just an idea... 2 LCD screen mirror cab with change-able backdrop????

[Bender]

I just had an idea and wanted some feedback on it
as was brought up in some recent posts, some classics like Space Invaders used a 2way mirror to give the illusion that the image was floating in the cab, it also used a lit back-drop behind the mirror to create the background. With LCD's being so thin now, I though you could use one as the backdrop and be able to change  the image, or even have a moving image for the backdrop
could even use a CRT for the main monitor(bottom) to get the game image to be more authentic
What do you think?

[TopJimmyCooks]

Questions:
Would it be any good at all for non background/floater games?
Would you have to put the background lcd fairly far away from the user to keep things lined up, like against the back of a cab?
Do you have to be able to adjust "Keystone" to make the game look square to the viewer?  Guess not since it's close together.

Solution:  do it, but set up the bottom monitor to flip up and be the primary when non background games are selected.  Heck, set it up to rotate while you're at it .  It's a good idea. 

What about instead of the rear LCD maybe use a gel scroller (i.e. theatrical lighting equipment) and use it to display paper backgrounds for 6-8 different background games, scroll up/down to the one for the game?  Throwing out ideas here.  The 2 monitors is probably cleaner and better.

[VanillaGorilla]

Not to be a party pooper, but, would it work? The back LCD would be emitting light thru the back of the mirror, which would probably wash out the reflected image on the front. The old backdrops were usually just a UV-reactive black light poster, not a light emitting source...

Solution:  do it, but set up the bottom monitor to flip up and be the primary when non background games are selected. 

IF it could actually work: Its a 2-way mirror, you could just disable the lower monitor when no backdrop is required, and just use the 'backdrop' monitor as primary.

I'd be intrigued if someone actually attempted any of this.

[DataWest]

Im going to say it wont be clear because of the brightness of the back screen. VanillaGorilla is right.

Please let us know if you try it though! Interesting idea....

[Spacejack]

I've tried this! It works fine. The trick is to use a brighter image for the game than for the backdrop (I was using a CRT for the game and an old-ish LCD for the backdrop.) No big deal there.

Mind you, I did not build a full cabinet, just a mockup. But it worked wonderfully, and that was without any kind of containment. The illusion is called "Pepper's Ghost."

I think you've got the glass angled the wrong way in the image though. Your Space Invaders would be getting bigger as they got further away.

I was considering trying to work out a way to run pinball tables like this with the DMD behind them, which would be a total inversion of the usual but still might allow for seeing them both easily at the same time.

[Bender]

is that the wrong way? does the 45º go the other way? It's been a while since I actually looked inside one
I don't think the light from the LED would be an issue, there are so many way to knock it down, either adjustments on the set itself, tinted plexi, neutral density filter,or a combination etc.

with a 45º mirror you shouldn't need any keystone correction

Vanilla, great idea about using the rear monitor for horizontal games (no Backdrops)

Spacejack, got any pictures?

Right now it's just an idea, but down the road who knows?

Thanks for the input everyone!

[Spacejack]

Sorry, no pictures... it was nothing special though. I just flipped the CRT on its back and duct taped a piece of furniture glass to the front and the LCD sitting behind it. I guess the other end of the glass was probably just sitting on top of the LCD. I did it that way because I was presuming one wanted some amount of keystoning for effect. (making Invaders more "3-d") I wasn't using a real Invaders cab as a basis, just throwing stuff together to see it if would work.

Using it as a way of having a full vertical display on the glass and a full horizontal display on the background was a primary intention. I was also able to get some interesting interaction between non-backdrop type games and their bezels. I could line up the Pac-Man bezel on one monitor with the accompanying game image appearing behind it at an angle (or something like that anyway, it's been a while). I think this involved manipulating the monitors physically though, to line up the stuff. I never really followed up on it because it meant building a whole other cab and I tend to just lazily play on my crappy converted Dynamo mini, which utterly kills my back. Think it might be time to go ahead!

This would also be a way to use a more commonly available 16x9 LCD monitor (for the vertical part at least) without noticing the pillarboxing or having to make extra space between controls and monitor.

edit: Crazy thought... what about using the monitor from one of those digital fireplaces where you get a fully transparent LCD screen? You could stack those things and create some pretty wild effects.

