Creating a texture from the front and backbuffer

[cronodragon]

It was probably related to some interaction [driver bug ?] of different sizes of original (640x480) DepthBuffer and your new (512x512) renderTarget.
You can try to create and set new DepthBuffer with 512x512 size and assign at the same time with new renderTarget.

Ok.

PS. Creating / destroying VertexBuffer each frame is REALLY BAD!

Really?! Hmm, I will create a global mesh for my filters. Thanks

By the way, I found out that it's better to disable texture smoothing when creating those filters.