agg/inc/agg_bspline.h

   1 //----------------------------------------------------------------------------
   2 // Anti-Grain Geometry - Version 2.3
   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_basics.h"
  24
  25 namespace 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();
  45         bspline(int num);
  46         bspline(int num, const double* x, const double* y);
  47
  48         void   init(int num);
  49         void   add_point(double x, double y);
  50         void   prepare();
  51
  52         void   init(int num, const double* x, const double* y);
  53
  54         double get(double x) const;
  55         double get_stateful(double x) const;
  56
  57     private:
  58         bspline(const bspline&);
  59         const bspline& operator = (const bspline&);
  60
  61         static void bsearch(int n, const double *x, double x0, int *i);
  62         double extrapolation_left(double x) const;
  63         double extrapolation_right(double x) const;
  64         double interpolation(double x, int i) const;
  65
  66         int     m_max;
  67         int     m_num;
  68         double* m_x;
  69         double* m_y;
  70         double* m_am;
  71         mutable int m_last_idx;
  72     };
  73
  74
  75 }
  76
  77 #endif