[Necro]

Bender, odd you posted this.  I  was thinking of attempting something like this but hadn't posted yet.  If we can get some definitive answer on if this works I can add it to the Mirror Cab FAQ .  This would let me do mirror for MAME and MESS and use the back screen for other emus (arcade) that don't have a mirror flip option.

[Necro]

...also, if anyone does this before I do there's another problem.  Given you can get MAME to split the display across two monitors, you also need it to flip one screen and not another...which I don't think it does now (either of the options, but particularly the only flip one screen thing).  Should be solvable just by flipping the backdrop image so MAME flips it back to the proper orientation.

[RandyT]

Maybe I'm a little slow tonight, but what, other than the ability to reproduce the background images on games like Space Invaders (and there aren't that many) would one hope to gain by doing this?

Trying to line up Pac-Man on his maze, for instance, would be a nightmare, unless you were looking at it straight on.  And at that point, it makes no sense to not just keep him on the same plane. 

Tell me what I am missing.

[drventure]

My guess he's only talking about games where there is a generic non-aligned "backdrop" image, and not actually anything that would need to be aligned to the image of the game itself.

For instance, Star Castle used tinted glass to make the circles in the middle different colors, when the vector display itself was just black and white. I can't imagine that it'd be possible to somehow split that so that the castle was in the background and the ships in front.

OTOH, you +could+ have an image of space with stars and galaxies in the background, and the game playing in front.

Good question, though as to how many games would benefit from such a treatment.

[Xiaou2]

Maybe I'm a little slow tonight, but what, other than the ability to reproduce the background images on games like Space Invaders (and there aren't that many) would one hope to gain by doing this?

 I dont get your comment at all.

 There are a few games such as Asteroids Deluxe, that use a blacklit piece of artwork behind the mirror..  and the vector display in front, which appears to hover in the middle of the air due to the distance between the backdrop and the projected display.

 The stereoscopic 3D  "IS"  the reason why people want to do this.

 Discs of Tron is another classic with 3d artwork.  Its not the number of games, but the fact that these games are great classics, that we wish to experience as they were meant to be experienced... in all their stereoscopic 3D glory.


 Ive brought up this topic many yrs ago... but not too much reply.  I believe you can pick up cheap teleprompter plexi that will work.  Not sure how much true front-silvered glass would cost.

 In mirror games, the image isnt distorted like whats being discussed.  Its much like a periscope... or quite simply, your car mirrors.

[RandyT]

I dont get your comment at all.

I'll explain.  It seems like a lot of effort and cost for the few titles where this was done, and where the optical arrangement actually messes with the presentation of every other title where it wasn't.  But I guess I can see your point if you wanted to dedicate a machine to accurately recreate the effect for the few titles which use it.  I'm not sure that's how this was being presented.

The other thing to consider is that the image will be overlayed at the same plane as the backdrop in this optical configuration.  Note the total distance between the eye and both screens.  It does not work as illustrated.

For instance, Star Castle used tinted glass to make the circles in the middle different colors, when the vector display itself was just black and white. I can't imagine that it'd be possible to somehow split that so that the castle was in the background and the ships in front.

True, but in the "overlay" case, they were just colored filters right on the monitor face.  That particular effect is fine when done in software at the same plane.

[Xiaou2]

'll explain.  It seems like a lot of effort and cost for the few titles where this was done, and where the optical arrangement actually messes with the presentation of every other title where it wasn't.  But I guess I can see your point if you wanted to dedicate a machine to accurately recreate the effect for the few titles which use it.  I'm not sure that's how this was being presented.

 Its not a lot of effort and cost doesnt come into factor when you want this artwork and effect.

 Some say 3d movies dont do anything for them.  Im sure many people said the same thing about mono-vs-stereo in the past.  Can we live without Surround sound in our home movies?  Sure.  But do we want to?

 How about limiting color depth from 16 to 8 bit?  Or 44000 khz to 22000?

 How about a virtual pinball machine, basically Pinmame on a pc  -vs- a real machine?

 Why not play vector games on a pc monitor, rather than a real vector monitor?


 The 3d effects in these games adds an artistic experience that is really cool, and enhances the experience and enjoyment of the game. 

