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3party/agg/agg_bspline.h

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+//----------------------------------------------------------------------------
+// Anti-Grain Geometry - Version 2.4
+// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
+//
+// Permission to copy, use, modify, sell and distribute this software 
+// is granted provided this copyright notice appears in all copies. 
+// This software is provided "as is" without express or implied
+// warranty, and with no claim as to its suitability for any purpose.
+//
+//----------------------------------------------------------------------------
+// Contact: mcseem@antigrain.com
+//          mcseemagg@yahoo.com
+//          http://www.antigrain.com
+//----------------------------------------------------------------------------
+//
+// class bspline
+//
+//----------------------------------------------------------------------------
+
+#ifndef AGG_BSPLINE_INCLUDED
+#define AGG_BSPLINE_INCLUDED
+
+#include "agg_array.h"
+
+namespace agg
+{
+    //----------------------------------------------------------------bspline
+    // A very simple class of Bi-cubic Spline interpolation.
+    // First call init(num, x[], y[]) where num - number of source points, 
+    // x, y - arrays of X and Y values respectively. Here Y must be a function 
+    // of X. It means that all the X-coordinates must be arranged in the ascending
+    // order. 
+    // Then call get(x) that calculates a value Y for the respective X. 
+    // The class supports extrapolation, i.e. you can call get(x) where x is
+    // outside the given with init() X-range. Extrapolation is a simple linear 
+    // function.
+    //
+    //  See Implementation agg_bspline.cpp
+    //------------------------------------------------------------------------
+    class bspline 
+    {
+    public:
+        bspline();
+        bspline(int num);
+        bspline(int num, const double* x, const double* y);
+
+        void   init(int num);
+        void   add_point(double x, double y);
+        void   prepare();
+
+        void   init(int num, const double* x, const double* y);
+
+        double get(double x) const;
+        double get_stateful(double x) const;
+    
+    private:
+        bspline(const bspline&);
+        const bspline& operator = (const bspline&);
+
+        static void bsearch(int n, const double *x, double x0, int *i);
+        double extrapolation_left(double x) const;
+        double extrapolation_right(double x) const;
+        double interpolation(double x, int i) const;
+
+        int               m_max;
+        int               m_num;
+        double*           m_x;
+        double*           m_y;
+        pod_array<double> m_am;
+        mutable int       m_last_idx;
+    };
+
+
+}
+
+#endif