[MOAB-dev] Boundary nodes and faces

[Tim Tautges]

Don't forget to check the return value for errors :).

You can get the adj element using get_adjacencies.

- tim

On 08/15/2013 02:26 AM, Vijay S. Mahadevan wrote:
> This was actually simpler than I thought. Couple of lines solved the issue:
>
> skinner.find_skin(fileset, elocal, false, bndyfaces, bndyelems);
> pcomm->filter_pstatus(bndyfaces,PSTATUS_NOT_OWNED,PSTATUS_NOT);
> mbiface->get_connectivity(bndyfaces, bndyvtx, false);
>
> I thought that the bndyelems range would contain all the element handles that contain the face after the find_skin call.
> But this is not the case. My next related question (but not about the skinner though) is whether I can do the reverse
> lookup of the element to which a face belongs to ?
>
> Vijay
>
>
> On Wed, Aug 14, 2013 at 10:01 PM, Vijay S. Mahadevan <vijay.m at gmail.com <mailto:vijay.m at gmail.com>> wrote:
>
>     Tim, Iulian,
>
>     Thanks for the pointers. I think going from the highest-dimension down and removing shared entities from the list
>     makes sense. I have a partial implementation that already does this and will check whether this algorithm yields
>     what I need.
>
>     I was originally thinking that Skinner:: find_geometric_skin would give me the boundary vertices but doing it by the
>     process of elimination might be the right way since there is no reliance on GEOM_DIMENSION tag being explicitly defined.
>
>     Shall update soon.
>     Vijay
>
>
>     On Wed, Aug 14, 2013 at 9:50 PM, Tim Tautges <tautges at mcs.anl.gov <mailto:tautges at mcs.anl.gov>> wrote:
>
>         Note, I've added this to the MOAB faq, http://trac.mcs.anl.gov/__projects/ITAPS/wiki/__ParallelGeomSkin
>         <http://trac.mcs.anl.gov/projects/ITAPS/wiki/ParallelGeomSkin>.
>
>         - tim
>
>
>         On 08/14/2013 09:31 PM, Tim Tautges wrote:
>
>             This is tricky.  As you say, if you get the local skin, that'll include interior entities shared
>             with/ghosted from other
>             procs.  If you get the skin and remove the shared entities, that'll remove the vertices that are on the
>             geometric skin
>             but also shared with other procs.  The right way to do this is:
>
>             - get the highest-dimensional entities on the skin (1d if in 2d, 2d if in 3d)
>             - remove any shared entities from that range (because if it's shared, then by definition there will be d+1 -
>             dimensional
>             entities on the other proc)
>             - if you're in 3d and you also want skin edges, get the edges adj to the entities in the range (remember the
>             UNION arg
>             on get_adjacencies), put in tmp range, then do the same for vertices, also put in tmp range
>             - merge the tmp range with the original range
>
>             Like I said, tricky, but welcome to parallel mesh.
>
>
>         --
>         ==============================__==============================__====
>         "You will keep in perfect peace him whose mind is
>            steadfast, because he trusts in you."               Isaiah 26:3
>
>                       Tim Tautges            Argonne National Laboratory
>                   (tautges at mcs.anl.gov <mailto:tautges at mcs.anl.gov>)      (telecommuting from UW-Madison)
>           phone (gvoice): (608) 354-1459 <tel:%28608%29%20354-1459>      1500 Engineering Dr.
>                      fax: (608) 263-4499 <tel:%28608%29%20263-4499>      Madison, WI 53706
>
>
>

-- 
================================================================
"You will keep in perfect peace him whose mind is
   steadfast, because he trusts in you."               Isaiah 26:3

              Tim Tautges            Argonne National Laboratory
          (tautges at mcs.anl.gov)      (telecommuting from UW-Madison)
  phone (gvoice): (608) 354-1459      1500 Engineering Dr.
             fax: (608) 263-4499      Madison, WI 53706