 Mirror games with 3d effects have been in the arcades since before the 70s, in EM machines.  The last game I recall to use them as a 3d effect, was Terminator 2.  Theres actually 2 flashers behind the mirror... with a screened colored artwork of an explosion.  When you get hit, it makes a translucent 3d colored explosion in mid-air.  Most people never have seen it, because when the bulbs died.. the Ops never replaced them.
 

The other thing to consider is that the image will be overlayed at the same plane as the backdrop in this optical configuration.  Note the total distance between the eye and both screens.  It does not work as illustrated.

 Im not entirely sure I understand your description.  However, I will enhance My description... as I may have caused the confusion.

 The effect isnt really Stereoscopic.  However, it IS 3D.  Sorta like a pop up book. Each display is pictured on 2 different planes of actual depth, and you can can easily see the depth between them.

 If the projected game image is Zero on the ruler... the artwork placed 2 inches behind the end of the furthest edge of the mirror, will appear show as being 2 inches behind the image. (measurements are approximations, but should be about right. Ive yet to go down and check actual distances at this time)

and where the optical arrangement actually messes with the presentation of every other title where it wasn't

 This isnt true at all.  Any game displayed in a single display method, will look exactly the same.  It will just appear a little bit further away.

 Im pretty surprised that you have never seen a classic that has a 3d mirror setup.

[Xiaou2]

Btw, heres an example of a true stereoscopic display using dual lcds, and polarized glasses.

http://www.aldous.net/photo/project08.htm

 The concept is the exact same, so you can see how you can use a dual display for many uses, rather than merely showing arcade art in 3d.

[RandyT]

Steve, you have no idea what you are talking about.  There is no "3D effect" in the system shown in this thread.  My name is on several optical 3D system patents, so I have some idea as to how these things work.  I'm not even 100% convinced that Space Invaders was "multi-planar".  My recollections of the game was that it was simply overlaid onto the artwork, and that was only necessitated by the fact that actual artwork looked far better than computer graphics at the time.  Something that is not so in today's world.



Two monitors with one edge touching (or an equal distance from the beamsplitter, as shown above), and a 45 degree beamspitter between them, place one image exactly on top of the other, AKA superimposition.  There are ways to achieve the effect discussed here, but not the way it has been shown.  In order to make a "Pepper's Ghost", one would need to move the rear screen perceptively further back than the front screen is high.  You cannot, with just a mirror, bring the foreground image closer.  To do that, you start needing to create virtual images with real optics.

And Steve, if you want to play thousands of regular games at half brightness with the screen "pasted" on the back of a deep cabinet, or swimming around somewhere slightly closer when you move your head, and consider that more "accurate" than using software underlays for the handful that actually used graphic underlays, then I can only surmise that your train has finally gone the rest of the way 'round the bend.  Make the argument that it could be a cool dedicated unit, if you must.  But please don't pretend that the negatives from doing so on regular titles don't grossly outweigh the positives on those where it works.

[drventure]

if you want to play thousands of regular games at half brightness with the screen "pasted" on the back of a deep cabinet, or swimming around somewhere slightly closer when you move your head, and consider that more "accurate" than using software underlays for the handful that actually used graphic underlays

Good points. It might be an interesting exercise, but it might not be worth it in the end. (but then, my entire cab is basically "an interesting exercise that might not be worth it in the end" 

[Necro]

Since I'm (I believe) the only one currently with a cab where this would be feasible in the short term and something I'm interested in, I'll elaborate on the thought process I had that popped it into my head (a completely separate event than Bender having the idea).

I'm working on an OmegaRace cabinet, it's a simple mirror setup with the artwork behind lit by a blacklight to make the game itself 'hover' in the asteroid field.  This is similar to Space Invaders, Asteroids, and a few other setups I believe (albeit not always with black lights).  Because I like the mirror effect, I want to have the cab use the mirror configuration to give the additional distance to viewing.  However, the issue is you either yoke flip a tube based monitor or use an LCD and only use software that can inherently flip as there isn't a driver based way (that doesn't come at a HUGE performance cost) to do it.  So, I'm using an LCD now for maximum viewing size, weight, and ease of use.   By using two LCD monitors in this configuration, I can do the following:

- Maintain the ability to play OmegaRace as it looked 'natively' (or semi-natively)
- Vary the 'floating' art per game so anything that used a mirror setup for 'art' purposes, I can reproduce.
- For games, software, etc., that don't support mirroring you can use the 'rear' LCD to play them on instead. 
- If you set things up a certain way, you can have both a vertical and horizontal monitor in your cab and have each monitor used as appropriate for the game of that type.  This would, obviously, effect the ability to do the first three items to some degree.


