VectorUtil.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
 
/* ROOT headers. */
#include <Math/Vector3D.h>
#include <TVector3.h>
 
namespace Belle2 {
  static constexpr auto XYZToTVector = [](const ROOT::Math::XYZVector& a)
  {
    return TVector3(a.X(), a.Y(), a.Z());
  };
 
  namespace VectorUtil {
 
    inline void setMagThetaPhi(ROOT::Math::XYZVector& vector,
                               double mag, double theta, double phi)
    {
      const double amag = std::abs(mag);
      const double sinTheta = std::sin(theta);
      const double x = amag * sinTheta * std::cos(phi);
      const double y = amag * sinTheta * std::sin(phi);
      const double z = amag * std::cos(theta);
      vector.SetXYZ(x, y, z);
    }
 
    inline void setMag(ROOT::Math::XYZVector& vector, double mag)
    {
      setMagThetaPhi(vector, mag, vector.Theta(), vector.Phi());
    }
 
    inline void setTheta(ROOT::Math::XYZVector& vector, double theta)
    {
      setMagThetaPhi(vector, vector.R(), theta, vector.Phi());
    }
 
    inline void setPhi(ROOT::Math::XYZVector& vector, double phi)
    {
      setMagThetaPhi(vector, vector.R(), vector.Theta(), phi);
    }
 
    inline void setPtThetaPhi(ROOT::Math::XYZVector& vector,
                              double pt, double theta, double phi)
    {
      const double aPt = std::abs(pt);
      const double x = aPt * std::cos(phi);
      const double y = aPt * std::sin(phi);
      const double tanTheta = std::tan(theta);
      const double z = tanTheta ? aPt / tanTheta : 0;
      vector.SetXYZ(x, y, z);
    }
 
  }
 
}