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Damage Formulas 101 (MV Edition)


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#1 Glasses

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Posted 15 December 2015 - 10:54 AM

Damage Formulas 101
MV Edition
 
You probably wondered how to make a skill do more damage against enemies with a state, or heal more if player has a state, or deal exactly half of enemy's HP. And so on.
 
All of that and more can be done through custom damage formula.
692ef73ebc.png
 
 
Basics:
 
Type - sets what does the formula damage or heal.
None - Nothing, no damage will be dealt.
HP Damage - HP will be damaged
MP Damage - MP will be damaged
HP Recover - HP will be restored
MP Recover - MP will be restored
HP Drain - Deals damage to enemy HP and restores that much HP for attacker
MP Drain - Deals damage to enemy MP and restores that much MP for attacker
 
Element - Sets which element to use. Normal attack - means will use same element as weapon.
 
Variance - How will damage fluctuate. E.g. If skill formula says it deals 100 damage and variance is 20%, the skill will deal between 80 and 120 damage.
 
Critical - Can skill critically hit, dealing increased damage by 300%.
 
And now, the actual fun part - formulas!
It decides how much damage will opponent take or ally will heal.
 
Let's dissect one of basic formulas that come with RPG Maker MV - Fire
100 + a.mat * 2 - b.mdf * 2
 
What do things like a and b mean?
a - attacker
b - defender
So if Actor Glasses were to cast Fire on a Slime. a would be Glasses and b would be Slime.
 
Meaning the takes double of Glasses mat (Magic Attack) parameter and subtracts double of Slime's mdf (Magic Defense) parameter and adds that to the 100 in the beginning ofthe formula.
E.g. Glasses has 100 mat and Slime has 20 mdf. If we were to convert fomula using those numbers, we'd have - 100 + 100*2 - 20*2, after calculation we see with those parameters Fire would deal 260 damage if there were no variance.
 
But only last number in the formula deals damage. If you had 2 lines of formula. (semicolon ; tells where line ends for the program)
E.g. a.atk; a.atk*2
Only a.atk*2 would be calculated for damage.
 
Are there more letters other than a and b for the formulas? 
Yes. There are variables. Which are used like this: v[ID]. ID - index of the variable.
So you could have a skill that gets stronger the higher variable is.
E.g. v[10] * 2 - b.def * 3
 
Is there a way to make skill even more complex, e.g. if some variable is over 100, deal extra damage?
Yes, in that case we can use if else statements.
How if else statement looks:
if (statement)
{
   formula1;
}
else
{
   formula2;
}
 
But how to write it to the damage formula? It only has 1 line!
Just write everything together~
if (statement) { formula1; } else { formula2; }
E.g.: 
if (v[10] > 100) { a.atk*4 - b.def*2 } else { a.atk*2 - b.def*2 }
Which can be shortened to this if you're using only 1 line of formula.
if (statement)
   formula1;
else
   formula2;
E.g.: 
if (v[10] > 100) a.atk*4 - b.def*2; else a.atk*2 - b.def*2;
 
And you can shorten it even further using ternary operator (my favorite one):
statement ? formula1 : formula2;
E.g.:
 v[10] > 100 ? a.atk*4 - b.def*2 : a.atk*2 - b.def*2;
 
Symbols for statements:
> - more than
< - less than
>= more than or equal to
<= less than or equal to
=== equal to
&& and
|| or
!== not equal
! not
 
