added KeyPoint::hash() (ticket #1100)

modules/features2d/include/opencv2/features2d/features2d.hpp

@@ -236,6 +236,9 @@ public:
             float _response=0, int _octave=0, int _class_id=-1)
             : pt(x, y), size(_size), angle(_angle),
             response(_response), octave(_octave), class_id(_class_id) {}
+    
+    size_t hash() const;
+    
     //! converts vector of keypoints to vector of points
     static void convert(const std::vector<KeyPoint>& keypoints,
                         CV_OUT std::vector<Point2f>& points2f,

modules/features2d/src/keypoint.cpp

@@ -44,6 +44,19 @@
 namespace cv
 {
 
+size_t KeyPoint::hash() const
+{
+    size_t _Val = 2166136261U, scale = 16777619U;
+    Cv32suf u;
+    u.f = pt.x; _Val = (scale * _Val) ^ u.u;
+    u.f = pt.y; _Val = (scale * _Val) ^ u.u;
+    u.f = size; _Val = (scale * _Val) ^ u.u;
+    u.f = angle; _Val = (scale * _Val) ^ u.u;
+    u.f = response; _Val = (scale * _Val) ^ u.u;
+    _Val = (scale * _Val) ^ ((size_t) octave);
+    _Val = (scale * _Val) ^ ((size_t) class_id);
+    return _Val;
+}    
 
 void write(FileStorage& fs, const string& objname, const vector<KeyPoint>& keypoints)
 {