FF7/DamageFormula

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Revision as of 20:00, 17 May 2021 by NFITC1 (talk | contribs) (→‎0: Physical Accuracy Check: I can't decide on a layout, but this is slightly more organized and understandable)

Accuracy Function considerations

Each of the upper nybble of the damage calculation determines what checks are done to accuracy of the action and whether or not it will connect, be critical or miss. Here are the functions in order processed based on the upper nybble:

Upper Nybble Functions
0 None (always hits)
1 Physical Accuracy, Critical Check
2 Magical Accuracy
3 Dummy [3] (always hits)
4 Dummy [4] (always hits)
5 Dummy [5] (always hits)
6 Physical Accuracy, Critical Check
7 Magical Accuracy
8 Level-based Accuracy
9 Manipulate
A Physical Accuracy, Critical Check
B Physical Accuracy
C None (always hits)
D None (always hits)
E None (always hits)
F None (always hits)

Contents

Damage Calculations

These are the damage functions according to an unmodded FF7-ENG 1.02 (1998)

Standard Formulae

X0:

0x5DE5C0 

Sets Target's 02h flag to 1. (Unknown effect)

X1:

0x5DE5DF 

If Attack Property "Always Critical" is Set
	Set Critical Damage Flag
End If

x = ( Actor's Level * Actor's (M)Attack ) / 32
y = ( Actor's Level + Actor's (M)Attack ) / 32
z = Actor's (M)Attack + ( x * y )
z = z * ( 512 - target's defense ) * Attack's Power
Damage = z >> 13
//This is a bit-shift left by 13 which is mathematically equivalent to dividing by 8192, but it's important to note that it doesn't actually divide as this is the source of the damage overflow glitch

If Critical Damage Flag is set
	Damage = Damage * 2
End If

If Actor's Statuses include Berserk
	Damage = Damage * 3 / 2
End If

Long_Range = 0
If Target is in Back Row
	Set Long_Range = 1
End If

If Attack is Short Range OR Command is Enemy Attack
	If Actor is in Back Row
		Long_Range = 1
	End If
Else
	Long_Range = 0
End If

If Long_Range != 0
	Damage = Damage / 2
End If

If Target is Defending
	Damage = Damage / 2
End If

If Target's Back is exposed
	Damage = Damage * ( Target's Back Attack Modifier / 8 )
End If

If Actor's Statuses includes Frog
	Damage = Damage / 4
End If

Damage = Sadness( Damage )
Damage = Split( Damage, 0 )
Damage = Barrier( Damage )
  
If Actor's Statuses include Mini
	Damage = 0
End If
Damage = Variance( Damage )

X2:

0x5DE9B8 

multiNoSplit = ( ( ( Attack's Target Flags AND Ch ) - 4 ) == 0 ? 1 : 0 )
Base = (Actor's Attack + Actor's Level) * 6
Damage = (512 - Target's Defense) * Base * Attack's Power / 8192
Damage = Sadness( Damage )
Damage = SplitDamage( Damage, multiNoSplit )
Damage = Barrier( Damage )
Damage = Variance( Damage )

X3:

0x5DEA6D 

If Attack Properties Damage MP is clear
	Damage = Target's HP
Else
	Damage = Target's MP
End If

Damage = Damage * Attack's Power / 32

If ActionData[AC] != 0 (?)
	Damage = Damage / 2
End If

X4:

0x5DEAF7 

If Attack Properties Damage MP is clear
	Damage = Target's MHP
Else
	Damage = Target's MMP
End If

Damage = Damage * Attack's Power / 32

If ActionData[AC] != 0 (?)
	Damage = Damage / 2
End If

X5:

0x5DEB81 

Damage = (Actor's (M)Attack + Actor's Level) * 6 + (Attack's Power * 22)
Damage = SplitDamage( Damage )
Damage = Barrier( Damage )
Damage = Variance( Damage )

X6:

0x5DEBE5 

Damage = Attack's Power * 20

X7:

0x5DEC0A 

Damage = ( ( 512 - Target's Def ) * Attack's Power / 32 )
Damage = Variance( Damage )

X8:

0x5DEC52 

If ActionData[0x230] AND 40h
	ActionData[0x230] = 1
Else
	ActionData[0x230] = 80h
End If
//presumably this checks if the target heals from restore element and will either recover or kill based on the result

