(Cycles bug) I need render only specific pass without process combined pass...

How can render only AO pass or only shadow pass without process combined pass…
It is an essential feature in any engine that boasts.


I have tried some tests and I have not been able to not do the combined pass, even when it is not selected.

What I did:
Under the Layer settings menu, select Passes, and then select AO. Deselecing the combined pass (and depth) makes no difference as the combined pass is rendered anyway. Not sure if this is a bug.
Go to the node editor, select compositing, and then attach the AO pass to the input of the composite node, giving an AO output.

It has to be a bug, unchecking the combined pass should not waste time or resources to calculate something the user is specifying that you do not need. Someone should report

bug created (rather badly): https://developer.blender.org/T46326?workflow=create

Quick response:

Sergey Sharybin (sergey) added a comment.
I wouldn’t consider this a bug. Blender Internal renderer can’t skip doing combined pass at all. Cycles in theory can skip writting to combined pass but internally it’ll still be doing all calculations needed for it so there’ll be no performance gain.

Main reason of current behavior of combined pass is due to general approach to controlling render passes and some render engines might respect settings and some might ignore them.

I can see how it might be confusing, but wouldn’t really consider a bug. Maybe good to place this to @severin radars for gaining some bifgger interface picture for improvement.

So thanks for the report, but closing as a TODO.

@BiggR thanks.