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Author Topic: FF5 Bugs & Glitches  (Read 23831 times)

noisecross

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Re: FF5 Bugs & Glitches
« Reply #45 on: February 25, 2015, 11:27:42 AM »
I prefer the first one [...]

Me too for the same reasons.

samurai goroh

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Re: FF5 Bugs & Glitches
« Reply #46 on: February 25, 2015, 05:11:27 PM »
With paging renaming not being an issue at all, then I vote for the first one:
http://slickproductions.org/slickwiki/index.php/FF5_Bug:Walk_through_walls_in_the_Pyramid

I'll try creating one and playing with it to see what information can be placed
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samurai goroh

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Transforming Item bug
« Reply #47 on: March 14, 2015, 01:08:52 AM »
I wanted to try and replicate the Transform Item bug (the main reason I wanted to do videos of the bugs). At first I had the impresion that the bug was hard to pull, but all that matters is the frame on when you kill the caster (And you have all the time you want to use after Quick). I made a quick script that replicated suiciding on the first attack just delaying the attack 1 frame each time and indeed it had about 25% chances of happening (in average every 2 of 8 frames, but not necessary in 1 out of 4 frames). I still have no clue what trigger this (as in why it works in some frames but not in others), but it seems is partially related to the RNG battle counters (7E003A, 7E003B), but that's just a coincidence.

I tried equipping different items, but was only able to do it with the ones mentioned originally PLUS the Giant's Gloves (wonder why Ebmid missed this one), which also gives Vitality bonus (All but the White Robe gives +5, the robe gives +3). I also tried equipping the Bone Mail which takes away Vitality points (-5), but the bug could not be reproduced. I also tried switching 1 item at a time with no avail. So it seems only having 3 out of 5 possible items (Ribbon, White Robe / Angel Robe, Guard Ring / Giant's Gloves) is the key to reproduce the bug it seems, so it's a very limited bug. (The weapon equipped does not matter, just what you have equipped on the Left Hand which is going to be morphed matters)

Here's the video in action:
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samurai goroh

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Re: FF5 Bugs & Glitches
« Reply #48 on: March 30, 2015, 09:46:01 PM »
I was lurking in youtube and found a video with what it seems like a bug (unless is using cheats, but I doubt). It happens at 3:50

Since is in Japanese, I can't tell exactly what happens, but from what I can tell is that Butz gets zombie status (Zombie Breath) and he's alive with 0 HP (he no longer has "near death" status). My guess is that it has equipped the Angel Ring and that's why the attack didn't killed him (Although if that's the case, he shouldn't be with 0 HP as far as I know, but could be wrong).

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Djibriel

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Re: FF5 Bugs & Glitches
« Reply #49 on: April 02, 2015, 01:49:35 PM »
Seems like Zombie is set. Zombie Breath sets Zombie if it kills. Butz has 0 HP and moves to attack his own party/himself. I see nothing wrong here (except for the Undead).

If there is a bug here, it's the oversight that a full party, or at least all considered alive, can be Hidden in a boss fight simultaneously. Also, the 00 Doom counter on the Zombie should be removed. Or maybe it triggers as soon as you cure Zombie?

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samurai goroh

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Re: FF5 Bugs & Glitches
« Reply #50 on: April 02, 2015, 07:02:42 PM »
I'm sure Zombie should override other status, so the sprite should change accordingly. The algorithm FAQ says you're immune to a lot of status if you are a zombie, though it has no mention what if the other way around happens...

So if a zombie frog has the look of a normal frog, that's a bad design IMO. Same goes if it happens with mini status.
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Djibriel

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Re: FF5 Bugs & Glitches
« Reply #51 on: April 04, 2015, 10:59:57 AM »
Zombies are immune to Darkness, Poison, Float, Mini and Toad, but characters with those status ailments are not immune to Zombie. Having Zombie remove those statuses would have been an understandable design choice, but they didn't make it.

