[MOAB-dev] Order of the nodes in get_connectivity

[Vijay S. Mahadevan]

Hi Filipe,

Are you asking specifically about how to look at the numbering for the
nodes in each element type ? These are available in the CN (Canonical
Numbering) class [1]. If you are looking at numbering for specific
element types, you can look more closely at the mConnectivityMap
declaration in [2].

> 1. Is there a method from MOAB to calculate areas and volumes?

There are examples that do this. Again, what element types are you
interested in?

You can look at the methods exposed by verdict.h and use the area
calculation method corresponding to your element.

> 2. How are the nodes ordered in the get_connectivity method?

The ordering in the get_connectivity uses the internal MOAB numbering
in the local space.

Vijay

[1] https://ftp.mcs.anl.gov/pub/fathom/moab-docs-develop/CN_8cpp.html
[2] https://ftp.mcs.anl.gov/pub/fathom/moab-docs-develop/MBCNArrays_8hpp_source.html

On Tue, Sep 22, 2020 at 1:44 PM Filipe Antônio Cumaru Silva Alves
<facsa at cin.ufpe.br> wrote:
>
> Hello,
>
> I'm developing a tool for multiscale mesh preprocessing using MOAB and
> I'm currently working on a method to calculate areas and volumes for the
> mesh elements. This task depends on the order of the nodes returned by
> the get_connectivity method. However, I can't find any information in
> the documentation on how the nodes are sorted other than the definition
> (here
> <https://ftp.mcs.anl.gov/pub/fathom/moab-docs-develop/classmoab_1_1ElementSequence.html#a918f9016130f7b0d7e3598dda2984430>)
> and the implementation (here
> <https://ftp.mcs.anl.gov/pub/fathom/moab-docs-develop/classmoab_1_1UnstructuredElemSeq.html#af0d6d48f8d60cd82a1a8abc3a7d433ca>).
>
> Thus, I have two questions:
>
>  1. Is there a method from MOAB to calculate areas and volumes?
>  2. How are the nodes ordered in the get_connectivity method?
>
>
> Many thanks,
>
> --
> Filipe Antônio Cumaru Silva Alves
>