Hello today I am posting this post to ask you what would you smart guys do
to solve this kind of problem (ok … at first I thought it was easy and I’ve spent days and hours looking for the solution from my head and … I admit I am stupid ! I need your help)
My goal is simple (I think it’s simple but I can’t find the solution)
It is to render 2 different objects separately
but they should look the same as what we see
in the blender’s viewport
We don’t have lots of objects we have just 3 :
A red house + Fake dummy windows
Windows (Real Windows)
I just want to render a red house
and windows
separately
but they should look the same as what we are seeing in the viewport like this
Depending of your methods, we might not need the fake windows
but for me I needed it so I created it but I failed the result what I am getting
is different as what we are seeing in the viewport.
What I’ve done is the following (you might notice where to change and improve by
reading my work log below)
1.I’ve created a red house inside the “red house collection”
2.I’ve created the windows inside the “real windows collection”
3.I’ve created 2 different layers and activated their corresponding collections
4.I’ve managed the composition node tree
5.I’ve pushed the rendering button but HDRI background was there in each layer (ops !)
(so positioning a layer in front of another layer didn’t matter) I forgot to turn on the transparency
in film which is in the rendering configuration
6.I’ve turned on the transparency in the film section and pressed the rendering button ggain and noticed the hdri background is gone as expected and now positioning a layer in front of another layer did matter so I’ve tried one before another, two times but both didn’t work as intended the result was like these
7.I noticed my mistakes, I forgot to add the dummy holdout object at the place of the windows
so, my red house layer with dummy hold out object is in front of the windows layer.
(dummy hold out object will be transparent so the layer behind of it, the windows layer will show its object there)
8.The theory and the logic was good I’ve applied it but I was not that smart I was a fool. The result
what I am getting is like this
(So… in my understanding the dummy hold out window seems to be hiding the interior of the
house in which should be visible)
Here is my blender file + my compositing node tree set up to help your understanding
6-blender file.blend (984.9 KB)
I need help I know it is not a hard problem but I just cant do it lol
I really need heeeeeeeelp guyz thanks in advance 
For those who are thinking that I am not working seriously (just by looking the simple figure)
You are right, just by looking the screenshots and the simple 3d object you might think
that I am playing and joking with you, I understand your feelings, but I am serious.
To be honest this blender file is not the blender file which I am working on atm
The blender file and example picture uploaded are a simple demonstration files
(made within 5minutes) to show you and describe
the problem what I am facing as clearly, simply, easily as possible
(Please understand my privacy 
)