[WIP] Moon Patrol conversion

[Cimmerian]

Sorry,excited to play

[jotd]

Originally Posted by Cimmerian

You ok with me porting to Genesis or Jaguar Jotd?I'm one of the programmers on https://datacrystal.tcrf.net/wiki/Ca...es_by_platform

No problem, the games are designed to separate the host code from main code. Xevious & Galaxian are done that way too and run on NeoGeo and amiga. I'd like any ports of my collection on any 68000 machine. I think an Atari ST port could be quite a challenge for any game of the collection.

Sorry gentlemen but I'm excited for this game,how it goes Jotd?

I had quite a breakthrough this week-end, and also a disappointment but at least took a decision. ECS A500 version won't be dual playfield but also won't be 50Hz as there are too many blits taking place, specially the backgrounds.

There are 3 different scrollable backgrounds (so bye bye dual playfield, also really not enough colors...) with 2 or 3 planes each, which end up amounting to one whole screen blit with 3 planes. Game barely bears that, but as soon as other objects appear, game starts slowing down.
I have used multiplexed sprites, but I can't use them for all objects (there are max 48 16x16 objects on screen which is a lot)

I've tried removing the mountain backgrounds but then the game looks like ... Super Jeep. We don't need Super Jeep. Oric has it already.

So about the compromises:

- I'm deciding to make it run 25Hz (which is cool) with HW sprites updated at 50Hz if possible. We'll see how it goes.
- I'm keeping the mountains
- I'm displaying the ground/holes with only 1 bitplane
- The moon base at start has to go too, it causes a lot of problems
- We'll see about the title screen later.

And then releasing an AGA version at 50 Hz with full features if possible (using 16/16 color dual playfield like Xevious, possibly extra copper effects, more/wider HW sprites, earth in the sky... we'll see what can be done).

[jotd]

here's a video of the latest build. Playable at least, cycle exact emulation.

[ Show youtube player ]

[TCD]

Looks very promising

[jotd]

the graphical rendering phase is almost as exhausting as Xevious.

I have tested the HW sprite rendering at 50Hz and it's great. A lot of games use that mixed refresh and in the end, the eye sees that there's something moving at 50Hz and is fooled that everything moves à 50Hz too

No9 just started to send some tunes... Hoping for a playable demo/version soon.

[KONEY]

In 1982 my uncle owned an arcade room. He would open the coin door of a cabinet of my choice, add as many credits as the machine could take and let me play for hours...

Now guess my choice 99% of the times

Project looks great, can't see the time it's out!

[VladR]

Originally Posted by jotd

No problem, the games are designed to separate the host code from main code. Xevious & Galaxian are done that way too and run on NeoGeo and amiga. I'd like any ports of my collection on any 68000 machine. I think an Atari ST port could be quite a challenge for any game of the collection.

Could you expand a little bit on the separation of the host code from main code ?

If I wanted to do the port of your version to Jaguar (crediting you obviously), do you also release the source assembler 68000 code ? I'm guessing you're not just writing hexa asm, right ? You do have the original machine code translated into the 68000 ASM, correct ?

[kremiso]

just have read this cut that i didn't know :

Moon Patrol was the first game to introduce full parallax scrolling to video games. And whilst it's been ported many times, the arcade version has never been bettered.

what better to the Amiga then?

[ransom1122]

Looking forward to no9's tunes...

Jotd, keep up the good work

[jotd]

Originally Posted by VladR

Could you expand a little bit on the separation of the host code from main code ?

If I wanted to do the port of your version to Jaguar (crediting you obviously), do you also release the source assembler 68000 code ? I'm guessing you're not just writing hexa asm, right ? You do have the original machine code translated into the 68000 ASM, correct ?

yes the code is converted. Which means you'll have to reconvert as the Jaguar has a RISC cpu not a 68k...

And the source is available as always https://github.com/jotd666/mpatrol. I try to backport all the reversing I'm doing on the 68000 on the original Z80 source which is also included. You may be better off porting the Z80 source, but porting the 68000 source will probably make more sense as the 8-bit coding is reduced, plus I have completely removed service mode, which isn't used in the game: less stuff to port.

But it's a huge effort. I developped a tool to convert Z80 code to 68K, which does a lot. Then comes the manual rework of things that didn't build (still severak hours of work), the comes the debug (more hours!!). But first step would have taken me a month of tedious work and now it's done in seconds. Without such a tool, the porting is really a bore, I couldn't stand more than doing 100 lines when I did Galaxian, then I wrote a converter.

