TiledEtaPhiMap.h

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// emacs, this is -*- C++ -*-
 
/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/

 
#ifndef JETUTIL_TILEDETAPHIMAP_H
#define JETUTIL_TILEDETAPHIMAP_H
 
 
#include <list>
#include <vector>
 
#include <cmath>
 
 
#include "FourMomUtils/xAODP4Helpers.h"
 
namespace JetTiledMap {
 
  struct utils {
    static constexpr double DR2(double eta1, double phi1, double eta2,double phi2) {
      double deta = eta1 - eta2;
      constexpr double pi = M_PI;
      constexpr double twopi = 2.0*pi;
      double dphi = phi1 - phi2;
      while ( dphi > pi ) dphi -= twopi;
      while ( dphi <= -pi ) dphi += twopi;
      return dphi*dphi + deta*deta;
    }
  };
 
  enum Directions {
    N=0, NE,E,SE,S,SW,W,NW
  };
  

  template<class POINT, class DIST2>
  class Tile : public std::list<POINT> {
  public:
    typedef typename std::list<POINT> tilecontainerbase_t;
    typedef typename tilecontainerbase_t::iterator iterator;
    typedef typename tilecontainerbase_t::const_iterator const_iterator;
    typedef typename std::vector<POINT> pointvec_t;
    
    Tile() = default;
    Tile(POINT tileCenter) : center(tileCenter) {}
    
    void fillPointsInDr2(POINT &p, double r2, pointvec_t& points ) const;
    
    static const Tile voidTile;
  public:
    const Tile<POINT,DIST2>* m_neighbour[8] = {nullptr};
    static const DIST2 dr2;
    POINT center;
  };
  
 
  
  
  template<class POINT, class DIST2 = typename POINT::DR2>
  class TiledEtaPhiMap { 
  public:
    typedef  Tile<POINT, DIST2> tile_t;
 
  public:
    TiledEtaPhiMap():  m_etarange(10.0), m_halfetarange(5.), m_size(0) {};
    virtual ~TiledEtaPhiMap(){}
    void init(double rmax);    
    
    void insert(POINT & p);   

    std::vector<POINT> pointsInDr(POINT &p, double r) const ;
 
    virtual void clear();
 
    virtual void reset(){m_tiles.clear();m_size=0;}
    
    unsigned int size()const {return m_size;} ;
    
    void setEtaRange(double r){m_etarange=r; m_halfetarange = r/2;}
 
  protected:
 
    double  m_etarange{} ;
    double  m_halfetarange{};
    double m_rmax{};
    size_t m_ndivX=1, m_ndivY=1;
    double m_sizeX{},m_sizeY{};
    
    unsigned int m_size{};
    

    size_t tileIndex(POINT &p) const {
 
      int indx = int( (p.x()+m_halfetarange)/m_sizeX) ;
      if(indx<0) indx=0;
      if(indx>=static_cast<int>(m_ndivX)) indx=static_cast<int>(m_ndivX)-1;
      int indy = int((M_PI-p.y())/m_sizeY);      
      if(indy>=static_cast<int>(m_ndivY)) indy=static_cast<int>(m_ndivY)-1;
      
      return tileIndex_i(indx,indy);
    }

    size_t tileIndex_i(int ix, int iy) const {return ix*m_ndivY + iy;};
    
    std::vector<tile_t> m_tiles;
    
  };
  
  
}
 
#include "JetUtils/TiledEtaPhiMap.icc"
 
#endif