Black Tiger port (OCS/ECS)

[chadderack]

Time to make this official, I guess.

Hi, I'm Chad. I'm relatively new to Amiga hardware coding, but have been programming since 1980 or so. I've been coding assembler since 1984 (16 years old) on the Commodore 64 (6502/6510). I was a kid of the golden age of the arcade (1977-1990), and just as I started college, my favorite arcade game ever came out--Black Tiger.

I've wanted to do something with Black Tiger for ages, and decided to re-port the game to the Amiga because of the lousy US Gold version that never worked properly on my ECS Amiga 500. Currently the project is already underway; I started posting here in a Black Tiger request thread, since it seemed to be on-topic.

Rather than create a whole new thread, I'd preferred that an admin split the request thread into a project thread... but they could still split and merge part of that thread into this thread if they desire (after post #1).

-----------------------------------------------------------------------------------------------------

Current project state:
8-way scroll is implemented; I'm temporarily decoding part of the arcade version's Level 1 tile map to the screen and can scroll in all 8 directions with a joystick. (video)

Next up:
Map tiles and palettes and color reductions and all that fun stuff.

FAQ (this will grow):
Q: Why OCS/ECS?
A: The real challenge is to create a great game on the most limited version of Amiga hardware. Plus, I want a nice version of Black Tiger that I *could* have played back in the day on my Amiga 500 instead of the US Gold version

LINKS:
Source ctrl for the game project: https://github.com/admiral68/BTA
Source ctrl for the Black Tiger arcade reverse engineering project: https://github.com/admiral68/gh_black_tiger

[saimon69]

Best of luck and ask for any help!

[chadderack]

Best of luck and ask for any help!

Thanks saimon69.

26/10/2021:

I'm not taking the "rip from MAME" approach to the graphics because there are 16 different tile palettes. This means keeping around many source files with all of tiles rendered in all possible palettes. Instead, I'm using the arcade source to help calculate the optimal palettes for each level... then whittle down unneeded tiles/colors/palettes from there.

If using that approach, we need to find out how many colors are used per level; how many times a tile is used; and how many times a tile has different palettes applied to it. That's done in a script (in my case, a C# console program) against the arcade source code.

I recently noticed that some of the color/palette/tile data had been decoded wrongly. Here are the corrected values.

Level 1 (map); unique palettes used: 10; unique colors used: 70
LEVEL PALETTES: 0,1,2,3,6,9,A,B,E,F
LEVEL COLORS: 000,035,060,090,0E0,110,111,146,257,368,430,431,433,455,
              479,533,540,544,556,566,58A,641,644,650,653,666,747,750,
              753,754,763,776,777,778,842,864,868,874,889,940,974,975,
              985,986,998,A53,A74,A8A,A97,AAA,ABC,B87,C64,C84,C85,C95,
              CA8,CAC,CCA,DA6,DB8,EC7,ED8,EEA,EEF,F85,FC4,FF9,FFA,FFF

Level 2 (map); unique palettes used: 10; unique colors used: 76
LEVEL PALETTES: 5,6,7,9,A,B,C,D,E,F
LEVEL COLORS: 000,035,040,046,050,064,086,0A7,0C9,110,111,146,257,340,
              345,368,430,431,440,450,455,456,479,533,540,554,560,566,
              567,58A,600,641,650,665,670,678,750,753,763,776,780,789,
              7EC,864,874,887,899,89C,900,940,985,986,990,998,A74,A75,
              A96,A97,AA0,AAA,ABC,AFD,BA7,C85,C86,CB8,CC0,DA6,DE0,E70,
              EA7,EC7,EF0,FC8,FF9,FFA

Level 3 (map); unique palettes used: 7; unique colors used: 44
LEVEL PALETTES: 5,7,9,A,D,E,F
LEVEL COLORS: 000,040,050,110,111,340,430,431,450,455,533,540,560,600,
              641,650,670,700,750,753,763,780,864,874,900,940,985,986,
              A74,A96,A97,BA7,C70,C85,CB8,CC0,D90,DA6,DD0,DE0,E70,EC7,
              EF0,FF9

