On Wed, Jun 24, 2009 at 09:54:10AM +0200, Kent Andre wrote: > On ti., 2009-06-23 at 11:09 -0600, Bartosz Sawicki wrote: > > Kent Andre wrote: > > > On ma., 2009-06-22 at 20:57 +0200, Anders Logg wrote: > > >> On Mon, Jun 22, 2009 at 12:46:09PM -0600, Bartosz Sawicki wrote: > > >>> Kent Andre wrote: > > >>>> On ma., 2009-06-22 at 00:40 -0600, Bartosz Sawicki wrote: > > >>>>> On 22/06/09 12:06 AM, Anders Logg wrote: > > >>>>>> On Sun, Jun 21, 2009 at 11:36:29PM -0600, Bartosz Sawicki wrote: > > >>>>>>> On 19/06/09 02:53 PM, kent-...@simula.no wrote: > > >>>>>>>> When using VMTK the boundary indicators are stored as a set of > > >>>>>>>> arrays > > >>>>>>>> with names > > >>>>>>>> boundary facet cells, > > >>>>>>>> boundary facet numbers > > >>>>>>>> boundary indicators > > >>>>>>>> The two first arrays are used to find the global facet numbers. > > >>>>>>>> The function computes a mesh function based on these arrays. > > >>>>>>>> > > >>>>>>>> This was what Anders prefered since VMTK does not now anything > > >>>>>>>> about the global numbering of facets in Dolfin (without linking it > > >>>>>>>> into > > >>>>>>>> Dolfin). > > >>>>>>>> > > >>>>>>>> This is not a VMTK specific problem, but I do think VMTK is the > > >>>>>>>> only > > >>>>>>>> mesh-generator > > >>>>>>>> that let you store boundary indicators at the moment. I guess we > > >>>>>>>> should add > > >>>>>>>> this to NetGen as well, both Hans Petter Langtangen and Douglas > > >>>>>>>> Arnold has > > >>>>>>>> bugged > > >>>>>>>> me about this the last few days. > > >>>>>>> I'm every day user of this functionality. I use Netgen generated > > >>>>>>> models, > > >>>>>>> but also other software which add boundary indicators to existing > > >>>>>>> meshes. Netgen supports boundary indicators quite well, both by geo > > >>>>>>> files, and by GUI. I don't understand what you want to add? > > >>>>>> Is it possible to set DOLFIN boundary indicators from Netgen? I > > >>>>>> didn't > > >>>>>> know. > > >>>>> It is definitely possible :) I don't have direct converter from > > >>>>> Netgen > > >>>>> vol to Dolfin xml. Most of my old models were stored in Diffpack grid > > >>>>> format, so I'm using grid to xml converter. > > >>>>> Netgen can export to the grid format, so this is not a big issue. > > >>>> It is not possible to store the boundary indicators in Dolfin format > > >>>> using Netgen, at the current time. I wrote the Netgen -> dolfin filter > > >>>> in Netgen so I should know :). > > >>>> > > >>>> But it should be possible to include support for that in a similar > > >>>> fashion as we did in VMTK. > > >>> You are right that Netgen doesn't support Dolfin XML mesh format. But > > >>> it > > >>> doesn't mean that is not possible to use boundary indicators generated > > >>> by Netgen in Dolfin. Converterting via Diffpack grid file preserves > > >>> boundaries. > > >>> > > >>> The algoritm is simple: > > >>> 1. Generate mesh using Netgen. > > >>> 2. Mark boundaries indicators. > > >>> 3. Export to Diffpack format. > > >>> 4. Convert Diffpack to XML. > > >>> 5. Enjoy boundary indicators in Dolfin. > > >>> > > >>> cheers, > > >> Nice, but not optimal. At some point, we need an application that can > > >> do all of these (and more). There seem to be a couple of different > > >> options: > > >> > > >> 1. Extend Netgen with full support for DOLFIN (and change the > > >> toolkit...) > > >> 2. Extend Gmsh with full support for DOLFIN (and change the toolkit...) > > >> 3. Extend MeshBuilder to do mesh generation (using for example Netgen) > > >> 4. ? > > >> > > >> Any thoughts on these options? > > >> > > >> The problem with (3) is that no one is really developing MeshBuilder, > > >> except when we pay Kalkulo (http://simula.no/applications/kalkulo/) to > > >> do it. > > >> > > > > > > It should be fairly easy to include bc indicators in NetGen. I can look > > > at it, I think I need to update the filter anyway to make sure the mesh > > > is ordered correctly according to UFC. > > > > Are you going to extend Netgen to enable export into dolfin-xml? > > You mentioned about some filter, is it somewhere in dolfin repository? I > > can't find anything. Can upload your code into dolfin-convert utility? > > Netgen, in its newest version, can export to dolfin xml. But only the > mesh, not the bc indicators. > > > > > > In general it is rather easy to write out the mesh and indicators > > > compared to actually making it. I bet we can make Gmsh write Dolfin mesh > > > in just a few hours (but I have not looked at Gmsh). > > > > I'm sure that it will be easy. But don't you thing that good converter > > is more flexible solution? > > > > cheers, > > > > I don't know.
Writing directly to DOLFIN from inside Gmsh should be just as flexible as first writing to Diffpack and then converting. But having a good conversion tool is also important. -- Anders
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