surf/detail/InvolutePoint.hh

0001 //----------------------------------*-C++-*----------------------------------//
0002 // Copyright 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/surf/detail/InvolutePoint.hh
0007 //---------------------------------------------------------------------------//
0008 #pragma once
0009
0010 #include <cmath>
0011
0012 #include "corecel/Types.hh"
0013 #include "corecel/cont/Array.hh"
0014 #include "orange/OrangeTypes.hh"
0015
0016 namespace celeritas
0017 {
0018 namespace detail
0019 {
0020 //---------------------------------------------------------------------------//
0021 /*!
0022  * Find point on involute using involute equation.
0023  *
0024  *  * \f[
0025  *   x = r_b (\cos(t+a) + t \sin(t+a))
0026  * \f]
0027  * \f[
0028  *   y = r_b (\sin(t+a) - t \cos(t+a))
0029  * \f]
0030  *
0031  */
0032 class InvolutePoint
0033 {
0034   public:
0035     //!@{
0036     //! \name Type alias
0037     using Real2 = Array<real_type, 2>;
0038
0039   public:
0040     // Construct involute from parameters
0041     inline CELER_FUNCTION InvolutePoint(real_type r_b, real_type a);
0042
0043     // Calculate point on an involute
0044     inline CELER_FUNCTION Real2 operator()(real_type theta) const;
0045
0046     //// ACCESSORS ////
0047
0048     //! Get involute parameters
0049     CELER_FUNCTION real_type r_b() const { return r_b_; }
0050     CELER_FUNCTION real_type a() const { return a_; }
0051
0052   private:
0053     //// DATA ////
0054     // Involute parameters
0055     real_type r_b_;
0056     real_type a_;
0057 };
0058
0059 //---------------------------------------------------------------------------//
0060 // INLINE DEFINITIONS
0061 //---------------------------------------------------------------------------//
0062 /*!
0063  * Construct from involute parameters.
0064  */
0065 CELER_FUNCTION InvolutePoint::InvolutePoint(real_type r_b, real_type a)
0066     : r_b_(r_b), a_(a)
0067 {
0068     CELER_EXPECT(r_b > 0);
0069     CELER_EXPECT(a >= 0);
0070 }
0071
0072 /*!
0073  * Calculate the point on an involute.
0074  */
0075 CELER_FUNCTION Real2 InvolutePoint::operator()(real_type theta) const
0076 {
0077     real_type angle = theta + a_;
0078     Real2 point;
0079     // TODO: check that compiler avoids recomputing trig functions
0080     point[0] = r_b_ * (std::cos(angle) + theta * std::sin(angle));
0081     point[1] = r_b_ * (std::sin(angle) - theta * std::cos(angle));
0082
0083     return point;
0084 }
0085 //---------------------------------------------------------------------------//
0086 }  // namespace detail
0087 }  // namespace celeritas