Scanlines are good only when an integer resolution is applied, but is required to disable scaling in gpu driver, so i have to use "no scaling" and gpu scaling is necessary... (tested a resolution of 1600x1000 with some 320x200 games and 1280x960 with some 640x480 games, output=opengl, scaler=scan3x first and scaler=tv3x next for 320x200 games, scaler=scan2x and scaler=tv2x for 640x480 games; with a non-integer resolution there are bad scanlines and many distorsions, so is the same problem... tested also output=openglnb but it cause some distorsions also with all these resolutions, so is not recommended... and i think that output=surfacenp is the same, but i haven't tested it for now)
So if i want to use scanlines with games i have to use output=opengl because output=surfacepp is... "capped" to scaler=none...
i've tested the same games also with scaler=normal5x but is not the same... so output=opengl wih 1600x1000 resolution on 320x200 games is not the same as native resolution and output=surfacepp... (with native resolution and surfacepp all images and pixels are perfect with all games, but lack scanlines...)
Many old games are good only with scanlines... i suggest to add support of scanlines also for Pixel-Perfect Patch, without add a 2x or 3x scaling (that is not need with native resolution i think, and Pixel-Perfect patch use only scaler=none because a scaling 2x or 3x is not needed)
some scanlines are these https://www.google.it/search?safe=active&hl=i … i30.1rgD_vuEvV4
note: that Pixel-Perfect patch will not be needed (i think) if nVidia, Amd and Intel will add integer scaling in a next driver (but we don't know if can happen... so don't remove it)