HexSphereTopology.h

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#pragma once
#include "common/Export.h"
 
 
#include "common/Result.h"
#include "hexmap/HexMetrics.h"
 
#include <cstdint>
#include <vector>
 
namespace eve::hexmap {
 
using HexSphereCell = std::int32_t;
 
inline constexpr HexSphereCell kNoHexSphereCell = -1;
 
inline constexpr std::int32_t kMaxHexSphereSubdivision = 7;
 
class EVENGINE_API_WORLD HexSphereTopology {
public:
    HexSphereTopology() = default;
 
    [[nodiscard]] static Result<HexSphereTopology> build(std::int32_t subdivision);
 
    [[nodiscard]] bool empty() const noexcept { return directions_.empty(); }
    [[nodiscard]] std::int32_t subdivision() const noexcept { return subdivision_; }
    [[nodiscard]] std::int32_t frequency() const noexcept { return frequency_; }
    [[nodiscard]] std::int32_t cellCount() const noexcept { return static_cast<std::int32_t>(directions_.size()); }
    [[nodiscard]] std::int32_t pentagonCount() const noexcept { return empty() ? 0 : 12; }
    [[nodiscard]] std::int32_t edgeCount() const noexcept { return static_cast<std::int32_t>(neighbors_.size() / 2u); }
    [[nodiscard]] std::int32_t cornerCount() const noexcept {
        return static_cast<std::int32_t>(cornerDirections_.size());
    }
 
    [[nodiscard]] bool contains(HexSphereCell cell) const noexcept { return cell >= 0 && cell < cellCount(); }
    [[nodiscard]] bool isPentagon(HexSphereCell cell) const noexcept {
        return contains(cell) && neighborCount(cell) == 5;
    }
    [[nodiscard]] std::int32_t neighborCount(HexSphereCell cell) const noexcept;
    [[nodiscard]] HexSphereCell neighbor(HexSphereCell cell, std::int32_t direction) const noexcept;
    [[nodiscard]] std::int32_t directionOf(HexSphereCell cell, HexSphereCell other) const noexcept;
    [[nodiscard]] std::int32_t oppositeDirection(HexSphereCell cell, std::int32_t direction) const noexcept;
 
    [[nodiscard]] HexVec3 direction(HexSphereCell cell) const noexcept;
    [[nodiscard]] std::int32_t cornerCountOf(HexSphereCell cell) const noexcept;
    [[nodiscard]] HexVec3 corner(HexSphereCell cell, std::int32_t corner) const noexcept;
 
    [[nodiscard]] HexSphereCell cellAt(HexVec3 unitDirection) const noexcept;
    [[nodiscard]] static float angularDistance(HexVec3 a, HexVec3 b) noexcept;
 
private:
    std::vector<HexVec3>       directions_;        
    std::vector<std::int32_t>  cellOffsets_;       
    std::vector<HexSphereCell> neighbors_;         
    std::vector<std::int32_t>  corners_;           
    std::vector<HexVec3>       cornerDirections_;  
    std::int32_t               subdivision_ = 0;
    std::int32_t               frequency_   = 1;
};
 
}  // namespace eve::hexmap