Over the years i have played MAME with bilinear on and used Real_Scanlines.png ( https://imgur.com/a/EzkDl ) as the effect. I noticed some MAME effect files in the Retroarch overlays dir. Is it possible to use these in Retroarch in the same way? For other systems… not just MAME?
You can convert them to overlays pretty easily, you just have to repeat them in Photoshop/GIMP/whatever until they’re big enough to cover the image. We typically recommend using shaders, though.
I wouldnt have the slightest idea of how to do that hehe but thanks. At least i know its possible! 
Reason i ask is that i’m working with an Intel HD 2500. I can get CRT shaders working ok up to 16-bit era. Prefer easymode but hillian or cgwg-fast work better. But NOTHING works for PS1. Not even CRT-Pi will work without a few glitches. PS1 just looks so ugly with crsip pixels 
Found the basic scanline.cg … finally something that works with PS1 :D… Looks a tad uneven on the white part of the BIOS screen but good in games.