[petsc-users] DMPlexCreateFromDAG and orientation

[Matthew Knepley]

On Sun, Nov 19, 2017 at 4:59 PM, Yann Jobic <yann.jobic at univ-amu.fr> wrote:

> Hello,
>
> I want to create my custom DMPLEX by using DMPlexCreateFromDAG(). I tried
> with only one cell. I have :
>

It looks like a hex cell. Here is how I order hex cells:

https://bitbucket.org/petsc/petsc/src/d89bd21cf2b5366df29efb6006298d2bc22fb509/src/dm/impls/plex/plexinterpolate.c?at=master&fileviewer=file-view-default#plexinterpolate.c-113

The first four vertices are on the bottom, last four on the top. Those
faces start with vertices right above each other, and
the faces have outward orientation. You can check your structure by looking
at the faces specified above, and see if it
matches yours, with outward orientation for all.

Eventually me, or someone, will draw pictures of these for the manual.

  Thanks,

    Matt


>   type: plex
> Mesh 'DM_0x3dd7df0_0':
> orientation is missing
> cap --> base:
> [0] Max sizes cone: 8 support: 1
> [0]: 1 ----> 0
> [0]: 2 ----> 0
> [0]: 3 ----> 0
> [0]: 4 ----> 0
> [0]: 5 ----> 0
> [0]: 6 ----> 0
> [0]: 7 ----> 0
> [0]: 8 ----> 0
> base <-- cap:
> [0]: 0 <---- 1 (0)
> [0]: 0 <---- 5 (0)
> [0]: 0 <---- 7 (0)
> [0]: 0 <---- 3 (0)
> [0]: 0 <---- 2 (0)
> [0]: 0 <---- 6 (0)
> [0]: 0 <---- 8 (0)
> [0]: 0 <---- 4 (0)
> coordinates with 1 fields
>   field 0 with 3 components
> Process 0:
>   (   1) dim  3 offset   0 0. 0. 0.
>   (   2) dim  3 offset   3 0. 0. 0.01
>   (   3) dim  3 offset   6 0. 0.01 0.
>   (   4) dim  3 offset   9 0. 0.01 0.01
>   (   5) dim  3 offset  12 0.01 0. 0.
>   (   6) dim  3 offset  15 0.01 0. 0.01
>   (   7) dim  3 offset  18 0.01 0.01 0.
>   (   8) dim  3 offset  21 0.01 0.01 0.01
>
>
> Which is not correct when i'm trying to see the DM in visit. I tried one
> from the example ex4.c, which gives :
>
> base <-- cap:
> [0]: 0 <---- 1 (0)
> [0]: 0 <---- 2 (0)
> [0]: 0 <---- 3 (0)
> [0]: 0 <---- 4 (0)
> [0]: 0 <---- 5 (0)
> [0]: 0 <---- 6 (0)
> [0]: 0 <---- 7 (0)
> [0]: 0 <---- 8 (0)
> coordinates with 1 fields
>   field 0 with 3 components
> Process 0:
>   (   1) dim  3 offset   0 -1. -1. -1.
>   (   2) dim  3 offset   3 -1. 1. -1.
>   (   3) dim  3 offset   6 1. 1. -1.
>   (   4) dim  3 offset   9 1. -1. -1.
>   (   5) dim  3 offset  12 -1. -1. 1.
>   (   6) dim  3 offset  15 1. -1. 1.
>   (   7) dim  3 offset  18 1. 1. 1.
>   (   8) dim  3 offset  21 -1. 1. 1.
>
> And this one is perfect.
>
> I may have a problem with the "cone orientation", but i really don't
> understand how to set it. I tried the use DMPlexOrient(), but i still have
> the problem.
>
> However, my connectivity looks good. What i am doing wrong ? This is even
> more complicated when i have two cells sharing a face.
>
> Thanks for the  help !
>
> Regards,
>
> Yann
>
>
>
>
>


-- 
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.caam.rice.edu/~mk51/>
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