CGAL users discussion list

[Andreas Fabri <>]

Hi Antonino,

I still insist that you better first read the manual.
It is organized in a user manual coming with examples,
and a reference manual listing the classes and functions.

A function called is_bisector()  sounds and is a function
returning a boolean value, not a vertex.

best regards,

andreas



Antonino Mistretta wrote:
> Hi Andreas,
>
> in attachment is a jpeg with original polygon and skeleton nodes(in red).
> This is the code that make this result:
>
>         //! create cgal polygon by my polygon.
>         Base::PolygonPtr _poly;
>         _poly = Base::PolygonPtr( new Base::Polygon2D() );
>         int startVertex = currPolygon->nVertices-2;
>         int end = 0;
>         for(int i=startVertex; i>=end; i--)
>                 (*_poly).push_back( Base::Point( currPolygon->padfX[i],
> currPolygon->padfY[i]) );
>         cgalPoly.push_back(_poly);
>
>         //! make skeleton
>         //! Insert vertex in skeleton_builder
>         for( RegIt bit = cgalPoly.begin(), ebit = cgalPoly.end() ; bit !=
> ebit ; ++ bit )
>         {
>                 builder.enter_contour((*bit)->begin(),(*bit)->end());
>         }
>         //! build skeleton
>         if ( !( skeleton = builder.construct_skeleton() ) )//!// Proceed only
> if the skeleton was correctly constructed.
>                 throw string("Impossibile creare lo skeleton per questo 
> poligono.");
>         
>
>         //!get skeleton points
>         for (Base::Halfedge_iterator i = (*skeleton).halfedges_begin(); i !=
> (*skeleton).halfedges_end(); ++ i )
>         {
>                 //il punto fa parte dello skeleton??
>                 if (i->is_bisector())
>                 {
>                         outX.push_back(i->vertex()->point().x());
>                         outY.push_back(i->vertex()->point().y());
>                 }
>         }
>
> Why is_bisector() method returns not skeleton node?
> I don't understant how I must do to use StraightSkeletonVertex class.
>
> Thanks and excuse me to my english...
>
> 2008/4/4, Andreas Fabri 
> <>:
> > Hi Antonino,
> >
> >  Did you read the manual already. I think this is covered.
> >
> >  andreas
> >
> >
> >
> >  Antonino Mistretta wrote:
> >
> > > Can you show me a little example?
> > > How I obtain StraightSkeletonVertex_2 object by Skeleton_Builder?
> > > Thanks
> > >
> > > 2008/4/4, Fernando Cacciola
> > <>:
> > > >  wrote:
> > > >
> > > >
> > > > > Hi All,
> > > > >
> > > > > I am using Straight Skeleton concept to find the skeleton polygon
> > points.
> > > > > I call a construct_skeleton() method on istance of skeleton builder to
> > > > > compute this(It's correct?).
> > > > Yes.
> > > >
> > > >
> > > >
> > > > > My question is - how can I get the coordinates of the skeleton vertex?
> > > > Using the 'point()' function as stated in the manual:
> > http://www.cgal.org/Manual/3.3/doc_html/cgal_manual/Straight_skeleton_2_ref/Concept_StraightSkeletonVertex_2.html#Cross_link_anchor_783
> > > > HTH
> > > >
> > > > Fernando Cacciola
> > > > GeometryFactory
> > > >
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>
>
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