/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

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  following disclaimer.

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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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*/

/** Small helper classes to optimize finding vertices close to a given location
 */
#pragma once
#ifndef AI_D3DSSPATIALSORT_H_INC
#define AI_D3DSSPATIALSORT_H_INC

#ifdef __GNUC__
#   pragma GCC system_header
#endif

#include <assimp/types.h>
#include <vector>
#include <stdint.h>

namespace Assimp    {

// ----------------------------------------------------------------------------------
/** Specialized version of SpatialSort to support smoothing groups
 *  This is used in by the 3DS, ASE and LWO loaders. 3DS and ASE share their
 *  normal computation code in SmoothingGroups.inl, the LWO loader has its own
 *  implementation to handle all details of its file format correctly.
 */
// ----------------------------------------------------------------------------------
class ASSIMP_API SGSpatialSort {
public:
    SGSpatialSort();

    // -------------------------------------------------------------------
    /** Construction from a given face array, handling smoothing groups
     *  properly
     */
    explicit SGSpatialSort(const std::vector<aiVector3D>& vPositions);

    // -------------------------------------------------------------------
    /** Add a vertex to the spatial sort
     * @param vPosition Vertex position to be added
     * @param index Index of the vrtex
     * @param smoothingGroup SmoothingGroup for this vertex
     */
    void Add(const aiVector3D& vPosition, unsigned int index,
        unsigned int smoothingGroup);

    // -------------------------------------------------------------------
    /** Prepare the spatial sorter for use. This step runs in O(logn)
     */
    void Prepare();

    /** Destructor */
    ~SGSpatialSort() = default;

    // -------------------------------------------------------------------
    /** Returns an iterator for all positions close to the given position.
     * @param pPosition The position to look for vertices.
     * @param pSG Only included vertices with at least one shared smooth group
     * @param pRadius Maximal distance from the position a vertex may have
     *   to be counted in.
     * @param poResults The container to store the indices of the found
     *   positions. Will be emptied by the call so it may contain anything.
     * @param exactMatch Specifies whether smoothing groups are bit masks
     *   (false) or integral values (true). In the latter case, a vertex
     *   cannot belong to more than one smoothing group.
     * @return An iterator to iterate over all vertices in the given area.
     */
    // -------------------------------------------------------------------
    void FindPositions( const aiVector3D& pPosition, uint32_t pSG,
        float pRadius, std::vector<unsigned int>& poResults,
        bool exactMatch = false) const;

protected:
    /** Normal of the sorting plane, normalized. The center is always at (0, 0, 0) */
    aiVector3D mPlaneNormal;

    // -------------------------------------------------------------------
    /** An entry in a spatially sorted position array. Consists of a
     *  vertex index, its position and its pre-calculated distance from
     *  the reference plane */
    // -------------------------------------------------------------------
    struct Entry {
        unsigned int mIndex;    ///< The vertex referred by this entry
        aiVector3D mPosition;   ///< Position
        uint32_t mSmoothGroups;
        float mDistance;        ///< Distance of this vertex to the sorting plane

        Entry() AI_NO_EXCEPT
        : mIndex(0)
        , mPosition()
        , mSmoothGroups(0)
        , mDistance(0.0f) {
            // empty
        }

        Entry( unsigned int pIndex, const aiVector3D& pPosition, float pDistance,uint32_t pSG)
        : mIndex( pIndex)
        , mPosition( pPosition)
        , mSmoothGroups(pSG)
        , mDistance( pDistance) {
            // empty
        }

        bool operator < (const Entry& e) const {
            return mDistance < e.mDistance;
        }
    };

    // all positions, sorted by distance to the sorting plane
    std::vector<Entry> mPositions;
};

} // end of namespace Assimp

#endif // AI_SPATIALSORT_H_INC
