CGAL users discussion list

Ok, I see. So all shalfedges are inside spheremaps, and the spheremaps connect
to each other on a face using next() and prev(). What I didn't understand
earlier, is that the edge-uses are not represented explicitly, but as a next()
move from one spheremap to another.

Thanks.
Amir.

Quoting Peter Hachenberger 
<>:

> There is only one type shalfedges and it includes the following
> handles(pointers):
> class SHalfedge{...SHalfedge_handle next;SHalfedge_handle
> prev;SHalfedge_handle snext;SHalfedge_handle sprev;...};
> The latter two pointers navigate on a sphere map. So if you have a cube
> andyou have the shalfedge of the sphere map of the vertex in the lower left
> frontcorner that belongs to the lower facet of the cube, then the
> snext-handle pointsto a shalfedge on the same sphere map that belongs to the
> front face of the cube.Likewise, the sprev-handle points to a shalfedge on
> the same sphere map that belongsto the left facet of the cube. The next and
> the prev handle both point to shalfedgesof that belong to the lower facet of
> the cube---on of them is on the sphere mapof the lower left back corner and
> the other is on the sphere map of the lower right frontcorner.
> Peter -----
>  wrote: -----
> 
> To: 
> 
> From: 
> 
> Date: 03/12/2009 12:35AM
> Subject: Re: [cgal-discuss] Another question regardin Nef polyhedra -
> shalfedges
> 
> so.. the edge-uses, are they data-typed as shalfedges? if so, then these are
> "shalfedges" which are not on the spheremap, no? 
> 
> Quoting Peter Hachenberger 
> <>:
> 
> > Hi Amir,
> > you got that a bit wrong. Every shalfedge is on a sphere map. SHalfedges
> > occurr
> > in two types of cycles in cycles around sfaces on a sphere map and in
> > halffacet cycles.
> > In the latter case we call the traversing of the shalfedges an edge-use.
> > 
> > Peter
> > 
> > -----"Amir Vaxman" 
> > <>
> >  wrote: -----
> > 
> > To: 
> > <>
> > From: "Amir Vaxman" 
> > <>
> > Date: 03/11/2009 02:17PM
> > Subject: [cgal-discuss] Another question regardin Nef polyhedra -
> shalfedges
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > Hello,
> > 
> > Â 
> > 
> > If I understand correctly, when I traverse a halffacet
> > cycle, I get a cyclic list of shalfedges. I gatherd that every other
> > shalfedge
> > is on the spheremap of a vertex (and the others are what is called
> > â€&#65533;oriented
> > edge-useâ€&#65533;). How do I know which is which?
> > 
> > Â 
> > 
> > Amir.
> > 
> > 
> > 
> > 
> 
> 
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