X9:

0x5DEC8A 

Actor's Attack = Actor's Strength * 2
Use Damage X1 with adjusted stat

XA:

0x5DECAA 

Damage = ( Attack's Power + Number of Targets - 1 ) / Number of Targets

Additional Checks

Sadness( Damage )

0x5DE958 

If Target's Status includes Sadness
	Damage = Damage - (Damage * 3 / 10)
End If
Return Damage

SplitDamage( Damage, multiNoSplit )

0x5DE8F4 

If multiNoSplit == 0
	If No. of Attack's Targets >= 2
		Set Attack's split damage Target Flag
	Else
		Set multiNoSplit == 1
	End If
End If

If ActionData[0xAC] == 0
	Damage = Damage / 2
Else
	If multiNoSplit == 0
		Damage = Damage * 3 / 2
	End If
End If
Return Damage

Barrier( Damage )

0x5DE82C 

If Attack Property "Physical" is 0
	If Target's Statuses include MBarrier
		Set ActionData "MBarrier Active" flag
	End If
Else
	If Target's Statuses include Barrier
		Set ActionData "Barrier Active" flag
	End If
End If

If ActionData "MBarrier Active" or "Barrier Active" flags are set
	Damage = Damage / 2
End If

If attack is Magic and EnabledMagic[7] == 0 (?)
	Damage = Damage + ( Damage * ( EnabledMagic[7] * (10 / 32) ) / 100 )
End If
Return Damage

Variance( Damage ):

0x5DE988 

Damage = Damage ([0..255] + 3841) >> 12  //from RNGLUT in KERNEL.BIN
//Again, we have another chance for overflow.

If Damage == 0
	Damage == 1
End If
Return Damage

Secondary Damage Formulae

X0:

0x5DECFB 

Damage = Attacker's HP

X1:

5DED1E 

Damage = Attacker's MHP - Attacker's HP

X8:

0x5DED73 

Dice_Count = Attacker's Level / 10

If Dice_Count < 2 then
	Dice_Count = 2
Elseif Dice_Count > 6
	Dice_Count = 6
End If

total_dice_roll = 0
For ( d_loop = 0; d_loop < Dice_Count; d_loop++ )
	die = [0..5]
	all_dice[d_loop] = die
	total_dice_roll += die + 1

	set die visualization based on roll
Loop

value_repeat = 0
For ( d_value = 0; d_value < 6; d_value++ )

	repeat_count = 0
	For ( d_loop = 0; d_loop < Dice_Count; d_loop++ )

		If all_dice[d_loop] = d_value then
			repeat_count++
		End If
	Loop

	If repeat_count > value_repeat then
		value_repeat = repeat_count
	End If

Loop

Damage = value_repeat * 100 * total_dice_roll

X9

0x5DEEEF 

Damage = Number of Successful Escapes

XA

0x5DEF1D 

Damage = Target's HP - 1

XB

0x5DEF44 

Damage = (Game Time Hours * 100) + (Game Time Minutes)

XC

0x5DEF88 

Damage = Target's Kill Count * 10
//This is intended to be used only on players
//This will cause a memory leak if done on enemies

XD

0x5DEFDD 

If target is playable character
	MateriaCount = 0;
	For ( MateriaLoop = 0; MateriaLoop < 8; MateriaLoop++ )
		If target has materia in weapon slot [MateriaLoop] then MateriaCount++
		If target has materia in armor slot [MateriaLoop] then MateriaCount++
	Loop
	Damage = MateriaCount * 1111
End If

Accuracy Functions

The point of these is to set the "attack will miss" flag in the current action memory structure.

0: Physical Accuracy Check

0x5DDBB0 

;For the purposes of this code, "Dex" means the adjusted Dexterity of the actor/target if any in-battle dex bonuses have been granted.
;Same holds for the Physical Evade. Physical Hit rate has no in-game bonus opportunities.