So, it's a novelty to some degree...but isn't having a MAME cab in some ways always a novelty?

[Xiaou2]

And Steve, if you want to play thousands of regular games at half brightness with the screen "pasted" on the back of a deep cabinet, or swimming around somewhere slightly closer when you move your head, and consider that more "accurate" than using software underlays for the handful that actually used graphic underlays, then I can only surmise that your train has finally gone the rest of the way 'round the bend.  Make the argument that it could be a cool dedicated unit, if you must.  But please don't pretend that the negatives from doing so on regular titles don't grossly outweigh the positives on those where it works.

 Ok, I agree it was a misunderstanding.  Your description threw me off.  Yes, the rear screen has to be pushed back a few inches.

 
 As for the rest, its not quite true.   You can use the front image rather than the back for non-3d games... thus the image will be nearly full brightness.  Theres little losses in even a full half silvered mirror... and even if you noticed a difference, you could adjust the monitor settings.  Maybe even pre adjust them in the settings, so no fiddling is required.

 The problem would be finding a way to flip the front monitor image.  On a CRT it can be rewired.  Not sure what options there are for LCDs.

 And finally, I believe there are many more people who would love to build such a design.  There has been talk about it ever so often, here and other message boards elsewhere.   Just because you have no desire for a certain experience, doesnt mean that you represent the mass opinions of others.  Especially for those who have actually seen and played the games in reality.

[Bender]

So, it's a novelty to some degree...but isn't having a MAME cab in some ways always a novelty?

Well said!
Great minds think alike and all  

you're years closer to implementing this than me, so I hope you and make it work, it would just be fantastic to see!

just so you know, my friend has a Vizo LCD TV (I think, I'll find out for the brand sure) and it has a flip (mirror) option in the setup menu, not sure why but it's there and can be exploited

[RandyT]

As for the rest, its not quite true.   You can use the front image rather than the back for non-3d games... thus the image will be nearly full brightness.  Theres little losses in even a full half silvered mirror... and even if you noticed a difference, you could adjust the monitor settings.  Maybe even pre adjust them in the settings, so no fiddling is required.

Sigh.....A 50/50 beamsplitter knocks both images in half for brightness.  Usually a bit more, due to the losses inherent in the optical coatings themselves.  You should get some experience with optics (or do some research) before forming some of these conclusions.

The problem would be finding a way to flip the front monitor image.  On a CRT it can be rewired.  Not sure what options there are for LCDs.

Some have the option, but most don't.  The industrial and OEM style chassis displays usually do, because the manufacturer never knows how they will be used.

And finally, I believe there are many more people who would love to build such a design.  There has been talk about it ever so often, here and other message boards elsewhere.   Just because you have no desire for a certain experience, doesnt mean that you represent the mass opinions of others.  Especially for those who have actually seen and played the games in reality.

Stop stating that I stated something I did not.  I have no problem with people doing whatever they want to do.  I'm only trying to help folks make some good decisions on how to proceed based on the expected result, and the many years of experience I have had doing the exact thing in this thread, in a commercial environment.  FWIW, none of this is a slight against Bender.  When I first started working in that company many years ago, I thought it would work the same way.

And like I said, if the goal is to replicate something, it would be prudent to make sure that you are actually replicating it.  My memory of the game used in the example is that it was simple "superimposition", which is somewhat pointless with two video screens, rather than a "multi-planar" display.  And without taking measurements of the optical systems inside the games, and having a working knowledge of how they function, you are just making a lot of assumptions about them that have a high likelihood of not even being accurate.  And even so, each of these optical systems will be different, so one setup will not have at shot of replicating the majority of them.

If the OP just wants to do it for the sake of doing it, then by all means.  Sounds like he was asking for input, so it's being provided...by someone who has had much first-hand experience doing it.

[Necro]

just so you know, my friend has a Vizo LCD TV (I think, I'll find out for the brand sure) and it has a flip (mirror) option in the setup menu, not sure why but it's there and can be exploited

What model?  I have two vizio tv's and neither have this.

