Object index assignments on group instances?

Support Compositing and Post Processing
1

Hi all,

I’m new to Blender but not to 3D, and so far I must say I’m happy to leave Maya behind. Well at least for now.

From the title you can probably guess the question, but let me explain.

I understand how to use the “Object Index” assignments to output holdout mattes for my geometry. However, I’d like to know if it’s possible to assign an “Object Index” to a “Group Instance” instead of assigning them to the individual objects directly. This would be convenient since all my layout assets exist in external blend files, and I’d like to be able to change their indicies as a group without batch assigning.

OR am I missing something and is there a better way to manage and generate holdouts? I should also mention that assigning an object index to a group instance applies only to the null that references the object and not their geometry.

Much appreciated.
Evan

2

I don’t think there is an easy way to do it.
First of all you can’t assign index to “empty” and the group is in fact an empty.
Second - Your objects are in different files and it’s impossible to change some of their properties in file they are linked to.

Maybe with a bit of help of python something could be done, but at the moment I don’t have a good idea for it.
The solution I am thinking about wouldn’t of-course let you “assign” index to group, but maybe some workaround would be possible.