How does Alias sort layers by hierarchy?

[sgeggie]

For background: I'm writing an importer for Alias data, and I want to maintain scene structure as precisely as possible.

I am wondering if anyone could explain what the sorting mechanism is for layers in the Object Lister when sorting "by hierarchy (SBD)".

I've been comparing the Layer view with the Object view, since I thought they would be related. I had assumed at first that the layer with the first object in the Object view (sorted by SBD) would come first. That doesn't always seem to be the case, however.

A general explanation of how layers are sorted with "By Hierarchy" would be great. If anyone has experience with the API and knows of a simple way to retrieve this order, that would be even better! 😄

Thanks in advance,

- Sean

[Anonymous]

hi,

i use SBD a lot but i cant see any relation between the hierarchy sorting and the SBD.

There is no layer-hierarchy in SBD as much as i know. The SBD is a module from the very beginning of Alias and they did not tune it so much over the decades...

As i understand it, the hierarchy option sorts layers as you put them eather in object lister or layer bar. Maybe its simply a wrong title for the sort option - an admittedly bold assumption...

Regards

[sgeggie]

Thanks a ton for the input!

I think you have a point here. I tried taking my standard testing model and reassigning everything to one layer. This did not change the sorting order one bit, even when I reassigned it all to a different layer.

So the sorting of layers under Hierarchy doesn't seem to have anything to do with what's on them.

It seems the sorting of layers is done completely manually. For instance, using the "Insert new layer" command in the object lister allows you to insert a layer where you want to in the hierarchy. It looks like Alias just tracks this ordering of layers somewhere.

So what I'm looking for is some way of extracting the order information from a .wire file using the Alias API.
Here's hoping there's an API pro lurking somewhere on this board!

Thanks,

- Sean

[Anonymous]

well, unfortunately i have no clue of the Alias API. Actually i tried to get into it, but since i dont have enough knowledge i put this on the "to-do-later-list".

But there is the guy who made the Alias 2 Rhino-import/export plugin. You find him on  digital-sculptors.com .  He definitely had to deal with the Alias layer-structure. Maybe he would give you some hints... Check the Contacts page...

[c3systems]

Hi Sean,

I am "that" guy.. I was surprised to find Alias API questions in the forum... happy to know other OpenAlias/OpenModel users out there.

Internally every Alias layer has a number. The numbers are exclusive and cannot be changed after the layer creation. 0 is the Default Layer.

Please refer AlLayer class for more info.

Also, I was reading through your other question on Instances. Please be aware that there can be multiple levels of Instances .. Layer symmetry is also an instance.

Regards,

rajeev