[cgma-dev] Inconsistency in getEntities for iGeom interface. Causes problems in iRel.

[Patrick Shriwise]

Hi all,

After a lot of investigation, I've discovered an inconsistency in the 
iGeom function getEntities() (line 1149 iGeom_CGMA.cc). This problem can 
actually be seen throughout the file iGeom_CGMA.cc file, but I'm using 
getEntities as an example.

When entities are loaded from a standard geom EntSet (or a group), 
CubitEntities are returned.

However, when querying from the root_set, RefEntities are returned.

In most cases this seems to be ok, except for the case of Volumes. When 
volumes are queried at the with the root_set as the set_handle, the 
RefEntitiy for the body that contains that volume is returned. However, 
if a volume (not the body it belongs to) is added to an EntSet or Group, 
the volume CubitEntity will be returned from iGeom's getEntities.

This causes problems in iRel when trying to populate groups in other 
software (to be specific, Meshkit). When ModelEnts are created upon 
loading a file they are created for the bodies, meaning that iRel 
associates a meshset with the bodies. Then upon populating groups that 
contain volumes, iRel cannot find a relation between the geom Entity and 
the mesh EntitySet for the volume.

So..... I'm not really clear as to whether or not this is a problem with 
returning CubitEntities vs. RefEntities or if its a more conceptual 
issue cause by the different EntityType definitions between CGM and 
iGeom, shown below.

const char *iGeom_entity_type_names[] = {"vertex", "curve", "surface", 
"body"};
const char *cgm_type_names[] = {"vertex", "curve", "surface", "volume", 
"body"};

What's the best way to remedy this? Is there a way to get volumes within 
bodies via iGeom?

-- 
Patrick C. Shriwise
Research Assistant
University of Wisconsin - Madison
Engineering Research Building - Rm. 428
1500 Engineering Drive
Madison, WI 53706
(608) 446-8173

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