Program Listing for File HashedVoxelPointCloud.h

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/*               _
 _ __ ___   ___ | | __ _
| '_ ` _ \ / _ \| |/ _` | Modular Optimization framework for
| | | | | | (_) | | (_| | Localization and mApping (MOLA)
|_| |_| |_|\___/|_|\__,_| https://github.com/MOLAorg/mola

 Copyright (C) 2018-2026 Jose Luis Blanco, University of Almeria,
                         and individual contributors.
 SPDX-License-Identifier: GPL-3.0
 See LICENSE for full license information.
*/

#pragma once

#include <mola_metric_maps/index3d_t.h>
#include <mrpt/core/round.h>
#include <mrpt/img/TColor.h>
#include <mrpt/img/color_maps.h>
#include <mrpt/maps/CMetricMap.h>
#include <mrpt/maps/CSimplePointsMap.h>
#include <mrpt/maps/NearestNeighborsCapable.h>
#include <mrpt/math/TBoundingBox.h>
#include <mrpt/math/TPoint3D.h>
#include <tsl/robin_map.h>

#include <array>
#include <functional>
#include <optional>

// #define HASHED_VOXEL_POINT_CLOUD_WITH_CACHED_ACCESS

namespace mola
{
class HashedVoxelPointCloud : public mrpt::maps::CMetricMap,
                              public mrpt::maps::NearestNeighborsCapable
{
  DEFINE_SERIALIZABLE(HashedVoxelPointCloud, mola)
 public:
  // Prevent copying and moving
  HashedVoxelPointCloud(const HashedVoxelPointCloud&)            = default;
  HashedVoxelPointCloud& operator=(const HashedVoxelPointCloud&) = default;
  HashedVoxelPointCloud(HashedVoxelPointCloud&&)                 = default;
  HashedVoxelPointCloud& operator=(HashedVoxelPointCloud&&)      = default;

  constexpr static std::size_t SSO_MAX_POINTS_PER_VOXEL    = 32;
  constexpr static std::size_t GLOBAL_ID_SUBVOXEL_BITCOUNT = 5;
  static_assert(SSO_MAX_POINTS_PER_VOXEL <= (1 << GLOBAL_ID_SUBVOXEL_BITCOUNT));

  using global_index3d_t = index3d_t<int32_t>;

  using global_plain_index_t = uint64_t;

  inline global_index3d_t coordToGlobalIdx(const mrpt::math::TPoint3Df& pt) const
  {
    return global_index3d_t(
        static_cast<int32_t>(pt.x * voxel_size_inv_),  //
        static_cast<int32_t>(pt.y * voxel_size_inv_),  //
        static_cast<int32_t>(pt.z * voxel_size_inv_));
  }

  inline mrpt::math::TPoint3Df globalIdxToCoord(const global_index3d_t idx) const
  {
    return {
        idx.cx * voxel_size_,  //
        idx.cy * voxel_size_,  //
        idx.cz * voxel_size_};
  }

  static inline global_plain_index_t g2plain(const global_index3d_t& g, int subVoxelIndex = 0)
  {
    constexpr uint64_t SUBVOXEL_MASK = ((1 << GLOBAL_ID_SUBVOXEL_BITCOUNT) - 1);
    constexpr auto     OFF           = GLOBAL_ID_SUBVOXEL_BITCOUNT;
    constexpr int      FBITS         = 20;  // (64 - OFF)/3, rounded if needed
    constexpr uint64_t FMASK         = (1 << FBITS) - 1;

    return (static_cast<uint64_t>(subVoxelIndex) & SUBVOXEL_MASK) |
           (static_cast<uint64_t>(g.cx & FMASK) << (OFF + FBITS * 0)) |
           (static_cast<uint64_t>(g.cy & FMASK) << (OFF + FBITS * 1)) |
           (static_cast<uint64_t>(g.cz & FMASK) << (OFF + FBITS * 2));
  }

