//-----------------------------------------------------------
// File and Version Information:
// $Id$
//
// Description:
//      Distortion with fixed direction and Gaussian profile
//      
//
// Environment:
//      Software developed for a real experiment
//
// Author List:
//      Felix Boehmer                     (original author)
//      Physik Department E18, TUM
//
//-----------------------------------------------------------

#include "TpcMMLocalGaussDistortion.h"
#include "TMath.h"


TpcMMLocalGaussDistortion::TpcMMLocalGaussDistortion() 
  :
  fDirection(0.,0.,0.),
  fPos(0.,0.,0.),
  fSigma(0.)
{;}


TpcMMLocalGaussDistortion::TpcMMLocalGaussDistortion(double sig, const TVector3& dir, const TVector3& pos)
  :
  fDirection(dir),
  fPos(pos),
  fSigma(sig)
{;}

void
TpcMMLocalGaussDistortion::distort(const std::vector<TpcCluster*>& cls)  {
  
  //loop over clusters:
  for(unsigned int icl=0; icl<cls.size(); icl++) {
    TVector3 pos = cls[icl]->pos();
    TVector3 diff = pos-fPos;
    //skip everything farther away than 3sig
    if(diff.Mag()>3*fSigma)
      continue;
    //magnitude at pos:
    double norm = TMath::Gaus(diff.Mag(),0,fSigma);
    TVector3 shift = fDirection*norm;
    pos+=shift;
    cls[icl]->SetPos(pos);
    //TODO: check if we need to remove clusters that "leave"
    //the detector volume
    
  } //end loop over cluster

}