HomgLine2D.cpp

/* This file is part of the BIAS library (Basic ImageAlgorithmS).

   Copyright (C) 2003-2009    (see file CONTACT for details)
   Multimediale Systeme der Informationsverarbeitung
   Institut fuer Informatik
   Christian-Albrechts-Universitaet Kiel

   BIAS is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation; either version 2.1 of the License, or
   (at your option) any later version.
   
   BIAS 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 Lesser General Public License for more details.
   
   You should have received a copy of the GNU Lesser General Public License
   along with BIAS; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA*/
#include "HomgLine2D.hh"
#include <limits>

using namespace BIAS;
using namespace std;

bool HomgLine2D::
GetIntersectionsWithImage(unsigned int width, unsigned int height,
                          unsigned int coo[4])
{
  //const bool debug = false;

  int intersectioncount = 0;
  HomgPoint2D edges[4]; // 0=left, 1=right, 2=top, 3=bottom
  HomgLine2D left(-1.0, 0.0, 0.0);
  HomgLine2D right(-1.0, 0.0, width-1);
  HomgLine2D top(0.0, -1.0, 0.0);
  HomgLine2D bottom(0.0, -1.0, height-1);

  edges[0] = Intersection(left);
  edges[1] = Intersection(right);
  edges[2] = Intersection(top);
  edges[3] = Intersection(bottom);

//   if (debug){
//     cerr << setprecision(25);
//     cout << setprecision(25);
//     cerr << "HomghLine2D.cc:" << endl;
//     for (int i =0; i<4; i++){
//       cerr << "edges[" << i << "] : " << edges[i] << endl;
//     }
//   }

  // deal with compiler precision
  for (unsigned int i=0; i<4; i++){
    if (!edges[i].IsAtInfinity()) {
      edges[i].Homogenize(); 
      if (edges[i][0] < 0.0 && edges[i][0] > -HOMGLINE2D_EPS)
        edges[i][0] = 0.0;
      if (edges[i][1] < 0.0 && edges[i][1] > -HOMGLINE2D_EPS)
        edges[i][1] = 0.0;
      if (edges[i][0] > (double)width-1.0 &&  
          edges[i][0] < (double)width-1.0 +HOMGLINE2D_EPS)
        edges[i][0] = (double)width-1.0;
      if (edges[i][1] > (double)height-1.0 &&  
          edges[i][1] < (double)height-1.0 +HOMGLINE2D_EPS)
        edges[i][1] = (double)height-1.0;
    } else {
      edges[i][0] = edges[i][1] = -numeric_limits<double>::max();
    }
  }

//   if (debug){
//     cerr << setprecision(25);
//     cout << setprecision(25);
//     cerr << "HomghLine2D.cc:" << endl;
//     for (int i =0; i<4; i++){
//       cerr << "edges[" << i << "] : " << edges[i] << endl;
//     }
//   }

  // left
  if ((edges[0][1]>=0.0 && edges[0][1]<=(double)height-1.0)){
    intersectioncount++;
    coo[0] = 0;
    coo[1] = (unsigned int)rint(edges[0][1]);
//     if (debug) cout << "int with left: "<<coo[0]<<", "<<coo[1]<<endl;
  } 
  // right
  if ((edges[1][1]>=0.0 && edges[1][1]<=(double)height-1.0)){
    coo[intersectioncount*2]   = width - 1;
    coo[intersectioncount*2+1] = (unsigned int)rint(edges[1][1]); 
//     if (debug) cout << "int with right: "<<coo[intersectioncount*2]
//                     <<", "<<coo[intersectioncount*2+1]<<endl;
    intersectioncount++;
  } else {
//     if (debug) cout <<"not right: "<<edges[1][1]<<endl
//                     <<"\t"<<(double)(height)-1.0<<"  "<<boolalpha
//                     <<(edges[1][1]<=(double)height-1.0)<<"  "
//                     <<(edges[1][1]>=0.0)<<endl
//                     <<(double)(height)-1.0-edges[1][1]<<endl;
  }
  // top
  if ((edges[2][0]>=0.0 && edges[2][0]<=(double)width-1.0)){
//     if (debug) cout << "int with top: ";
    switch (intersectioncount){
    case 0:
      coo[0] = (unsigned int)rint(edges[2][0]);
      coo[1] = 0; 
//       if (debug) cout << "first: "<< coo[0] << ", "<<coo[1]<<endl;
      break;
    case 1:
      coo[2] = (unsigned int)rint(edges[2][0]);
      coo[3] = 0; 
//       if (debug) cout << "second: "<<  coo[2] << ", "<<coo[3]<<endl;
      break;
    default:
//       if (debug) cout << "already two intersections\n";
      break;
    }
    intersectioncount++;
  } 
  // bottom
  if ((edges[3][0]>=0.0 && edges[3][0]<=(double)width-1.0)){
//     if (debug) cout << "int with bottom: ";
    switch (intersectioncount){
    case 0:
      coo[0] = (unsigned int)rint(edges[3][0]);
      coo[1] = height -1; 
//       if (debug) cout << "first: "<<coo[0] << ", "<<coo[1]<<endl;
      break;
    case 1:
      coo[2] = (unsigned int)rint(edges[3][0]);
      coo[3] = height -1; 
//       if (debug) cout << "second: "<<  coo[2] << ", "<<coo[3]<<endl;
      break;
    case 2:
      if (sqrt(pow((double)(coo[0]-coo[2]),2) + 
               pow((double)(coo[1]-coo[3]),2))< 
          sqrt(pow((double)(coo[0]-(unsigned int)rint(edges[3][0])),2) + 
               pow((double)(coo[1]-(height -1)),2))){
        coo[2] = (unsigned int)rint(edges[3][0]);
        coo[3] = height -1;
 //        if (debug) cout << "replacing second intersection: " 
//                         << coo[2] << ", "<<coo[3]<<endl;
      }  
      break;
    default:
//       if (debug) cout << "already three intersections\n";
      break;
    }
    intersectioncount++;
  } 


  return (intersectioncount >1);
}