Examples:
v[10] > 100 ? 1000 : 100; (If variable 10 is more than 100, it'll deal 1000 damage, else it'll only deal 100)
 
v[10] < 100 ? 1000 : 100; (If variable 10 is less than 100, it'll deal 1000 damage, else, it'll only deal 100)
 
v[10] >== 100 ? 1000 : 100; (If variable is 100 or more, it'll deal 1000 damage, else it'll only deal 100)
 
v[10] <== 100 ? 1000 : 100; (If variable is 100 or less, it'll deal 1000 damage, else it'll only deal 100)
 
v[10] === 100 ? 1000: 100; (If variable is equal to 100, it'll deal 1000 damage, else it'll only deal 100)
 
v[10] > 50 && v[11] >== 25 ? 1000 : 100; (If variable 10 is more than 50 and variable 11 is 25 or more, it'll deal 1000 damage, else it'll only deal 100)
 
v[10] > 50 || v[11] > 50 ? 1000 : 100; (If variable 10 is more than 50 or variable 11 is more than 50 then it'll deal 1000 damage, it'll only deal 100)
 
v[10] !== 100 ? 1000 : 100; (If variable 10 is not equal to 100, it'll deal 1000 damage else it'll only deal 100)
 
What about parameters to use for a and b?
Here's a whole list of them:
 
Current: (All flat numbers, e.g.: 900, 999, 11)
level - current level (Actor only by default)
hp - current hp
mp - current mp
tp - current tp
 
Params: (All flat numbers, e.g.: 1337, 7331, 156)
mhp - max hp
mmp - max MP
atk - attack
def - defence
mat - magic attack
mdf - magic defence
agi - agility
luk - luck
 
XParams: (All decimal numbers symbolizing percent, e.g. 1.0, 0.5, 0.75, 2.44 would be 100%, 50%, 75%, 244%)
hit - Hit rate
eva - Evasion rate
cri - Critical rate
cev - Critical evasion rate
mev - Magic evasion rate
mrf - Magic reflection rate
cnt - Counter attack rate
hrg - HP regeneration rate
mrg - MP regeneration rate
trg - TP regeneration rate
 
SParams:(All decimal numbers symbolizing percent, e.g. 1.0, 0.5, 0.75, 2.44 would be 100%, 50%, 75%, 244%)
tgr - Target Rate
grd - Guard effect rate
rec - Recovery effect rate
pha - Pharmacology
mcr - MP Cost rate
tcr - TP Charge rate
pdr - Physical damage rate
mdr - Magical damage rate
fdr - Floor damage rate
exr - Experience rate
 
How about changing HP/MP/TP?
gainHp(value) - restores HP by value
gainMp(value) - restores MP by value
gainTp(value) - restores TP by value
 
setHp(hp) - sets HP to value
setMp(mp) - sets MP to value
setTp(tp) - sets TP to value
E.g. a.setHp(a.mhp)
E.g. a.setHp(a.hp + 100)
 
clearTp() - sets TP to 0
 
 
What about advanced stuff where you can influence formulas with states?
We got all that!
isStateAffected(stateId) - checks if battler has state inflicted to them.
E.g. b.isStateAffected(10) ? 10000 : 1;
 
isDeathStateAffected() - checks if battler has death state inflicted to them.
E.g. b.isDeathStateAffected() ? 10000 : 1;
 
resetStateCounts(stateId) - refreshes how long state will last for the battler
if (b.isStateAffected(10)) b.resetStateCounts(10); 100
 
updateStateTurns() - shortens all states on battler by 1 turn
b.updateStateTurns(); 100
 
addState(stateId) - adds state to the battler
if (!b.isStateAffected(10)) b.addState(10); 100
 
isStateAddable(stateId) - checks if state can be added to the battler
c=100; if (b.isStateAddable(10)) b.addState(10); else c=4000; c
 
removeState(stateId) - removes state from the battler
if (a.isStateAffected(10)) a.removeState(10); 0
 
 
 
What about buffs? Can we buff and debuff battlers?
Yes!
addBuff(paramId, turns) - adds a buff for a parameter
a.addBuff(0, 3); b.def*10
 
addDebuff(paramId, turns) - adds a debuff for a parameter
b.addDebuff(2, 10); 9999
 
removeBuff(paramId) - removes a buff or debuff from a battler
removeAllBuffs() - removes all buffs and debuffs from a battler
 
Parameter IDs
0 - Max HP
1 - Max MP
2 - Attack
3 - Defence
4 - Magic Attack
5 - Magic Defence
6 - Agility
7 - Luck
 
