llnl / llnl/conduit

Evaluate face node ordering in TOPO_WEDGE_EMBEDDING, TOPO_PYRAMID_EMBEDDING.

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C++
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Description

The face node ordering in TOPO_*_EMBEDDING shapes is counter-clockwise when viewed from the outside of the element for TET and HEX elements. The pyramid and wedge (wedge especially) contains some triangles that are clockwise from the outside of the element - using a VTK node ordering. It seems they should be consistent (all counter-clockwise) but this will change the element edge ordering, if that matters.

VTK wedge
```
2 1
*------------*
|\ /|
| \ / |
| \ / |
| \ / |
| *0 |
| | |
| 5 | |
*-------|----*4
\ | /
\ | /
\ | /
\|/
*3
```
There are different possible starting nodes. Here are some possibilities.

Wedge:
0,1,3 -> 1,0,3
1,2,4 -> 1,4,2
2,0,5 -> 0,2,5
3,4,5 -> 3,5,4

Pyramid:
0,1,2 ->1,0,2

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start from the TOPO_WEDGE_EMBEDDING and TOPO_PYRAMID_EMBEDDING definitions and compare their face and edge ordering with the VTK wedge and pyramid diagrams in the issue. Determine whether changing the clockwise faces preserves required edge ordering; done means the ordering decision is implemented consistently or the compatibility concern is resolved and documented.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
data, hpc
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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