I’d say any 4.1 TV preset would fit. Since they were commonly hooked to consumer TV’s, scanlines/gaps were not much visible, if visible at all, so you may/not want to tweak the preset to make them more or less evident.
TV-PAL-myold recreates what I remember them to look like on my setup.
Interesting, never heard of such thing till now, so there is no way to simulate that.
It seems to act like an image mask/filter, so the implentation itself is as easy as content*image mask, but I need to check how much perf it would steal.
– It is a WIP and I’ve still to measure what’s the performance impact.
While the content itself is convincing (and definitely sexy!) some other things arise that may push the gpu requirements too high, unfortunately. but I’ll try.
-edit-
Upon further testing, my conclusion is that to add consistent reflections and ambientlight without impacting performance in a way that does not justify the gain, the following are necessary:
backdrop coordinates needs to be relative to the content instead of the screen, so any preset using the backdrop/reflections,scratches would need to be updated. @Starman99x, this may be good for you, if I remember well, you asked for global zoom level to not touch the ambient reflection/scratches and so on.
backdrop will not tilt, nor wil be curved (now is that way, but the overlay thing may need tilt or curvature. @estefan3112
The implementation would be replace the current “backdrop/mid image” blending function, so one would have to switch between modes, making them mutually exclusive, like it happens on MAME, if I understood well.
… still tinkering.
Yes. Making the backdrop image follow the global shift/zoom would make things more consistent across different presets with different zoom levels. (Less headaches, less parameters). Because the current implementation can get messy when content is rotated (regarding X/Y shift).
This would also be nice, making the backdrop curve and tilt makes it even more flexible and consistent. Even if that may not be 1:1 accurate with real backdrops.
This is now leaning more towards the colored gel feature from Mega Bezel which has served me well with backdrops and GameBoyPlayer borders.
Unfortunately that’s out of question :((
No problem.
Regarding the issue @estefan3112 faced, when I’m met with backdrop games that require a color overlay, I don’t rely on shaders at all, instead I create a stripped down mame artwork lay. With only the color overlay being used:
Wow, nice! If you refer to ‚stripped down lay‘, do you imply this works for you in RetrpArch? Would be interesting in settings (download link), as my attempts to configure lay files in MacOS failed. Thank you!
Very exciting, thank you! If you see @Starman99x s screenshot of Space Imvaders Delexe, this seems to be a combination of backdrop and overlay. Indeed, the MAME implementation allows a combination of an overlay with a backdrop. But I appreciate any further development of these rather remote topics very much!
Yes, this is working in RetroArch. You can find examples, instructions, and some lay files I made in my arcade pack here (featuring @soqueroeu).
Message me if you need further instructions.
I hope it is done and complete, because my mind is about to explode while trying to fit things into the shader and keeping the resource use relatively low; expect about 1% performance impact (measured on intel Haswell).
The new parameter “Content blend mode”, will be used when “Display only on content” is enabled:
Multiplicative blending just on the tube, jpg @estefan3112 :
Multiplicative blending just on the tube, png with alpha @Starman99x :
Additive blending just on the tube, jpg:
Caveat: Ambient reflections don’t play nice with tilt, since they should stay straight, so you’d need to couteract that by anti-tilt them before if really needed.
All is still in this branch, please test it:
Amazing work 
. I’ll test these ASAP.
So I finished testing these out. I absolutely loved all the new changes. Here’s my feedback:
I opted for rotating the image file itself instead of wildcards, this is similar to the old koko-aio behavior/solution (easy-peasy):
Before:
After:
Tilt works nice and fine with backdrop games though:
Very nice, and it was a very good idea to keep the original behavior when “Display only on content” is disabled, that’s useful for my VGA CRT setup, especially in some edge cases like this one:
But I wish the mid overlay’s blending and opacity params can work when “Display only on content” is disabled (maybe with alpha png too?).
This works very nicely with my Tamagotchi backdrop:
Unfortunately, I can’t make proper use of this cool feature with my Game Boy Player borders:
However, If “Override Content Geometry” can exclude the mid-overlay, then I can fit the inner 4:3 border properly around the 3:2 content image.
Actually, I think this has become generally necessary in light of the new changes. It does not make sense for “Override Content Geometry” to override the Mid-Overlay at all. This is going to create inconsistencies with all presets that depend on both features, for example even simple reflections will scale weirdly, not just my “hacky borders”.
