1//----------------------------------------------------------------------------
2// Anti-Grain Geometry - Version 2.4
3// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
4//
5// Permission to copy, use, modify, sell and distribute this software
6// is granted provided this copyright notice appears in all copies.
7// This software is provided "as is" without express or implied
8// warranty, and with no claim as to its suitability for any purpose.
9//
10//----------------------------------------------------------------------------
11// Contact: mcseem@antigrain.com
12//          mcseemagg@yahoo.com
13//          http://www.antigrain.com
14//----------------------------------------------------------------------------
15//
16// class bspline
17//
18//----------------------------------------------------------------------------
19
20#ifndef AGG_BSPLINE_INCLUDED
21#define AGG_BSPLINE_INCLUDED
22
23#include "agg_array.h"
24
25namespace agg
26{
27    //----------------------------------------------------------------bspline
28    // A very simple class of Bi-cubic Spline interpolation.
29    // First call init(num, x[], y[]) where num - number of source points,
30    // x, y - arrays of X and Y values respectively. Here Y must be a function
31    // of X. It means that all the X-coordinates must be arranged in the ascending
32    // order.
33    // Then call get(x) that calculates a value Y for the respective X.
34    // The class supports extrapolation, i.e. you can call get(x) where x is
35    // outside the given with init() X-range. Extrapolation is a simple linear
36    // function.
37    //
38    //  See Implementation agg_bspline.cpp
39    //------------------------------------------------------------------------
40    class bspline
41    {
42    public:
43        bspline();
44        bspline(int num);
45        bspline(int num, const double* x, const double* y);
46
47        void   init(int num);
48        void   add_point(double x, double y);
49        void   prepare();
50
51        void   init(int num, const double* x, const double* y);
52
53        double get(double x) const;
54        double get_stateful(double x) const;
55
56    private:
57        bspline(const bspline&);
58        const bspline& operator = (const bspline&);
59
60        static void bsearch(int n, const double *x, double x0, int *i);
61        double extrapolation_left(double x) const;
62        double extrapolation_right(double x) const;
63        double interpolation(double x, int i) const;
64
65        int               m_max;
66        int               m_num;
67        double*           m_x;
68        double*           m_y;
69        pod_array<double> m_am;
70        mutable int       m_last_idx;
71    };
72
73
74}
75
76#endif
77