SummedAreaTable

/* -*-c++-*- */
#pragma once

#include "Cubemap"


/**
 * Luminance Summed Area Table
 * https://en.wikipedia.org/wiki/Summed_area_table
 * Aka Integral Image (for order > 1)
 * Accelerate Sum computation
 * Create a luminance summed area table from an image.
 */
class SummedAreaTable
{
protected:

    int _width, _height;

    // perf: could be AOS instead of SAO
    // as usage is AOS (creation is SAO though)
    std::vector<double> _sat;

    std::vector<double> _sat1;
    std::vector<double> _sat2;
    std::vector<double> _sat3;
    std::vector<double> _sat4;
    std::vector<double> _sat5;

    std::vector<double> _r;
    std::vector<double> _g;
    std::vector<double> _b;

    // error reducing values
    double _minLum, _maxLum;
    double _minPonderedLum, _maxPonderedLum;
    double _minR, _maxR;
    double _minG, _maxG;
    double _minB, _maxB;
    double _weightAccum;
    double _sum;

    
public:
    double getMaxLum() const 
    {
        return _maxLum;        
    }
    double getMinLum() const 
    {
        return _minLum;        
    }
    
    double getSum() const 
    {
        return _sum;        
    }

    double getMaxPonderedLum() const 
    {
        return _maxPonderedLum;        
    }
    double getWeightAccumulation() const
    {
        return _weightAccum;
    }    
    double getMaxR() const 
    {
        return _maxR;        
    }
    double getMaxG() const 
    {
        return _maxG;        
    }
    double getMaxB() const 
    {
        return _maxB;        
    }
    
    double I(const int x, const int y) const
    {
        if (x < 0 || y < 0) return 0.0;
        if (x >= _width || y >= _height) return 0.0;
        const uint i = y*_width + x;
        return _sat[i];
    }

    double I1(const int x, const int y) const
    {
        if (x < 0 || y < 0) return 0.0;
        if (x >= _width || y >= _height) return 0.0;
        const uint i = y*_width + x;
        return _sat1[i];
    }

    double I2(const int x, const int y) const
    {
        if (x < 0 || y < 0) return 0.0;
        if (x >= _width || y >= _height) return 0.0;
        const uint i = y*_width + x;
        return _sat2[i];
    }

    double I3(const int x, const int y) const
    {
        if (x < 0 || y < 0) return 0.0;
        if (x >= _width || y >= _height) return 0.0;
        const uint i = y*_width + x;
        return _sat3[i];
    }

    double I4(const int x, const int y) const
    {
        if (x < 0 || y < 0) return 0.0;
        if (x >= _width || y >= _height) return 0.0;
        const uint i = y*_width + x;
        return _sat4[i];
    }
    double I5(const int x, const int y) const
    {
        if (x < 0 || y < 0) return 0.0;
        if (x >= _width || y >= _height) return 0.0;
        const uint i = y*_width + x;
        return _sat5[i];
    }

    double R(const int x, const int y) const
    {
        if (x < 0 || y < 0) return 0.0;
        if (x >= _width || y >= _height) return 0.0;
        const uint i = y*_width + x;
        return _r[i];
    }
    double G(const int x, const int y) const
    {
        if (x < 0 || y < 0) return 0.0;
        if (x >= _width || y >= _height) return 0.0;
        const uint i = y*_width + x;
        return _g[i];
    }
    double B(const int x, const int y) const
    {
        if (x < 0 || y < 0) return 0.0;
        if (x >= _width || y >= _height) return 0.0;
        const uint i = y*_width + x;
        return _b[i];
    }

    void createLum(float* rgb, const uint width, const uint height, const uint nc);

    uint width() const  { return _width;  }
    uint height() const { return _height; }

    /**
     * Returns the sum of a region defined by A,B,C,D.
     *
     * A----B
     * |    |  sum = C+A-B-D
     * D----C
     */
    double sum(const int ax, const int ay, const int bx, const int by, const int cx, const int cy, const int dx, const int dy) const
    {
        return I(cx, cy) + I(ax, ay) - I(bx, by) - I(dx, dy);
    }

    double sumR(const int ax, const int ay, const int bx, const int by, const int cx, const int cy, const int dx, const int dy) const
    {
        return R(cx, cy) + R(ax, ay) - R(bx, by) - R(dx, dy);
    }

    double sumG(const int ax, const int ay, const int bx, const int by, const int cx, const int cy, const int dx, const int dy) const
    {
        return G(cx, cy) + G(ax, ay) - G(bx, by) - G(dx, dy);
    }

    double sumB(const int ax, const int ay, const int bx, const int by, const int cx, const int cy, const int dx, const int dy) const
    {
        return B(cx, cy) + B(ax, ay) - B(bx, by) - B(dx, dy);
    }

    double sum1(const int ax, const int ay, const int bx, const int by, const int cx, const int cy, const int dx, const int dy) const
    {
        return I1(cx, cy) + I1(ax, ay) - I1(bx, by) - I1(dx, dy);
    }

    double sum2(const int ax, const int ay, const int bx, const int by, const int cx, const int cy, const int dx, const int dy) const
    {
        return I2(cx, cy) + I2(ax, ay) - I2(bx, by) - I2(dx, dy);
    }
    double sum3(const int ax, const int ay, const int bx, const int by, const int cx, const int cy, const int dx, const int dy) const
    {
        return I3(cx, cy) + I3(ax, ay) - I3(bx, by) - I3(dx, dy);
    }
    double sum4(const int ax, const int ay, const int bx, const int by, const int cx, const int cy, const int dx, const int dy) const
    {
        return I4(cx, cy) + I4(ax, ay) - I4(bx, by) - I4(dx, dy);
    }
    double sum5(const int ax, const int ay, const int bx, const int by, const int cx, const int cy, const int dx, const int dy) const
    {
        return I5(cx, cy) + I5(ax, ay) - I5(bx, by) - I5(dx, dy);
    }

};