Arcade / Console --> Amiga conversion discussions

[zero]

There is a hard limit to how much you can write to the screen per frame on the Amiga due to memory bandwidth limits, and blitter sprites need loads of memory access cycles.

For every bitplane you need:

1 bitplane read/write to save background image
3 bitplanes read (mask + graphic) and 1 bitplane write to render sprite image
1 bitplane read/write to restore background

You can reduce it if you use a blank background bitmap, e.g. dual playfield or sprite background. Bit basically for every bitplane you need 8 memory access cycles per 16 pixels minimum, and more if the sprite isn't word aligned in the destination bitmap (so 15 out of 16 cases).

[idrougge]

Originally Posted by kovacm

Pinball Dreams is quite different while Braindamage, as far as I can tell from video on youtube, is almost identical to Obsession (and I played Obsession quite a lot; I even made fanpage: http://milan.kovac.cc/atari/obsession/ )

I will try Braindamage. I wonder if same people was involved in developing Braindamage and Obsession...

Not at all. Braindamage is made in Germany while Obsession is made in Sweden.

Originally Posted by kovacm

why do you call Braindamage and Obsession "clone" of Pinball Dreams? I mean they are all pinball games... is Slam Tilt also "clone" of Pinball Dreams in your book?

Of course it is. There is a clear "before" and "after" Pinball Dreams. Before, pinball games usually didn't scroll or added fancy gimmicks that could only be done on a computer. Pinball Dreams was a straight pinball simulator, and the first computer pinball game people actually remember and like to play even today.

Obsession was made out of frustration that the ST didn't get a port of Pinball Dreams, spurred by the fact that Pinball Dreams was the first commercially successful game to come out of Sweden.

[kovacm]

You are right: Pinball Dreams was indeed first Pinball game to have table scrolling like that...

btw Obsession is for STe, not ST.

[sandruzzo]

Originally Posted by zero

There is a hard limit to how much you can write to the screen per frame on the Amiga due to memory bandwidth limits, and blitter sprites need loads of memory access cycles.

For every bitplane you need:

1 bitplane read/write to save background image
3 bitplanes read (mask + graphic) and 1 bitplane write to render sprite image
1 bitplane read/write to restore background

You can reduce it if you use a blank background bitmap, e.g. dual playfield or sprite background. Bit basically for every bitplane you need 8 memory access cycles per 16 pixels minimum, and more if the sprite isn't word aligned in the destination bitmap (so 15 out of 16 cases).

With triple buffer, you only to restore screen and not to save it!

[zero]

Good point!

The Amiga port of Midnight Resistance wasn't bad, but I think it could be better than the actual arcade game.

The arcade system has a lot of slow down.

[kovacm]

Originally Posted by nobody

I would redesign the game, make smaller play area (256x192 or so) and redraw smaller sprites (32x32 instead of 48x48), and make it sort of multiload-stop action to load new stuff eg in the middle of level 1. You can't just run like that a CPS1 game on an Amiga 500 or 1200, it's too much. Look at requirements on STE, 32 Mhz and 14 mb for 16 colors.

New preview of Ghouls 'n Ghosts - gameplay demo running on an original Atari STE (8 MHz, 4 MB RAM):

[ Show youtube player ]

[sandruzzo]

Originally Posted by kovacm

New preview of Ghouls 'n Ghosts - gameplay demo running on an original Atari STE (8 MHz, 4 MB RAM):

[ Show youtube player ]

So Amiga Can!

[kovacm]

Originally Posted by sandruzzo

So Amiga Can!

Amiga should do much more!

[dlfrsilver]

this is such a brilliant job

Richarrrdddd Just look what can be done with Final Fight too !!!

Since the CPS1 game have a game program structured exactly the same, any CPS1 game could be adapted the same way

[kovacm]

Originally Posted by dlfrsilver

this is such a brilliant job

Richarrrdddd Just look what can be done with Final Fight too !!!

Since the CPS1 game have a game program structured exactly the same, any CPS1 game could be adapted the same way

ah, yes.

This is Anima test of sprite speed on STe with Final Fight graphics:

[ Show youtube player ]

[dlfrsilver]

What's great is the way the palette has been done. The result is very good

[alpine9000]

It's hard to tell from the video, but is it running 25fps?

[sandruzzo]

If would have some gfx, I could try to do some stress test

[kovacm]

Originally Posted by alpine9000

It's hard to tell from the video, but is it running 25fps?

It run at 25fps.

Here you have another Anima test:

21 32 x 32 Pixel Blitter objects @ 50 Hz in 16 colours with background clearing

[ Show youtube player ]

and here you have thread about it: http://www.atari-forum.com/viewtopic...28469&start=50

Amiga 500 and STe are almost egal in bobs speed (count).

[AnimaInCorpore]

Seriously: who wants to be a volunteer to make a proper "arcade perfect" port for the Amiga OCS/ECS?

[zero]

I really wish I had the time, but with full time work...

[sandruzzo]

Originally Posted by AnimaInCorpore

Seriously: who wants to be a volunteer to make a proper "arcade perfect" port for the Amiga OCS/ECS?

Without some kind of funding is not possible

[ovale]

Originally Posted by AnimaInCorpore

Seriously: who wants to be a volunteer to make a proper "arcade perfect" port for the Amiga OCS/ECS?

If you don't mind put the STE version on GitHub then someone could pick it up contribute and port it to other platforms over time without having to commit here now.

I'm mean, this will increase the chances compared to a 'now or never' approach.

... and by the way, your systematic approach to ports has a lot of things to teach and can be useful to spread it so other people can try it and maybe succeed in porting other titles.

[ovale]

Regarding to a possible OCS version, there is no doubt Fast RAM is required to pair the STE requirements.

With 16 colors the 68k has always free access to chipram when blitter is not used. So a straight port from STE (no Blitter use) will have 7.19/8 the speed of STE (10% slower).

But, since we have fast RAM we can exploit the parallelism that exists between CPU and Blitter. This is a specific advantage of the Amiga architecture (and by the way it is a shame the A500 didn't integrate 32K of Fast RAM from day one).

For example, it is possible to draw the sprites in fast RAM with the CPU while the blitter renders the tiles from a LRU cache in chip RAM.

[sandruzzo]

Originally Posted by ovale

Regarding to a possible OCS version, there is no doubt Fast RAM is required to pair the STE requirements.

With 16 colors the 68k has always free access to chipram when blitter is not used. So a straight port from STE (no Blitter use) will have 7.19/8 the speed of STE (10% slower).

But, since we have fast RAM we can exploit the parallelism that exists between CPU and Blitter. This is a specific advantage of the Amiga architecture (and by the way it is a shame the A500 didn't integrate 32K of Fast RAM from day one).

For example, it is possible to draw the sprites in fast RAM with the CPU while the blitter renders the tiles from a LRU cache in chip RAM.

Gotcha! With only 32k of fast ram A500 would have being a lot more fast!