I seem to remember that eyes turn fully white when turned into a Zombie, so a Frog under the effects of Zombie is distinguishable from a 'normal' Frog. It's kind of hard to see in the video since there's no normal frog pose to compare it to.
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samurai goroh

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Re: FF5 Bugs & Glitches
« Reply #52 on: April 04, 2015, 08:00:51 PM »
I see, they have no pupils when they turn into frog zombies. Yea, hard to find if you're not familiar with it. Thanks Djibriel.

So, when you are affected by zombie while being doomed, the countdown freezes instead of disappear once it reaches 0, huh. That doesn't seem right.
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LightPhoenix

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Re: FF5 Bugs & Glitches
« Reply #53 on: April 05, 2015, 06:12:54 PM »
Regarding the Item Transform Bug... I'm tooling around with it trying to find the cause.  I'm still in the setup phase, but I just had it happen to the item in the right hand - my Tempest became a Masamune (using two weapons).  Will post more as I find out more.

EDIT: Looks like I figured it out.  I haven't written a fix, but it's easy enough to do.

FF5's Main Battle Loop (MBL) can be found at C2/5872.  It runs every tick, and checks various conditions.  There are two variables we're interested in.  The first $7C51, which is a flag that notes if a character has the Quick status.  The other is $7C54, which is a flag that is set every four ticks, and for the purpose of this big handles HP Leak timing, among other things.

Part of the MBL is a check for Quick status being nullfied (C2/627B) - say by killing yourself off.  This is where the bug is.  This clears the flag correctly, but then calls JSR $24E4.  The code is as follows:

Code: [Select]
C2/627B: AD 51 7C     LDA $7C51 If Quick Flag not set, skip this part
C2/627E: F0 31        BEQ $62B1
C2/6280: A5 0E        LDA $0E If Creature Number /= 7CB6, skip this
C2/6282: CD B6 7C     CMP $7CB6
C2/6285: D0 2A        BNE $62B1
C2/6287: BD 1A 20     LDA $201A,X If Zombie, Petrify, Dead...
C2/628A: 29 C2        AND #$C2
C2/628C: D0 1D        BNE $62AB
C2/628E: BD 1B 20     LDA $201B,X ...Berserk, Charm, Paralyze, Sleep...
C2/6291: 29 78        AND #$78
C2/6293: D0 16        BNE $62AB
C2/6295: BD 1C 20     LDA $201C,X ...Stop...
C2/6298: 29 10        AND #$10
C2/629A: D0 0F        BNE $62AB
C2/629C: BD 1D 20     LDA $201D,X ...Singing, Erased...
C2/629F: 29 84        AND #$84
C2/62A1: D0 08        BNE $62AB
C2/62A3: BD 06 20     LDA $2006,X ...or HP = 0...
C2/62A6: 1D 07 20     ORA $2007,X
C2/62A9: D0 06        BNE $62B1
C2/62AB: 9C 51 7C     STZ $7C51 ...Clear Quick Flag
C2/62AE: 20 E4 24     JSR $24E4 ...and clear 3EAB array (#0C values)
C2/24E4: 7B           TDC
C2/24E5: AA           TAX
C2/24E6: 9E AB 3E     STZ $3EAB,X
C2/24E9: E8           INX
C2/24EA: E0 0C 00     CPX #$000C
C2/24ED: D0 F7        BNE $24E6
C2/24EF: 60           RTS

See the bug?

24E4 overwrites the X register, which is supposed to be holding the character data offset.  It never gets saved/restored.  Oops.

