I tried this, thanks. Neat. Something feels a little off, though, with how interlacing is handled. When scenes are still I see a fair bit of excessive “smoothing” going on compared with my old standby from the Analog Shader Pack v. 3 - Nanao Soft. The second oddity is how the image is “broken” into blurred scanlines in areas of movement. Super Contra is a good example of where I have observed this with the machine gun fire and becomes very apparent by level 2. Using Nanao Soft in pre-slang Retroarch, however, there is no such issue, yet that shader heavily relies on interlacing as well.
I grew up with CRT televisions and there was no such issue with motion. There was never any “separation into scanline blur zones.” What did exist, though, is a pseudo-faux smoothing around the edges of objects and zones due to the blur of the alternating scanlines from the interlacing–that I could always see. Maybe this is due to how I have retroarch running? I’ll have to try some tweaks that I had to do with my dos exclusive 32 bit version to ensure the refresh rate was at a stable 60 fps.