Get alpha from Post process material??

Hi everyone,
Right now I’m working on draw buffer from post process material to render target. So,I would like to get alpha channel from post process material. Then I found this setting like this image.

217525-1.png

I set it true but the alpha didn’t come. How can I get alpha with rgb color and draw to render target. Thank you!!

1 Like

I’d really like to know what this setting does, too. It adds “Opacity” output to the material. But I could not see any change while testing. Right now (UE 4.18) it seems not to be completely implemented:

Outputting alpha is not yet supported (should go through Opacity).

Maybe this helps you: You can lerp your PP effect with SceneTexture:PostProcessInput0 to make it look like it has transparency…