ProjectileDirectionRotator.hh

//
// This file is part of MARLEY (Model of Argon Reaction Low Energy Yields)
//
// MARLEY is free software: you can redistribute it and/or modify it under the
// terms of version 3 of the GNU General Public License as published by the
// Free Software Foundation.
//
// For the full text of the license please see COPYING or
// visit http://opensource.org/licenses/GPL-3.0
//
// Please respect the MCnet academic usage guidelines. See GUIDELINES
// or visit https://www.montecarlonet.org/GUIDELINES for details.
 
#pragma once
 
// MARLEY includes
#include "marley/EventProcessor.hh"
#include "marley/RotationMatrix.hh"
 
namespace marley {

  class ProjectileDirectionRotator : public EventProcessor {
 
    using ThreeVector = std::array<double, 3>;
 
    public:

      ProjectileDirectionRotator( const ThreeVector& dir = {0., 0., 1.} );
 
      inline virtual ~ProjectileDirectionRotator() = default;

      virtual void process_event( HepMC3::GenEvent& ev,
        marley::Generator& gen ) override;
 
      inline const ThreeVector& projectile_direction() const
        { return dir_vec_; }
 
      inline void set_projectile_direction( const ThreeVector& dir ) {
        dir_vec_ = marley::RotationMatrix::normalize( dir );
        last_pdir_ = dir_vec_;
      }
 
      ThreeVector sample_isotropic_direction( marley::Generator& gen ) const;
 
      void set_randomize_directions( bool do_sampling );
 
    protected:

      ThreeVector dir_vec_ = {{ 0., 0., 1. }};

      ThreeVector last_pdir_ = {{ 0., 0., 1. }};

      marley::RotationMatrix rot_matrix_;

      void rotate_event( HepMC3::GenEvent& ev );

      bool randomize_projectile_direction_ = false;
  };
 
}