Need help navigating MAME source

[AlanS17]

Yes, I know I shouldn't meddle, but I can't help it!

The MAME source code is 10MB so I could use a point in the right direction from someone who's walked around inside it before.

I'm a programmer by trade so (hopefully) I can figure out what's going on when I get in there.

This is what I want to do... I want to add a switch (I can handle that part) to to create a special viewing mode. I want to split the screen down the middle and rotate the 2 halves to face the left and right. That way I can play horizontal 2-player games from the opposite ends of a cocktail cab.

Anyone out there that point me in the right direction?

[Dire Radiant]

Haven't a clue but it's a terrific idea!

[wpcmame]

Depends on which mame version you use.

If you use the normal win32 version you should look into the src/windows directory.

You need to update the files winddraw.c wind3d.c.

- Update the code that selects a screen resolution
- Update the code that blits the game image to the screen

[AlanS17]

Depends on which mame version you use.

If you use the normal win32 version you should look into the src/windows directory.

You need to update the files winddraw.c wind3d.c.

- Update the code that selects a screen resolution
- Update the code that blits the game image to the screen

Muchas gracias! That's what I'm looking for. I'll give it a shot when I get home from work.

[EndTwist]

Muchas gracias! That's what I'm looking for. I'll give it a shot when I get home from work.

That's a great idea and I've always wanted to do this, but don't know enough C (I did manage to do this for a VB NES emulator  ).

Anways, if you do get it working, might I be able to get a look at the code changes? (I'd like to apply it to my customized version of MAME 0.59)

[AlanS17]

Depending on the changes you've made, it might just be plug-and-play. We shall see!

Can anybody recommend a good debugger? :-)

[EndTwist]

Depending on the changes you've made, it might just be plug-and-play. We shall see!

Can anybody recommend a good debugger? :-)

If it isn't, I can always make some modifications myself (I can get that far).

Have you made any progress yet?

[AlanS17]

LOL gimme a break! I just got home. 

My c sucks, too. I'm a VB guy. There are variables everywhere!!!

[EndTwist]

LOL gimme a break! I just got home. 

My c sucks, too. I'm a VB guy. There are variables everywhere!!!

I wonder if 2 VB guys make 1 C guy? 

I took a look at winddraw.c and, well, it doesn't look as easy as I thought (although I am looking at the MAME 0.59 code, not the latest 0.96)...

[AlanS17]

LOL gimme a break! I just got home.

[wpcmame]

Had a quick look and this works (actually took longer to write this post).

File: winddraw.c

function: render_to_primary

Change 1: Remove multipliers so that the game doen't automatically fills the screen
Replace the line
   win_compute_multipliers(&inner, &xmult, &ymult);
with
   xmult = ymult = 1;


Change 2: Don't center the game vertically so both images fit
Replace the line
   inner.top = outer.top + ((outer.bottom - outer.top) - (win_visible_height * ymult)) / 2;
with
   inner.top = outer.top;

Change 3: Output the second image flipped
After the line
   win_perform_blit(&params, update);
Add the following lines
   params.dstyoffs      = inner.top + win_visible_height * ymult;
   params.flipx      = !blit_flipx;
   params.flipy      = !blit_flipy;
   win_perform_blit(&params, update);

To test it you need to use a resolution big enough to fit the game twice

mame game -resolution 1024x768 -flipx -flipy

(The flipx and flipy are just because it was easier to keep the original image on top)


Now you need to make it an option and calculate the correct multipliers etc

[EndTwist]

Wow! Who would of figured it's that easy?!

Edit: Ahh nuts...In MAME 0.59 there is no params.flipx and params.flipy...The flipping is done elsewhere (src/drawgrfx.c)

Edit 2: Nevermind, I'll just use MAME 0.63

Awesome. I'll have to take a look at how to calculate the correct multipliers...hopefully that's easy too

[AlanS17]

Very slick, wpcmame.

I didn't have the time last night to get into like I wanted to. Looks like you've done most of the hard work, though.

[AlanS17]

By creating a switch, flipping cocktail games could still be played full-screen. The same switch should probably also trigger the -flipx and -flipy switches.

