Arcade / Console --> Amiga conversion discussions

[sandruzzo]

Originally Posted by dlfrsilver

the arcade is 384x224 for GnG + 192 palettes of 16 colors.

[zero]

Originally Posted by frank_b

What happens if the weaker system wasn't taken into account when the game was designed? Sounds like the game would have to be hacked to bits or significant time would be spent optimising every last cycle. It's easier to port upwards IMHO.

You cut out stuff until it works. That's close to the best that the system can manage.

Porting up means you need to add stuff, which means you need someone to create extra graphics and sound, extra levels, you need to design extra effects in.

Sure, a crappy port upwards is easy and quick, but I was only talking about good ports.

[zero]

Originally Posted by dlfrsilver

the arcade is 384x224 for GnG + 192 palettes of 16 colors.

The main thing with a GnG port would be to get it moving at 50 fps. That game has a lot of very precise timing and movement required, like when the devils attack you.

Even with reduced graphic quality, as long as it moved well it would play well. GnG is actually not too bad in terms of having massive amounts of stuff on screen most of the time. The sprites are relatively small for the most part too.

I'm sure a better port than we got would be possible.

[sandruzzo]

Originally Posted by zero

The main thing with a GnG port would be to get it moving at 50 fps. That game has a lot of very precise timing and movement required, like when the devils attack you.

Even with reduced graphic quality, as long as it moved well it would play well. GnG is actually not too bad in terms of having massive amounts of stuff on screen most of the time. The sprites are relatively small for the most part too.

I'm sure a better port than we got would be possible.

With reduce screen size 256*192, we could allmost 50hz conversion.

[DanScott]

Originally Posted by sandruzzo

With reduce screen size 256*192, we could allmost 50hz conversion.

I think that a 50fps conversion could be done at 352x224 quite easily, just requires that certain elements that are non-essential are dropped (eg. Parallax back layer etc..)

It would be terrible to reduce the screen size on a game like this.

[sandruzzo]

Originally Posted by DanScott

I think that a 50fps conversion could be done at 352x224 quite easily, just requires that certain elements that are non-essential are dropped (eg. Parallax back layer etc..)

It would be terrible to reduce the screen size on a game like this.

I dont' think so. Look at rygar. With 352x224 you cant' hit 50hz

[DanScott]

Originally Posted by sandruzzo

With 352x224 you cant' hit 50hz

Yes you can

[sandruzzo]

Originally Posted by DanScott

Yes you can

Yes, maybe if you do a little demo, but game, no way, since you need an extra word for scrolling...So far HW sprite!

[mcgeezer]

Possible maybe with the AGA, but as DanScott says... lots of compromises need to be made.

The blowing tree effect mid level 1 is just one example.

[DanScott]

Originally Posted by sandruzzo

Yes, maybe if you do a little demo, but game, no way, since you need an extra word for scrolling...So far HW sprite!

Yes, you lose the last hardware sprite's DMA slot.

But this sprite can still be used

Anyway, losing one sprite's DMA does not mean that you can't scroll a 16 colour background in overscan, and draw plenty of blitter objects

[DanScott]

Originally Posted by mcgeezer

Possible maybe with the AGA, but as DanScott says... lots of compromises need to be made.

The blowing tree effect mid level 1 is just one example.

I think AGA could do a pretty spot-on conversion of GnG (with parallax too)

For instance, the blowing tree effect.. you could have a few different versions of your playfield, and just switch which playfield you will display for each "frame" you want to animate the trees for. When plotting your tile data at the edges, you would need to update the "other" playfields, and use an alternate block set for the animated tree parts. It would take more chip-memory.. but it is definitely possible when you have 2mb chip to play with

[mcgeezer]

Originally Posted by DanScott

I think AGA could do a pretty spot-on conversion of GnG (with parallax too)

For instance, the blowing tree effect.. you could have a few different versions of your playfield, and just switch which playfield you will display for each "frame" you want to animate the trees for. When plotting your tile data at the edges, you would need to update the "other" playfields, and use an alternate block set for the animated tree parts. It would take more chip-memory.. but it is definitely possible when you have 2mb chip to play with

If you're familiar with AGA then I'll take your word for it, I'm more of an OCS man. I didn't realise the A1200 had stock 2mb chip either.

