SpatialHashGrid.h

#ifndef BOIDS_SPATIALHASHGRID_H
#define BOIDS_SPATIALHASHGRID_H

#include<unordered_set>

#include <SFML/System.hpp>

#include "Boid.h"

class SpatialHashGrid {
private:
    int m_cellSize;
    sf::Vector2u m_gridDimensions; // dim of the grid cells (e.g. 3 by 2)
    sf::Vector2u m_windowDimensions; // dim of the screen that grid covers (window in our case)
    std::map<int, std::unordered_set<std::shared_ptr<Boid>>> m_grid;

    // numOffsetsWithinDist[i] contains no. of cells in the grid which are within squared distance <i> from center of grid (cumulative sum)
    int* m_nOffsetsWithinSqDist; // maxSquaredDist + 1 in size
    int* m_globalOffset; // numCells in size

    int createKey(int x, int y);
    sf::Vector2i getIndices(sf::Vector2f p);

public:
    SpatialHashGrid() = default;
    SpatialHashGrid(const sf::Vector2u& winDim, int cellSize);
    ~SpatialHashGrid();

    SpatialHashGrid(SpatialHashGrid&& other) noexcept;
    SpatialHashGrid& operator=(SpatialHashGrid&& other) noexcept;

    void addBoid(std::shared_ptr<Boid> boid);
    void removeBoid(std::shared_ptr<Boid> boid);
    void updateBoid(std::shared_ptr<Boid> boid);
    void clear();
    std::vector<std::shared_ptr<Boid>> radiusSearch(std::shared_ptr<Boid> query, int radius);
};

#endif //BOIDS_SPATIALHASHGRID_H