dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Mar 17, 2008 at 05:50:10PM -0500, Matthew Knepley wrote:
> On Mon, Mar 17, 2008 at 5:46 PM, Anders Logg <logg@xxxxxxxxx> wrote:
> > Yes, the mesh ordering used in DOLFIN (intentionally) screws up any
> >  ordering, like all cells being "right-oriented" or similar.
> >
> >  If this is a problem for GTS, we need to do something about the GTS
> >  interface (not the mesh).
> 
> The solution we use in Sieve is to reconstruct a "right-oriented" closure
> from information in the arrows. This is stored just like a section, only its
> over arrows, not points. You could also think of an arrow as carrying a
> "payload" (this is how Dmitry's system works).
> 
> This way you can have whatever system you want in your mesh itself,
> but construct oriented simplices when GTS needs them.
> 
>   Matt

That could be a solution, either create a copy of the mesh with a
different ordering and hand that to GTS, or create a MeshFunction over
cells (which holds the orientation for each cell), but it would be
better to figure out where the ordering is used, either in GTS or our
interface to it so we could avoid having to store extra data.

-- 
Anders