GFWireHitPolicy.cxx

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/* Copyright 2008-2010, Technische Universitaet Muenchen,
   Authors: Christian Hoeppner & Sebastian Neubert

   This file is part of GENFIT.

   GENFIT is free software: you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as published
   by the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   GENFIT is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with GENFIT.  If not, see <http://www.gnu.org/licenses/>.
*/
// ----------------------------------------------------------
// Please see GFWireHitPolicy.h  before using this class.
// ----------------------------------------------------------

#include "GFWireHitPolicy.h"

#include "assert.h"
#include <cmath>

#include "TMath.h"
#include "TVector3.h"

#include "GFAbsRecoHit.h"
#include "GFException.h"

const std::string GFWireHitPolicy::fPolicyName = "GFWireHitPolicy";

GFWireHitPolicy::GFWireHitPolicy() :fMaxdistance(1.E50) {;}

TMatrixT<double> 
GFWireHitPolicy::hitCoord(GFAbsRecoHit* hit,const GFDetPlane& plane)
{
  TMatrixT<double> returnMat(1,1);

  checkPlane(hit, plane);

  // raw x1, y1, z1, x2, y2, z2, rdrift
  TMatrixT<double> rC = hit->getRawHitCoord();

  returnMat[0][0] = rC[6][0];
  return returnMat;
}

TMatrixT<double> 
GFWireHitPolicy::hitCov(GFAbsRecoHit* hit,const GFDetPlane& plane)
{
  checkPlane(hit, plane);

  TMatrixT<double> returnCov(1,1);
  TMatrixT<double> rawCov = hit->getRawHitCov();

  returnCov[0][0] = rawCov[6][6];

  return  returnCov;
}



void GFWireHitPolicy::checkPlane(GFAbsRecoHit* hit,const GFDetPlane& plane)
{
  // raw x1, y1, z1, x2, y2, z2, rdrift, zreco
  TMatrixT<double> rC = hit->getRawHitCoord();

  assert(rC.GetNrows()==7);
  
  TVector3 wire1(rC[0][0], rC[1][0], rC[2][0]);
  TVector3 wire2(rC[3][0], rC[4][0], rC[5][0]);
  TVector3 wiredirection = wire1 - wire2;
  
  TVector3 vaxis = plane.getV();
  wiredirection.SetMag(1.);
  vaxis.SetMag(1.);

  if(fabs(TMath::Abs(wiredirection.Dot(vaxis)) - 1) > 1e-3)
    {
     
      std::cout << "GFWireHitPolicy: plane not valid!!" << std::endl;
    }
}


const GFDetPlane& 
GFWireHitPolicy::detPlane(GFAbsRecoHit* hit, GFAbsTrackRep* rep)
{

  TMatrixT<double> x=hit->getRawHitCoord();
  assert(x.GetNrows()==7);
  TVector3 wire1(x[0][0],x[1][0],x[2][0]);
  TVector3 wire2(x[3][0],x[4][0],x[5][0]);

  //  distance of one (the first) of the wire extremities from the plane
  Double_t d_from_refplane =  fDetPlane.dist(wire1).Mag();
  if(d_from_refplane < 1e-5) return fDetPlane;

  
  // point of closest approach
  TVector3 poca, poca_onwire, dirInPoca;
  
  rep->extrapolateToLine(wire1, wire2, poca, dirInPoca, poca_onwire);
  
  
  Double_t distance;
  distance = TMath::Sqrt(fabs(((wire1-poca).Mag2()*(wire2-wire1).Mag2()-pow((wire1-poca).Dot(wire2-wire1),2))/(wire2-wire1).Mag2()));
  
  // check poca inside tube 
  if(distance > fMaxdistance) {
    GFException exc("distance poca-wire > maxdistance", __LINE__,__FILE__); 
    throw exc;    
  }
  
  // find plane
  // unitary vector along distance
  // poca (on track), poca_onwire (on wire)
  TVector3 fromwiretoextr = poca - poca_onwire;     
  fromwiretoextr.SetMag(1.);
  // unitary vector along the wire
  TVector3 wiredirection = wire2 - wire1; 
  wiredirection.SetMag(1.);
  
  // check orthogonality
  if(fabs(fromwiretoextr * wiredirection) > 1e-3) {
    GFException exc("fromwiretoextr*wiredirection > 1e-3", __LINE__,__FILE__);  
    throw exc;    
  }
  
  TVector3 U;
  U = fromwiretoextr;
  TVector3 V;
  V = wiredirection;
  U.SetMag(1.);
  V.SetMag(1.);
  
  TVector3 O = poca_onwire;
  
  fDetPlane = GFDetPlane(O, U, V);
  
  return fDetPlane;
}

ClassImp(GFWireHitPolicy)