It would be an interesting challenge... but at least a 2 year project for a single home brew coder with a full time job and a family. And for that amount of time i'd rather spend it doing a hotline Miami type game

I'd be interested to see the performance gains on AGA vs OCS. Do you still lose DMA when all over 4 bitplanes are enabled? I really am tempted to buy an AGA machine.

[DanScott]

Originally Posted by mcgeezer

I'm more of an OCS man.

ha! me too

AGA has 64bit bitplane and sprite DMA fetch. I've not really looked into is a great deal. A lot of the AGA games that I did see, did not really look any much better than the good OCS/ECS games.

But I do think that in the right hands, a lot could be done on the base A1200

However I still believe a great version of G&G is possible on A500 (with some slight compromise)

[sandruzzo]

with 352 you lost more that one sprite and doing 16 colors game like GnG would be ugly!

[zero]

320 pixels wide is pretty standard for games, 352 is overscanned the way most people have their computers set up. It's all driven by Workbench being 640 pixels wide by default and the Amiga horizontal scan rate being inflexible.

If you look at the arcade version of GnG I think the collision detection for your weapon is kinda bad, like it uses an 8x8 tile hit box or something. That makes it easier to implement on the Amiga. You could use a sprite for Arthur and dual playfield, with enemies on the foreground playfield for fast blitting and sprite/bitplane collision detection similar to Leander.

[MigaTech]

Would it not of been better for programmers to offer high resolution back drops with lower resolution sprites or visa versa?

Also could it not be possible to present B&W back drops and use colours on graphical characters, rather than entire game?

Mixing resolution modes is possible when both are singled out. Backdrop high res, Sprite Character low res, meaning faster movement overall.

After all most Amiga backdrops were static anyways without further interaction, with perhaps maybe the exception of door opening, which was added afterwards as an overlay.

Didn't they use these tactics on Ultimate Body Blows and Galactic?

[zero]

Originally Posted by MigaTech

Would it not of been better for programmers to offer high resolution back drops with lower resolution sprites or visa versa?

Also could it not be possible to present B&W back drops and use colours on graphical characters, rather than entire game?

The main issue is memory bandwidth. If you use high resolution modes the display DMA needs more slots, and the CPU slows down. AGA is a little better but on OCS the effect is pretty bad.

The best trade off is lores 16 colours, because it allows the CPU to have the maximum number of memory access cycles and the a good number of colours on screen.

Another popular mode is to use sprites for the background, which consume much less DMA slots than bitmaps or dual playfield 8/8 mode. Dual playfield consumes more DMA slots but has some nice advantages like making sprite/playfield collision detection useful and reducing the workload for the blitter.

[DanScott]

Originally Posted by sandruzzo

and doing 16 colors game like GnG would be ugly!

Far from it.... a decent artist and a well chosen 16 colour palette can look beautiful.

I myself have reduced the blocksets and sprites for a Capcom game down to a fixed 16 colour palette. Sure there have to be some compromises somewhere along the way, but the results were really nice!!! A lot better than the "official" conversion of the game (which was a straight ST to Amiga port)

At the end of the day, it's about playability, while still trying to look nice.

G&G is definitely possible at 50fps (maybe not 352 wide, but certainly 320 wide... just losing one sprite that can be actually loaded by the copper anyway), with 16 colours, and would still look really gorgeous.

[ross]

Originally Posted by zero

The best trade off is lores 16 colours, because it allows the CPU to have the maximum number of memory access cycles and the a good number of colours on screen.

Another popular mode is to use sprites for the background, which consume much less DMA slots than bitmaps or dual playfield 8/8 mode.

And this is what you can do combining 4bpl/full sprite background:
[ Show youtube player ]
You can have practically for free (hmm, chip usage ) a full animated background.

I ever liked much this Apidya level, is astonish.
Anyway it's not the only game using this technique.

Back in the days (tm), i've toyed with dual playfiels, lionheart like linescroll, full shaded copper and full screen anim sprite background (3 indipendent and active full screen layer). Well, DMA usage was a bit excessive

[sandruzzo]

But why dont' scale gfx a little bit and having 32 colors and full sprite do to a lot of stuff?