[Smtk-developers] Polygon question

Robert Michael O'Bara bob.obara at kitware.com
Sun Sep 20 23:06:32 EDT 2015


Hey David,

Technically the user would not be allowed to create that edge since it would intersect the large face - the user could one of the following though:

1. Delete the model face, then create the edge, then build all possible faces (in this case 2)
2. Perform a split face operation which will result in the same topology as 1.

Bob

Robert M. O'Bara, MEng.
Assistant Director of Scientific Computing

Kitware Inc.
28 Corporate Drive
Suite 101
Clifton Park, NY 12065

Phone: (518) 881- 4931




> On Sep 20, 2015, at 6:25 PM, David Thompson <david.thompson at kitware.com> wrote:
> 
> Hi Bob,
> 
>> The situation you described would be invalid for 2d domains.  Either there is the one large polygonal model face or there are two.  To have all three would mean that a point in space would be "owned" by more than one model entity.  If we were modeling a 3D contact type of problem then a spatial point could be owned by more than one model entity; however, those model entities could not belong to the same topological "network".  
>> 
>> Does that make sense?
> 
> I am happy to take things that way. :-) However, I suspect at some point we will see someone complain about a mangled model because they created the "large" face manually; then created the middle edge and ran the "create all faces" operator — which would either fail or create an inconsistent model.
> 
> Right now, the "create edge" operator in my branch verifies the edge does not self-intersect but it doesn't do any checks against existing model faces or edges. Arguably it should not, since – as you say – users might want to construct several independent "networks."
> 
> Maybe we should have a "model geometry lint" filter?
> 
> 	David

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