/home/hauberg/Dokumenter/Capture/humim-tracker-0.1/src/project2d.h

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// Copyright (C) 2011 Soren Hauberg
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 3
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, see <http://www.gnu.org/licenses/>.
 
#ifndef PROJECT2D
#define PROJECT2D

#include "opencv_helper.h"
#include "auxil.h"

//#define PROJ2D_SCALE 0.25
#define PROJ2D_SCALE 1.0

class project2d
{
public:
  project2d ()
    : dist (NULL)
    {
      size = cvSize (0, 0);
    }
  
  void update_segment (IplImage *new_segment)
    {
      // Should we resize the distance map?
      const CvSize new_size = cvGetSize (new_segment);
      if (size.width != new_size.width || size.height != new_size.height)
        {
          if (dist != NULL)
            cvReleaseImage (&dist);
          dist = cvCreateImage (new_size, IPL_DEPTH_32F, 1);
          size = new_size;
        }
      
      // Compute distance map
      cvNot (new_segment, new_segment);
      cvDistTransform (new_segment, dist);
    }
  
  CvPoint project (CvPoint p) const
    {
      CvPoint retval;

      // Ensure we are within the image before accessing pixels
      p.x = force_in_range (p.x, 0, size.width-1);
      p.y = force_in_range (p.y, 0, size.height-1);
  
      // Calculate derivative of 'dist' at 'p'
      const float val = GRAY32F (dist, p.x, p.y);
      if (val > 0) // outside
        {
          const float dx = 0.5 * (GRAY32F (dist, p.x + 1, p.y) - GRAY32F (dist, p.x - 1, p.y));
          const float dy = 0.5 * (GRAY32F (dist, p.x, p.y + 1) - GRAY32F (dist, p.x, p.y - 1));
          const float norm = sqrt (dx*dx + dy*dy);
          retval.x = p.x - dx * val / norm;
          retval.y = p.y - dy * val / norm;
        }
      else // inside (no need for projection)
        {
          retval.x = p.x;
          retval.y = p.y;
        }

      return retval;
    }
  
  bool is_inside (CvPoint p) const
    {
      // Ensure we are within the image before accessing pixels
      p.x = force_in_range (p.x, 0, size.width-1);
      p.y = force_in_range (p.y, 0, size.height-1);
  
      // Check status
      const float val = GRAY32F (dist, p.x, p.y);
      return (val <= 0.0);
    }
  
  CvSize get_size () const
    {
      return size;
    }

private:
  IplImage *dist;
  CvSize size;
};

#endif // PROJECT2D