Thank you for the in depth test.
The proper way of handling all of this would be to have not 1, but 3 different textures; 1 for the mirror, 1 for the gel and another for the ambient reflections each with it’s own blend mode, this is not doable since texture “slots” in the final pass are almost exhausted.
Why? Right now the backdrop simulates the mirror reflected screen; I fail to find a legit usecase for another blending method. Also, I smell complications ahead dealing with ambientlight and background pictures in this regard; gut feeling.
This is the best tradeoff I went up to. The shader cheaply reuses the content coordinates, so it can tilt, curve, but will also zoom with the content, and yes, I’m aware it generates an inconsistence when you expect it to simulate ambient reflections, but it is fine when it simulates the gel, which is supposed to follow the content.
I could counteract it with yet other conditions and code branches, all with a performance cost I didn’t even tried to implement, but keep in mind that the backdrop has a zoom function that you can use by hand when content zoom is enabled to position it exactly where you want.
I can’t see why this isnt possible. Aspect issues need to be dealed with outside of the shader by padding the png image with blank space (or crop existing padding, or pre-resizing) to make it fit in the virtual tube, as it will be stretched to its dimensions.
As per the unsolvable issues, we’ll have to make the choice of accepting them or roll back to the previous behaviour; testing is the purpose of the branch, after all; if it’s 2 steps forward, one step back, then I’m fine with it; but if it complicate things, we can just ditch it.
Maybe you got me wrong, I’m not asking for a new blending mode, I just tried to use the existing modes, and tried increasing and decreasing the backdrop amount, but none of that takes effect over the backdrop image unless “Display only on content” is enabled. A tiny bit confusing, but I can totally live without it 99% of the time.
Alright this might fix it, I’ll give it a try.
I’d say we’re 4 steps forward. Your effort is very much appreciated and I hope this branch will get merged into the main one soon.
Thank you for the hard and amazing work.
EDIT:
Thank you for the suggestion, it worked beautifully:
I’m very happy now.
@kokoko3k - couldn’t do much testing of the branch, but really seems to be fit for purpose, immediately looks beautifully - many thanks!
PLUS: So many thanks to @Starman99x for explaining the correct application of MAME lay files. Invaders Deluxe looks absolutely stunning with the additional overlay!
Bonus question to @kokoko3k - example Invaders Deluxe: The Backdrop runs over the entire width, whereas the monitor is vertical in the middle. Right now, I can only either blow up the screen (screenshot 1) or set up the screen correctly - with a far too small backdrop (screenshot 2). This means that the geometry of the backdrop should not be identical with the geometry of the screen. Just asking 
.
Try these steps:
1440 x 1080) and add padding to the top and bottom until it becomes a 3:4 portrait shape (the aspect of the game).1440 x 4 ÷ 3 = 1920 so we need a new canvas size of 1440 x 1920
Before:
After:
ASPECT_X = "3.000000" ASPECT_Y = "4.000000"
DO_GAME_GEOM_OVERRIDE = "1.000000" GAME_GEOM_ASPECT = "-0.010000"
BACKDROP_ZOOM = "1.783491"
Result:
The downside to this method is improper reflections. So I prefer to just cut the backdrop into a 3:4 aspect instead:
It looks beautiful. Maybe we can come up with a better workaround, idk. But judging from your screenshots you don’t seem to be relying on reflections to begin with, so I assume this solution is perfect for your presets. Overall I really hope we won’t ditch the new changes, I think the shader is better now with room for improvements.
I’m sorry, but I’m not sure to undetstand.
Backdrops (cabs with the mirror trick) are intended to be rendered on the whole screen, not just on the content, and the behaviour of that hasn’t been changed since the very first implementation, i think. So if it is acting differently now, it has to be a bug. Is that the case?
Wops, nice find, but I think it is fixable.
This “issue” only happens with rotated games. Their aspect ratio is essentially 3:4, while the backdrop needs to be displayed in 4:3 to appear “full”. You can’t do this without workarounds if you want to enable “Display only on content” hence my solution above. And I don’t think this is a bug, it’s just something we have to deal with. I don’t recall that this was different in the main branch, not sure.
Reflections on the wrong side is clearly not intended, hence a bug to be fixed.
My other point is that “backdrops” require a blend function unavailable when “display only on content” is enabled so would not match the real thing.
Display on content should be used just for glue,ambient reflections and so on.
This should be fixed now.