General Battler Stuff
die() - kills the battler
b.die(); 0
 
revive() - revives the battler
a.revive(); 1000
 
paramBase(paramId) - gets base parameter
a.paramBase(3)*10 - b.def*2
 
paramPlus(paramId) - gets the bonus of parameter
a.paramPlus(3)*2 - b.def*2
 
paramMax(paramId) - gets max possible value of parameter
b.paramMax(0)
 
elementRate(elementId) - checks element rate of the battler (rate being decimal numbers representing %)
b.elementRate(10) >== 0.5 ? 10000 : a.mat*4;
 
isStateResist(stateId) - checks whether the battler resists state
c=0; b.isStateResist(10) ? c+=2000 : b.addState(10); c
 
isSkillTypeSealed(stypeId) - checks if battler's skill type is sealed
isSkillSealed(skillId) - checks if battler's skill is sealed
isEquipTypeSealed(etypeId) - checks if battler's equip type is sealed
isDualWield() - checks if battler can dual wield
isGuard() - checks if battler is guarding
recoverAll() - removes all states, restores HP and MP to max
 
hpRate() - checks HP rate of battler
mpRate() - checks MP rate of battler
tpRate() - checks TP rate of battler
b.hpRate() < 0.5 ? b.hp-1 : 100;
 
isActor() - checks if battler is actor
isEnemy() - checks if battler is enemy
escape() - escapes from battle
b.escape() (makes enemy run away)
 
consumeItem(item) - eat up an item
a.consumeItem($dataItems[15]); 100
 
 
 
For actor only:
currentExp() - current EXP
currentLevelExp() - EXP needed for current level
nextLevelExp() - EXP needed for next level
nextRequiredExp() - EXP left until next level
maxLevel() - max level of actor
isMaxlevel() - is actor max level (true/false)
hasWeapon() - is actor wielding a weapon (true/false)
hasArmor() - is actor wearing any armor (true/false)
clearEquipments() - unequip everything actor is wearing
isClass(gameClass) - checks if actor is of a class (gameClass - $dataClasses[ID])
hasNoWeapons() - checks if actor doesn't have any weapons
levelUp() - levels actor up
levelDown() - level actor down
gainExp(exp) - gives actor exp
learnSkill(skillId) - makes actor learn a skill
forgetSkill(skillId) - makes actor forget a skill
isLearnedSkill(skillId) - checks if actor has a skill learned
actorId() - returns Actor's ID
 
 
For enemy only:
enemyId() - returns Enemy's ID
 
What about Math? Can we use Math methods inside the formula?
Yup, you totally can.
 
Math.random() - returns a random number between 0 and 1 (0 <= n < 1)
Math.min(numbers) - returns a minimum number from provided numbers.
E.g. Math.min(10, 50, 40, 200) - would return 10.
 
Math.max(numbers) - returns a maximum number from provided numbers.
E.g. Math.max(10, 50, 40, 200) - would return 200.
 
Math.round(number) - rounds a number to nearest integer.
Math.ceil(number) - rounds the number up to nearest integer.
Math.floor(number) - rounds the number down to nearest integer.
 
Math.rand() returns a number between 0 and 1, but can we get a random number between 1 and 100? Or 5 and 200?
No problem:
 
Math.floor(Math.random()*100)+1
^ That would return a number between 1 and 100. If we didn't add 1 at the end, it'd only return a number between 0 and 99.
 
But that's a lot of text? Could we simplify somehow?
Thankfully, there's a method in rpg_core.js that adds Math.randomInt(max);
So we can write the same using:
Math.randomInt(100)+1
 
If you have any questions, feel free to ask or discuss various ways to make specific skills.

Edited by Glasses, 29 January 2016 - 09:50 AM.

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#2 Cookie Ninja

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Posted 16 December 2015 - 09:07 AM

Nice! Loveley to see this topic!

