refactor!: Grid specialization for Cylindrical geometry (#2858)

Follow up from #2854 

In this PR I am defining a grid geometry for a cylindrical experiment with (phi, z) bins. This is done in a specific file that is included in the GridSpacePoint file. Other specializations can then be easily added in the same fashion (e.g. a pre-defined grid for telescope geometry).

Requires: 
- #2838
- #2854
- #2835

Core/include/Acts/Seeding/BinnedGroup.hpp

@@ -9,7 +9,6 @@
 #pragma once
 
 #include "Acts/Seeding/BinnedGroupIterator.hpp"
-#include "Acts/Seeding/SpacePointGrid.hpp"
 #include "Acts/Utilities/GridBinFinder.hpp"
 #include "Acts/Utilities/GridIterator.hpp"
 #include "Acts/Utilities/Holders.hpp"
@@ -94,9 +93,3 @@ class BinnedGroup {
 }  // namespace Acts
 
 #include "Acts/Seeding/BinnedGroup.ipp"
-
-namespace Acts {
-template <typename external_spacepoint_t>
-using BinnedSPGroup =
-    Acts::BinnedGroup<Acts::SpacePointGrid<external_spacepoint_t>>;
-}

Core/include/Acts/Seeding/BinnedGroupIterator.hpp

@@ -8,7 +8,6 @@
 
 #pragma once
 
-#include "Acts/Seeding/SpacePointGrid.hpp"
 #include "Acts/Utilities/GridIterator.hpp"
 #include "Acts/Utilities/Holders.hpp"
 #include "Acts/Utilities/detail/grid_helper.hpp"
@@ -120,9 +119,3 @@ class BinnedGroupIterator {
 }  // namespace Acts
 
 #include "Acts/Seeding/BinnedGroupIterator.ipp"
-
-namespace Acts {
-template <typename external_spacepoint_t>
-using BinnedSPGroupIterator =
-    BinnedGroupIterator<Acts::SpacePointGrid<external_spacepoint_t>>;
-}

Core/include/Acts/Seeding/Neighbour.hpp

@@ -1,14 +1,14 @@
 // This file is part of the Acts project.
 //
-// Copyright (C) 2023 CERN for the benefit of the Acts project
+// Copyright (C) 2024 CERN for the benefit of the Acts project
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 #pragma once
 
-#include "Acts/Seeding/SpacePointGrid.hpp"
+#include "Acts/Utilities/Grid.hpp"
 
 namespace Acts {
 
@@ -27,37 +27,27 @@ namespace Acts {
 /// have a higher radius. That means that there is no point in looking at
 /// neighbour space point before itr, since we know they will be out of range.
 
-template <typename external_spacepoint_t>
+template <typename grid_t>
 struct Neighbour {
   /// @brief default constructor
   Neighbour() = delete;
 
-  /// @brief Constructor with grid as rvalue
-  /// @param grid The grid containing the space points
-  /// @param idx The global index of the bin in the grid
-  /// @param lowerBound The lower bound of the allowed space points
-  Neighbour(Acts::SpacePointGrid<external_spacepoint_t>&& grid, std::size_t idx,
-            const float lowerBound) = delete;
-
   /// @brief Constructor
   /// @param grid The grid containing the space points
   /// @param idx The global index of the bin in the grid
   /// @param lowerBound The lower bound of the allowed space point
-  Neighbour(const Acts::SpacePointGrid<external_spacepoint_t>& grid,
-            std::size_t idx, const float lowerBound);
+  Neighbour(const grid_t& grid, std::size_t idx, const float lowerBound);
 
   /// The global bin index on the grid
   std::size_t index;
   /// The iterator containing the position of the first space point in the valid
   /// radius range
-  typename Acts::SpacePointGrid<
-      external_spacepoint_t>::value_type::const_iterator itr;
+  typename grid_t::value_type::const_iterator itr;
 };
 
-template <typename external_spacepoint_t>
-Neighbour<external_spacepoint_t>::Neighbour(
-    const Acts::SpacePointGrid<external_spacepoint_t>& grid, std::size_t idx,
-    const float lowerBound)
+template <typename grid_t>
+Neighbour<grid_t>::Neighbour(const grid_t& grid, std::size_t idx,
+                             const float lowerBound)
     : index(idx) {
   /// Get the space points in this specific global bin
   const auto& collection = grid.at(idx);

Core/include/Acts/Seeding/SeedFinder.hpp

@@ -1,6 +1,6 @@
 // This file is part of the Acts project.
 //
-// Copyright (C) 2023 CERN for the benefit of the Acts project
+// Copyright (C) 2024 CERN for the benefit of the Acts project
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -19,6 +19,7 @@
 #include "Acts/Seeding/SeedFinderConfig.hpp"
 #include "Acts/Seeding/SeedFinderUtils.hpp"
 #include "Acts/Seeding/SpacePointGrid.hpp"
+#include "Acts/Utilities/detail/grid_helper.hpp"
 
