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#include "AlgorithmGrayCode.h"
#include <cmath>

#ifndef log2f
#define log2f(x) (log(x)/log(2.0))
#endif

//using namespace std;

/*
 * The purpose of this function is to convert an unsigned
 * binary number to reflected binary Gray code.
 *
 * The operator >> is shift right. The operator ^ is exclusive or.
 * Source: http://en.wikipedia.org/wiki/Gray_code
 */
static unsigned int binaryToGray(unsigned int num) {
    return (num >> 1) ^ num;
}

/*
 * From Wikipedia: http://en.wikipedia.org/wiki/Gray_code
 * The purpose of this function is to convert a reflected binary
 * Gray code number to a binary number.
 */
static unsigned grayToBinary(unsigned num, unsigned numBits)
{
    for (unsigned shift = 1; shift < numBits; shift <<= 1){
        num ^= num >> shift;
    }
    return num;
}

/*
 * Function takes the decimal number
 * Function takes the Nth bit (1 to 31)
 * Return the value of Nth bit from decimal
 * Source: http://icfun.blogspot.com/2009/04/get-n-th-bit-value-of-any-integer.html
 */
static int get_bit(int decimal, int N){

    // Shifting the 1 for N-1 bits
    int constant = 1 << (N-1);

    // If the bit is set, return 1
    if( decimal & constant ){
        return 1;
    }

    // If the bit is not set, return 0
    return 0;
}

static inline int powi(int num, unsigned int exponent){
    // NOT EQUIVALENT TO pow()
    if(exponent == 0)
        return 1;

    float res = num;
    for(unsigned int i=0; i<exponent-1; i++)
        res *= num;

    return res;
}

// Algorithm
AlgorithmGrayCode::AlgorithmGrayCode(unsigned int _screenCols, unsigned int _screenRows, CodingDir _dir) : Algorithm(_screenCols, _screenRows, _dir){

    // Number of horizontal encoding patterns
    Nhorz = ceilf(log2f((float)screenCols))*2;

    // Number of vertical encoding patterns
    Nvert = ceilf(log2f((float)screenRows))*2;

    // on/off patterns
    this->N = 2;

    // Set total pattern number
    if(dir & CodingDirHorizontal)
        this->N += Nhorz;

    if(dir & CodingDirVertical)
        this->N += Nvert;

    // all on pattern
    cv::Mat pattern(1, 1, CV_8UC3);
    pattern.setTo(cv::Vec3b(255.0,255.0,255.0));
    patterns.push_back(pattern);

    // all off pattern
    pattern.setTo(cv::Vec3b(0.0,0.0,0.0));
    patterns.push_back(pattern);

    if(dir & CodingDirHorizontal){
        // Precompute horizontally encoding patterns
        for(unsigned int p=0; p<Nhorz; p++){
            cv::Mat patternP(1, screenCols, CV_8UC3);
            // Loop through columns in first row
            for(unsigned int j=0; j<screenCols; j++){
                unsigned int jGray = binaryToGray(j);
                // Amplitude of channels
                float amp = get_bit(jGray, Nhorz-p);
                patternP.at<cv::Vec3b>(0,j) = cv::Vec3b(255.0*amp,255.0*amp,255.0*amp);
            }
            patterns.push_back(patternP);
        }
    }
    if(dir & CodingDirVertical){
        // Precompute vertical encoding patterns
        for(unsigned int p=0; p<Nvert; p++){
            cv::Mat patternP(screenRows, 1, CV_8UC3);

            // Loop through rows in first column
            for(unsigned int i=0; i<screenRows; i++){

                unsigned int iGray = binaryToGray(i);