Also, regarding using the front monitor for regular stuff - if you kill the black lights and have behind the silvered mirror be dark it's appears nearly the same brightness as the monitor directly.  At least, it is on the cab I have.

[Xiaou2]

 This is a closeup with a bright flash in order to show the mirror inside the usually darkened environment... (normally you cant see any trace of the mirror).

 In this pic, you can see the red line artwork on the left and right sides of mirror.  Each one of them is a triangle shape, stapled to the cab sides.  The mirror reflects the image to make the rest of the lines match up... so it appears more like a square.

 The colors of the reflection are visibly the same brightness / color.  Theres no noticable degradation.  You can also see the complete reflection of the monitor, and again, no visible degradation.

 Behind the mirror, you can barely detect the artwork, because of the amount of light from the flash has canceled it out.  Still if you look closely, theres a faint red-line bezel around the monitor border.  That IS reduced in brightness, because its BEHIND the glass...  where as the bottom monitor is in FRONT of the glass.  Anything in front of the glass will have almost no loss in reflection.

 Things in the rear will be a little dimmer, but with monitor adjustments, you could cancel out some of the losses.  Then again, you really dont need to, as any artwork being displayed would had a slight loss... thus it would probably be close anyways.

 
 While you may have experience with optics and special equipment in a Related field..  I have experience with the actual equipment.  In fact, I own both an Asteriods Deluxe, as well as an old mechanical gun game which also uses a 2way mirror + screened art on the rear of the mirror.  And Ive both seen and worked on almost every well known classic that used a 2way mirror display.





 Edit:  Btw - I believe the ratio for the mirror is  70/30.

[RandyT]

 The colors of the reflection are visibly the same brightness / color.  Theres no noticable degradation.  You can also see the complete reflection of the monitor, and again, no visible degradation.

I'm not sure what this has to do with the discussion (maybe you can clarify) but regardless, the lines and monitor face reflected by the beamsplitter are clearly darker in the photo.  Of course, you've managed to zero in on the most minor of the detractions.  The subdued brightness isn't the biggest issue, it's the fact that you end up with the game image buried deep inside the cabinet.

Anything in front of the glass will have almost no loss in reflection.

Good lord, Steve, this depends entirely on the optical design of the system.  You can have beamsplitters made in nearly any ratio you want.  You can even use a piece of window glass in there if you want, and it will still work.  But since
window glass has a ~4% reflection from each surface, whatever is in front of the glass will be at ~4% reflection (with a ghost image that is almost as bright coming from the other side), while whatever is behind the glass will have a ~92% transmission.  I.e. a 92% loss for what is in front of the glass.  Your example is obviously not as exaggerated a difference, but there will always be a loss that is greater than the transmission of the optic.

Things in the rear will be a little dimmer, but with monitor adjustments, you could cancel out some of the losses.  Then again, you really dont need to, as any artwork being displayed would had a slight loss... thus it would probably be close anyways.

It's all relative, artwork or monitor, it makes no difference.  You can always change the intensity of one or the other to accommodate the effect you are looking for.  The lines on the side of the DOT cabinet will always be what they are as a function of the T/R ratio.
 

While you may have experience with optics and special equipment in a Related field..  I have experience with the actual equipment.  In fact, I own both an Asteriods Deluxe, as well as an old mechanical gun game which also uses a 2way mirror + screened art on the rear of the mirror.  And Ive both seen and worked on almost every well known classic that used a 2way mirror display.

Good.  Go use some of that experience and tell me the difference in the distance between the viewer's eye and both the real and the virtual images in your Asteroids Deluxe, then show your work.  It's important to know this for the purposes of this thread.

[Xiaou2]

Heh, Gota love it.  Its like you want to win your argument so bad, that you will spout anything, even if its unrelated or unrealistic.

 Why on earth would you quote facts about window glass?  Everyone clearly knows that its not the optic of choice... and does not even come close to factoring in here.

 Maybe theres a 4% loss in clarity with a half silvered mirror... Maybe!  Can anyone really tell?!    (Heck, I cant even get people to see flaws in their pinball playfields at mere inches away)   As can be seen from these pics... the level of degradation is so minimal, as to be completely insignificant. The argument would be valid if you were losing over 20% of the clarity and intensity. Its not even close.

