View through gate as alpha channel

Hello everyone!

I have created a space ship gate, which opens and closes in an animation.
Now I would like the view through this gate (the light gray area in the attached picture) being rendered as an alpha channel.
The goal is to be able to put this opening and closing gate in Premiere over various other contents.

My idea would be to create an area directly behind the gate and assign the corresponding property (via material?). But how exactly does it work?
Or do you have to take a different approach?
What makes the thing a bit more difficult now is that I use an HDRI image. Thus I always have an background.
Otherwise it would be quite easy.

Would be very happy about help.


Simpleā€¦ Properties Editor > Render > Film > Transparent (check)

http://i.imgur.com/tn9sQ2Q.jpg

PS
be sure to render/save using image format supporting alpha channel
it also works in real time IPR (see to be sure)

Awesome, thanks.

:slight_smile:
please mark thread as solved (advanced settings)