Test of Metal Slug screens on MSX 2/2+

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Par albs_br

Champion (336)

Portrait de albs_br

09-04-2021, 03:11

I made some tests using BMP2MSX on how it would be a Metal Slug port to MSX:

Screen 5: for me it looks pretty good. On real gameplay with lots of shots / players / animations all around the little details made by dithering would be no problem, I think.

Screen 12: a perfect copy of the original. Plus the great advantage of hardware horizontal scrolling, saving CPU for other uses.

Hope you guys enjoy.

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Par santiontanon

Paragon (1482)

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09-04-2021, 04:46

Looks amazing! Btw, I am not very familiar with the MSX2 video modes. But, would it be able to move all the sprites at that graphic quality at a decent framerate?!

Par Daemos

Paragon (1952)

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09-04-2021, 07:17

I don't know about this game but offcourse for porting ask yourself a few questions. Do you need scrolling? If yes count at 15% of clockcycles per 4px per direction in screen5 @ 30fps (damn we could almost define a new quantification here).

Sprites how many. If you need more than 8 per scanline it gets tricky. It is possible to put many sprites in screen especially if they are all the same but the 8 per scanline cannot be tricked.

Softsprites limits you alot. Count 15% per sprite for 16x16 sprites @ 30 fps. You still need other stuff like eventhandlers, controls etc. Doable but tricky.

Looks very great. Conversions of gfx would be easy.

Par Metalion

Paragon (1444)

Portrait de Metalion

09-04-2021, 09:28

Very nice project !

The problem will be the size of graphic data.
Metal Slug levels are (https://vgmaps.com/Atlas/Neo-Geo/#M):
- 16 screens long for level 1
- 15 screens long for level 2
- 6 screens long for level 3
- 17 screens long for level 4
- 8 screens longs for level 5
(and I'm not even counting the vertical size)

That's a total of 62 screens, and :
- in screen 5, that's 1674 Kb
- in screen 12, that's 3348 Kb

Unless you want to play from a HDD, this will pretty much limit what you can do.

Par geijoenr

Champion (267)

Portrait de geijoenr

09-04-2021, 09:25

Yeah, that is a worthy goal. And the graphics look good, but when you try to do some actual BLIT with soft sprites you soon find out any MSX can barely lift it's weight.
Metal Slug has massive sprites and is really fast paced. I don't think is possible to have a meaningful port in MSX.

Par Daemos

Paragon (1952)

Portrait de Daemos

09-04-2021, 09:56

Gfx and mapdata can be compressed allowing for a lot more but still it is advised to use hdd as the data source. Problem is that the bkgdata isn't tiledata so maps will become huge. If the scrolls are unidirectional and horizontal alot of clocktime will remain there. The sprites will be your limit. Using linecopy's the way sf2 does it you can get pretty far along the way and on r800 some precalculations can sqeeuze out even a little bit more then combining hard and softsprites can do something for you but there is a clear limit in the end.

Par theNestruo

Champion (315)

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09-04-2021, 10:24

My two cents:

Aiming to "port" Metal Slug 1st/2nd Mission (the Neo Geo Pocket games) would already be an overwhelming task, but there would be a little hope of success or, at least, feasibility.
Just a few levels of Metal Slug Advance would be a titanic amount of work, and I have severe doubts about if the result will be enjoyable (or even playable).
But aiming to "port" even one single level of a Neo-Geo Metal Slug game is just... delusional.

Par Daemos

Paragon (1952)

Portrait de Daemos

09-04-2021, 10:57

Just checked the youtube vids on this one. Forget it. Gfx9000 maybe. Plain msx2 no way. The amount of sprites is just waaaay to much to handle. Bkg and scrolls perfectly doable. Sprites impossible.

Par erpirao

Paragon (1217)

Portrait de erpirao

09-04-2021, 11:33

A few weeks ago I saw this project that they are doing in Spain, for Atari STe: metal slug AtariSTe
really impressive, but 3.7MB of data per level.
Could you make a "decent" port in turboR ?, in msx2 it is impossible and in msx2 + I think too.
Another thing is to use the v9990 + turboR (this game has a lot of sprites on screen).

since we are with the conversions
a flashback / prince of persia / anthother world on sc7 for msx2 +?

Par Grauw

Ascended (10062)

Portrait de Grauw

09-04-2021, 12:53

Background can be streamed from ROM.

To add to Daemos’ estimate, for screen 7-12 it’s 25% CPU time per 4px per direction @ 30fps.

As for softsprites, if you use them you need double buffering, which doubles the background draw cost and memory use. In screens 7-12 you will run into memory and performance limits. Due to YJK / YAE in screen 11 softsprites are more complicated to draw and in screen 12 pretty much impossible.

So when there is a scroll I would only attempt to do softsprites in screen 5 at 30 fps at most. For the higher-bandwidth screens 7-11 I would only do softsprites on static screens without scrolls. In either case, use hardsprites as much as possible.

A final reminder, in screen 8 hardware sprites have colour restrictions.

Par Metalion

Paragon (1444)

Portrait de Metalion

09-04-2021, 15:54

IMHO, it's only doable on V9990, and even so, there's a lot of issues regarding the size of the GFX.

Besides all those issues, you got to ask yourself one question (as Dirty Harry would say) : is the colossal work worth it ? In these times where you have emulators for everything, it is easy to pick any NeoGeo emulator and relive the experience. Now in the 80's or 90's, that was a different story, because if your computer did not have the port of the game, you could not play the game, and that was it. So a port was worth it.

So in the end, porting such a game to MSX becomes "only" a technical challenge, and does not bring something new in the gameplay or the context. On the other hand, if you're up for the technical challenge, and it's something you really want to do, then go for it ! Wink

Just my 2 cents.

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