orange/g4org/Scaler.hh

0001 //----------------------------------*-C++-*----------------------------------//
0002 // Copyright 2023-2024 UT-Battelle, LLC, and other Celeritas developers.
0003 // See the top-level COPYRIGHT file for details.
0004 // SPDX-License-Identifier: (Apache-2.0 OR MIT)
0005 //---------------------------------------------------------------------------//
0006 //! \file orange/g4org/Scaler.hh
0007 //---------------------------------------------------------------------------//
0008 #pragma once
0009
0010 #include <utility>
0011 #include <G4ThreeVector.hh>
0012 #include <G4TwoVector.hh>
0013
0014 #include "corecel/Assert.hh"
0015 #include "corecel/cont/Array.hh"
0016 #include "geocel/detail/LengthUnits.hh"
0017
0018 namespace celeritas
0019 {
0020 namespace g4org
0021 {
0022 //---------------------------------------------------------------------------//
0023 /*!
0024  * Convert a unit from Geant4 scale to another.
0025  *
0026  * The input is the length scale of the original input in the new units.
0027  */
0028 class Scaler
0029 {
0030   public:
0031     //! Default scale to CLHEP units (mm)
0032     Scaler() : scale_{celeritas::lengthunits::millimeter} {}
0033
0034     //! Scale with an explicit factor, probably for testing
0035     explicit Scaler(double sc) : scale_{sc} { CELER_EXPECT(scale_ > 0); }
0036
0037     //! Multiply a value by the scale
0038     double operator()(double val) const { return val * scale_; }
0039
0040     //! Convert and scale a 2D point
0041     Array<double, 2> operator()(G4TwoVector const& vec) const
0042     {
0043         return this->to<Array<double, 2>>(vec.x(), vec.y());
0044     }
0045
0046     //! Convert and scale a 3D point
0047     Array<double, 3> operator()(G4ThreeVector const& vec) const
0048     {
0049         return this->to<Array<double, 3>>(vec.x(), vec.y(), vec.z());
0050     }
0051
0052     //! Create an array or other object by scaling each argument
0053     template<class S, class... Ts>
0054     S to(Ts&&... args) const
0055     {
0056         return S{(*this)(std::forward<Ts>(args))...};
0057     }
0058
0059   private:
0060     double scale_;
0061 };
0062
0063 //---------------------------------------------------------------------------//
0064 }  // namespace g4org
0065 }  // namespace celeritas