Physics Simulation Forum

void ClothSimulator::solveCollision(REAL dt)
{
   BT_PROFILE("solveCollision");
   //TODO: Handle multiple rigid objects
   
   //.. find rigid object
   btCollisionObject* cyl_obj = m_world->getCollisionObjectArray()[1];
   btTransform t = cyl_obj->getWorldTransform();
   btConvexShape* cyl_shape = (btConvexShape*) cyl_obj->getCollisionShape();
   
   btVector3 aabbMin, aabbMax;
   cyl_shape->getAabb(t,aabbMin,aabbMax);   
   
   btVoronoiSimplexSolver   simplexSolver;

   const unsigned npoints = m_particle.m_p.size();
   for ( size_t i=0; i<npoints; i++)
   {
      bool hasHit = false;
      btScalar closestHitResults = 1.f;
      btConvexCast::CastResult rayResult;
      btSphereShape pointShape(0.0f);
 
                vec3 from =......
                vec3 to = .......

      btTransform rayFromTrans;
      btTransform rayToTrans;
      
      rayFromTrans.setIdentity();
      rayFromTrans.setOrigin( btVector3(from.x,from.y,from.z) );
      
      rayToTrans.setIdentity();
      rayToTrans.setOrigin(btVector3(to.x,to.y,to.z));
      
      btScalar hitLambda = 1.f;
      btVector3 hitNormal;

      btVector3 rayFrom = btVector3(from.x,from.y,from.z);
      btVector3 rayTo = btVector3(to.x,to.y,to.z);

                this is the the code for simple ray test:
      btCollisionWorld::ClosestRayResultCallback cb(rayFrom, rayTo);
      m_world->rayTestSingle(rayFromTrans,rayToTrans, cyl_obj, cyl_obj->getCollisionShape(), t, cb);
      //m_world->rayTest(rayFrom, rayTo, cb );

      if (cb.hasHit())
      {
                       ..............
      }
      
                this is the code for convex cast ray test:      
      if (btRayAabb(rayFrom, rayTo, aabbMin, aabbMax, hitLambda, hitNormal))
      {
         btTransform transform;
         //btSubsimplexConvexCast convexCaster(&pointShape, cyl_shape,&simplexSolver);
         btGjkConvexCast convexCaster(&pointShape, cyl_shape,&simplexSolver);
         if (convexCaster.calcTimeOfImpact(rayFromTrans,rayToTrans,t,t,rayResult))
         {
            if (rayResult.m_fraction < closestHitResults)
            {
               closestHitResults = rayResult.m_fraction;
   
               hasHit = true;
               if (hasHit)
               {
                                       .................
               }
            }
         }   
      }
      
      //-- try to discover difference between convex caster and simple ray test
      if (cb.hasHit() && hasHit)
      {
         btVector3 delta = cb.m_hitPointWorld - rayResult.m_hitPoint;
         printf("delta=(%f,%f,%f)\n",delta.getX(),delta.getY(),delta.getZ());
         
      }
      if (hasHit && !cb.hasHit())
      {
         printf("missing detection by simple ray cast\n");
      }
      if (cb.hasHit() && !hasHit)
      {
         printf("missing detection by convex ray cast\n");
      }
   }
}