 The argument that you do have, is distance.  But anyone whos played a mirror cab in person, knows its not bad at all.  Unless you intend to make a pedestal cabinet, your gona be fine with a mirror cab.  In fact, plenty of people were fine playing mirror cabs in the arcades... and there was never any complaints about distance... nor loss of clarity.  And all this with a small 19 inch monitor.   Nothing stopping people from using dual 25" or larger monitors.    Heck, I personally found that the 90s cabs with the 25" or larger monitors were a bit too close.

 But no matter.  Any person whos ever seen the beauty and cool factor of these games isnt going to mind the extra distance, nor the 2 to 4% loss of clarity. (maybe lower than most normal arcade machines, due to dust that needs cleaning on the inside-monitor glass)

 If anything, you might see an opportunity to stock up on half silvered mirrors.
Personally, I dont get your attitude.

[RandyT]

Heh, Gota love it.  Its like you want to win your argument so bad, that you will spout anything, even if its unrelated or unrealistic.

I had a feeling you wouldn't understand a word I said.  One more try;

Go use some of that experience and tell me the difference in the distance between the viewer's eye and both the real and the virtual images in your Asteroids Deluxe, then show your work.  It's important to know this for the purposes of this thread.  Your random strawman arguments aren't useful at all, but here's your chance to add something of value, since you have a machine the rest of us can use for a reference.  Thanks.

[scofthe7seas]

I don't want to get yelled at ( You guys seem pretty heated)  but I still think, regardless of 3d, or other game use, things like asteroids, or maybe warlords (kind of a grassy medieval background?) might look pretty cool, even if some picture quality is lost.

[RandyT]

I don't want to get yelled at ( You guys seem pretty heated)  but I still think, regardless of 3d, or other game use, things like asteroids, or maybe warlords (kind of a grassy medieval background?) might look pretty cool, even if some picture quality is lost.

No-one is yelling   But we do enjoy spirited discussion from time to time, and that's just the passion talking.  I agree that it could be cool to be able to assign your own colorful backdrops to some of the old monochrome games which didn't use the underlays.  I'm pretty sure that MAME allows for backdrops on those which used them.  If it isn't already, it would be interesting to see if the dev team could be coaxed into making the backdrop function more universal by allowing any of the games to use them, and letting the user select the "transparent color".

[nitz]

Randy, you can do it using Autohotkey! When you said "transparent color", I immediately thought of ahk's transcolor option. Put the following in a ahk script:

F1::
Winset, transcolor, black, MAME
return

F2::
Winset, transcolor, off, MAME
return

F1 will make black invisible to show what is underneath it, and F2 will shut it off. Of course you can substitute other keys to suit your preference, or work with your frontend to have a script that launches and does this automatically when certain games are run. And if you want something other than black to be the transparent color, you can use the PixelGetColor command to find the RGB value of the color, and then sub that in. Basically you could just have your backdrop as your desktop. Or to integrate this with a frontend or use different backdrops for different games, you could probably use ahk's SplashImage command. (This isn't something I'm especially interested in, so I'm going to leave it to others to work out all the little details. )

The caveat is that you will need to set mame's video mode to gdi for this to work - DirectDraw and Direct3d seem to be a no go. I tried this with Ms. Pacman. Worked beautifully other than giving me quite a performance hit on my machine. I fixed it by setting frame skipping to 6/10 but that makes it a little choppy. I'm thinking using older mame with a decent PC for those games you want backdrops on could work.

[RandyT]

Randy, you can do it using Autohotkey! When you said "transparent color", I immediately thought of ahk's transcolor option. Put the following in a ahk script:

 

Awesomeness....  That's a great solution to use until the MAME devs can be convinced, or a way is found to do it within MAME's confines.  Sounds like the AHK solution might work for other apps as well, which is a bonus!

[Bender]

just so you know, my friend has a Vizo LCD TV (I think, I'll find out for the brand sure) and it has a flip (mirror) option in the setup menu, not sure why but it's there and can be exploited

What model?  I have two vizio tv's and neither have this.

ok it's a Sharp Aquos LC-26GA5U Mirror option right in the menu, sweet!!!

[Necro]

Damn...that's a horrible size for a cab though.  Can't even turn it vertically to get more width because it's only 16 inches high. :/

[Bender]

I'd be surprised if some larger models in the same line didn't have the same feature