  HashedVoxelPointCloud(float voxel_size = 1.00f);

  ~HashedVoxelPointCloud();

  void setVoxelProperties(float voxel_size);

#if 0
    using point_vector_t =
        mrpt::containers::vector_with_small_size_optimization<
            mrpt::math::TPoint3Df, SSO_MAX_POINTS_PER_VOXEL>;
#endif

  using point_vector_t = std::array<mrpt::math::TPoint3Df, SSO_MAX_POINTS_PER_VOXEL>;

  struct VoxelData
  {
   public:
    VoxelData() = default;

    struct PointSpan
    {
      PointSpan(const point_vector_t& points, uint32_t n) : points_(points), n_(n) {}

      size_t size() const { return n_; }
      bool   empty() const { return n_ == 0; }

      const mrpt::math::TPoint3Df& operator[](int i) const { return points_[i]; }

     private:
      const point_vector_t& points_;
      const uint32_t        n_;
    };

    auto points() const -> PointSpan { return PointSpan(points_, nPoints_); }

    void insertPoint(const mrpt::math::TPoint3Df& p)
    {
      if (nPoints_ < SSO_MAX_POINTS_PER_VOXEL) points_[nPoints_++] = p;
    }

    // for serialization, do not use in normal use:
    size_t size() const { return nPoints_; }

   private:
    point_vector_t points_;
    uint32_t       nPoints_ = 0;
  };

  using grids_map_t = tsl::robin_map<global_index3d_t, VoxelData, index3d_hash<int32_t>>;

  // clear(): available in base class

  inline VoxelData* voxelByGlobalIdxs(const global_index3d_t& idx, bool createIfNew)
  {
    // 1) Insert into decimation voxel map:
    VoxelData* voxel = nullptr;

#if defined(HASHED_VOXEL_POINT_CLOUD_WITH_CACHED_ACCESS)
    for (int i = 0; i < CachedData::NUM_CACHED_IDXS; i++)
    {
      if (cached_.lastAccessVoxel[i] && cached_.lastAccessIdx[i] == idx)
      {
        // Cache hit:
#ifdef USE_DEBUG_PROFILER
        mrpt::system::CTimeLoggerEntry tle(profiler, "insertPoint.cache_hit");
#endif
        voxel = cached_.lastAccessVoxel[i];
        break;
      }
    }

    if (!voxel)
    {
#endif
#ifdef USE_DEBUG_PROFILER
      mrpt::system::CTimeLoggerEntry tle(profiler, "insertPoint.cache_misss");
#endif

      auto it = voxels_.find(idx);
      if (it == voxels_.end())
      {
        if (!createIfNew)
          return nullptr;
        else
          voxel = &voxels_[idx];  // Create it
      }
      else
      {
        // Use the found grid
        voxel = &it.value();
      }
#if defined(HASHED_VOXEL_POINT_CLOUD_WITH_CACHED_ACCESS)
      // Add to cache:
      cached_.lastAccessIdx[cached_.lastAccessNextWrite]   = idx;
      cached_.lastAccessVoxel[cached_.lastAccessNextWrite] = voxel;
      cached_.lastAccessNextWrite++;
      cached_.lastAccessNextWrite &= CachedData::NUM_CACHED_IDX_MASK;
    }
#endif
    return voxel;
  }

  const VoxelData* voxelByGlobalIdxs(const global_index3d_t& idx  //
                                     /*, bool createIfNew this must be false for const! */) const
  {  // reuse the non-const method:
    return const_cast<HashedVoxelPointCloud*>(this)->voxelByGlobalIdxs(idx, false);
  }

