Hi James, I read your original question more carefully, and it looks like you want a separate followed by a join to have the same sub-object ordering as the original pre-separated object? Unfortunately I don't think there will be any reliable way to control that, the join process does not try to preserve ordering, it just combines faces into one brep and then goes through unjoined edges, comparing them to other unjoined edges, gluing them together if they are within tolerance. It's not surprising that some traces of the original order will remain but I don't think that it's going to be reliable.

One thing that might work for you though is to track things by setting object names on sub-objects. For example if you assign a unique object name to each edge of the original object, that name will come through the separate and rejoin process and so if the name was the index value in the original object you could recover the original index that way. I think that should work for both face and edge sub-objects.

- Michael

Hi Michael,

I can understand why the ordering objects may not be preserved after joining and then separating. But in the instance of the node files attached to last email:
a lofted surface Loft/Style: Straight when separated breaks into an array of surfaces
that are indexed sequentially in rows as would be expected.

However applying an Offset to the lofted surface, prior to separating, will result in a disordered indexing of objects.

>>One thing that might work for you though is to track things by setting object names on sub-objects.<<

I can see how it might be possible automatically generate names for each new object after separation and catalogue them in order. Then if they become disordered by the application of joining & separating or offsetting, the original index could be reinstated as per object catalogue.

Anyway, thank you for responding to my query.

All the best with your work on V4. You seem to be edging ever closer

Regards James

Hi Michael,

I manager to achieve the desired result by splitting array of facets into alternating rows (idxSelect), then joining (Join) each of the new arrays, bundling (bundleArray)& joining again (Join) then offsetting (Offset) and finally separating (separateObj).

It seems like a circuitous route but it ensures the original ordering is preserved.
It would not have occurred to me, had you not explained the operation of these processes.

So thank you, James

You're welcome James, your result is looking good!

- Michael