Level 4 (map); unique palettes used: 9; unique colors used: 60
LEVEL PALETTES: 2,5,6,7,A,B,C,D,F
LEVEL COLORS: 000,040,046,050,064,086,0A7,0C9,110,111,340,345,431,440,
              450,456,533,540,560,566,567,641,665,670,678,750,753,776,
              780,789,7EC,864,887,899,89C,940,974,986,990,998,A74,A75,
              A97,AA0,AAA,AFD,C84,C85,C86,CC0,DA6,DE0,E70,EA7,EC7,EEF,
              EF0,FC8,FF9,FFA

Level 5 (map); unique palettes used: 13; unique colors used: 84
LEVEL PALETTES: 0,1,2,3,4,5,6,7,9,A,B,E,F
LEVEL COLORS: 000,035,040,046,110,111,340,345,433,450,455,456,520,533,
              540,544,556,560,566,567,600,641,644,650,666,670,678,730,
              747,750,753,754,763,776,778,789,842,864,868,874,889,89C,
              900,940,974,975,985,986,990,998,A53,A74,A75,A8A,A96,A97,
              AAA,B50,B87,BA7,C64,C84,C85,C86,C95,CA8,CAC,CB8,CCA,D60,
              DA6,DB8,DD0,E70,EA7,EC7,EEA,EEF,F80,F85,FC4,FC8,FF9,FFA

Level 6 (map); unique palettes used: 8; unique colors used: 57
LEVEL PALETTES: 6,7,9,A,B,C,E,F
LEVEL COLORS: 000,035,040,046,050,064,086,0A7,0C9,110,111,146,257,340,
              345,430,456,540,560,567,641,650,678,700,750,753,763,776,
              789,7EC,864,874,887,89C,900,940,985,998,A74,A75,A96,AAA,
              ABC,AFD,BA7,C70,C85,C86,CB8,D90,DA6,DD0,E70,EA7,EC7,FC8,
              FFA

Level 7 (map); unique palettes used: 8; unique colors used: 46
LEVEL PALETTES: 5,6,7,8,A,B,D,F
LEVEL COLORS: 000,046,110,111,340,345,431,435,450,455,456,533,540,560,
              566,567,600,640,641,670,678,750,753,776,780,789,857,864,
              89C,900,940,986,990,A74,A97,B5A,B75,C85,CC0,DA6,DE0,E70,
              EC7,EF0,FF9,FFA

Level 8 (map); unique palettes used: 13; unique colors used: 85
LEVEL PALETTES: 1,4,5,6,7,8,9,A,B,C,D,E,F
LEVEL COLORS: 000,035,040,050,064,086,0A7,0C9,110,111,146,257,340,368,
              431,433,450,455,479,520,533,540,554,560,566,567,58A,600,
              641,650,665,666,670,678,700,730,750,753,754,763,776,780,
              789,7EC,842,864,874,887,899,89C,900,940,974,985,986,990,
              998,A53,A74,A75,A96,A97,AA0,AAA,ABC,AFD,B50,B87,BA7,C64,
              C85,C86,CB8,CC0,DA6,DB8,E70,E98,EA7,EC7,EF0,FB9,FC8,FF9,
              FFA

Here is the list of tiles used in all levels , also corrected. (Scroll down to line 37691--or search for the text "TILE INDICIES (PER LEVEL)")

KEY
---
0xXXX = 11-bit tile index
(FL)  = Tile is horizontally fllipped
:X    = palette applied to this tile

This data is also available in source control.

[saimon69]

I'm not taking the "rip from MAME" approach to the graphics because there are 16 different tile palettes. This means keeping around many source files with all of tiles rendered in all possible palettes. Instead, I'm using the arcade source to help calculate the optimal palettes for each level... then whittle down unneeded tiles/colors/palettes from there.