 #include <array>
 #include <limits>
@@ -41,6 +42,7 @@ class SeedFinder {
   ///////////////////////////////////////////////////////////////////
   // Public methods:
   ///////////////////////////////////////////////////////////////////
+  using grid_t = Acts::CylindricalSpacePointGrid<external_spacepoint_t>;
 
  public:
   struct SeedingState {
@@ -63,9 +65,11 @@ class SeedFinder {
         candidates_collector;
 
     // managing doublet candidates
-    boost::container::small_vector<Acts::Neighbour<external_spacepoint_t>, 9>
+    boost::container::small_vector<Acts::Neighbour<grid_t>,
+                                   Acts::detail::ipow(3, grid_t::DIM)>
         bottomNeighbours;
-    boost::container::small_vector<Acts::Neighbour<external_spacepoint_t>, 9>
+    boost::container::small_vector<Acts::Neighbour<grid_t>,
+                                   Acts::detail::ipow(3, grid_t::DIM)>
         topNeighbours;
 
     // Adding space point info
@@ -99,7 +103,7 @@ class SeedFinder {
   template <template <typename...> typename container_t, typename sp_range_t>
   void createSeedsForGroup(
       const Acts::SeedFinderOptions& options, SeedingState& state,
-      const Acts::SpacePointGrid<external_spacepoint_t>& grid,
+      const grid_t& grid,
       std::back_insert_iterator<container_t<Seed<external_spacepoint_t>>> outIt,
       const sp_range_t& bottomSPs, const std::size_t middleSPs,
       const sp_range_t& topSPs,
@@ -126,8 +130,7 @@ class SeedFinder {
   /// @returns a vector of seeds.
   template <typename sp_range_t>
   std::vector<Seed<external_spacepoint_t>> createSeedsForGroup(
-      const Acts::SeedFinderOptions& options,
-      const Acts::SpacePointGrid<external_spacepoint_t>& grid,
+      const Acts::SeedFinderOptions& options, const grid_t& grid,
       const sp_range_t& bottomSPs, const std::size_t middleSPs,
       const sp_range_t& topSPs) const;
 
@@ -150,9 +153,9 @@ class SeedFinder {
   template <Acts::SpacePointCandidateType candidateType, typename out_range_t>
   void getCompatibleDoublets(
       Acts::SpacePointData& spacePointData,
-      const Acts::SeedFinderOptions& options,
-      const Acts::SpacePointGrid<external_spacepoint_t>& grid,
-      boost::container::small_vector<Neighbour<external_spacepoint_t>, 9>&
+      const Acts::SeedFinderOptions& options, const grid_t& grid,
+      boost::container::small_vector<Acts::Neighbour<grid_t>,
+                                     Acts::detail::ipow(3, grid_t::DIM)>&
           otherSPsNeighbours,
       const InternalSpacePoint<external_spacepoint_t>& mediumSP,
       std::vector<LinCircle>& linCircleVec, out_range_t& outVec,

Core/include/Acts/Seeding/SeedFinder.ipp

@@ -1,6 +1,6 @@
 // This file is part of the Acts project.
 //
-// Copyright (C) 2023 CERN for the benefit of the Acts project
+// Copyright (C) 2024 CERN for the benefit of the Acts project
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -39,7 +39,7 @@ template <typename external_spacepoint_t, typename platform_t>
 template <template <typename...> typename container_t, typename sp_range_t>
 void SeedFinder<external_spacepoint_t, platform_t>::createSeedsForGroup(
     const Acts::SeedFinderOptions& options, SeedingState& state,
-    const Acts::SpacePointGrid<external_spacepoint_t>& grid,
+    const grid_t& grid,
     std::back_insert_iterator<container_t<Seed<external_spacepoint_t>>> outIt,
     const sp_range_t& bottomSPsIdx, const std::size_t middleSPsIdx,
     const sp_range_t& topSPsIdx,
@@ -197,10 +197,11 @@ template <Acts::SpacePointCandidateType candidateType, typename out_range_t>
 inline void
 SeedFinder<external_spacepoint_t, platform_t>::getCompatibleDoublets(
     Acts::SpacePointData& spacePointData,
-    const Acts::SeedFinderOptions& options,
-    const Acts::SpacePointGrid<external_spacepoint_t>& grid,
-    boost::container::small_vector<Neighbour<external_spacepoint_t>, 9>&
-        otherSPsNeighbours,
+    const Acts::SeedFinderOptions& options, const grid_t& grid,
+    boost::container::small_vector<
+        Acts::Neighbour<
+            typename SeedFinder<external_spacepoint_t, platform_t>::grid_t>,
+        Acts::detail::ipow(3, grid_t::DIM)>& otherSPsNeighbours,
     const InternalSpacePoint<external_spacepoint_t>& mediumSP,
     std::vector<LinCircle>& linCircleVec, out_range_t& outVec,
     const float deltaRMinSP, const float deltaRMaxSP, const float uIP,
@@ -820,8 +821,7 @@ template <typename external_spacepoint_t, typename platform_t>
 template <typename sp_range_t>
 std::vector<Seed<external_spacepoint_t>>
 SeedFinder<external_spacepoint_t, platform_t>::createSeedsForGroup(
-    const Acts::SeedFinderOptions& options,
-    const Acts::SpacePointGrid<external_spacepoint_t>& grid,
+    const Acts::SeedFinderOptions& options, const grid_t& grid,
     const sp_range_t& bottomSPs, const std::size_t middleSPs,
     const sp_range_t& topSPs) const {
   SeedingState state;

