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Author Topic: Dr. Hello graphics format?  (Read 890 times)

pangenttech

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Dr. Hello graphics format?
« on: April 11, 2022, 06:41:16 am »
https://www.spriters-resource.com/master_system/drhellobootleg/sheet/112336/
https://www.youtube.com/watch?v=8Ut16JNQNv0

   There is an unlicensed Korean Dr. Mario knockoff called "Dr. Hello," originally for MSX and ported to the Sega Master System.
   The two versions are very similar.

   Due to its unlicensed nature, it's not hard to find ROMs of the game.

   I have attempted to load the game's graphics into YY-CHR and Tile Layer Pro without success.

   Viewing it in the more complex Master System format brings up pretty much just garbled nonsense. Viewing it in a simpler format, like 1-color 1BPP, shows that the graphics are there, but no format seemed to work to display the graphics sensibly. I hoped that the MSX format would come close, but "close" is not close enough.

   Does anyone have any idea how to display these graphics accurately so that I can edit them?
« Last Edit: April 13, 2022, 02:10:08 am by pangenttech »

FAST6191

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Re: Dr. Hello graphics format?
« Reply #1 on: April 11, 2022, 08:26:23 am »
It won't be until you get to fairly modern console and PC efforts that you will see intermediate formats. Everything older, especially this old, will be close to the hardware at some level -- no great need to try other consoles unless they somehow match the hardware you care about (and there are only so many ways).

Not being visible then usually means compression. Compression on the master system, never mind unlicensed stuff, I am not familiar with but most things on things this weak will be rle (run length encoding, as in get a run of values and it will put the equivalent of 4hx10 rather than 4444444444) or maybe huffman (any repeated segments are replaced with a lookup value). https://ece.uwaterloo.ca/~ece611/LempelZiv.pdf being my usual link for compression overview (the LZ of the pdf name is the focus but the intro covers good stuff for everything else). If 1bpp displays something it could be some kind of unpacking (usually seen more for text where you can have fonts either there or not as it were).

Before getting there though have you tried grabbing the data from VRAM and searching the ROM for it or fragments of it? Also seeing what the VRAM says as far as modes available.

goldenband

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Re: Dr. Hello graphics format?
« Reply #2 on: April 11, 2022, 05:32:07 pm »
This game uses TMS9918 graphics (it won't run on a Mega Drive, for example) so I would think it ought to be compatible with whatever mode I used to do the SG-1000 games, namely 1BPP with byte advance, unless it uses compression.

By the way this is a nice Dr. Mario clone for the hardware! There isn't any Korean-language text in it, I don't think. Were you planning to hack it into something else?

pangenttech

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Re: Dr. Hello graphics format?
« Reply #3 on: April 11, 2022, 07:23:40 pm »
I guess 1BPP makes sense given the MSX origins of the game, but that presents further problems.

I'm not familiar with how MSX and SG-1000 handle colors but sprites on those platforms do always seem very 1-bit monochrome.

Looking at the graphics in 1BPP monochrome does give fairly sensible results:




You can see Mario's sprites, and facial elements of the red virus, then a font and pills/viruses.

I had hoped for something more like NES, with more colors. Especially since this is on the Master System.



The game sprites use multiple colors but maybe this is an overlay of multiple 1-bit monochrome sprites to create that illusion?

If I were doing something like Dr. Garfield, I would need at least three colors - orange, white and black/background. The NES offered four ...
https://www.romhacking.net/hacks/5452/


Another question: NES emulators like Mesen and FCEUX are useful for ROMhacking. They let you see under the hood at what the ROM is doing. You can look at PPU RAM and CHR ROM graphics, background nametable construction, sprite construction, the ROM and RAM in general, and so on.

Is there any equivalent like that for Sega Master System games? Or Game Gear, SG-1000, Genesis/Mega Drive?
« Last Edit: April 12, 2022, 10:11:42 am by pangenttech »

KingMike

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Re: Dr. Hello graphics format?
« Reply #4 on: April 12, 2022, 09:48:22 am »
I believe the TMS could ONLY display monochrome sprites.

I think the format for tiles (which can be up to 16 colors, which I think uses a hard-coded palette) is planar, but unlike NES, etc. the plane size is the entire tileset, not per tile.
(that is for the standard "graphics" mode.
The MSX game I've done the most extensive hacking on though is a MSX2 game which uses the MSX2's bitmap graphics mode which functions different, so doesn't help this question.)
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goldenband

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Re: Dr. Hello graphics format?
« Reply #5 on: April 12, 2022, 11:03:22 am »
Yes, you'd have to rewrite the entire game (or at least the graphics engine) to use the Master System's color palette or multicolor sprite capabilities.

The graphics mode used by Dr. Hello essentially puts the console in SG-1000 compatibility mode, with no access to the Mark III's increased capabilities (except RAM I think) -- everything is ColecoVision-level, in a very literal sense since the SG-1000 architecture is near-identical to the CV (the BIOS and controllers are different, most everything else is the same).

In fact I initially wondered if you might be trying to hack it to work on the ColecoVision, since SG-1000 to CV ports are generally quite feasible -- has anyone done that with Dr. Hello yet?

pangenttech

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Re: Dr. Hello graphics format?
« Reply #6 on: April 13, 2022, 02:12:52 am »
   It would be a good idea to port this from SG-1000 mode to Colecovision. I know there are a lot of homebrewers who do that. I don't know exactly what needs to be done for that to work.

  I suppose if I could move the sprites around a little and change their colors, I could still turn it into Dr. Garfield - I'd just need some white highlights on a pink sprite.