m_simplexSolver(simplexSolver),
m_minkowskiA(objectA),
m_minkowskiB(objectB),
m_ignoreMargin(false)
{
}

void GjkPairDetector::GetClosestPoints(const ClosestPointInput& input,Result& output,class IDebugDraw* debugDraw)
{
      SimdScalar distance=0.f;
      SimdVector3 normalInB(0.f,0.f,0.f);
      SimdVector3 pointOnA,pointOnB;

      float marginA = m_minkowskiA->GetMargin();
      float marginB = m_minkowskiB->GetMargin();

      //for CCD we don't use margins
      if (m_ignoreMargin)
      {
            marginA = 0.f;
            marginB = 0.f;
      }

int curIter = 0;

      bool isValid = false;
      bool checkSimplex = false;
      bool checkPenetration = true;

      {
            SimdScalar squaredDistance = SIMD_INFINITY;
            SimdScalar delta = 0.f;
            
            SimdScalar margin = marginA + marginB;
            
            

            m_simplexSolver->reset();
            
            while (true)
            {
            

                  SimdVector3 seperatingAxisInA = (-m_cachedSeparatingAxis)* input.m_transformA.getBasis();
                  SimdVector3 seperatingAxisInB = m_cachedSeparatingAxis* input.m_transformB.getBasis();

                  SimdVector3 pInA = m_minkowskiA->LocalGetSupportingVertexWithoutMargin(seperatingAxisInA);
                  SimdVector3 qInB = m_minkowskiB->LocalGetSupportingVertexWithoutMargin(seperatingAxisInB);
                  SimdPoint3  pWorld = input.m_transformA(pInA);  
                  SimdPoint3  qWorld = input.m_transformB(qInB);
                  
                  SimdVector3 w     = pWorld - qWorld;
                  delta = m_cachedSeparatingAxis.dot(w);

                  // potential exit, they don't overlap
                  if ((delta > SimdScalar(0.0)) && (delta * delta > squaredDistance * input.m_maximumDistanceSquared)) 
                  {
                        checkPenetration = false;
                        break;
                  }

                  //exit 0: the new point is already in the simplex, or we didn't come any closer
                  if (m_simplexSolver->inSimplex(w))
                  {
                        checkSimplex = true;
                        break;
                  }
                  // are we getting any closer ?
                  if (squaredDistance - delta <= squaredDistance * rel_error2)
                  {
                        checkSimplex = true;
                        break;
                  }
                  //add current vertex to simplex
                  m_simplexSolver->addVertex(w, pWorld, qWorld);

                  //calculate the closest point to the origin (update vector v)
                  if (!m_simplexSolver->closest(m_cachedSeparatingAxis))
                  {
                        checkSimplex = true;
                        break;
                  }

                  SimdScalar previousSquaredDistance = squaredDistance;
                  squaredDistance = m_cachedSeparatingAxis.length2();
                  
                  //redundant m_simplexSolver->compute_points(pointOnA, pointOnB);

                  //are we getting any closer ?
                  if (previousSquaredDistance - squaredDistance <= SIMD_EPSILON * previousSquaredDistance) 
                  { 
                        m_simplexSolver->backup_closest(m_cachedSeparatingAxis);
                        checkSimplex = true;
                        break;
                  }
                  bool check = (!m_simplexSolver->fullSimplex());
                  //bool check = (!m_simplexSolver->fullSimplex() && squaredDistance > SIMD_EPSILON * m_simplexSolver->maxVertex());

                  if (!check)
                  {
                        //do we need this backup_closest here ?
                        m_simplexSolver->backup_closest(m_cachedSeparatingAxis);
                        break;
                  }

                        //rare failure case, perhaps deferate shapes?
                  if (curIter++ > gGjkMaxIter)
                  {

#define CATCH_ME 1
#ifdef CATCH_ME
//this should not happen, we need to catch it
//#if defined(DEBUG) || defined (_DEBUG)
                        if (gIrregularCatch)
                        {
                              gIrregularCatch = false;

                              printf("Problem with collision geometry\n");
                                    printf("sepAxis=(%f,%f,%f), squaredDistance = %f, shapeTypeA=%i,shapeTypeB=%i\n",
                                    m_cachedSeparatingAxis.getX(),
                                    m_cachedSeparatingAxis.getY(),
                                    m_cachedSeparatingAxis.getZ(),
                                    squaredDistance,
                                    m_minkowskiA->GetShapeType(),
                                    m_minkowskiB->GetShapeType());

                              printf("If you can reproduce this, please email bugs@continuousphysics.com\n");
                              printf("Please include above information, your Platform, version of OS.\n");
                              printf("Thanks.\n");
                        }
//#endif
#endif //CATCH_ME

                        break;

                  }

            }

            if (checkSimplex)
            {
                  m_simplexSolver->compute_points(pointOnA, pointOnB);
                  normalInB = pointOnA-pointOnB;
                  float lenSqr = m_cachedSeparatingAxis.length2();
                  //valid normal
                  if (lenSqr > (SIMD_EPSILON*SIMD_EPSILON))
                  {
                        float rlen = 1.f / SimdSqrt(lenSqr );
                        normalInB *= rlen; //normalize
                        SimdScalar s = SimdSqrt(squaredDistance);
                        ASSERT(s > SimdScalar(0.0));
                        pointOnA -= m_cachedSeparatingAxis * (marginA / s);
                        pointOnB += m_cachedSeparatingAxis * (marginB / s);
                        distance = ((1.f/rlen) - margin);
                        isValid = true;
                  }
            }

            if (checkPenetration && !isValid)
            {
                  //penetration case
            
                  //if there is no way to handle penetrations, bail out
                  if (m_penetrationDepthSolver)
                  {
                        // Penetration depth case.
                        isValid = m_penetrationDepthSolver->CalcPenDepth( 
                              *m_simplexSolver, 
                              m_minkowskiA,m_minkowskiB,
                              input.m_transformA,input.m_transformB,
                              m_cachedSeparatingAxis, pointOnA, pointOnB,
                              debugDraw
                              );

                        if (isValid)
                        {
                              normalInB = pointOnB-pointOnA;
                              float lenSqr = normalInB.length2();
                              if (lenSqr > (SIMD_EPSILON*SIMD_EPSILON))
                              {
                                    normalInB /= SimdSqrt(lenSqr);
                                    distance = -(pointOnA-pointOnB).length();
                              } else
                              {
                                    isValid = false;
                              }
                        }
                  }
            }
      }

      if (isValid)
      {
            output.AddContactPoint(
                  normalInB,
                  pointOnB,
                  distance);
            //printf("gjk add:%f",distance);
      } 


}






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