Object ID Stacks in Rhino and List Order

I'm trying to figure out some list ordering between grasshopper definitions ad rhino edits

I need to know if I should be able to retain, or at least know, a list order through the following set of actions:

1. bake a set of objects into a 3dm file, onto a layer solely dedicated to them

2. move and rotate the objects in the 3dm file

3. save the 3dm file

4. open the 3dm file on another computer

5. Bring the same set of objects into a new grasshopper definition, using "Set Multiple" and then selecting by layer.

Should the set of objects have the same order after step 5 as they did in step 1? The reverse order? Another order altogether? Does moving and rotating affect the order of the object IDs in the 3dm file?

Any help appreciated.

Thanks!

Replies to This Discussion

Permalink Reply by Damien Alomar on June 15, 2010 at 9:09pm

You will not be able to rely on the order of objects after doing any modification to them in the Rhino document, and especially after saving the document and reopening it. I'm sure there is some logic there, but ultimately, I wouldn't depend on it being consistent. At times when I've tried to check the order Rhino maintains I sometimes get consistent answers and sometimes do not. If you need a specific order of the objects in question, I strongly recommend that you find a way to keep that order yourself. Something like saving the order of the UUIDs to a text file should work alright.

Permalink Reply by Benjamin Golder on June 15, 2010 at 10:57pm

Thanks Damien!

So to maintain an order, I could bake the objects into Rhino, and immediately bring them back into Grasshopper, and then use an "ID" parameter and a panel to draw out a list of GUIDs into a text file. (I'm not totally clear on the difference between UUIDs and GUIDs, but the ID parameter says that it lists GUIDs)

In terms of maintaining consistent IDs, which kinds of Rhino transformations destroy the ID? My impression has been that moving and rotating objects would not change their IDs, but that something like rebuilding a curve would basically create a new object, and therefore would have a different ID. Will IDs remain consistent if the objects are only moved and rotated? if they are scaled? Are object names more reliable? What kinds of edits would eliminate the link to an object name?

maintaining a list of IDs seems simpler than object names, because it would not require the use of VB components to name and to call in each object.

Permalink Reply by Benjamin Golder on June 16, 2010 at 1:11am

So far, creating a text file with a list of GUIDs has worked great. Thanks again Damien. I appreciate it.

Permalink Reply by David Rutten on June 16, 2010 at 4:13am

UUID = Universally Unique IDentifier
GUID = Globally Unique IDentifier

However the terms are used interchangeably. Whenever you see "uuid", just think "guid" and you'll be fine.

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by Benjamin Golder on June 16, 2010 at 5:22am

Thanks David!

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