imstkGridBasedNeighborSearch.h

/*
** This file is part of the Interactive Medical Simulation Toolkit (iMSTK)
** iMSTK is distributed under the Apache License, Version 2.0.
** See accompanying NOTICE for details.
*/

#pragma once

#include "imstkSpinLock.h"
#include "imstkUniformSpatialGrid.h"
#include "imstkVecDataArray.h"

namespace imstk
{
class GridBasedNeighborSearch
{
public:
    GridBasedNeighborSearch() = default;

    GridBasedNeighborSearch(const double radius) : m_SearchRadius(radius), m_SearchRadiusSqr(radius * radius) {}

    void setSearchRadius(const double radius);

    double getSearchRadius() const { return m_SearchRadius; }

    std::vector<std::vector<size_t>> getNeighbors(const VecDataArray<double, 3>& points);

    void getNeighbors(std::vector<std::vector<size_t>>& result, const VecDataArray<double, 3>& points);

    void getNeighbors(std::vector<std::vector<size_t>>& result, const VecDataArray<double, 3>& setA, const VecDataArray<double, 3>& setB);

private:
    double m_SearchRadius    = 0.0;
    double m_SearchRadiusSqr = 0.0;

    // Data store in each grid cell
    // This entire struct can be replaced by tbb::concurrent_vector<size_t>, however, with lower performance
    struct CellData
    {
        std::vector<size_t> particleIndices; // Store list of particles
        ParallelUtils::SpinLock lock;        // An atomic lock for thread-safe writing
    };
    UniformSpatialGrid<CellData> m_Grid;
};
} // namespace imstk