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-   -   [brainstorm] Problems in porting megadrive games to amiga hw (http://eab.abime.net/showthread.php?t=75051)

saimon69 09 September 2014 20:16

[brainstorm] Problems in porting megadrive games to amiga hw
 
Being not exactly a coder (i work in web development and you know is a very different thing) i sometimes try to approach things in a way that a real coder will look at me with skewed head and question my sanity, but many times good things get unnoticed because a technical point of view is -sometimes - too technical and missing other experiences to see the feasibility or less of things.

So let me send another brainstorm here and see what analysis can lead:

Been around enough to know that, despite having the same processor, a Sega Megadrive and an Amiga have little in common: the first has a character display and a good sprite engine while the second has our beloved blitter and copper display, that however give us less palette colors but let us play with it nicely.

Yesterday stumbled in the out run megadrive and we know that, despite being not a 1:1 arcade port is still a good port and LIGHT YEARS better than the probe one; so i wonder: if someone would decide to try to port it to the miggy, what are the steps required to make the code work?

For sure graphics will need to be adapted: if not to 32 at least to 16 colors; top parallax backgrounds can be mostly left alone or at least brought to 8 colors each plane to have again parallax and raster for sky;
for road and side sprites i think they used an approach not too different from the Space Harrier on c-64: character banks with a mask and double buffering; problem is characters might be 8x8 while the smaller chunk blitter can move IIRC is 16x16;

music of course need to be rewritten as MOD and to use a 3 channels + 1 jolly channel for sound effects;

however, solving those problems and -essentially- rewriting the graphic renderer, what else might need to be done? How the final result will look on a target machine - like in example an A500 + 512k chip? How smooth will run? (i odubt 50fps but 25 like lotus is at least a good result) How much space will take everything?
and so on...

Akira 09 September 2014 23:51

You should look into that released Turrican 3 + Mr. Nutz code, which includes code for both Amiga and Megadrive versons of such games.

Galahad/FLT 10 September 2014 01:22

The Amiga can handle Out Run without a problem.

The problem for the Amiga version was it was written for the Atari ST first back in 1988, and the Amiga version other than the enhanced titlescreen sound was unchanged.

The Megadrive version came out THREE years later, which in games writing terms is massive.

You only have to look at some of the coders who started early on Amiga and developed well like David Broadhurst that turned out the lamentable Ghouls n Ghosts, but really got the hang of Amiga hardware with Dojo Dan and Assassin.

You only have to look at the likes of the Lotus series, Prime Mover and a few other select racers to see that graphically the Mega Drive version could have been done with ease.

Theres quite a bit of clever cheating in the Megadrive version, theres massive space in the centre of the sky, which is for plotting "Extended play" messages and other such stuff like that, but when the sky dips up and down, it never writes to that space, only when you're driving on level ground, so theres a pretty big area not having to be plotted to.

Also, the Megadrive version of Out Run seems to have a lower horizon than the Lotus series, which means less road to draw, and Lotus 2 on Amiga has a higher horizon and is using a faster road draw routine.

Backdrops are nothing special, judicious use of the copper to spruce them up further making it look better than the Megadrive version is pretty easy.

If the Amiga version was written later in the days of Amiga, theres no doubt it would have been a better version than it was.

Same for Afterburner.

s2325 10 September 2014 01:31

There is something more unplayable than Out Run https://www.youtube.com/watch?featur...JyLO2yFQ#t=293 Game was developed much later (1996).

saimon69 10 September 2014 02:26

Still a better racing game than Outrun :P

BTW that one hits home: my auntie had the small 'cinquecento' and my mom an olive green 1974 Fiat 126, passed then to me and that got called later "the corpse" :P
and also got portraited here (video link): N.O.L.W. - the night of the living wrecks

s2325 10 September 2014 02:31

You can't steal Fiat 126 if you don't know basics.

saimon69 10 September 2014 20:06

@s2325

yup, fiat 126 was nothing else than a refactored 500, this means to start you have to use the two levers close to the stick shift (left for the air, right to ignite, pull until the engine starts) :)

http://4.bp.blogspot.com/-Lo762FJxOO...1600/choke.JPG

Gzegzolka 10 September 2014 22:04

Quote:

Originally Posted by s2325 (Post 975026)
There is something more unplayable than Out Run https://www.youtube.com/watch?featur...JyLO2yFQ#t=293 Game was developed much later (1996).

