// This code implementation is the intellectual property of
// the GEANT4 collaboration.
//
// By copying, distributing or modifying the Program (or any work
// based on the Program) you indicate your acceptance of this statement,
// and all its terms.
//
// $Id: G4NormalNavigation.icc,v 1.3 2000/11/20 18:59:40 gcosmo Exp $
// GEANT4 tag $Name: geant4-03-00 $
//
// 
// G4NormalNavigation Inline Implementation

inline G4bool G4NormalNavigation::LevelLocate(G4NavigationHistory &history,
			   const G4VPhysicalVolume *blockedVol,
                           const G4int,
                           const G4ThreeVector &globalPoint,
                           const G4ThreeVector* globalDirection,
			   const G4bool  pLocatedOnEdge, 
			   G4ThreeVector &localPoint)
{
  G4VPhysicalVolume *targetPhysical,*samplePhysical;
  G4LogicalVolume *targetLogical;
  G4VSolid *sampleSolid;
  G4ThreeVector samplePoint;
  G4int targetNoDaughters,sampleNo;
  
  targetPhysical=history.GetTopVolume();
  targetLogical=targetPhysical->GetLogicalVolume();
  targetNoDaughters=targetLogical->GetNoDaughters();
  
  if (targetNoDaughters==0) return false;
  
//
// Search daughters in volume
//
  for (sampleNo=targetNoDaughters-1;sampleNo>=0;sampleNo--)
    {
      samplePhysical=targetLogical->GetDaughter(sampleNo);
      if (samplePhysical!=blockedVol)
	{
	  // Setup volume with mother ptr
	  samplePhysical->Setup(targetPhysical);
	  history.NewLevel(samplePhysical, kNormal, samplePhysical->GetCopyNo());
	  sampleSolid=samplePhysical->GetLogicalVolume()->GetSolid();
	  samplePoint=history.GetTopTransform().TransformPoint(globalPoint);
#if 1
	  if( G4AuxiliaryNavServices::
              CheckPointOnSurface(sampleSolid, samplePoint, globalDirection, 
				  history.GetTopTransform(), pLocatedOnEdge) 
	    )
	    {
	      // Enter this daughter
	      //      blockedVol=0;
	      localPoint=samplePoint;
	      return true;
	    }
	  else
	    {
	      history.BackLevel();
	    }
#else
          EInside sampleInside = sampleSolid->Inside(samplePoint);

	  if( sampleInside == kOutside)
	    {
	      history.BackLevel();
	    }
	  else
	    {
	      if( !pLocatedOnEdge )
	        {
		  // Enter this daughter
		  // blockedVol=0;
		  localPoint=samplePoint;
		  return true;
		}
	      else
		{
                  // We are probably located on an edge.
		  sampleDirection= history.GetTopTransform()
		                          .TransformAxis(globalDirection); 

		  // Check whether we enter the volume
		  // 
                  sampleNormal= sampleSolid->SurfaceNormal(samplePoint);
		  if ( sampleNormal.dot(sampleDirection) <= 0 )
		    {
		      // Enter this daughter
		      // blockedVol=0;
		      localPoint=samplePoint;
		      return true;
		    }
		}
	    }
#endif
	}
    }
  return false;
}