PatchSampler.h

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/****************************************************************************
 *
 * (c) 2009-2024 QGROUNDCONTROL PROJECT <http://www.qgroundcontrol.org>
 *
 * QGroundControl is licensed according to the terms in the file
 * COPYING.md in the root of the source code directory.
 *
 ****************************************************************************/
 
#pragma once
 
#include <QtCore/QList>
#include <QtCore/QVarLengthArray>
 
#include "ElevationTilePyramid.h"
#include "TileMath.h"
 
class PatchSampler
{
public:
    struct EdgeStep
    {
        float step = 0.0f;      
        int row = 0;            
        int col = 0;
        int ownZoom = -1;       
        int boundaryZoom = -1;  
    };
 
    PatchSampler(const ElevationTilePyramid& pyramid, const TileMath::TileKey& key, int gridSize,
                 EdgeStep* edgeStep = nullptr);
 
    QList<float> sample();
 
    static double heightAtUV(const ElevationTilePyramid::Grid& grid, double u, double v);
 
private:
    struct BoundaryVertex
    {
        float height = 0.0f;    
        float mismatch = 0.0f;  
        int zoom = -1;          
    };
 
    float _viewHeight(const ElevationTilePyramid::View& view, qint64 n, qint64 m) const;
    BoundaryVertex _boundaryVertex(qint64 n, qint64 m, float own);
    float _interiorCorrection(int row, int col) const;
    void _trackEdgeStep(const QList<float>& corrections);
    ElevationTilePyramid::View _resolveCell(qint64 cx, qint64 cy);
    int _touchingCells(qint64 s, qint64 (&cells)[2]) const;
 
    struct TileMemo
    {
        TileMath::TileKey tile;
        ElevationTilePyramid::View view;
    };
 
    const ElevationTilePyramid& _pyramid;
    const TileMath::TileKey _key;
    const int _gridSize;
    const int _shiftToMax;
    const ElevationTilePyramid::View _patchView;
    EdgeStep* const _edgeStep;
    QVarLengthArray<TileMemo, 9> _memos;
    QList<BoundaryVertex> _north;  
    QList<BoundaryVertex> _south;
    QList<BoundaryVertex> _west;   
    QList<BoundaryVertex> _east;
};