Debabelizer and other image processing programs call this approach 'superpalette' - i would however keep it for the first 16 colors so to have the player sprite always the same 17-32 color palette group, but that is me...

[Frog]

Hi,
beautiful project.
The hardware limitations as presented are very useful.
I hope that you will succeed and overcome the difficulties to come to supplement the version of US Gold and... a version similar to that of the arcade cabinet.

I played a lot in my teens and... i’m a brave black tiger myself (with only 1 credit of course)

[chadderack]

Originally Posted by saimon69

Debabelizer and other image processing programs call this approach 'superpalette' - i would however keep it for the first 16 colors so to have the player sprite always the same 17-32 color palette group, but that is me...

Whoa, thanks for reminding me about DeBabelizer. Seems Equilibrium isn't updating it, but I have an ancient installer for the demo version (which worked great) ... probably from 2002 or something.

You could sort the palette or protect certain colors before reducing the palette, which was cool.

No worries on the player/character palettes. I'm tentatively thinking ~16 colors (tiles) + ~16 colors (enemies/player)... which might mean 32 colors (5 bitplanes) but I know there are some overlapping colors. I may also use sprites for the player character.

Originally Posted by Frog

I played a lot in my teens and... i’m a brave black tiger myself (with only 1 credit of course)

[Cammy]

Hi chadderack! I think it's fantastic that you're working on a new port of Black Tiger, it's a great game and a shame the US Gold port didn't really shine on the Amiga. Your port would make a super entry into this year's AmiGameJam if you haven't considered it already (this year's theme being ports).

Since it's not really possible for your hard work on an unlicensed port to be re-compensated normally, I think prizes in a contest could help repay people like yourself for the effort you put in, so I hope we'll see your Black Tiger port in the contest.

See https://itch.io/jam/amigamejam for more details.

[chadderack]

Originally Posted by Cammy

Hi chadderack! I think it's fantastic that you're working on a new port of Black Tiger, it's a great game and a shame the US Gold port didn't really shine on the Amiga. Your port would make a super entry into this year's AmiGameJam if you haven't considered it already (this year's theme being ports).

Since it's not really possible for your hard work on an unlicensed port to be re-compensated normally, I think prizes in a contest could help repay people like yourself for the effort you put in, so I hope we'll see your Black Tiger port in the contest.

See https://itch.io/jam/amigamejam for more details.

Hmm... interesting. January 2022, you say? I may make the deadline; but will be away on vacation for half of December. Thank you for the suggestion! I may do it.

....

Looking for some opinions on palette reductions.

Ive decided it might be best to divide each level into sections where the palettes can vary. For instance, the dungeon, the regular level, and the wise man graphic (which is rendered in map tiles). For the regular level tiles in Level 1, I combined all of the elements into a single picture just to play with the palettes in Pro Motion and DeBabelizer.

The unmodified source is all of the main color elements copy/pasted on to a single image so that all colors have a chance to be represented. It looks like this, and has 42 total colors



If we decide that the dinosaur skull and the atomic-green bones can change colors and "share" colors with the rest of the level tiles, I've tried a couple of options.

Converting the bones to the "blue wall" hues. 21 total colors:



If we use the tan/red/greenish hues... 23 total colors:



Keep in mind we can't really dither the colors into the final colors, because they have to be in the special set of RGB colors that reduce down to 4 bits per channel.

Any thoughts or preferences? or better approaches? Thanks.

[Silverstreak]

This is looking nice! I feel the second option feels a little more harmonious, but I'm not a coder, so no sure of the implications!

[dlfrsilver]

ouch, now it becomes complicated. This will be the complicated part.

[chadderack]

Originally Posted by Silverstreak

This is looking nice! I feel the second option feels a little more harmonious, but I'm not a coder, so no sure of the implications!

Noted. One vote for tan bones!

Originally Posted by dlfrsilver

ouch, now it becomes complicated. This will be the complicated part.

