[cgma-dev] Faceting tolerances in OCC

[Steve Jackson]

On Dec 8, 2011, at 12:33 , Tim Tautges wrote:
> Steve, in general, users should beware of this tolerance setting for all engines, since it's commonly taken as "advice" to the engine.  

Agreed.  The Acis engine is particularly dodgy about following the edge length tolerance.  

Anyway, my thanks to Jane for addressing this.
~S

> 
> On 12/08/2011 11:41 AM, Steve Jackson wrote:
>> I am interested in two functions in CGM's OCCQueryEngine: get_graphics( Surface* ... ), and get_graphics( Curve* ... ).  Both these functions take faceting tolerances as arguments, and then silently ignore them.
>> 
>> This becomes confusing for users who convert CAD geometries to Moab meshes (e.g. using dag-mcnp5, dagmc_preproc, or mbconvert).  When OCC is the CGM backend for a client of Moab's ReadCGM, all faceting tolerances are silently ignored.  This behavior should be documented, at minimum; it may also be helpful if ReadCGM issues a warning that faceting tolerances are being ignored for an OCC-based backend.  The ideal would be a fix to the OCCQueryEngine to support the faceting tolerance parameters.
>> ~S
> 
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>             Tim Tautges            Argonne National Laboratory
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