CGAL users discussion list

["Shi Yan" <>]

so, there is no ready made ostream for obj format, right?

CGAL claims that it supports the obj output format, but i can't find
the obj_ostream.

on this page, only four ostreams are listed:

http://www.math.unizh.ch/sepp/cgal-2.4-mo/basic_lib/Polyhedron/Chapter_main.html


Additional formats supported for writing are OpenInventor (.iv)
[Wer94], VRML 1.0 and 2.0 (.wrl) [BPP95, VRM96, HW96], and Wavefront
Advanced Visualizer object format (.obj). Another convenient output
function writes a polyhedral surface to a GeomView process spawned
from the CGAL program. These output functions are provided as stream
operators, now acting on the stream type of the respective format.

#include <CGAL/IO/Inventor_ostream.h>


#include <CGAL/IO/VRML_1_ostream.h>


#include <CGAL/IO/VRML_2_ostream.h>


#include <CGAL/IO/Geomview_stream.h>


thank you.

On Sun, Jun 29, 2008 at 5:17 AM, Pierre Alliez
<>
 wrote:
> hi Bill,
>
> one solution is to hack something like (assume member function of your
> enriched polyhedron)
>
>  // write in obj file format (OBJ).
>  void write_obj(char *pFilename,
>                  int incr  = 1) // 1-based by default
>  {
>    std::ofstream stream(pFilename);
>
>    // output vertices
>    for(Point_iterator pPoint = points_begin();
>        pPoint != points_end();
>        pPoint++)
>      stream << 'v' << ' ' << pPoint->x() << ' ' <<
>                              pPoint->y() << ' ' <<
>                              pPoint->z() << std::endl;
>
>    // precompute vertex indices
>    this->set_index_vertices();
>
> // this assumes you have defined an index per vertex
> // and the function:
>
>  void set_index_vertices()
>  {
>    unsigned int index = 0;
>    for(Vertex_iterator v = vertices_begin();
>        v!= vertices_end();
>        v++)
>      v->index(index++);
>  }
> // or something with a STL map to associate one index per vertex
>
>
>    // output facets
>    for(Facet_iterator pFacet = facets_begin();
>        pFacet != facets_end();
>        pFacet++)
>    {
>      stream << 'f';
>      Halfedge_around_facet_circulator pHalfedge = pFacet->facet_begin();
>      do
>        stream << ' ' << pHalfedge->vertex()->index()+incr;
>      while(++pHalfedge != pFacet->facet_begin());
>      stream << std::endl;
>    }
>  }
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-- 
Dept. of Computer Science
University of California, Davis
Homepage:http://wwwcsif.cs.ucdavis.edu/~yans/