[petsc-users] [Gmsh] Access both default sets and region names

[Noam T.]

Without using the flag -dm_plex_gmsh_use_regions, the DMGetNumLabels says there are 5, named celltype, depth, cell/face/vertex sets.
With the flag, the labels are celltype, depth, my_vol, my_surface (using the same example as before).
Am I misusing the flag somehow, and I should be able to access those of cell/face/vertex as well?

PS: Using PETSc 3.20.3

Thanks,
Noam
On Thursday, January 11th, 2024 at 5:28 PM, Matthew Knepley <knepley at gmail.com> wrote:

> On Thu, Jan 11, 2024 at 11:18 AM Noam T. via petsc-users <petsc-users at mcs.anl.gov> wrote:
>
>> Would it be feasible to have an option (e.g. new flag along the lines of -dm_plex_gmsh_...) that allows the user to access both the default sets (Cell / Face / Vertex) together with user-defined gorups (those under $PhysicalNames, available when using -dm_plex_gmsh_use_regions)?
>
> I am not sure I understand the question. When you turn on regions, it makes extra labels, but the generic labels still exist.
>
> Thanks,
>
> Matt
>
>> That is, with a *.msh file containing
>>
>> $PhysicalNames
>> 2
>> 2 100 "my_surface"
>> 3 200 "my_vol"
>>
>> the return of DMGetLabelName(dm, n, name) would be (order may differ)
>>
>> n = 0, name = "celltype"
>> n = 1, name = "depth"
>> n = 2, name = "Cell Sets"
>> n = 3, name = "my_vol"
>> n = 4, name = "Face Sets"
>> n = 5, name = "my_surface"
>> ...
>>
>> I poked into src/dm/impls/plex/plexgmsh.c and have managed to print all the labels after changing a couple of variable values, so perhaps it is doable.
>> The changes made are not a solution, simply naively set some variables to skip checking for the use_regions flag, so it understandably crashes soon after.
>>
>> Thanks, Noam
>
> --
>
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener
>
> [https://www.cse.buffalo.edu/~knepley/](http://www.cse.buffalo.edu/~knepley/)
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