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#include "CodecGrayCode.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, CodecDir _dir) : Algorithm(_screenCols, _screenRows, _dir){

    // Number of horizontal encoding patterns

    Nhorz = ceilf(log2f((float)screenCols));;

    // Number of vertical encoding patterns

    Nvert = ceilf(log2f((float)screenRows));;

    // Set total pattern number

    if(dir & CodecDirHorizontal)

        this->N += Nhorz;

    if(dir & CodecDirVertical)

        this->N += Nvert;

    if(dir & CodecDirHorizontal){

        // 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 & CodecDirVertical){

        // 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];

}

// Algorithm

AlgorithmGrayCode::AlgorithmGrayCode(CodecDir _dir, int _screenResX, int _screenResY) : Algorithm(_dir, _screenResX, _screenResY){

    // Number of horizontal encoding patterns

    Nhorz = ceilf(log2f((float)screenCols));;

    // Number of vertical encoding patterns

    Nvert = ceilf(log2f((float)screenRows));;

}

void AlgorithmGrayCode::getCorrespondences(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){

}