Core/include/Acts/Seeding/SpacePointGrid.hpp

@@ -8,113 +8,7 @@
 
 #pragma once
 
-#include "Acts/Definitions/Units.hpp"
-#include "Acts/Geometry/Extent.hpp"
-#include "Acts/Seeding/InternalSpacePoint.hpp"
-#include "Acts/Seeding/SeedFinderConfig.hpp"
-#include "Acts/Utilities/Grid.hpp"
-#include "Acts/Utilities/detail/Axis.hpp"
+// Define specialization for Cylindrical detector geometry
+#include "Acts/Seeding/detail/CylindricalSpacePointGrid.hpp"
 
-#include <memory>
-
-#include <boost/container/flat_set.hpp>
-
-namespace Acts {
-
-struct SpacePointGridConfig {
-  // minimum pT to be found by seedFinder
-  float minPt = 0;
-  // maximum extension of sensitive detector layer relevant for seeding as
-  // distance from x=y=0 (i.e. in r)
-  float rMax = 0;
-  // maximum extension of sensitive detector layer relevant for seeding in
-  // positive direction in z
-  float zMax = 0;
-  // maximum extension of sensitive detector layer relevant for seeding in
-  // negative direction in z
-  float zMin = 0;
-  // maximum distance in r from middle space point to bottom or top spacepoint
-  float deltaRMax = 0;
-  // maximum forward direction expressed as cot(theta)
-  float cotThetaMax = 0;
-  // maximum impact parameter in mm
-  float impactMax = 0;
-  // minimum phi value for phiAxis construction
-  float phiMin = -M_PI;
-  // maximum phi value for phiAxis construction
-  float phiMax = M_PI;
-  // Multiplicator for the number of phi-bins. The minimum number of phi-bins
-  // depends on min_pt, magnetic field: 2*M_PI/(minPT particle phi-deflection).
-  // phiBinDeflectionCoverage is a multiplier for this number. If
-  // numPhiNeighbors (in the configuration of the BinFinders) is configured to
-  // return 1 neighbor on either side of the current phi-bin (and you want to
-  // cover the full phi-range of minPT), leave this at 1.
-  int phiBinDeflectionCoverage = 1;
-  // maximum number of phi bins
-  int maxPhiBins = 10000;
-  // enable non equidistant binning in z
-  std::vector<float> zBinEdges;
-  bool isInInternalUnits = false;
-  SpacePointGridConfig toInternalUnits() const {
-    if (isInInternalUnits) {
-      throw std::runtime_error(
-          "Repeated conversion to internal units for SpacePointGridConfig");
-    }
-    using namespace Acts::UnitLiterals;
-    SpacePointGridConfig config = *this;
-    config.isInInternalUnits = true;
-    config.minPt /= 1_MeV;
-    config.rMax /= 1_mm;
-    config.zMax /= 1_mm;
-    config.zMin /= 1_mm;
-    config.deltaRMax /= 1_mm;
-
-    return config;
-  }
-};
-
-struct SpacePointGridOptions {
-  // magnetic field
-  float bFieldInZ = 0;
-  bool isInInternalUnits = false;
-  SpacePointGridOptions toInternalUnits() const {
-    if (isInInternalUnits) {
-      throw std::runtime_error(
-          "Repeated conversion to internal units for SpacePointGridOptions");
-    }
-    using namespace Acts::UnitLiterals;
-    SpacePointGridOptions options = *this;
-    options.isInInternalUnits = true;
-    options.bFieldInZ /= 1000_T;
-
-    return options;
-  }
-};
-
-template <typename external_spacepoint_t>
-using SpacePointGrid = Grid<
-    std::vector<
-        std::unique_ptr<Acts::InternalSpacePoint<external_spacepoint_t>>>,
-    detail::Axis<detail::AxisType::Equidistant,
-                 detail::AxisBoundaryType::Closed>,
-    detail::Axis<detail::AxisType::Variable, detail::AxisBoundaryType::Bound>>;
-
-class SpacePointGridCreator {
- public:
-  template <typename external_spacepoint_t>
-  static Acts::SpacePointGrid<external_spacepoint_t> createGrid(
-      const Acts::SpacePointGridConfig& _config,
-      const Acts::SpacePointGridOptions& _options);
-
-  template <typename external_spacepoint_t,
-            typename external_spacepoint_iterator_t, typename callable_t>
-  static void fillGrid(
-      const Acts::SeedFinderConfig<external_spacepoint_t>& config,
-      const Acts::SeedFinderOptions& options,
-      Acts::SpacePointGrid<external_spacepoint_t>& grid,
-      external_spacepoint_iterator_t spBegin,
-      external_spacepoint_iterator_t spEnd, callable_t&& toGlobal,
-      Acts::Extent& rRangeSPExtent);
-};
-}  // namespace Acts
-#include "Acts/Seeding/SpacePointGrid.ipp"
+// Define specialization for other detector geometries