I'll look into those multipliers, too.

I'll *try* to get around to that tonight. I don't want to make any promises since it didn't happen last night.

[creatine28]

This will be great for Cocktail games!

Are there any plans to make the source available once your done?    

[EndTwist]

Technically, the screens should be side-by-side, not displayed vertically (so when you put -rol or -ror on, it displays as in the screenshot, but sideways). I was able to do that somewhat, but it isn't very pretty. As for scaling, well...I couldn't really get that

[lokki]

Hi,
I was thinking of a slightly different approach to this. but let me start with a refresher of the MAME Architecture. (in order to justify my reasoning)

MAME is crossplatorm and has a core source code that is used by all platforms that support MAME (DOS,windows, Mac, Linux, etc).

[EndTwist]

Hi,
I was thinking of a slightly different approach to this. but let me start with a refresher of the MAME Architecture. (in order to justify my reasoning)

MAME is crossplatorm and has a core source code that is used by all platforms that support MAME (DOS,windows, Mac, Linux, etc).  and a OS (platform) specific layer. The methods that are platform specific start with osd (for example osd_create_display,osd_close_display etc).


The basic idea is that if you want to port MAME to a new platform then all you have to do is implement the osd layer for your platform.  (you have to make sure the rest of the core compiles but after that basically all you have to do is implement the methods on the OSD layer).

The way this works is because when mame (the core product) is emulating a game it does not care how it will eventually be displayed, this is left to the osd layer to figure out.  What mame does it draws the screen on a virtual canvas (bitmap) and the OSD is responsible for decoding that bitmap and rendering it to the user.  (similar thing happens for  sound mame)

Here is where things start getting interesting.  The bitmap is of the size of games resolution (not the screen resolution) so the for example the bitmap for space invadres (sivc) will be 224x240. and you can take advantage of your platform's feature.  instead of streaching this to fit a bigger screen you can use the videocards stretch feature.  (hope fully this makes sense)

The method OSD method that mame (core) calls to update the video and sound is called osd_update_video_and_audio, eventually this method calls render_frame which calls draw_video_contents passing it the bit map.

The idea is to take the oringal bitmap passed to this method and replace it with a new bitmap (twice the size, with copy and reverse copy), and leave the rest of mame the same. Hopefully this willmean that all other features will continue to work as before. (use of direct3d,ddraw rotation etc)

No idea how fast (read slow) this will be since will have to copy the bitmap, or if it will even work. but  Time permitting I should have something in a few days hopefully this will work.


I may have over simplified a few things, but hopefully I did not get many things awfully wrong :-)

Interesting take. Let's see what you can come up with.

[AlanS17]

That approach already crossed my mind, but I'm wondering what sort of effect that may have on performance.

Plus to be totally honest, I'm not particularly concerned with cross-platform portability. Most "flavors" of MAME are AFAIK exclusive to Windows, and nobody has ever really complained about them not being available on other platforms.

Certainly give it a shot, though. Don't let me stop you. If you can find that it doesn't hurt performance then I say go for it.

P.S. I didn't get home til midnight last night so I wasn't able to look into it yet again. Plus I found that my brother forgot to pay the phone bill so out DSL was out. 

[lokki]

That approach already crossed my mind, but I'm wondering what sort of effect that may have on performance.

Plus to be totally honest, I'm not particularly concerned with cross-platform portability. Most "flavors" of MAME are AFAIK exclusive to Windows, and nobody has ever really complained about them not being available on other platforms.

Certainly give it a shot, though. Don't let me stop you. If you can find that it doesn't hurt performance then I say go for it.

P.S. I didn't get home til midnight last night so I wasn't able to look into it yet again. Plus I found that my brother forgot to pay the phone bill so out DSL was out.

[AlanS17]

Maybe I'm getting way ahead of myself, but I just applied for permission to use the MAME in the event that we choose to redistribute this build.

[lokki]

Maybe I'm getting way ahead of myself, but I just applied for permission to use the MAME in the event that we choose to redistribute this build.