Noted. No votes!

Another option: leave the bones alone, and just modify the skull colors to match. 30 colors. 5 bitplanes still possible:



Another approach is to swap palettes dynamically as the player reaches an area with different colors. For instance, maybe the green bones are only seen in a certain combination of X/Y map coordinates... so those colors are left out until the player reaches that area.

[chadderack]

Originally Posted by chadderack

Another approach is to swap palettes dynamically as the player reaches an area with different colors. For instance, maybe the green bones are only seen in a certain combination of X/Y map coordinates... so those colors are left out until the player reaches that area.

Here's what I mean. The following is a miniature version of the Level 1 map. The green rectangle represents the maximum size of the playable screen (256px x 224px).



If we scroll that around (like a view finder) to spots where the most colors show up in the rectangle, we can grab the colors from the rectangle only and concentrate on palette reductions or palette changes for those areas. Then, in code, when we reach or leave those areas, we do the palette changes.

Another option is to go grayscale and "re-color" all the pixels in the level using a 4096 color palette, trying to keep it under a max of 32 colors.

[Mixel]

If you’re choosing between tan and greyblue for those bones I think tan makes a lot more sense considering you can climb on them.. against the grey background they need to stand out.

I really like the idea of a dynamic palette based on what’s on screen though, is that going to cause havoc for the enemies etc? Looking forward to seeing what solution you go with!

[dlfrsilver]

Originally Posted by chadderack

Here's what I mean. The following is a miniature version of the Level 1 map. The green rectangle represents the maximum size of the playable screen (256px x 224px).



If we scroll that around (like a view finder) to spots where the most colors show up in the rectangle, we can grab the colors from the rectangle only and concentrate on palette reductions or palette changes for those areas. Then, in code, when we reach or leave those areas, we do the palette changes.

Another option is to go grayscale and "re-color" all the pixels in the level using a 4096 color palette, trying to keep it under a max of 32 colors.

why not trying to cheat with the copper to keep the arcade colors ?

[saimon69]

Originally Posted by dlfrsilver

why not trying to cheat with the copper to keep the arcade colors ?

Not to different from the idea i had to subdivide the screen in a copper grid some time ago, however got told there was not enough DMA time - if he can achieve it, why not?!
I however would suggest some fixed color palette spots for enemy sprites

[lmimmfn]

I think this is overcomplicating things tbh and taking away from the work on the gameplay.
1. Get someone good at pixel art to support you/provide 16 colour background + enemies per level and 16 colour sprite for main character(shared or whatever)
2. Whoever is responsible for the gfx provide a tool chain for the Amiga gfx so if later changed to use copper or dynamic palette on scroll that this can be accomodated.

Better just to use basic 16 colour per level for bg and enemies and 16 colour main character sprite + bullets and improve latter when everything else is working.

[Retro1234]

I definitely would find it hard/impossible to get down to 16 colour but I've seen some guys around here do some amazing stuff with 16 colours maybe they could pipe up.

[dlfrsilver]

Originally Posted by lmimmfn

I think this is overcomplicating things tbh and taking away from the work on the gameplay.
1. Get someone good at pixel art to support you/provide 16 colour background + enemies per level and 16 colour sprite for main character(shared or whatever)
2. Whoever is responsible for the gfx provide a tool chain for the Amiga gfx so if later changed to use copper or dynamic palette on scroll that this can be accomodated.

Better just to use basic 16 colour per level for bg and enemies and 16 colour main character sprite + bullets and improve latter when everything else is working.

That's also why i hope an A1200 version will possibly be made.

[Solo Kazuki]

Originally Posted by dlfrsilver

That's also why i hope an A1200 version will possibly be made.

Also i'm for AGA (then not only A1200 ) version.
Cut here to the max, cut there to the max, reduce here to the max... that's how games "not as good as for (write platfom here)" begin to appear.
I'm not against OCS/ECS version, I'm for separate AGA version - that's just in case my opinion.

