No, I know it's possible without render to texture because transparent entities are sorted like 2D images (because problems occur when two transparent entities are drawn together). This means they're drawn sorted like layers. I need something that, right when an entity is about to be drawn, to distort the pixels behind it.

Nothing in computer programming is impossible, it's just knowing how to do it. I doubt such an amazing engine as Acknex would have no support for drawing on top of already-rendered pictures.

However it's starting to sound more like a DirectX .dll plugin than a regular shader. >_<

Something that draws circles of blur like a facing sprite would be great since my need is for simplicity and speed over realistic stuff (refraction has to render another view which costs alot more than a copy and paste blitter).