Hi
I want to get objects invisible in render but masking the visible ones. I can use holdout but it works using materials and it could be nice to do that as objects because one object can use a lot of materials. Does it exist any alternative to this? Thanks
I think cryptomatte will do that.
https://docs.blender.org/manual/en/latest/render/layers/passes.html#cryptomatte
You can use the obj pass index (for example here suzanne set to 10) and get the masking with the ID mask node and a set alpha node :
See you 
++
Tricotou
Thanks both. So it’s not possible directly from render it takes compo work 
Well, I suppose I should change my mind from the other soft I used 
but have both ways would be nice
You kind of can if you are willing to use one giant material for all objects in the scene. Then, you can use object id based masks to set the shaders for each object. Just don’t assign an id mask to any object that should use the holdout shader in the following example:
You can nest really complex shaders into one material using this method.