I can't help but think that one of the mame developers could do this in a couple of hours. (if they wanted).

I think you probably want to see about the code getting into one of the existing builds out there like AdvancedMAME.
Or some build that includes
http://scale2x.sourceforge.net/

[AlanS17]

Well "vanilla" MAME (as found on mame.net) is strictly for emulating the functionallity of the game. They're less concerned with special options like this, and more concerned with authenticity.

As for AdvanceMAME, I don't know. Their angle is that they supply beefed up video modes to get more of the original arcade "feel" into your games. They're certainly more interested in real-world application than plain ol' MAME, though. Still, it's hard to say if they'd be interested in something like this.

I'd have no objection to someone else adopting this feature. That just means less work for me! 

[lokki]

Well "vanilla" MAME (as found on mame.net) is strictly for emulating the functionallity of the game. They're less concerned with special options like this, and more concerned with authenticity.

I did not mean that official MAME should consider this is a feature. I meant that a MAME Dev would know how this works, and be able to quickly throw something together. as opposed to the fumbling around that I have been doing :-)

[AlanS17]

Well "vanilla" MAME (as found on mame.net) is strictly for emulating the functionallity of the game. They're less concerned with special options like this, and more concerned with authenticity.

I did not mean that official MAME should consider this is a feature. I meant that a MAME Dev would know how this works, and be able to quickly throw something together. as opposed to the fumbling around that I have been doing :-)

AH! Yes, most certainly. I get dizzy looking at it.

[lokki]

Made a little bit of progress. The function to copy the new bit map seems to be working.  A new bit map twice the size of the original bitmap is created

Unfortunatly it looks like MAME is clipping and only showing what it expects to be the visible area of the bitmap. (this means that only half of the bit map is displayed and I'm kind of assuming that the other half looks OK, I have tested copying half and half and it seems to be doing what I expect, but until I can see the full image will not know for sure)


Need to figure out how, the clipping area is defined. (a bounds rectagle is passed in modying this bound causes mame to crash, so I need to figure out where this is happening)

The other good news is that performance does not seem to affected to terribly. tried a few neogeo games and they don't seem to suffer from too much. (but will need to do timing tests)

[EndTwist]

Awesome.

Now my next question for this thing will be -- what horizontal, simultaneous games will this be good for? (Other than the obvious Mario Bros, and the Vs. games)

[lokki]

Street figther face to face.
All the figthers should play great.

[Howard_Casto]

Beat em ups also.... tmnt and the like would be great. 


Since people besides me are finally interested in messing with the screen (btw i've contacted the mame devs before.... they aren't too interested in doing this).  Could somebody look into enumerating a secondary display?  I've been trying off and on for a year or two now to get games that originally had two monitors (playchoice, punchout, xmen 6p, ect)  to actually run on two monitors via windows extended desktop.  I've isolated where mame handles the calculations for the two "virtual screens" and I can manipulate the size and offset of them, but I can't initilize the secondary monitor when mame boots up, and thus I can't really do anything with my knowledge. 

It's a directdraw issue as well as a screen calculation issue (mame does some wierd stuff with the windows api calls to get the screen size and bases all aspect and scaling calculations on it) but if enough people worked on it, it could be fixed. 


I would also like to point out that making a "custom" build of mame is not the way to go.  The way to do it is to get the hack working well enough that the mame devs can fix it and thus have it included in mame's official source.  Custom builds are a pain to maintain... besides, if it's in the offical source, then it would be included in other potential custom builds by default.

I would also like to point out that even in the official build, some screen options, particularly those related to rendering, are windows only.  For example, my true dual display idea might work in windows, linux, and possibly osX, but it's not going to work in dos, the support just isn't there. 

[AlanS17]

I don't know if I can see the MAME devs adopting this.

I could see them adopting dual-screen support for dual-screen games, but not the split-screen stuff.

[wpcmame]

I don't know if I can see the MAME devs adopting this.

I have submitted several things over the years that simplifies life in a cabinet and none of it has been accepted by the mame devs.

