HexGrid.cpp

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/*
 * AIDA Detector description implementation 
 * 
 * Copyright (C) Organisation europeenne pour la Recherche nucleaire (CERN)
 * All rights reserved.
 *
 * For the licensing terms see $DD4hepINSTALL/LICENSE.
 * For the list of contributors see $DD4hepINSTALL/doc/CREDITS.
 *
 * HexGrid.cpp  
 *
 * Created on: August 9, 2023
 *      Author: Sebouh J. Paul, UC Riverside
 */
#include "DD4hep/Factories.h"
#include "DDSegmentation/HexGrid.h"
 
namespace dd4hep {
  namespace DDSegmentation {
 
    HexGrid::HexGrid(const std::string& cellEncoding) :
      Segmentation(cellEncoding) {
        _type = "HexGridXY";
    _description = "Hexagonal segmentation in the local XY-plane";
 
    // register all necessary parameters
    registerParameter("stagger", "stagger mode", _stagger, 1);
    registerParameter("side_length", "Cell size", _sideLength, 1., SegmentationParameter::LengthUnit);
    registerParameter("offset_x", "Cell offset in X", _offsetX, 0., SegmentationParameter::LengthUnit, true);
    registerParameter("offset_y", "Cell offset in Y", _offsetY, 0., SegmentationParameter::LengthUnit, true);
    registerIdentifier("identifier_x", "Cell ID identifier for X", _xId, "x");
    registerIdentifier("identifier_y", "Cell ID identifier for Y", _yId, "y");
    registerParameter("stagger_keyword", "Volume ID identifier used for determining which volumes to stagger", _staggerKeyword, (std::string)"layer", SegmentationParameter::NoUnit, true);
    }
 
    HexGrid::HexGrid(const BitFieldCoder* decode) : Segmentation(decode) {
        // define type and description
    _type = "HexGridXY";
    _description = "Hexagonal segmentation in the local XY-plane";
 
    // register all necessary parameters                                                                        
        registerParameter("stagger", "stagger mode", _stagger, 1);
    registerParameter("side_length", "Cell size", _sideLength, 1., SegmentationParameter::LengthUnit);
    registerParameter("offset_x", "Cell offset in X", _offsetX, 0., SegmentationParameter::LengthUnit, true);
    registerParameter("offset_y", "Cell offset in Y", _offsetY, 0., SegmentationParameter::LengthUnit, true);
    registerIdentifier("identifier_x", "Cell ID identifier for X", _xId, "x");
    registerIdentifier("identifier_y", "Cell ID identifier for Y", _yId, "y");
    registerParameter("stagger_keyword", "Volume ID identifier used for determining which volumes to stagger", _staggerKeyword, (std::string)"layer", SegmentationParameter::NoUnit, true);
    
    }
 
    HexGrid::~HexGrid() {
    }
 
    Vector3D HexGrid::position(const CellID& cID) const {
        int layer=0;
    if (_stagger) layer= _decoder->get(cID,_staggerKeyword);
        
    Vector3D cellPosition;
    cellPosition.X = _decoder->get(cID,_xId )*1.5*_sideLength+_offsetX+_sideLength/2.;
    cellPosition.Y = _decoder->get(cID,_yId )*std::sqrt(3)/2.*_sideLength+ _offsetY+_sideLength*std::sqrt(3)/2.;
    if (_stagger==0)
      cellPosition.X+=_sideLength;
    else if (_stagger==1)
      cellPosition.X+=(layer%3)*_sideLength;
    else if (_stagger==2){
      switch (layer%4){
      case 0:
        cellPosition.X-=0.75*_sideLength;
        break;
      case 1:
        cellPosition.Y+=std::sqrt(3)/4*_sideLength;
        break;
      case 2:
        cellPosition.Y-=std::sqrt(3)/4*_sideLength;
        break;
      case 3:
        cellPosition.X+=0.75*_sideLength;
        break;
      }
    }
    return cellPosition;
    }
 
    inline double positive_modulo(double i, double n) {
      return std::fmod(std::fmod(i,n) + n,n);
    }
 
    
    CellID HexGrid::cellID(const Vector3D& localPosition, const Vector3D& /* globalPosition */, const VolumeID& vID) const {
        CellID cID = vID ;
    int layer=0;
    if (_stagger) layer= _decoder->get(cID,_staggerKeyword);
 
    double x=localPosition.X-_offsetX;
    double y=localPosition.Y-_offsetY;
    if (_stagger==0)
      x-=_sideLength;
    else if (_stagger==1)
          x-=(layer%3)*_sideLength;
    else if (_stagger==2){
          switch (layer%4){
      case 0:
        x+=0.75*_sideLength;
        break;
          case 1:
            y-=std::sqrt(3)/4*_sideLength;
            break;
          case 2:
            y+=std::sqrt(3)/4*_sideLength;
            break;
          case 3:
            x-=0.75*_sideLength;
        break;
          }
        }
    
    double a=positive_modulo(y/(std::sqrt(3)*_sideLength),1);
    double b=positive_modulo(x/(3*_sideLength),1);
    int ix = std::floor(x/(3*_sideLength/2.))+      
      (b<0.5)*(-std::abs(a-.5)<(b-.5)*3)+(b>0.5)*(std::abs(a-.5)-.5<(b-1)*3);
    int iy=std::floor(y/(std::sqrt(3)*_sideLength/2.));
    iy-=(ix+iy)&1;
    
    _decoder->set( cID,_xId, ix );
    _decoder->set( cID,_yId, iy );
    return cID ;
    }
 
    std::vector<double> HexGrid::cellDimensions(const CellID&) const {
#if __cplusplus >= 201103L
      return {2*_sideLength, std::sqrt(3)*_sideLength};
#else
      std::vector<double> cellDims(2,0.0);
      cellDims[0] = 2*_sideLength;
      cellDims[1] = std::sqrt(3)*_sideLength;
      return cellDims;
#endif
}
 
  } /* namespace DDSegmentation */
} /* namespace dd4hep */