On Tue, Jun 23, 2009 at 09:25:19AM +0200, 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. > > 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). > > The Dolfin XML file format needs to be documented.
Yes, and there's some ongoing work on creating schemas and validating against these schemas when parsing (Relax-NG using libxml2). Ilmar has been working on it but I don't know the current status. Ilmar? Ola? -- Anders
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