So X is now #000C, and the MBL continues as normal until we get to the HP Leak Check (C2/6301).
Code: [Select]
C2/6301: BD 1D 20     LDA $201D,X If HP Leak...
C2/6304: 1D 73 20     ORA $2073,X
C2/6307: 29 08        AND #$08
C2/6309: F0 2C        BEQ $6337
C2/630B: AD 54 7C     LDA $7C54 ...and Tick Flag set...
C2/630E: F0 27        BEQ $6337
C2/6310: BD 1E 20     LDA $201E,X ...Exit if Jumping...
C2/6313: 29 10        AND #$10
C2/6315: D0 20        BNE $6337
C2/6317: C2 20        REP #$20
C2/6319: BD 06 20     LDA $2006,X If HP /= 0, HP--
C2/631C: F0 04        BEQ $6322
C2/631E: 3A           DEC
C2/631F: 9D 06 20     STA $2006,X
C2/6322: 7B           TDC
C2/6323: E2 20        SEP #$20
C2/6325: BD 1D 20     LDA $201D,X If Hidden, min HP = 1
C2/6328: 29 01        AND #$01
C2/632A: F0 0B        BEQ $6337
C2/632C: BD 06 20     LDA $2006,X
C2/632F: 1D 07 20     ORA $2007,X

Since X is never restored, it's now reading data off of the first character's data.  The first check (for HP Leak status) usually passes.  However, this code is only run every four ticks - hence the seemingly random nature of the bug.  Since it's now looking at weapon data, and since it's not usually going to be zero, it runs the DEX/STA, decrementing the weapon number. 

The obvious fix is to make 24E4 PHX/PLX like it should have.
« Last Edit: April 05, 2015, 07:16:21 PM by LightPhoenix »

Grimoire LD

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Re: FF5 Bugs & Glitches
« Reply #54 on: April 06, 2015, 01:56:30 PM »
Great find LightPhoenix! I'm surprised you were able to wade through the tick readings. I seem to have a bit of trouble with those.

samurai goroh

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Re: FF5 Bugs & Glitches
« Reply #55 on: April 06, 2015, 03:58:14 PM »
Great work LightPhoenix.

From the explanation I could understand why it happens and why it does in 1 out of 4 frames (ticks) in average.
But do you know why did it only happened with the specific items equipped? (the items that boost vitality)
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LightPhoenix

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Re: FF5 Bugs & Glitches
« Reply #56 on: April 06, 2015, 09:54:21 PM »
From the explanation I could understand why it happens and why it does in 1 out of 4 frames (ticks) in average.
But do you know why did it only happened with the specific items equipped? (the items that boost vitality)

I'm not certain, but $201D,X, with an index of X = #000C points you at $2026, which is Vitality.  $207F is a variable that I'm not entirely sure about.  It's probably that equipping those items allows the initial comparison to be more likely to pass.  Perhaps #20 is often set on $207F, and would only be set on $201D with vitality boosting equipment?  Honestly, I didn't test that part very well.

samurai goroh

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Re: FF5 Bugs & Glitches
« Reply #57 on: April 13, 2015, 07:22:02 PM »
I forgot about this bug until recently I wanted to reproduce a different one XD, I've named it the Shiny Dragon:
https://youtu.be/zeGIFvjPerw

The one I was trying is to get Boko stuck under the Fork Tower but I got it once and when I tried to optimize the video by leveling up the heroes, I could no longer reproduce it XD
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samurai goroh

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Re: FF5 Bugs & Glitches
« Reply #58 on: June 27, 2015, 03:18:08 PM »
Watching some Fiesta streams I learned about a few bugs:

First one is that when you are close to level up and are trying to learn a Lv spell, due to leveling up when you finish that battle, you won't be able to learn the magic. I have some vague memories that this happened to me on the Ancient Library when I got the GBA version long time ago. I would need to reproduce it, but I'm certain that this happens.

Second one is a visual one, when enemies that have a Wall run out of magic while trying to reflect the spell back to your team, the wall animation will be triggering despite being unable to cast at all. An example would be the Wall Mage.
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samurai goroh

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Re: FF5 Bugs & Glitches
« Reply #59 on: July 01, 2015, 01:14:03 PM »
Also watching streams (and while playing) I noticed that sometimes when you revive a Berserker, it will immediately attack. It seems that after certain amount of time has passed since the Berserked died, the ATB will be set to 1 (Like it happens in this video, although here it's set immediate after getting zombied...)

Also, I had long forgotten about skipping Kelb Town bug. Thanks to EiriasValar for rediscovering it.
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