Looks like Śląsk region of Poland with those factory in background :) man, that was horrible game, just like City Cars (but it this one someone at least try to put as much different road shape and objects as possible).

Amiga and Megadrive are two different systems. Maybe it is matter of having people who know how to do tricks in game code and make it fit and utilize best stuff that system can offer. Maybe porting to Atari was one more barrier that make Amiga conversions look worse. Or maybe just basic money and time. Who knows if devs was lazy, lack knowledge or just must fit what can they do to budget limitations. No body write games for free - I'm sure they take money for their work and have families to feed :) I still do not understood how they could mess so much with Flink or Wolfchild. Chuck Rock 2 was also bit a mess, but it also got some content that sega-cd do not have.

meynaf 11 September 2014 10:51

Porting a game from Sega is really another story than from the Atari ST, for sure.

The megadrive has some strange video chip, which we probably can't emulate in real time (unlike converting the ST screen).
There also is some kind of FM synth chip coming in the way.

In comparison, the embedded z80 is little problem ; its code can be disassembled and converted. But nevertheless.

So "porting" a game is probably more a matter of 100% rewriting the code and pre-converting the graphics.

Of course if someone has a good screen conversion routine and is able to emulate that FM chip, i would port Sonic, lol :cheese

dlfrsilver 11 September 2014 13:45

the FM music can be converted by our friend ADR design :) and yes, about the graphics, they need to be converted as amiga tiles (better 16x16 than 8x8 blocks).

Coagulus 12 September 2014 01:27

Any way of injecting the Out Run gfx, music and maps into Lotus II? Although the car would bounce off everything instead of crashing then. Just thinking out loud, I'm nowhere near talented enough to do that!

saimon69 12 September 2014 03:38

@coagulus

Thought of that too, will come out however an OutLotus,since gameplay is a bit different...:)

Cammy 13 September 2014 05:18

Let's make a new racing game aimed at both systems.

Nekoniaow 13 December 2014 21:37

Quote:

Originally Posted by Galahad/FLT (Post 975023)
The Amiga can handle Out Run without a problem.

The problem for the Amiga version was it was written for the Atari ST first back in 1988, and the Amiga version other than the enhanced titlescreen sound was unchanged.

I agree that the Amiga Outrun version is a disgrace to mankind (a qualifier shared with the ST version which also could do better), and that's really common in most arcade games ported to the Amiga and ST: the publishers just wanted the games out of the door at the lowest possible price since they knew the reputation of the arcade version alone would be enough to sell the game. Hell, even Super Hang On which is terrible if you compare to what Lotus II/III achieved reached the top of the charts (at least in the US).

This said, I would be extremely cautious to state that the Amiga "can handle Out Run without a problem".
The Arcade version is massively more powerful than an Amiga in terms of colors, number and size of sprites and road drawing capabilities. There are plenty of road side objects which extend all the way to the left and right of the screen, the size of the cars and trucks is quite important too. Also, the massive number of arches above the road implies a lot of very massive blits (*) which very frankly seem difficult to make fit in 1/50th of a second.

It's certainly possible for the Amiga to run a toned down version of Outrun but that won't be exactly a walk in the park.

Quote:

If the Amiga version was written later in the days of Amiga, theres no doubt it would have been a better version than it was.
Same for Afterburner.
I completely agree with this. Most US Gold games were likely written by overtimed, undersleeping, underpaid, power pressured programmers/artists and that certainly seemed to have been a deliberate strategy (or rather absence thereof) of that company given their general output.

Most Amiga arcade port are simply asking to be rewritten. :)

(*) or clever sprite-horizontal-reuse/vertical-plane-splitting tricks

turrican3 14 December 2014 04:57

like often, big arcade ports cost high to bought the licence and after they don't have enough budget to pay a correct development. There is hopefully exceptions to this like the ports from ocean france. :great
I wanted to know how much time they take to make the atari and after how much time to port to the amiga ??
Not only we have a crappy version and the sega fans can laugh in our faces !!!

Hewitson 14 December 2014 13:56

It has to be said that while the Megadrive version is far better than the Amiga it's still a pretty poor conversion.

adrdesign 20 January 2015 11:13

Quote:

Originally Posted by dlfrsilver (Post 975330)
the FM music can be converted by our friend ADR design :) and yes, about the graphics, they need to be converted as amiga tiles (better 16x16 than 8x8 blocks).

I think it would be awesome an Outrun port for accelerated amiga. Its music influenced me so far!

