naturalnbinterpolator.h

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#ifndef OPENSWMMVIS_MESH_NATURALNBINTERPOLATOR_H
#define OPENSWMMVIS_MESH_NATURALNBINTERPOLATOR_H
 
#include <QPair>
#include <QPointF>
#include <QString>
#include <QVector>
 
#include <utility>
#include <vector>
 
namespace mesh {
 
class NaturalNeighbourInterpolator
{
public:
    enum class Variant { Sibson, Laplace };
 
    NaturalNeighbourInterpolator() = default;
 
    void setVariant(Variant v) { m_variant = v; }
    Variant variant() const { return m_variant; }
 
    bool build(const QVector<QPointF> &pts, const QVector<double> &z, QString *err);
 
    bool build(const QVector<QPointF> &pts, QString *err);
 
    bool isValid() const { return m_valid; }
 
    double interpolate(double x, double y) const;
 
    bool weightsAt(double x, double y, QVector<QPair<int, double>> &out) const;
 
    const std::vector<int> &keptSeedIndices() const { return m_seedOf; }
 
private:
    bool computeWeights(double qx, double qy,
                        std::vector<std::pair<int, double>> &out) const;
 
    // Coordinates are normalised to a local [0,~1] space: translated by
    // (-m_ox, -m_oy) (the seed bbox minimum) then divided by m_scale (the
    // larger bbox side).  This keeps orientation / in-circle / circumcenter
    // determinants well-conditioned at projected-CRS magnitudes.  z, and the
    // Sibson (area-ratio) / Laplace (length-ratio) weights, are invariant
    // under this affine map.
    int locate(double qx, double qy) const;   // returns triangle index or -1 (outside hull)
 
    Variant m_variant = Variant::Sibson;
    bool    m_valid   = false;
 
    double  m_ox = 0.0, m_oy = 0.0;            // local-origin translation
    double  m_scale = 1.0;                     // normalisation scale (max bbox side)
 
    std::vector<double> m_px, m_py, m_pz;      // per Delaunay vertex (translated x,y; raw z)
    std::vector<int>    m_seedOf;              // Delaunay vertex -> original input index
    std::vector<int>    m_tris;                // 3 * numTri vertex indices (CCW)
    std::vector<int>    m_nbrs;                // 3 * numTri neighbour tri indices (-1 = hull)
    std::vector<double> m_ccx, m_ccy;          // circumcenter per triangle (NaN if degenerate)
    int                 m_numTri = 0;
 
    mutable int         m_lastTri = 0;         // jump-and-walk start hint
};
 
} // namespace mesh
 
#endif // OPENSWMMVIS_MESH_NATURALNBINTERPOLATOR_H