> Are there any shaders that emulate a slot mask? All I can seem to find are scan > lines.
There are a variety of filters that simulate an aperture grill. Either with alternating Magenta and Green vertical stripes to get an an evenly spaced RGB stripe in only 2 pixels, or in a regular RGB pattern.
The "CRT-geom" filter usually has Magenta/Green stripes in other emulators but hasn't in MAME because to do it right the shader needed to know what resolution was being output and MAME didn't give that to the shaders in GLSL (I think...)
I hacked it back in when I saw that MAME could do it now, along with some other crap (tint, saturation, fading out the aperture grill for high luminance colors to keep brightness high, cubic instead of lanczos horizontal scaling) but I haven't posted it anywhere because I didn't know if any if it was done quite correctly and I didn't want to post shoddy modifications to someone else's code. I could zip it up and post it here as long as people understand that it was done by someone with no graphics coding experience...