  VoxelData* voxelByCoords(const mrpt::math::TPoint3Df& pt, bool createIfNew)
  {
    return voxelByGlobalIdxs(coordToGlobalIdx(pt), createIfNew);
  }

  const VoxelData* voxelByCoords(const mrpt::math::TPoint3Df& pt) const
  {
    return const_cast<HashedVoxelPointCloud*>(this)->voxelByCoords(pt, false);
  }

  void insertPoint(const mrpt::math::TPoint3Df& pt);

  const grids_map_t& voxels() const { return voxels_; }

  mrpt::math::TBoundingBoxf boundingBox() const override;

  void visitAllPoints(const std::function<void(const mrpt::math::TPoint3Df&)>& f) const;

  void visitAllVoxels(
      const std::function<void(const global_index3d_t&, const VoxelData&)>& f) const;

  bool saveToTextFile(const std::string& file) const;

  [[nodiscard]] bool   nn_has_indices_or_ids() const override;
  [[nodiscard]] size_t nn_index_count() const override;
  [[nodiscard]] bool   nn_single_search(
        const mrpt::math::TPoint3Df& query, mrpt::math::TPoint3Df& result, float& out_dist_sqr,
        uint64_t& resultIndexOrID) const override;
  [[nodiscard]] bool nn_single_search(
      const mrpt::math::TPoint2Df& query, mrpt::math::TPoint2Df& result, float& out_dist_sqr,
      uint64_t& resultIndexOrID) const override;
  void nn_multiple_search(
      const mrpt::math::TPoint3Df& query, const size_t N,
      std::vector<mrpt::math::TPoint3Df>& results, std::vector<float>& out_dists_sqr,
      std::vector<uint64_t>& resultIndicesOrIDs) const override;
  void nn_multiple_search(
      const mrpt::math::TPoint2Df& query, const size_t N,
      std::vector<mrpt::math::TPoint2Df>& results, std::vector<float>& out_dists_sqr,
      std::vector<uint64_t>& resultIndicesOrIDs) const override;
  void nn_radius_search(
      const mrpt::math::TPoint3Df& query, const float search_radius_sqr,
      std::vector<mrpt::math::TPoint3Df>& results, std::vector<float>& out_dists_sqr,
      std::vector<uint64_t>& resultIndicesOrIDs, size_t maxPoints) const override;
  void nn_radius_search(
      const mrpt::math::TPoint2Df& query, const float search_radius_sqr,
      std::vector<mrpt::math::TPoint2Df>& results, std::vector<float>& out_dists_sqr,
      std::vector<uint64_t>& resultIndicesOrIDs, size_t maxPoints) const override;

  template <size_t MAX_KNN>
  void nn_multiple_search_impl(
      const mrpt::math::TPoint3Df& query, const size_t N,
      std::vector<mrpt::math::TPoint3Df>& results, std::vector<float>& out_dists_sqr,
      std::vector<uint64_t>& resultIndicesOrIDs) const;

  std::string asString() const override;

  void getVisualizationInto(mrpt::opengl::CSetOfObjects& outObj) const override;

  bool isEmpty() const override;

  void saveMetricMapRepresentationToFile(const std::string& filNamePrefix) const override;

  const mrpt::maps::CSimplePointsMap* getAsSimplePointsMap() const override;

  struct TInsertionOptions : public mrpt::config::CLoadableOptions
  {
    TInsertionOptions() = default;

    void loadFromConfigFile(
        const mrpt::config::CConfigFileBase& source,
        const std::string&                   section) override;  // See base docs
    void dumpToTextStream(std::ostream& out) const override;  // See base docs

    void writeToStream(mrpt::serialization::CArchive& out) const;
    void readFromStream(mrpt::serialization::CArchive& in);

    uint32_t max_points_per_voxel = 0;

    double remove_voxels_farther_than = .0;

    float min_distance_between_points = .0f;
  };
  TInsertionOptions insertionOptions;

  struct TLikelihoodOptions : public mrpt::config::CLoadableOptions
  {
    TLikelihoodOptions() = default;

    void loadFromConfigFile(
        const mrpt::config::CConfigFileBase& source,
        const std::string&                   section) override;  // See base docs
    void dumpToTextStream(std::ostream& out) const override;  // See base docs

