Topic: Games for Home Systems (adds and more...)

[Gab75]

Another great aftermarket game emulated by FBNeo (Megadrive roster)! A big thanks to dink!
Secret of the 4 Winds, The (2025)

PS: the game uses a sort of "software alpha channel" (semi-transparency) for the sprites of ghosts/wraiths... a feature far from obvious for the Megadrive hardware!

[eye2eye]

PS: the game uses a sort of "software alpha channel" (semi-transparency) for the sprites of ghosts/wraiths... a feature far from obvious for the Megadrive hardware!

i love kai magazine (caution irony), using yx5200-chip for mp3 playing, using a tf card (micro sd) for storing those mp3,
using a mct377 chip for graphical gimmicks but no sram chip on the pcb, they use the main game rom chip also for storing
their sram which does not really increase the lifespan of the cartridge...and in the code therefore constantly unlocking and
locking, read and write those sram area in main rom. and after all - all this sh** mainly for copy protection reasons - as far
as i can reconstruct the crack history - this russian dude needed about a week, maybe some days more - the libretro code
was done within 5-6 hours without testing - the biggest deal was to get the cartridge (which took several weeks), as they
don't send products directly to russia - well done!

[Gab75]

@eye2eye:
then I could deduce the translucent sprites are not a "miracle" of some very efficient software algorithms, but a feature obtained using the MCT377 chip. Is it right?

[eye2eye]

i can only assume this, didn't look into the grfx code. but there is no other graphical feature which could explain the use of this chip.
not more colors as usual, not more sprites, not more layers, scrolling/playfield is normal etc.

the problem is, i can not really debug the game, i patched the initial sram-check (not compatible bla bla) out, so i can use the debugger
in mame but it crashes later on, the debugger in fbn or retroarch is unusable. so i'm stuck here.

i tried to make a cheat feature for better and faster testing out if the game is really complete and you can play right to the end
(rom size 4mb and the last 100kb are empty/sram)
but does not work yet, all i know is that the hp (30) is stored in 0xe0ff0B35 but neither this or 0xe0ff0B34 (word) or 0xe0ff0B32 (long) is used directly
they use indirect pointer addressing like sub.l   D0, ($4,A2) which is a pain...without breakpointing

...and not even a cool title screen to use in fbn, for me the game looks again like an over-engineered, quickly cobbled together, not really finished
game - as you might know they started the game as msx2 project but switched during development to genesis...
e2e

[dink]

Another great aftermarket game emulated by FBNeo (Megadrive roster)! A big thanks to dink!
Secret of the 4 Winds, The (2025)

PS: the game uses a sort of "software alpha channel" (semi-transparency) for the sprites of ghosts/wraiths... a feature far from obvious for the Megadrive hardware!

It's just a palette trick, called shadow/hilight mode - which is basically a copy of the regular palette but with lower or higher brightness

best regards,
- dink

[dink]

@eye2eye:
then I could deduce the translucent sprites are not a "miracle" of some very efficient software algorithms, but a feature obtained using the MCT377 chip. Is it right?

I wonder what this chip really does - I can't find any info about it..

[Stifu]

@eye2eye:
then I could deduce the translucent sprites are not a "miracle" of some very efficient software algorithms, but a feature obtained using the MCT377 chip. Is it right?

As Dink said, it's just shadow and highlight mode. Many Sega Genesis games use it. Like, say, Rambo III for the character shadows, or The Haunting for the main character sprite.

About the chip:

The cartridge contains a custom board with an audio enhancement chip.
This game will make use of that audio chip but it can also be played with the console's original audio if desired.

[Loggan08]

where to put sot4w samples ?

[Gab75]

where to put sot4w samples ?

In the "samples" folder (inside a single zipped archive)... the default path should be */support/samples, but you can change it in FBNeo options (Misc/Configure support file paths...)

[Gab75]

It's just a palette trick, called shadow/hilight mode - which is basically a copy of the regular palette but with lower or higher brightness

A smart trick to simulate a real translucency effect... so, I presume, the "fake" translucent objects need to refresh their palette every single frame (at least when they are moving).

[Gab75]

Added the support to a new SG-1000 homebrew:
Solar Fox II (2025)

[Gab75]

Added the support to 6 new ZX Spectrum titles (5 classics + 1 homebrew):
Alcatrazz Harry 48K (1984)
Ali-Bebe 48K (Spanish)(1985)
Bebe Bigotes 48K (Spanish)(HB, 2021)
Beebul 16K (1984)
Fireman Fred 48K (1984)
Jogger 16K (1983)

[Stifu]

A smart trick to simulate a real translucency effect... so, I presume, the "fake" translucent objects need to refresh their palette every single frame (at least when they are moving).

No. When S/H mode is enabled, if a sprite uses the 4th color palette (PAL3), then the last 2 colors of that palette have special properties. The 15th color (color 14) shows the background behind it with colors that are 50% brighter, while the 16th color (color 15) shows the background behind it with colors that are 50% darker. This means it basically ignores what the last two colors are supposed to be, and instead applies a different logic. It looks like translucency, but it is just all about halfing or doubling the RGB values of the background behind it. In other words, it's like the console only supports translucent black and translucent white.

[Gab75]

No. When S/H mode is enabled, if a sprite uses the 4th color palette (PAL3), then the last 2 colors of that palette have special properties. The 15th color (color 14) shows the background behind it with colors that are 50% brighter, while the 16th color (color 15) shows the background behind it with colors that are 50% darker. This means it basically ignores what the last two colors are supposed to be, and instead applies a different logic. It looks like translucency, but it is just all about halfing or doubling the RGB values of the background behind it. In other words, it's like the console only supports translucent black and translucent white.

Thanks for the technical explanation!

[eye2eye]

Even if gab is satisfied, for me this explanation rises new questions:
- what does this chip which seems to be not relevant for emulation really do?
- a mysterious chip would be ideal for copy protection, so why don't
  they use this as a black box, put some values in and some other values come out and nobody knows how?
- i read this chapter about the vdp but your 50% rule does not really fit here, lets take an example:

this is a ghost in the hangar level, the background consists of 3 different colors,
let's look at grey (rgb 173,173,173), 50% darker 87/87/87 and 50% lighter 255/255/255 (it's more but this is already white)
the ghost has as dark grey 99/99/99 around him is a halo line this has 206/206/206
now we know that the genesis uses rgb-9 so 512 colors

we find here our background grey in the first line the second grey left from white (172/172/172 not being more papal than the pope himself)
we even find our desired 87/87/87, it's also in the first line the second grey right from the first black but in the whole color map there is no
99/99/99 as in the screenshot.
either fbn does something wrong or i misunderstood the functioning of the vdp, i thought it takes an other (darker/lighter) color out of the
9bit color universe for darkening and lightening and not generate a complete new color which is not nearly 50%

you can check the other colors - they just don't fit, neither in the color map nor to the 50% rule.
no, i did not change any gamma values in fbn, it's all default.

well, if i had the cartridge i would solder out this mct and would look what happens