Check_For_Cover()

HitChance = -1;

If "Always connect" flag set then HitChance = 255;

If target has one of the following statuses (Death, Sleep, Confu, Stop, Petrify, Manipulate, Paralysis) then
	Remove Sleep status
	Remove Confu status
	Remove Manipulate status
	HitChance = 255
End If

If action is flagged as "always hit" then HitChance = 255;

Physical Chance = (Actor's Dex >> 2) + action physical hit rate
Actor's evade = (Actor's Dex >> 2) + Actor's Physical evade
Target's evade = (Target's Dex >> 2) + Target's Physical evade

If HitChance = -1 Then
	HitChance = Physical Chance + Actor's evade - Target's evade
	HitChance = FuryAdjust(HitChance)
End If

If HitChance = 0 then HitChance = 1

Luck Chance = [0..99]
If (Actor's Luck / 4) > Luck Chance Then
	HitChance = 255 ;Lucky Hit
Else
	If Actor is Player Character targetting an enemy Then
		If (Target's Luck / 4) > Luck Chance
			HitChance = 0 ;Lucky Dodge
		End If
	End If
End If

Miss Chance = (([0..65535] * 99) / 65535) + 1 ;essentially [1..100]
if HitChance < Miss Chance then
	Set Miss flag
End If

Check_For_Cover

This is where the game checks if the target is covered under a "cover"ing ally. It only applies to Player Characters It might be more complicated than I'm seeing, but that is definitely ONE of its functions

FuryAdjust(HitChance)

	If HitChance < 255 then 
		If Actor is in Fury Status
			HitChance = HitChance - ((HitChance * 3) / 10)
		End If
	End If
	return HitChance

1: Magical Accuracy Check

0x5DDE5E 

acc = Action's Accuracy
tar_save = level / 2; //rounded down
acc_bonus = actor's level - tar_save
rand_0 = [0..99]
rand_1 = [0..99]
if acc < 255 then
   if target does not have instant-death, null, or heal properties to current attack then
      if attack is not (reflectable and target in reflect status) then
         if attack does not inflict statuses or inflicting status include: Death, Sleep, Confu, Stop, Petrify, or Paralysis then
            acc = Fury_Adj( acc );
            if target's M_Evade > rand_0 OR
                acc + acc_bonus < rand_1 then
               Set action miss flag
            end if
         end if
      end if
   end if
end if

2: Critical Hit Check

0x5DDF8E 

If attack does not miss then
   if actor in lucky girl status then
      critical_chance = 255
   else
      critical_chance = ((actor's luck + actor's level) - target's level ) >> 2;
      if actor is playable character then
         critical_chance += weapon's critical bonus //?
      end if
      Critical_random = ( ( [0..65535] * 99 ) / 65535 ) + 1;
      if critical_chance > critical_random then
         attack set to critical
      end if
   end if
end if

3, 4, and 5 don't exist. Since they don't set miss they will always hit.

6: Manipulate Accuracy (intended solely for playable characters)

0x5DE0D0 

int ally_loop;
ManipSuccess = 0;
for ( ally_loop = 0; ally_loop < 3; ally_loop++ )
{
   if target is currently under manipulation by an actor then
      break;
   end if
}
if target is not currently being manipulated AND
    target is not a playable character AND
    target is an enemy AND
    actor is not currently manipulating an enemy AND
    target is not under manipulate status AND
    target's timer bar is running AND //like they're not stopped, petrified, etc
    target's attack resistance is "always-hit" then //?
   Manip_Chance = actor's level + 50 - target's level; //no less than 0
   if target count > 1 then
      Manip_Chance = ( Manip_Chance << 2 ) / 5;
   end if
   if actor's [0xAC] == 0 then
      Manip_Chance >> 1;
   end if
   if target's attack resistance is "always-hit" then
      Manip_Chance = 255;
   end if
   if actor's accessory property == 5 //"Increase manip rate" property on Hypnocrown
      if Manip_Chance < 100 then
         Manip_Chance = 100;
      end if
   end if
   If Manip_Chance > [0..99] then
      ManipSuccess = 1;
   end if
end if
If ManipSuccess == 1 then
   Set actor's manipulated enemy to target
   Display String 5Ah {"Manipulated <Enemy>"}
   Clear Actor's 0xE4 value //unknown
else
   Set attack missed
end if

This doesn't actually place the target in the manipulate status. That happens elsewhere.

7: Level-based Accuracy

0x5DE08A 

If Action's Accuracy > 0 then
   If the remainder of ( Target's level / Action accuracy ) is non-zero then
      Set attack missed
   end if
end if

So if the accuracy IS 0, then it will always hit. This is to prevent a divide by zero error.

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