Acts/MagneticField/MultiRangeBField.hpp

0001 // This file is part of the ACTS project.
0002 //
0003 // Copyright (C) 2016 CERN for the benefit of the ACTS project
0004 //
0005 // This Source Code Form is subject to the terms of the Mozilla Public
0006 // License, v. 2.0. If a copy of the MPL was not distributed with this
0007 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
0008
0009 #pragma once
0010
0011 #include "Acts/Definitions/Algebra.hpp"
0012 #include "Acts/MagneticField/MagneticFieldContext.hpp"
0013 #include "Acts/MagneticField/MagneticFieldProvider.hpp"
0014 #include "Acts/Utilities/RangeXD.hpp"
0015
0016 namespace Acts {
0017
0018 /// @ingroup MagneticField
0019 ///
0020 /// @brief Magnetic field provider modelling a magnetic field consisting of
0021 /// several (potentially overlapping) regions of constant values.
0022 class MultiRangeBField final : public MagneticFieldProvider {
0023  private:
0024   struct Cache {
0025     explicit Cache(const MagneticFieldContext& /*unused*/);
0026
0027     std::optional<std::size_t> index = {};
0028   };
0029
0030   using BFieldRange = std::pair<RangeXD<3, double>, Vector3>;
0031
0032   // The different ranges and their corresponding field vectors. Note that
0033   // regions positioned _later_ in this vector take priority over earlier
0034   // regions.
0035   std::vector<BFieldRange> fieldRanges;
0036
0037  public:
0038   /// @brief Construct a magnetic field from a vector of ranges.
0039   ///
0040   /// @warning These ranges are listed in increasing order of precedence,
0041   /// i.e. ranges further along the vector have higher priority.
0042   explicit MultiRangeBField(const std::vector<BFieldRange>& ranges);
0043
0044   explicit MultiRangeBField(std::vector<BFieldRange>&& ranges);
0045
0046   /// @brief Construct a cache object.
0047   MagneticFieldProvider::Cache makeCache(
0048       const MagneticFieldContext& mctx) const override;
0049
0050   /// @brief Request the value of the magnetic field at a given position.
0051   ///
0052   /// @param [in] position Global 3D position for the lookup.
0053   /// @param [in, out] cache Cache object.
0054   /// @returns A successful value containing a field vector if the given
0055   /// location is contained inside any of the regions, or a failure value
0056   /// otherwise.
0057   Result<Vector3> getField(const Vector3& position,
0058                            MagneticFieldProvider::Cache& cache) const override;
0059 };
0060
0061 }  // namespace Acts