MpdRoot_KFParticle/physics/femto/MpdFemtoMaker/TpcLocalTransform.cxx

// ROOT headers
#include "TVector3.h"
#include "TMath.h"

//_________________
int TpcLocalTransform(TVector3& aPoint, int& aSector, int& aRow,
		      float& aU, double& aPhi) {

  static const int mNumberOfPadrows = 45;
  static const int mNumberOfPadrowsInner = 13;
  static const int mNumberOfSectors = 24;

  // Number of pad in a row for each padrow
  static int tNPadAtRow[mNumberOfPadrows] = {
    88, 96, 104, 112, 118, 126, 134, 142, 150, 158, 166, 174, 182,
    98, 100, 102, 104, 106, 106, 108, 110, 112, 112, 114, 116, 118, 120, 122, 122,
    124, 126, 128, 128, 130, 132, 134, 136, 138, 138, 140, 142, 144, 144, 144, 144
  };
  // Phi angle of each of 24 sectors
  static double tSectToPhi[mNumberOfSectors] = {
    2., 1., 0., 11., 10., 9., 8., 7., 6., 5., 4., 3.,
    4., 5., 6., 7., 8., 9., 10., 11., 0., 1., 2., 3.
  };

  // Pad size for innner and outer sector
  static double tPadWidthInner = 0.335;
  static double tPadWidthOuter = 0.67;

  static double tPi = TMath::Pi();

  // Find sector number
  aPhi = aPoint.Phi();
  if (aPhi < 0.) {
    aPhi += (2 * tPi);
  }
  aPhi += tPi / 12.;

  if (aPhi > 2 * tPi) {
    aPhi -= 2 * tPi;
  }

  int tiPhi = (int) (aPhi / tPi * 6.);
  if (aPoint.Z() < 0) {
    aSector = (tiPhi < 3) ? 3 - tiPhi : 15 - tiPhi;
  } else {
    aSector = (tiPhi < 4) ? 21 + tiPhi : 9 + tiPhi;
  }
  aPhi = tSectToPhi[aSector - 1] * tPi / 6.;

  //if((fabs(aPhi-aPoint.phi())>(tPi/12)){
  //cout << "Sector missmatch " << aPhi << " " << aPoint.phi() << " "
  // << aSector << endl;
  //}

  // Calculate local coordinate
  float tR = aPoint.X() * TMath::Cos(aPhi) + aPoint.Y() * TMath::Sin(aPhi);
  aU = -aPoint.X() * TMath::Sin(aPhi) + aPoint.Y() * TMath::Cos(aPhi);

  // Find pad row
  if (tR < 57.6) {
    aRow = 0;
    return 1;
  }
  float radmax = 62.4;
  float spacing = 4.8;
  aRow = 1;
  while ((tR > radmax) && (aRow < 46)) {
    aRow++;
    if (aRow == 8) {
      radmax = 96.2;
      spacing = 5.2;
    } else {
      // Row 13 is the last one of the inner sector
      if (aRow == mNumberOfPadrowsInner) {
	radmax = 126.195;
	spacing = 2.0;
      } else {
	radmax += spacing;
      }
    } //else
  } //while ( ( tR > radmax) && ( aRow < 46 ) )
  if (aRow > mNumberOfPadrows) {
    //cout << "No pad row " << tR << endl;
    return 2;
  }

  // Check if u (=aU) inbound
  double tPadWidth = (aRow < 14) ? tPadWidthInner : tPadWidthOuter;
  if (TMath::Abs(aU) > (tNPadAtRow[aRow - 1] * tPadWidth / 2.)) {
    return 3;
  }

  return 0;
}