BfldHandler.cxx

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// $Id: BfldHandler.cxx,v 1.10 2007/12/13 16:58:42 rhatcher Exp $
// 
// BfldHandler 
// 
// BfldHandler searches and interpolates BfldMesh (position info) structures
// (field values are in BfldMap).
//
// Author:  R. Hatcher 2000.06.20
//

#include "BField/BfldHandler.h"

#include "BField/BfldMap.h"
#include "BField/BfldMesh.h"

#include "TMath.h"

#include "MessageService/MsgService.h"
CVSID("$Id: BfldHandler.cxx,v 1.10 2007/12/13 16:58:42 rhatcher Exp $");

ClassImp(BfldHandler)

//_____________________________________________________________________________
BfldHandler::BfldHandler()
   : fInterpMethod(BfldInterpMethod::kDefault), fUseLastAsSeed(kTRUE),
     fCache(0), fMap(0), fMesh(0)
{
   // base handler ctor
   // clear basic components
}

//_____________________________________________________________________________
BfldHandler::~BfldHandler()
{
   // tell the held map and mesh that this handler no longer 
   // has need of them
   if (fMap)  fMap->DecrementRef();
   if (fMesh) fMesh->DecrementRef();
}

//_____________________________________________________________________________
TVector3 BfldHandler::GetBField(const TVector3& position, Bool_t isUVZ)
{
   // Return the field for the requested position.
   // Translate (if necessary) the position before passing it
   // to the workhorse routine, translate back if necessary.

   //MAXMSG("Bfld",Msg::kVerbose,5)
   //  << "GetBField pos=(" << position.x() << "," << position.y() << ")" << endl;
   if ( isUVZ == fMesh->GetIsUVZ() ) return GetBFieldMeshCoord(position);

   // mismatch ... do some work
   // we don't need to know the detector since only both NearDet & FarDet
   // use the same rotation .
   // (only CalDet doesn't and it has UVZ=XYZ, but it never has a field)

   MAXMSG("Bfld",Msg::kVerbose,5)
     << "BfldHandler::GetBField passed isUVZ= "
     << (isUVZ?"yes":"no")
     << " which didn't match Mesh."
     << endl;

   static const double kInvSqrt2 = TMath::Sqrt(0.5);
   if ( isUVZ ) {
     // position is UVZ, so mesh must be XYZ, but return B_uvz
     Double_t  u = position[0];
     Double_t  v = position[1];
     Double_t  z = position[2];
     TVector3  xyz(kInvSqrt2*(u-v),kInvSqrt2*(u+v),z);
     TVector3 bxyz = GetBFieldMeshCoord(xyz);
     Double_t bx = bxyz[0];
     Double_t by = bxyz[1];
     Double_t bz = bxyz[2];
     return TVector3(kInvSqrt2*(by+bx),kInvSqrt2*(by-bx),bz);
   }
   else {
     // position is XYZ, so mesh must be UVZ, but return B_xyz
     Double_t  x = position[0];
     Double_t  y = position[1];
     Double_t  z = position[2];
     TVector3  uvz(kInvSqrt2*(x+y),kInvSqrt2*(y-x),z);
     TVector3 buvz = GetBFieldMeshCoord(uvz);
     Double_t bu = buvz[0];
     Double_t bv = buvz[1];
     Double_t bz = buvz[2];
     return TVector3(kInvSqrt2*(bu-bv),kInvSqrt2*(bu+bv),bz);
   }
}

//_____________________________________________________________________________
void BfldHandler::SetInterpMethod(const BfldInterpMethod::InterpMethod_t method) 
{
   // set the interpolation method for this handler
   // specialized handler versions should override the 
   // translation of "kDefault" to their optimal choice
   // and should also disallow illegal choices

   BfldInterpMethod::InterpMethod_t chosen = method;

   if (BfldInterpMethod::kDefault == chosen) {
      // pick a default method
      // for the generic case we'll choose "kClosest" because
      // all approaches should easily support this
      chosen = BfldInterpMethod::kClosest;
   }

   fInterpMethod = chosen;
}

//_____________________________________________________________________________
void BfldHandler::SetMap(BfldMap* bmap)
{
   // tell this handler about the map

   if (fMap) fMap->DecrementRef();
   fMap = bmap;
   fMap->IncrementRef();
}

//_____________________________________________________________________________
void BfldHandler::SetMesh(BfldMesh* mesh)
{
   // tell this handler about the map

   if (fMesh) fMesh->DecrementRef();
   fMesh = mesh;
   fMesh->IncrementRef();
}

//_____________________________________________________________________________

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