headers/libs/agg/agg_shorten_path.h

   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 #ifndef AGG_SHORTEN_PATH_INCLUDED
  17 #define AGG_SHORTEN_PATH_INCLUDED
  18
  19 #include "agg_basics.h"
  20 #include "agg_vertex_sequence.h"
  21
  22 namespace agg
  23 {
  24
  25     //===========================================================shorten_path
  26     template<class VertexSequence>
  27     void shorten_path(VertexSequence& vs, double s, unsigned closed = 0)
  28     {
  29         typedef typename VertexSequence::value_type vertex_type;
  30
  31         if(s > 0.0 && vs.size() > 1)
  32         {
  33             double d;
  34             int n = int(vs.size() - 2);
  35             while(n)
  36             {
  37                 d = vs[n].dist;
  38                 if(d > s) break;
  39                 vs.remove_last();
  40                 s -= d;
  41                 --n;
  42             }
  43             if(vs.size() < 2)
  44             {
  45                 vs.remove_all();
  46             }
  47             else
  48             {
  49                 n = vs.size() - 1;
  50                 vertex_type& prev = vs[n-1];
  51                 vertex_type& last = vs[n];
  52                 d = (prev.dist - s) / prev.dist;
  53                 double x = prev.x + (last.x - prev.x) * d;
  54                 double y = prev.y + (last.y - prev.y) * d;
  55                 last.x = x;
  56                 last.y = y;
  57                 if(!prev(last)) vs.remove_last();
  58                 vs.close(closed != 0);
  59             }
  60         }
  61     }
  62
  63
  64 }
  65
  66 #endif