so, i've been cursing at this all evening, and googling and asking around has got me well on my way to the result I want but i'm still bugged by a giant problem. the result i'm trying to get here, is a fisheye effect, but only on the edges. sort of a vignette-masked distortion, if you will a short explanation of how this…
I didn't build your setup but I think ticking "Screen Align" in the properties of your Scene Texture Sample node can help. It helped me in a similar situation.
that gets the weirdest result; the scene is so distorted it's not recognizeable anymore, as essentially you're distorting it more towards the center and less towards the outside. the texcoord node is there to have a scene to distort, basically, so that's not a option i might be going about this the entirely wrong way…