 

I was wondering though, in Ace you had a character limit of 100, what is it in MV?

 

Ooo... and one more, if you wanted to go beyond those 100 char you could write something like:

 

class Game_Battler < Game_BattlerBase
  def cookie_skill(a,b)
    # Insert whatever you want it to do
  end
end
 
and then call that code in the damage formula box by writing:
a.cookie_skill(a,b)
 
How would you go about doing something similar in MV?
 
Thx alot for this wonderful post! :D

Edited by Cookie Ninja, 16 December 2015 - 09:09 AM.

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#3 Glasses

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Posted 16 December 2015 - 09:16 AM

@Cookie Ninja,

No character limit in MV.

 

And creating Game_Battler method in MV would look like.

Game_Battler.prototype.glassesSkill = function(a, b) {
  var v = $gameVariables._data;
  //Do Stuff here
};

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#4 Cookie Ninja

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Posted 16 December 2015 - 09:24 AM

Sweet!

 

No character limit!? :blink: Interesting, better make sure to get everything right when writing the longer type stuff! 

 

Thx!^^


Everything I ever make will be free for all to use for all purposes!

I rarely demand credits, but I would appreciate a thank you (not mandatory).


To me that is a great morale boost, it goes a long way in motivating to keep doing what I do :D


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#5 eatorl

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Posted 16 December 2015 - 02:35 PM

Hi there! Thank you! I have two questions:

-Is it possible to use two conditions in one damage formula? Like If(x){ if(y){a} else{b} }else{c} If not, should it be done through common event?

-Not sure if this is the place but: Which do you think is the minimum "numerical magnitude order"

Magnitude orderto work with when designing stats and skills? I found that there can be problems with some multipliers when you got values under 100, for example in a "berserker skill" where low health is important:
Spoiler

 

That makes me think that it depends on how many decimals you want to "save". I was using stats with the "minimum" number order (1) but it turns out that it got some limitations, well, a lot of limitations. Another example with multiple hits:
 

Spoiler

So.. do you think someone as a developer can adapt his formulas for simple interactions in low magnitude orders or is it much better to go to a "safe zone" and then do whatever you want with multipliers and stuff?

Thanks!


Edited by eatorl, 16 December 2015 - 02:36 PM.


#6 Glasses

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Posted 16 December 2015 - 03:12 PM

@eatorl,

Yes, you can use any number of nested if statements.

As for the numbers, I assume you ask how big the numbers should be for parameters/damage. Then, yeah, it depends if decimals are important to you - if they are, you move that many decimals to the right. And if they aren't, you can work with small numbers.


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#7 Amber

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Posted 17 December 2015 - 08:02 AM

I want to make a formula that if the caster's HP is below 25% it would deal much damage as normal attack (+ 100) and it heal the player, but I tried it gives me a 0. Is there a way to work around it



#8 Glasses

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Posted 17 December 2015 - 08:15 AM

@Amber,

What formula did you try. And how much damage does the skill do if the caster's HP is above 25%?

it could be be something like this.

if (a.hpRate() <== 0.25) { a.hp += 100; a.atk*4 - b.def*2 + 100; } else { a.atk*4 - b.def*2; }

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#9 Jeanne d'Ys

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Posted 17 December 2015 - 10:23 AM

Finally! This is really helpful, thanks a lot~ XD

 

I've been rooting for custom damage formulas in MV, since the way they're written are a bit different XD


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#10 Takeo212

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Posted 17 December 2015 - 11:08 AM

How would you make it so that your attack gradually increases with the more TP you have?

I've never been good with formula's (probably because I sucked at maths) so I can't get it to work exactly.



#11 Glasses

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Posted 17 December 2015 - 11:15 AM

@Takeo212,

Decide how much attack should increase depending on TP.

Maybe attack will deal 300% more damage if Actor has full TP, then.

