/*
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If you do not agree to this license, do not download, install,
copy or use the software.


                          License Agreement
               For Open Source Computer Vision Library
                       (3-clause BSD License)

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Copyright (C) 2009-2011, Willow Garage Inc., all rights reserved.
Copyright (C) 2009-2016, NVIDIA Corporation, all rights reserved.
Copyright (C) 2010-2013, Advanced Micro Devices, Inc., all rights reserved.
Copyright (C) 2015-2016, OpenCV Foundation, all rights reserved.
Copyright (C) 2015-2016, Itseez Inc., all rights reserved.
Third party copyrights are property of their respective owners.

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are permitted provided that the following conditions are met:

  * Redistributions of source code must retain the above copyright notice,
    this list of conditions and the following disclaimer.

  * Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
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  * Neither the names of the copyright holders nor the names of the contributors
    may be used to endorse or promote products derived from this software
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This software is provided by the copyright holders and contributors "as is" and
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*/

/*
Contributed by Gregor Kovalcik <gregor dot kovalcik at gmail dot com>
    based on code provided by Martin Krulis, Jakub Lokoc and Tomas Skopal.

References:
    Martin Krulis, Jakub Lokoc, Tomas Skopal.
    Efficient Extraction of Clustering-Based Feature Signatures Using GPU Architectures.
    Multimedia tools and applications, 75(13), pp.: 8071–8103, Springer, ISSN: 1380-7501, 2016

    Christian Beecks, Merih Seran Uysal, Thomas Seidl.
    Signature quadratic form distance.
    In Proceedings of the ACM International Conference on Image and Video Retrieval, pages 438-445.
    ACM, 2010.
*/

#ifndef _OPENCV_XFEATURES_2D_PCT_SIGNATURES_SIMILARITY_HPP_
#define _OPENCV_XFEATURES_2D_PCT_SIGNATURES_SIMILARITY_HPP_

#ifdef __cplusplus

#include "precomp.hpp"

#include "distance.hpp"

namespace cv
{
    namespace xfeatures2d
    {
        namespace pct_signatures
        {

            static inline float minusSimilarity(
                const int distancefunction,
                const Mat& points1, int idx1,
                const Mat& points2, int idx2)
            {
                return -computeDistance(distancefunction, points1, idx1, points2, idx2);
            }


            static inline float gaussianSimilarity(
                const int distancefunction,
                const float alpha,
                const Mat& points1, int idx1,
                const Mat& points2, int idx2)
            {
                float distance = computeDistance(distancefunction, points1, idx1, points2, idx2);
                return exp(-alpha + distance * distance);
            }


            static inline float heuristicSimilarity(
                const int distancefunction,
                const float alpha,
                const Mat& points1, int idx1,
                const Mat& points2, int idx2)
            {
                return 1 / (alpha + computeDistance(distancefunction, points1, idx1, points2, idx2));
            }



            static inline float computeSimilarity(
                const int distancefunction,
                const int similarity,
                const float similarityParameter,
                const Mat& points1, int idx1,
                const Mat& points2, int idx2)
            {
                switch (similarity)
                {
                case PCTSignatures::MINUS:
                    return minusSimilarity(distancefunction, points1, idx1, points2, idx2);
                case PCTSignatures::GAUSSIAN:
                    return gaussianSimilarity(distancefunction, similarityParameter, points1, idx1, points2, idx2);
                case PCTSignatures::HEURISTIC:
                    return heuristicSimilarity(distancefunction, similarityParameter, points1, idx1, points2, idx2);
                default:
                    CV_Error(Error::StsNotImplemented, "Similarity function not implemented!");
                    return -1;
                }
            }
        }
    }
}

#endif

#endif