Here are a few:
1. Move the UI button to be the second entry in the input menu so that it isn't so easy to overwrite it.
2. Separate exit buttons for menu and game.
3. Special ini files for each resolution e.g. "224x288V.ini". Makes it a lot easier to map game resolutions/stretch/vsync etc to monitor resolutions.
4. Multiple controller files so that you can have one with all the common buttons and then only map joystick/buttons differently for some games (e.g. I have one for single player games, one for dual player with player 1 on the left and one for dual player with player 1 on the right).
5. Delay loading of cheats until you activate them. Makes it possible to activate some standard cheats with a single button. Now my 6 year old son can enable unlimited lives cheats himself.

[AlanS17]

Well I just found out that my DSl at home is gonna be down til friday. Won't be able to do much before then...

[Howard_Casto]

I don't know if I can see the MAME devs adopting this.

I have submitted several things over the years that simplifies life in a cabinet and none of it has been accepted by the mame devs.

Here are a few:
1. Move the UI button to be the second entry in the input menu so that it isn't so easy to overwrite it.
2. Separate exit buttons for menu and game.
3. Special ini files for each resolution e.g. "224x288V.ini". Makes it a lot easier to map game resolutions/stretch/vsync etc to monitor resolutions.
4. Multiple controller files so that you can have one with all the common buttons and then only map joystick/buttons differently for some games (e.g. I have one for single player games, one for dual player with player 1 on the left and one for dual player with player 1 on the right).
5. Delay loading of cheats until you activate them. Makes it possible to activate some standard cheats with a single button. Now my 6 year old son can enable unlimited lives cheats himself.

Have you looked at 96u2 yet?  Someone, *cough* haze *cough* cough* must have been holding these additions back. 

Aaron just added many of these features, although they are slightly different (in a good way). 

Oh and pc10 single screen bios support, which means those games are actually playable now!

[lokki]

Hi,
Just a quick little update on pregress (or lack of  )
I haven't had as much time to spend on this as I would have liked. but I have managed to sneak in an hour here there for the past week.
Last time I was creating a new bitmap (twice the height, with a mirrored images of the original bitmap). But ran into problems trying to display it, mame would only display original resolution. If the original resoultion of the game was 224x240, the new bit map would be 228x480, but mame would still display the original 224x240.  Could not figure out how to get this to work correctly, after spending a couple of hours trying to figure this out. I started to look at MAMEPlus and how it handled the scale effects it has since it  looks like mameplus already does something very similar. Hopefully I can figure out how this works.

[AlanS17]

Well I've got some bad news on my end of things...

First of all, I haven't had the chance to touch most of it because I've got no internet connection at home until friday.

Second (are more importantly),  I was working on this with the intent to use it in a cocktail cabinet, but I've decided I won't be going that route so I've pretty much lost my incentive to work on it. I'll still look into it if it's something alot of people are really interested in, but I have no need for it anymore.

[Popcorrin]

I think it would be a great feature to have and I think once it's more well know there will be alot of people interested.

[lokki]

On another note...
What should this be called?

[AlanS17]

Well I'm not up to the task of maintaing a build for it. If someone else wants to, though, go for it. If you do decide you want to maintain your own build, how about...

SplitMAME
CocktailMAME
MirrorMAME

[lokki]

Hi,
I dont' think I am up to maintaining a build. I will submit this (if it works) to MAMEPlus and post the code here and maybe a couple of other places and see if any one wants to add it to their build.

But back to the name, I want this to be configured via a commandline switch.
so to run this the user will type

mame.exe -mirrorcocktail

Or something like that

[EndTwist]

Hi,
I dont' think I am up to maintaining a build. I will submit this (if it works) to MAMEPlus and post the code here and maybe a couple of other places and see if any one wants to add it to their build.

But back to the name, I want this to be configured via a commandline switch.
so to run this the user will type

mame.exe -mirrorcocktail

Or something like that

I probably will add this to my own build (can't release it though). I think it would be a fun feature to have -- It would be nice to play TMNT & Buster Bros. face-to-face (and I have no intent as of now to add a 3rd CP ).