/afs/cern.ch/work/a/aaltunda/public/www/CMSSW_6_2_7/src/Fireworks/Muons/src/SegmentUtils.cc

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#include "Fireworks/Muons/interface/SegmentUtils.h"
#include "Fireworks/Core/interface/fwLog.h"

#include "DataFormats/MuonDetId/interface/MuonSubdetId.h"

#include <math.h>

namespace fireworks
{
  void createSegment( int detector, 
                      bool matchedSegment,
                      float segmentLength,
                      float segmentLimit,
                      float* segmentPosition,   
                      float* segmentDirection,
                      float* segmentInnerPoint, 
                      float* segmentOuterPoint )
  {
    if( detector == MuonSubdetId::CSC )
    {
      if( matchedSegment )
      {
        segmentOuterPoint[0] = segmentPosition[0] + segmentLength*segmentDirection[0];
        segmentOuterPoint[1] = segmentPosition[1] + segmentLength*segmentDirection[1];
        segmentOuterPoint[2] = segmentLength;

        if( fabs(segmentOuterPoint[1]) > segmentLimit )
          segmentOuterPoint[1] = segmentLimit * ( segmentOuterPoint[1] / fabs( segmentOuterPoint[1] ));

        segmentInnerPoint[0] = segmentPosition[0] - segmentLength*segmentDirection[0];
        segmentInnerPoint[1] = segmentPosition[1] - segmentLength*segmentDirection[1];
        segmentInnerPoint[2] = -segmentLength;

        if( fabs(segmentInnerPoint[1]) > segmentLimit )
          segmentInnerPoint[1] = segmentLimit * ( segmentInnerPoint[1] / fabs( segmentInnerPoint[1] ));

        return;
      }     
      else 
      {
        segmentOuterPoint[0] = segmentPosition[0] + segmentDirection[0] * ( segmentPosition[2] / segmentDirection[2] );
        segmentOuterPoint[1] = segmentPosition[1] + segmentDirection[1] * ( segmentPosition[2] / segmentDirection[2] );
        segmentOuterPoint[2] = segmentPosition[2];

        if( fabs( segmentOuterPoint[1] ) > segmentLength )
          segmentOuterPoint[1] = segmentLength * ( segmentOuterPoint[1]/fabs( segmentOuterPoint[1] ));

        segmentInnerPoint[0] = segmentPosition[0] - segmentDirection[0] * ( segmentPosition[2] / segmentDirection[2] );
        segmentInnerPoint[1] = segmentPosition[1] - segmentDirection[1] * ( segmentPosition[2] / segmentDirection[2] );
        segmentInnerPoint[2] = -segmentPosition[2];

        if( fabs( segmentInnerPoint[1] ) > segmentLength )
          segmentInnerPoint[1] = segmentLength * ( segmentInnerPoint[1] / fabs( segmentInnerPoint[1] ));
      
        return;
      }
    }
    
    if ( detector == MuonSubdetId::DT )
    {
      if( matchedSegment )
      {
        segmentOuterPoint[0] = segmentPosition[0] + segmentLength*segmentDirection[0];
        segmentOuterPoint[1] = segmentPosition[1] + segmentLength*segmentDirection[1];
        segmentOuterPoint[2] = segmentLength;

        segmentInnerPoint[0] = segmentPosition[0] - segmentLength*segmentDirection[0];
        segmentInnerPoint[1] = segmentPosition[1] - segmentLength*segmentDirection[1];
        segmentInnerPoint[2] = -segmentLength;
         
        return;
      }
      else
      {
        double mag = sqrt( segmentDirection[0] * segmentDirection[0] + 
                           segmentDirection[1] * segmentDirection[1] +
                           segmentDirection[2] * segmentDirection[2] );
      
        double theta = atan2( sqrt( segmentDirection[0] * segmentDirection[0]
                                  + segmentDirection[1] * segmentDirection[1] ), segmentDirection[2] );

        double newSegmentLength = segmentLength / cos( theta );

        segmentInnerPoint[0] = segmentPosition[0] + ( segmentDirection[0] / mag ) * newSegmentLength;
        segmentInnerPoint[1] = segmentPosition[1] + ( segmentDirection[1] / mag ) * newSegmentLength;
        segmentInnerPoint[2] = segmentPosition[2] + ( segmentDirection[2] / mag ) * newSegmentLength;
        
        segmentOuterPoint[0] = segmentPosition[0] - ( segmentDirection[0] / mag ) * newSegmentLength;
        segmentOuterPoint[1] = segmentPosition[1] - ( segmentDirection[1] / mag ) * newSegmentLength;
        segmentOuterPoint[2] = segmentPosition[2] - ( segmentDirection[2] / mag ) * newSegmentLength;
        
        if( fabs(segmentOuterPoint[0]) > segmentLimit )
        {         
          segmentOuterPoint[0] = segmentLimit * ( segmentOuterPoint[0]/fabs( segmentOuterPoint[0] ));
          segmentOuterPoint[1] = ( segmentOuterPoint[1]/fabs( segmentOuterPoint[1] )) * tan( theta );
        }
        
        return;
      }  
    }
    
    fwLog( fwlog::kWarning ) << "MuonSubdetId: " << detector << std::endl;
    return;
  }
  

}