Originally Posted by kremiso

just have read this cut that i didn't know :

Moon Patrol was the first game to introduce full parallax scrolling to video games. And whilst it's been ported many times, the arcade version has never been bettered.

what better to the Amiga then?

Well, that will be close but a A500 won't run the game at 50FPS because of all the layers. But as said before, if the mountain layers are removed the game looks horribly bland. Let's hope for a better A1200 version.

[VladR]

Originally Posted by jotd

yes the code is converted. Which means you'll have to reconvert as the Jaguar has a RISC cpu not a 68k...

Sure, but Jaguar also has a 13.3 MHz 68000, so there shouldn't be any need to summon the GPU/DSP beasts. I can imagine lots of refactoring related to background gfx and how they'd be done via ObjectProcessor scrolling (most likely).

Originally Posted by jotd

And the source is available as always https://github.com/jotd666/mpatrol. I try to backport all the reversing I'm doing on the 68000 on the original Z80 source which is also included.

Oh, wow. Nice ! I wasn't aware you had it on GitHub ! Thanks!

[lionagony]

Originally Posted by jotd

There are 3 different scrollable backgrounds (so bye bye dual playfield, also really not enough colors...)

Have you thought of trying the Agony technique of splitting the bitplanes so you could have 3 layers in dual playfield? The back one in Agony doesn't scroll but it does in Ork. We talked about how it would be possible here https://eab.abime.net/showthread.php?t=115927 and the source code for Agony is here https://aminet.net/package/game/shoo...Grolet-sources Looking at your video the only compromise might have to be the second blue color on the back mountains. You could just use 1 bitplane for that layer with one color and transparency for a nice copper then have 2 bitplanes for the green mountains which would give you 3 colors plus transparency and then 3 bitplanes for the foreground and bobs so 7 colors plus transparency. Looks like that would be enough if the buggy is a sprite.

[jotd]

thanks but dual playfield is out of the question. There are so many other enemies to draw, rocks, ufos, tanks, ... you can't have sprites for all them (there can be up to NINE ufos at the same time) even with multiplexing like I'm doing. Dual playfield will be used in AGA.

I'm using quite a similar technique anyway: Blue mountains palette is arranged so it only uses 2 bitplanes, green uses 3 bitplanes, and foreground uses 1 bitplanes, which makes the blitting lighter. But separating the planes forces to set duplicate colors so the lone plane doesn't interact with the second plane (which then can only use 4 colors, you'll notice that in Ork. Not 8+8 but rather 1+4+8), something I can't afford either.

I'm also using this technique for the vertical shots. The 4th bitplane isn't used by the mountains, so I'm drawing the vertical shots with it, and I don't have to mask stuff. The color of the shot varies a bit but who cares?

Anyway, the game technical issues are behind, and I had a little play yesterday. No big issues that can't be fixed now.

[jotd]

Zoned an alpha release. Lots of graphical issues (specially colors) but game is playable and the music from no9 is there!

[ransom1122]

Very good for an Alpha release, Well done jotd & no9

[ Show youtube player ]

[Brenry]

jotd: Early Alpha was an exciting crowd pleaser on AmigaLive twitch channel. One thing we noted is Continue Game starts at very start of game, whereas on Mame a continue picks up at last checkpoint.

Hope this gets attention as you progress.
Amazing work !

[DanyPPC]

Looks and play good, litte gfx bug but nothing serious.

I think you can fix and optimize this version avoiding to make an AGA version.

[zzbylu]

Great game - I love Moon Patrol
[ Show youtube player ]

[jotd]

the "rainbow" that you see is to signal me a sprite that misses the mirror attribute, nothing problematic...

Yes AGA version could be not that different. FMODE=3, bigger sprites to save blits, dual playfield 16x16, accurate colors and ... 50 FPS

[kremiso]

fantastic
this little game does create dependency

jotd, if you want some picky test results, ofc considering the alpha stage (and limited to my side configs)

the game freeze after checkpoint 'P' and after checkpoint 'T' here

also, when you complete the first playthrough, there is a colour palette change, due the champion race, and some things arent displayed correctly anymore in the upper menu :



hope in a little faster acceleration/deceleration car response, i mean to reach to pass the minefield sequence without loosing all the lives

apart this, already awesome for being an alpha, expecially if runned with Fast RAM