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« on: November 23, 2017, 11:11:42 AM »
Hello, interested parties!
This is a thread where I'll be documenting the progress of a new "side project." Hopefully this will eventually become the definitive SNES FFIV "everyone gets stored in the Shadow Party" mod.
At this point, it's all conceptual and theoretical, but I'm pretty sure that, with enough time, I can make this mod work exactly according to the plan I'll describe here.
The goal of this project is to make the following changes to the Vanilla FFIIUS ROM:
1) All characters except Cecil can be stored in the shadow party data. As a general rule, characters in the shadow party will not earn experience.
2) Shadow party data, which will occupy the same amount of space in SRAM as it does in Vanilla, will be divided into two distinct parts. Part 1 (0x80 bytes) will store two full character records. Characters stored in part 1 will earn experience. By default, these full records will be used to store Kain (when he is under Golbez's control) and Rydia (between the shipwreck and her return as a teenager). Part 2 (0xB0 bytes) will store a set of essential data for Kain, Rydia, Tellah, Edward, Rosa, Yang, Palom, Porom, Cid, Edge and FySoYa. Characters stored in this section will not gain experience. The tradeoff is that all characters can leave and rejoin the party without losing stat information.
3) The Namingway screen will be removed and replaced with a party switch system, which I am calling the PHS (after the system in FFVII)
4) Character equipment will not be stored in shadow party data, but a hacker using this mod will be able to choose whether all equipment is lost forever or added to the player's inventory (or the fat chocobo's inventory?) when a character is moved to the shadow.
I think this mod will be interesting enough on its own that FFIV fans might want to try it just for fun. The great part about it, though, is that it will be fully compatible with FF4kster, so it will easily lend itself to others' hacking projects.
A few preemptive answers to some possible questions...
Why can't I store Cecil?
Essentially, I had to draw the line somewhere. The reason it's so hard to make a mod that fully stores every character in the shadow party is that the game only has 320 bytes available for the shadow party. I need 128 of those bytes for the records that can gain experience (I wanted 192, actually, but again I had to draw the line), which leaves me with only 192 for the non-experience slots. Even using a little compression trick I thought up, I still need 16 bytes for each character slot, and 16 x 11 (the total number of non-Cecil characters) = 176. I still have 16 bytes leftover then that could be used for Cecil, but that leaves open the possibility to face Zeromus without the ability to use the Crystal, which would leave the player in a game breaking dead end.
So then why include records that can gain experience at all?
In the default game story, I think it's necessary that Kain and Rydia gain experience when they are away. Story-wise, they are off actually doing things (as opposed to, say, Rosa, who spends her time away from the party completely tied up). And also, they are gone long enough that if they didn't level up, their return would be anticlimactic. Kain has, by far, the longest period of time away from the party. You don't want him rejoining at level 13. Rydia needs to come back and immediately provide significant help defeating Golbez and his shadow dragon. In a perfect world, Yang would level up, too, but there isn't enough room, and at least he's only gone for one chapter of the story so he doesn't miss out on very much levelling.
What are these "essential stats" that are getting stored?
A large portion of the character record is completely static and easily retrievable from ROM. What will be stored is everything that is not, specifically: Level, Persistent Negative Statuses, Current HP, Max HP, Current MP, Max MP, Base Str, Base Agi, Base Vit, Base Wis, Base Will, and Exp. I could have opted to save space by not including Persistent Statuses, Current HP and Current MP, but then the PHS system could be used as a free Cabin (for everyone except Cecil) and I feel like that would be a major flaw. The choice not to store equipment also saves seven bytes per record.
But wait - I just counted, and that all adds up to 18 bytes, not 16 - what's up with that?
You're absolutely right. I devised a bit of a compression trick. It's not much, but it saves two bytes per record. The highest possible value for Current and Max HP is 9999, or 0x270F, or #00100111 00001111. The highest possible value for Current and Max MP is 999, or 0x03E7, or #00000011 11100111. So HP never uses the two most significant bits, and MP never uses the six most significant bits. By shifting Max HP left by two bits I can combine it with Max MP into three instead of four bytes, and likewise for Current HP and MP.
So what happens with the stored characters' equipment?
As I said, the hacker will have the option when a character "leaves" to either discard current equipment outright, or to move the equipment into the player's inventory. To me, there are some instances when it makes sense in the story just to discard the equipment - specifically when a character leaves against the party's will (e.g. - Kain gets hypnotized, party gets shipwrecked); and there are times when a departing character might be able to leave equipment with the party (Palom & Porom get stoned, Cid stays in the Dwarf kingdom, any time PHS is used). I'm pretty sure I can work it out that if the player's inventory is full, the "swap or discard" screen will kick in, though I haven't actually tried yet...
So you're hacking the Namingway screen... How's that gonna work?
Well, I don't exactly know just yet. I can tell you that the player will lose the option to change Cecil's name to "Shitty," but the tradeoff should be worth it. As for how I actually come around to hacking the screen... Well you, dear reader, get to see that develop right before your very eyes. You see, I have a concept of how it will all work, but I don't know enough about the SNES PPU to code the visuals yet. Squall is helping me figure that all out on this forum, so you can watch as I learn what I need to learn.
Stay tuned!
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