(a.atk * 4 - b.def * 2) * (1 + 2 * a.tpRate())

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#12 Amber

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Posted 17 December 2015 - 11:42 AM

IT only do no damage and no full restore and I want with fully heal though



#13 Glasses

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Posted 17 December 2015 - 12:56 PM

@Amber,

Woops, my bad. Changed up the guide a little bit and added a few new methods. Should be fine now.

if (a.hpRate() <= 0.25) { a.setHp(a.mhp); a.atk*4-b.def*2 + 100; } else { a.atk*4 - b.def*2; }

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#14 Amber

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Posted 18 December 2015 - 06:42 AM

I wonder if there is a formula that have a random chance to debuff the caster/target or buffs the caster/target instead using the add buff/debuff from the effect section. I want to add a chance instead relying on those add buff/debuff all the time.



#15 eatorl

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Posted 21 December 2015 - 01:42 AM

I wonder if there is a formula that have a random chance to debuff the caster/target or buffs the caster/target instead using the add buff/debuff from the effect section. I want to add a chance instead relying on those add buff/debuff all the time.

 

Turns out Math.random() works in Damage Formula:

if(Math.random()<0.5)a.addBuff(paramId, turns); 100

Here you have a 50% chance to add the Buff, I guess you can control that with a variable or even control the chance with a parameter such as luck, etc.

if(Math.random()*100<(10 + a.luk))a.addBuff(paramId, turns); 100

If your luck values goes from 10 to 70 or something like that you could use a formula like that to "balance" that randomness, I guess.
Or use a game variable. I think it is with \v[id] or something, correct me if I am wrong.

Have a good one.
 


Edited by eatorl, 21 December 2015 - 01:48 AM.


#16 Takeo212

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Posted 30 December 2015 - 04:19 PM

How would you make a formula for something like;

The less HP the character has, the more damage they gain?

 

I've been messing around with this for a bit, but can't get it to work the way I want it too :<

Any help please?

 

EDIT

Also, if possible, how can I make a move that drains some mp from an enemy?

I can't get the formula right >.<

 

My BF is a math wiz.

I spent 1 minute explaining formula's to him, and he already knows how to make them better than me ;-;

I got these 2~ They were alot simpler that I was writing them...


Edited by Takeo212, 30 December 2015 - 04:55 PM.


#17 manoma

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Posted 09 January 2016 - 05:44 AM

is there a way to get the attacked actor ID? I wanted to make the characters earn MHP or/and DEF as they get hurt, for example each hit they take increases the maxhp by 1. i know i can make buffs, but what i want is something permanent.

 

well, while i wrote all that i also came up with new ideas of how to do it, but i still would like to know if there is a way to get attacker and defender ID. DMG dealt value would be nice too (for a alternative heal where you do DMG to a monster and acumulate part of it to use in a healing skill, is currently easy to do all of it with no variance in skills tought).

 

 

Edit: i managed to do it by making the attack teach a skill for the target and after that call a common event that would check who had the skill and would add +1mhp to him and delete the skill.


Edited by manoma, 09 January 2016 - 07:03 AM.


#18 Glasses

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Posted 09 January 2016 - 10:20 AM

You mean this?

b.actorId()

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#19 manoma

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Posted 09 January 2016 - 12:09 PM

You mean this?

b.actorId()

i tried this:

-------------------

formula:

 v[10] = b.actorId; d = a.atk * 4 - b.def * 2; if (d < 2) 1; else d;

notetag:

<Custom Execution>
$gameActors.actor(v[10]).setName(popo)
</Custom Execution>

----------------------------------
Formula:

d = a.atk * 4 - b.def * 2; if (d < 2) 1; else d;

notetag:

<Custom Execution>
$gameActors.actor(b.actorId).setName(popo)
</Custom Execution>

----------------------------
none of them worked :/ (i used setname to see the effect easily), could you give a example of how to use it?


Edited by manoma, 09 January 2016 - 12:11 PM.


#20 Glasses

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Posted 09 January 2016 - 01:28 PM

Well, yes, because it's 

b.actorId()

not,

b.actorId

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