    void writeToStream(mrpt::serialization::CArchive& out) const;
    void readFromStream(mrpt::serialization::CArchive& in);

    double sigma_dist = 0.5;

    double max_corr_distance = 1.0;

    uint32_t decimation = 10;
  };
  TLikelihoodOptions likelihoodOptions;

  struct TRenderOptions : public mrpt::config::CLoadableOptions
  {
    void loadFromConfigFile(
        const mrpt::config::CConfigFileBase& source,
        const std::string&                   section) override;  // See base docs
    void dumpToTextStream(std::ostream& out) const override;  // See base docs

    void writeToStream(mrpt::serialization::CArchive& out) const;
    void readFromStream(mrpt::serialization::CArchive& in);

    float point_size = 1.0f;

    mrpt::img::TColorf color{.0f, .0f, 1.0f};

    mrpt::img::TColormap colormap = mrpt::img::cmHOT;

    std::string recolorByPointField = "intensity";
  };
  TRenderOptions renderOptions;

 public:
  // Interface for use within a mrpt::maps::CMultiMetricMap:
  MAP_DEFINITION_START(HashedVoxelPointCloud)
  float voxel_size = 1.00f;

  mola::HashedVoxelPointCloud::TInsertionOptions  insertionOpts;
  mola::HashedVoxelPointCloud::TLikelihoodOptions likelihoodOpts;
  mola::HashedVoxelPointCloud::TRenderOptions     renderOpts;
  MAP_DEFINITION_END(HashedVoxelPointCloud)

 private:
  float voxel_size_ = 1.00f;

  // Calculated from the above, in setVoxelProperties()
  float                 voxel_size_inv_ = 1.0f / voxel_size_;
  float                 voxel_size_sqr_ = voxel_size_ * voxel_size_;
  mrpt::math::TPoint3Df voxelDiagonal_;

  grids_map_t voxels_;

  struct CachedData
  {
    CachedData() = default;

    void reset() { *this = CachedData(); }

    mutable std::optional<mrpt::math::TBoundingBoxf> boundingBox_;

#if defined(HASHED_VOXEL_POINT_CLOUD_WITH_CACHED_ACCESS)
    // 2 bits seems to be the optimum for typical cases:
    constexpr static int CBITS               = 2;
    constexpr static int NUM_CACHED_IDXS     = 1 << CBITS;
    constexpr static int NUM_CACHED_IDX_MASK = NUM_CACHED_IDXS - 1;

    int              lastAccessNextWrite = 0;
    global_index3d_t lastAccessIdx[NUM_CACHED_IDXS];
    VoxelData*       lastAccessVoxel[NUM_CACHED_IDXS] = {nullptr};
#endif
  };

  CachedData cached_;

 protected:
  // See docs in base CMetricMap class:
  void internal_clear() override;

 private:
  // See docs in base CMetricMap class:
  bool internal_insertObservation(
      const mrpt::obs::CObservation&                   obs,
      const std::optional<const mrpt::poses::CPose3D>& robotPose = std::nullopt) override;
  // See docs in base class
  double internal_computeObservationLikelihood(
      const mrpt::obs::CObservation& obs, const mrpt::poses::CPose3D& takenFrom) const override;

  double internal_computeObservationLikelihoodPointCloud3D(
      const mrpt::poses::CPose3D& pc_in_map, const float* xs, const float* ys, const float* zs,
      const std::size_t num_pts) const;

  void internal_insertPointCloud3D(
      const mrpt::poses::CPose3D& pc_in_map, const float* xs, const float* ys, const float* zs,
      const std::size_t num_pts);

  // See docs in base class
  bool internal_canComputeObservationLikelihood(const mrpt::obs::CObservation& obs) const override;

  mutable mrpt::maps::CSimplePointsMap::Ptr cachedPoints_;
};

}  // namespace mola