Persistent id on topology?

Hello,

does Rhino save persistent ids on the faces and the edges of breps ? If yes, please where can I find them with opennurbs ?

Regards.

Hi @jerome.roche,

No it does not. Why do you need this? What programming language are you working in?

– Dale

Hi Dale,

I import a 3dm brep and attach some information on some faces or edges. If the 3dm brep changes and if I import the changed version, I want to be able to recognize the faces or edges I previously imported.

I am using C++ programming language.

When working with the history activated, does not Rhino keep a track on the topology ?

Please what is the purpose of the following lines in opennurbs_brep.h ?
// Persistent id for this face. Default is ON_nil_uuid.
ON_UUID m_face_uuid = ON_nil_uuid;

Thank you for your answer.

Hi @jerome.roche,

Thanks for reminding me about ON_BrepEdge::m_face_uuid, I had forgotten we had added that. Sure, you can use that to track faces. There isn’t an equivalent on ON_BrepEdge. To track edges, you might consider adding either user text or user data to the edges underlying 3D curve, or ON_Brep::m_C. You can do something similar to faces if you choose not to use m_face_uuid. Here is an example:

/cmdSampleBrepFaceUserData.cpp

– Dale

1 Like

Hi Dale,

why did you add ON_BrepFace::m_face_uuid ? Is there a way to make Rhino set ON_BrepFace::m_face_uuid in 3dm files, without developping a custom command ?

Thank you for your answers.

No, there is not.

– Dale