Proposal for telling an implementation what adjacency info an app/service needs

[Carl Ollivier-Gooch]

Tim Tautges wrote:
> Hmm, I'm not sure I like this.  I thought setAdjTable was supposed to be 
> used to request which entities an application or service needed.  I've 
> coded it into MOAB's iMesh implementation that way, IIRC.  Looking at 
> the current comments to getAdjTable, we should put something there 
> describing what the values mean then.  I would vote for setAdjTable 
> being the function used to request intermediate-dimension entities.

What I meant, as Tim said, was that setAdjTable requests what the client 
needs, including whether an entity type will be iterable.  And yes, 
that's what MOAB's implementation of this (still unofficial) function does.

Not sure what you mean about intermediate dimension entities...

> Jason Kraftcheck wrote:
>>
>> I don't think this is the correct way to do this.  The getAdjTable 
>> function returns the cost of making such queries.  It doesn't say 
>> anything about whether not, for a database such as MOAB that uses a 
>> reduced representation, that the requested entities are guaranteed to 
>> exist.  I assume that with your setAdjTable command you are trying to 
>> require that the database guarantee that lower-dimension entities 
>> exist explicitly that correspond to sides of higher-dimension 
>> entities. Otherwise I'm not sure what it means to set the adjacency 
>> table.
>>
>> If my assumption is right, then the functionality you are requesting 
>> is not analogous to the getAdjTable function.  For example, with a 
>> reduced mesh database it is common for meshing applications to define 
>> the quads corresponding to sides of hexahedra only on the skin of a 
>> hex mesh.  The getAdjTable results give some indication of how quickly 
>> the database can find whether or not such quads exist for a given hex 
>> and return the ones that due.  It says nothing about whether or not 
>> you'll get six quads for a given hex.

Carl

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Dr. Carl Ollivier-Gooch, P.Eng.                   Voice: +1-604-822-1854
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