[MOAB-dev] Questions about side_number

[Chris Eldred]

Hey Moab-Dev,

I wanted to clarify my understanding of the side_number function for
polygon meshes in 2D. Specifically, given a parent-child element pair;
the function returns three parameters: side number, sense and offset.

For a face-edge pair, these parameters represent:
Side_number =the index of the edge in the array (NOT range) returned
by get_adjacencies(face,1,1,edges_associated_with_face)
Sense = the orientation of the normal of the edge with respect to the
face (ie positive for outward, negative for inward)

For a face-vertex pair, these parameter represent:
Side_number = the index of the vertex in the array (NOT range)
returned by get_adjacencies(face,1,0,vertices_associated_with_face)
Sense = 0

For an edge-vertex pair, these parameters represent:
Side_number = the index of the vertex in the array (NOT range)
returned by get_adjacencies(edge,1,0,vertices_associated_with_edge)
Sense = the orientation of the tangent of the edge with respect to the
vertex (ie positive for towards, negative for away)

Questions:

1) Is this understanding correct?

2) What does the offset parameter represent in these cases?

3) Is side_number working for meshes that contain polygons with
repeated vertices (like those used in MPAS)? My preliminary testing
based on the above understanding says no, but I wanted to check. If
not, will it be working soon?

4) Is there an iMESH function (or MOAB specific extension) that would
return similar information to side_number. I need to get access to the
information returned by side_number via Fortran 90 and iMESH is what I
am currently using to access MOAB via Fortran.

Thanks,
Chris Eldred

-- 
Chris Eldred
DOE Computational Science Graduate Fellow
Graduate Student, Atmospheric Science, Colorado State University
B.S. Applied Computational Physics, Carnegie Mellon University, 2009
chris.eldred at gmail.com / celdred at atmos.colostate.edu