                // Amplitude of channels
                float amp = get_bit(iGray, Nvert-p); // Nvert-p-1?
                patternP.at<cv::Vec3b>(i,0) = cv::Vec3b(255.0*amp,255.0*amp,255.0*amp);
            }
            patterns.push_back(patternP);
        }
    }
}

cv::Mat AlgorithmGrayCode::getEncodingPattern(unsigned int depth){
    return patterns[depth];
}


bool sortingLarger(cv::Vec4f i,cv::Vec4f j){ return (i[3]<j[3]);}
void getEdgeLabels(const cv::Mat& scanLine, int Nbits, std::vector<cv::Vec4f>& edges){

    int nCols = scanLine.cols;

    for(int col=1; col<nCols; nCols++){

        int labelLeft = scanLine.at<int>(0,col-1);
        int labelRight = scanLine.at<int>(0,col);

        if(labelLeft != -1 && labelRight != -1 && labelLeft != labelRight){

            int orderingRelation = (2 << Nbits)*labelLeft + labelRight;

            edges.push_back(cv::Vec4f(col, labelLeft, labelRight, orderingRelation));

        }
    }

    std::sort(edges.begin(), edges.end(), sortingLarger);
}

void AlgorithmGrayCode::getCorrespondences(SMCalibrationParameters calibration, const std::vector<cv::Mat>& frames0, const std::vector<cv::Mat>& frames1, std::vector<cv::Point2f>& q0, std::vector<cv::Point2f>& q1, std::vector<cv::Point3f>& color){

    assert(frames0.size() == N);
    assert(frames1.size() == N);

    // occlusion maps
    cv::Mat occlusion0 = (frames0[0] - frames0[1]) > 0;
    cv::Mat occlusion1 = (frames1[0] - frames1[1]) > 0;

    // decoded patterns
    cv::Mat code0, code1;

    int Nbits = (N-2)/2;
    for(int i=0; i<Nbits; i++){
        cv::Mat bit0 = (frames0[i*2+2] - frames0[i*2+3]) > 0;
        code0 += bit0*pow(2, i);
        cv::Mat bit1 = (frames1[i*2+2] - frames1[i*2+3]) > 0;
        code1 += bit1*pow(2, i);
    }

    // rectifying homographies
    cv::Size frameSize(frames0[0].cols, frames0[0].rows);
    cv::Mat R0, R1, P0, P1, Q;
    cv::stereoRectify(calibration.K0, calibration.k0, calibration.K1, calibration.k1, frameSize, calibration.R1, calibration.T1, R0, R1, P0, P1, Q);

    // interpolation maps
    cv::Mat map0X, map0Y, map1X, map1Y;
    cv::initUndistortRectifyMap(P0, calibration.k0, R0, cv::Mat(), frameSize, CV_32FC1, map0X, map0Y);
    cv::initUndistortRectifyMap(P1, calibration.k1, R1, cv::Mat(), frameSize, CV_32FC1, map1X, map1Y);

    // remap
    cv::remap(occlusion0, occlusion0, map0X, map0Y, cv::INTER_CUBIC);
    cv::remap(occlusion1, occlusion1, map1X, map1Y, cv::INTER_CUBIC);
    cv::remap(code0, code0, map1X, map1Y, cv::INTER_CUBIC);
    cv::remap(code1, code1, map1X, map1Y, cv::INTER_CUBIC);

    int nRows = occlusion0.rows;
    int nCols = occlusion0.cols;

    // matching
    for(int row=0; row<nRows; row++){

        std::vector<cv::Vec4f> edges0, edges1;

        getEdgeLabels(code0.row(row), Nbits, edges0);
        getEdgeLabels(code1.row(row), Nbits, edges1);

        // REMOVE DOUBLE ENTRIES!

        int i=0, j=0;
        while(i<edges0.size() && j<edges1.size()){

            if(edges0[i][3] == edges1[j][3]){
                q0.push_back(cv::Point2f(row, edges0[i][0]));
                q1.push_back(cv::Point2f(row, edges1[j][0]));
                i += 1;
                j += 1;
            } else if(edges0[i][3] < edges1[i][3]){
                i += 1;
            } else if(edges0[i][3] > edges1[i][3]){
                j += 1;
            }
        }


    }

    // retrieve color information
    int nMatches = q0.size();
    color.resize(nMatches);
    for(int i=0; i<nMatches; i++){

        cv::Vec3f color0 = frames0[0].at<cv::Vec3f>(q0[i].y, q0[i].x);
        cv::Vec3f color1 = frames1[0].at<cv::Vec3f>(q1[i].y, q1[i].x);

        color[i] = 0.5*(color0 + color1);
    }

}