Applying a visual effect to a players screen

[Mental]

I'm working on a weapon for ttt, and I would like to be able to apply an effect to the targets screen. I've searched around for a while and I can't find anything similar (in weapon form)

My question is basically, does anyone know a reasonably simple way to add an effect over a players screen? (like something from drug mod or the post processing effects in sandbox)

Apologies if I've missed something obvious, and thanks in advance for any help :)

Edit: To add more info, one of the issues I've found is that applying an effect such as DrawMotionBlur, is purely client side. As I'm trying to apply it from inside a SWEP, I have no way to run client side code on the person who's shot (I can run it on the owner of the gun)

[Acecool]

I'd say take a look into this hook: RenderScreenspaceEffects - it's client-side.

[url]http://wiki.garrysmod.com/page/GM/RenderScreenspaceEffects[/url]

Also check this list for some of the effects:
[url]http://wiki.garrysmod.com/index.php?title=Special%3ASearch&search=RenderScreenspaceEffects&fulltext=Search[/url]

It'd probably be best to network it. So, whoever gets shot; use a bullet callback or entity take damage hook if you want, then network from the server to the target and have the client render the effects.