For the record, Ive been port my favourite arcade tune 1:1 to 12ch Soundstudio MED. I will fix some note lengths in further versions and optimize it. Its just a proof of concept.

For 44100 mixing, open soundstudio in productivity screenmode and check the mixing settings (if your miggie is strong enough you can enable smoothing). Check also 100% stereo separation in UAE settings. For plain amigas you can play in 8 bit mode 16000 mixing freq.

Note ive FIXED the original drum samples as shown below. It seems Outrun was shipped originally with bad PCM samples.

Soundstudio Module

mp3 version

TuRRIcaNEd 30 September 2017 19:57

Hi Galahad,

Apologies for the thread necromancy first of all - I know it's not really the done thing, but if you've seen some of my posts I hope you'll understand why I'm talking about this now. To say I'd certainly welcome your input would be a considerable understatement. :)

Quote:

Originally Posted by Galahad/FLT (Post 975023)
The Amiga can handle Out Run without a problem.

I must admit that initially I thought "Wow - that's a big ask", but it just occurred to me (given the thread subject) that you were referring to the MD port/conversion rather than the arcade, which would be considerably more do-able.

In actual fact, I suspect that a conversion specifically tailored to the Amiga's strengths could well out-do the MD conversion in some aspects, and I'd be interested in your thoughts...

Quote:

The problem for the Amiga version was it was written for the Atari ST first back in 1988, and the Amiga version other than the enhanced titlescreen sound was unchanged.
Indeed, and because the Amiga release missed the Xmas '87 release date which made USG rush the developers of the other conversions in the first place, the whole thing was even more an afterthought than most ST ports.

Quote:

The Megadrive version came out THREE years later, which in games writing terms is massive.
Indeed it is - In Amiga terms it's the difference between Probe's OutRun and Gremlin/MF's Lotus! I think it's also worth pointing out that the Japanese teams who did the MD and PCE conversions seem to have had some access to the original arcade code and resources, whereas the UK teams who did the USG conversions did not.

Aside from that, there's the point that the MD was to all intents and purposes a cut-down implementation of the System 16 hardware (strictly tilemap, text and sprite-based) and as such the capabilities were relatively well-understood by the people doing the conversion. The Amiga video hardware, on the other hand, was a radical departure from what had come before (in fact it remains in many ways unique to this day) - which meant not only that it took some time for developers to learn and exploit, but also that converting games which used more advanced "pure" tilemap/sprite hardware sometimes required a fair bit of lateral thinking in terms of implementation.

Of course, that fundamental difference in architecture could cut both ways. One way in which this is apparent can be seen when comparing the Amiga and MD implementations of Lotus. The MD version has prettier sprites with more colours, but the road routine is nowhere near as smooth (indeed, on the MD OutRun conversion, the road stripes almost "flicker" past at high speed) - the combination of copper and blitter seems to suit that kind of drawing routine better than a tilemap layer.

Quote:

Theres quite a bit of clever cheating in the Megadrive version, theres massive space in the centre of the sky, which is for plotting "Extended play" messages and other such stuff like that, but when the sky dips up and down, it never writes to that space, only when you're driving on level ground, so theres a pretty big area not having to be plotted to.
That's an interesting catch. I did check on a YT video of the MD conversion and on some levels the background does write behind the "LAP" display immediately below the "EXTEND PLAY" banner. You can certainly see some "hacks" where they had to work around the MD's limited work RAM - for example how the horizon graphics fade out, disappear and fade back in between stages (the arcade trick was actually quite slick - using the hard left or right turn to slide in the new horizon graphic from the side, then it faded in the new sky colour on the straight before the checkpoint).

Quote:

Backdrops are nothing special, judicious use of the copper to spruce them up further making it look better than the Megadrive version is pretty easy.
For what it's worth; during my recent gardening leave I used the Cannonball LayOut utility to extract the sky, ground and road colours from the arcade stages and converted them to Amiga 12-bit RGB values, so that data's ready to go if anyone wants to experiment.

Quote:

Same for Afterburner.
Did you ever get to see the WeeBee Games conversion of AfterBurner (aka AfterBurner USA) back in the day? I was pleasantly surprised with how well they did, and it was certainly embarrassingly better than the Argonaut/Activision travesty most of us saw. The WeeBee AfterBurner also allowed the hapless Jason Brooke to redeem himself after Amiga OutRun - his conversions of the AfterBurner tunes in that version are an order of magnitude better than Dave Lowe's work for Activision.


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