VXDClusterParameters.cc

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
#include "VXDClusterParameters.h"
#include "VXDGeometry.h"


VXDClusterParameters::VXDClusterParameters(const gear::Vector3D& localPos, 
                                           const gear::Vector3D& a, const gear::Vector3D& b, 
                                           int lay,int lad) : 
  _localPos(localPos),
  _cluAxisA(a),
  _cluAxisB(b),
  _layerId (lay) ,
  _ladderId(lad) {
  
  // make sure a is the larger axes
  
  if( _cluAxisA.r() < _cluAxisB.r() ) {

    gear::Vector3D tmp = _cluAxisA ;
    _cluAxisA = _cluAxisB ;
    _cluAxisB = tmp ;
  }
}



bool VXDClusterParameters::isPointInClusterEllipse(const gear::Vector3D& pos) {


  // compute focal points of ellipse:

  double a = _cluAxisA.r() ;
  double b = _cluAxisB.r() ;
  double epsilon = sqrt( a*a - b*b ) ;

  gear::Vector3D f0 = _localPos +  epsilon/a * _cluAxisA  ;
  gear::Vector3D f1 = _localPos -  epsilon/a * _cluAxisA  ;

  // distance of points from focal points
  gear::Vector3D d0 = f0 - pos ;
  gear::Vector3D d1 = f1 - pos ;
  
  // ignore x-coordinate, i.e. project to ladder surface
  d0[0] = 0.0 ;
  d1[0] = 0.0 ;

  double dSum = d0.r() + d1.r() ;


  return dSum <= 2.* a ;

}