Just checked the filter code, and it’s just a simple pass one. I’ve not tested it but setting proper alpha shouldn’t change the rendering result in this case.
I had a similar issue using SSAO wiht the screen capture thing you help me with here
When adding the filter the background went black and I had to add the following code
if(texture2D(m_Normals, texCoord).a < 0.1)
discard
at the beginning of ssao.frag main: jmonkeyengine/ssao.frag at 98f6d326e1d062aa4e1103e4729c02f0c0f16cc1 · jMonkeyEngine/jmonkeyengine · GitHub
I’m using the exact same shader for regular SSAO filtering on the rendered viewport without issues