[chadderack]

Originally Posted by Mixel

If you’re choosing between tan and greyblue for those bones I think tan makes a lot more sense considering you can climb on them.. against the grey background they need to stand out.

I really like the idea of a dynamic palette based on what’s on screen though, is that going to cause havoc for the enemies etc? Looking forward to seeing what solution you go with!

This is what I thought, too. They do need to stand out. Dynamic palette based on map position is where I'm leaning... going to do some discovery to see if it is possible. Thanks!

Originally Posted by dlfrsilver

why not trying to cheat with the copper to keep the arcade colors ?

Engineering that is the trick I'd love to keep all of the colors, too. Dividing and conquering is the current strategy--dividing the map into palette areas seems like a good approach.

Originally Posted by saimon69

Not to different from the idea i had to subdivide the screen in a copper grid some time ago, however got told there was not enough DMA time - if he can achieve it, why not?!
I however would suggest some fixed color palette spots for enemy sprites

Enemies are most likely going to be BOBs... though the smaller ones might be doable. There's just too many color/width restrictions on HW sprites. I'll already be using at least one HW sprite to cover the fill column on the left side of the playfield.

There will be a separate copper per level for sure... and a separate copper for the wise man's shop, the cutscenes, and the intro and end sequences. Dynamic Copper lists will be a good strategy.

Originally Posted by lmimmfn

I think this is overcomplicating things tbh and taking away from the work on the gameplay.
1. Get someone good at pixel art to support you/provide 16 colour background + enemies per level and 16 colour sprite for main character(shared or whatever)
2. Whoever is responsible for the gfx provide a tool chain for the Amiga gfx so if later changed to use copper or dynamic palette on scroll that this can be accomodated.

That's along the lines of grayscaling the entire map in each level and re-coloring everything with a limited palette--but something that looks great. I'd prefer maintaining the same colors as the arcade version, though, so I'll be pursuing the palette area idea first.

Better just to use basic 16 colour per level for bg and enemies and 16 colour main character sprite + bullets and improve latter when everything else is working.

That would be great

Originally Posted by Retro1234

I definitely would find it hard/impossible to get down to 16 colour but I've seen some guys around here do some amazing stuff with 16 colours maybe they could pipe up.

I'm all ears

Originally Posted by dlfrsilver

That's also why i hope an A1200 version will possibly be made.

Originally Posted by Solo Kazuki

Also i'm for AGA (then not only A1200 ) version.
Cut here to the max, cut there to the max, reduce here to the max... that's how games "not as good as for (write platfom here)" begin to appear.
I'm not against OCS/ECS version, I'm for separate AGA version - that's just in case my opinion.

AGA is sort of my fallback. I don't want to charge off in that direction just yet; pushing around 6 bitplanes would give us pretty much all the colors we need (with a few modifications) but we also want full music and perfect frame rate. A lot to ask of OCS/ECS.

...

So I'm going to try the viewfinder/palette area option. So far, so good. The initial 3 screen areas in Level 1 have only 25 colors. I'm hoping 7 more colors gives enough colors (with color overlap) to put the orcs / firethrowers / pots / treasure chests / etc into the level at their full colors too. The Level 1 dungeon is only 25 colors as well. The wise man's shop is a special case... it could take all 32 color slots because no enemy will be on screen... and I can do a copper split for the selection box area.

Gotta make sure the areas I'm looking at align properly with actual gameplay (that I'm not just moving the viewfinder into impossible or impractical positions). Level 1 has ~70 colors for just the maps... plus additional colors for enemies. If I can engineer it, there will be a handful of "palette areas" defined for L1 which all stay under the 32 color limit.

...

There won't be a whole lot of code changes for a bit, for those who may be looking for source code updates. Need to get through some discovery phase stuff with palettes. Once there's a solution, I'm going to update the code to push 5 bitplanes and to use the new Amiga-specific map tiles. No ETA.