> I haven't noticed any interpolation using the attached GLSL shader based on Lottes' work. It is obvious from that screenshot you posted though.
I added an example of lottes implementation in my last post.
> Would rounding to the nearest integer for each scanline have a desirable effect or would that introduce other issues?
If I would force all scanlines to be integer sized, 220 scanlines would be exactly 4 pixel height and 4 scanline would be exactly 5 pixel height; based on the screen and game resolution used in my examples.
As I said before it would be the best to have a screen resolution which has a multiple of the game resolution. But then you would have a black border around the screen, depending on the real resolution of your monitor.