CircleDist2IP.h

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
 
#pragma once
 
#include <tracking/trackFindingVXD/filterMap/filterFramework/SelectionVariable.h>
#include <tracking/trackFindingVXD/filterMap/threeHitVariables/CircleCenterXY.h>
#include <tracking/trackFindingVXD/filterMap/threeHitVariables/CircleRadius.h>
#include <framework/geometry/B2Vector3.h>
#include <math.h>
 
#define CIRCLEDIST2IP_NAME CircleDist2IP
 
namespace Belle2 {
  template <typename PointType >
  class CIRCLEDIST2IP_NAME : public SelectionVariable< PointType, 3, double > {
  public:
 
    PUT_NAME_FUNCTION(CIRCLEDIST2IP_NAME);
 
    static double value(const PointType& outerHit, const PointType& centerHit, const PointType& innerHit)
    {
 
      B2Vector3D cCenter = CircleCenterXY<PointType>::value(outerHit, centerHit, innerHit);
      double circleRadius = CircleRadius<PointType>::calcAvgDistanceXY(outerHit, centerHit, innerHit, cCenter);
 
      // distance of closest approach of circle to the IP :
      // WARNING only valid for IP=0,0,X
      return (fabs(cCenter.Perp() - circleRadius));
    } // return unit: cm
  };
 
}