Damage Formulas 101

Skunk · 2017-07-28T16:33:52+0900

Please note: A discussion has already been started about different things you can do with these formulas so please direct those comments and question to the appropriate thread. https://forums.rpgmakerweb.com/index.php?threads/rmmv-damage-formula-ideas-and-help.47099/ A link to the list of script equivalents of event commands https://forums.rpgmakerweb.com/index.php?threads/rpg-maker-mv-script-call-list.46456/ 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. 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: Code: Code (Text): if (statement) { formula1; } else { formula2; } But how to write it to the damage formula? It only has 1 line! Just write everything together~ Code (Text): if (statement) { formula1; } else { formula2; } E.g.: Code (Text): 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. Code (Text): if (statement) formula1; else formula2; E.g.: Code (Text): 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.: Code (Text): v[10] > 100 ? a.atk*4 - b.def*2 : a.atk*2 - b.def*2; Symbols for statements: > - more than = more than or equal to 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 is 100 or more, 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 pe…

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Started by Skunk Jul 28, 2017, 07:33 AM 281 posts Page 2 of 15 View original ↗

Engr. Adiktuzmiko

#21 Jun 9, 2019, 10:44 AM Source
You should enclose what happens when the "if" is true in {}

Also, using + between each "action" means it will try to add the result of .addState() to the damage value. I dont think thats a good idea and might even cause problems down the line

I suggest to try transforming it into
Code:
if (b.def + b.agi <= (Math.randomInt(20) + 1 + a.mdf + a.mat)) {b.addState(43); Math.randomInt(8) + 1 + a.mdf}; else {0};
See if it works or not.
Commanderty

#22 Jun 11, 2019, 12:51 AM Source
Engr. Adiktuzmiko said:
You should enclose what happens when the "if" is true in {}

Also, using + between each "action" means it will try to add the result of .addState() to the damage value. I dont think thats a good idea and might even cause problems down the line

I suggest to try transforming it into

Code:
if (b.def + b.agi <= (Math.randomInt(20) + 1 + a.mdf + a.mat)) {b.addState(43); Math.randomInt(8) + 1 + a.mdf}; else {0};

See if it works or not.
This solved one of my problems, the spell is no longer applying the status on a miss. The problem is, that the spell no longer 'hits' anymore, always dealing 0 damage, and never applying the state. It would seem I still have work to do. (I even tried setting the enemy stats to 1's, and the battler's stats to never be low enough to miss, so it's not just bad RNG.)

Thank you for helping, it's nice to see a supportive community :)
Engr. Adiktuzmiko

#23 Jun 11, 2019, 03:37 AM Source

If it always do 0, its probable that the formula has an error because the damage formula evaluation code is set to do 0 damage if an error occurs
Commanderty

#24 Jun 12, 2019, 08:49 PM Source

I hadn't actually figured that out. I changed the else to do 2 dmg, yet the spell still did 0, so it's just an error through and through. Unfortunately I haven't been able to fix it, but I found a neat trick using Yanfly's plug-in for damage over time, and put the damage formula into the state instead of the skill, and that seems to work. Thankfully it was a state set to only last for one round, so it works.

Thank you again for the help :)
Oddball

#25 Aug 29, 2019, 09:40 AM Source

What about an attack that gets stronger if any other party member is below 50% Hp or dead?

Or an attack that crits if a variable is a certain number?
MetalLord4171

#26 Sep 3, 2019, 04:26 AM Source

Okay, so you can use a variable to alter a damage formula, but can you use a formula to change a variable? Also, do a skill's effects occur before or after a formula is executed (so you can use the newly changed variable in say a common event)?
Bex

#27 Sep 3, 2019, 08:46 AM Source

Just found this, thank you so much for sharing, this makes my life as person with Syntax Problems so much easier.
++good
Silva

#28 Sep 3, 2019, 06:32 PM Source
Oddball said:
What about an attack that gets stronger if any other party member is below 50% Hp or dead?

Or an attack that crits if a variable is a certain number?

The first part is easily manageable using the array function .some
Code:
if (a.friendsUnit().members().some(function(member) {return member.hpRate() < 0.5})) 50; else 30;
Where the 0.5 represents the 50% health. The 50 is the increased damage value, and the 30 is the reduced damage value.

To address if any allies are dead you could use something like this (again, 50 is increased damage, 30 is reduced).
Code:
if (a.friendsUnit().deadMembers().length > 0) 50; else 30;
Whether an attack is critical or not is decided Before the damage value is evaluated so would be difficult to control from the damage formula. You may want to look into a plugin to do this for you.

MetalKing11417 said:
Okay, so you can use a variable to alter a damage formula, but can you use a formula to change a variable? Also, do a skill's effects occur before or after a formula is executed (so you can use the newly changed variable in say a common event)?

You can use this function to control the value of your variables
Code:
$gameVariables.setValue(x, y); damageFormula
Where x = variable id
y = value to be assigned
damageFormula = your normal damage formula

Providing you don't have any plugins altering things your common events should execute after the damage formula is evaluated.
bigrockwall

#29 Sep 9, 2019, 07:28 PM Source

Having some issues getting the if/then in the damage formula to apply state. I want basically the same thing as an earlier post. If (1d20 + a.atk) >= (10 + b.def), apply state to defender.

I tried, and failed, using the following. And a couple variations where I removed some of the () and spaced out the +1.

if (a.atk + (Math.randomint(20)+1)) >= (b.def + 10) {b.addstate(3)} ; else{0} ;

Where state 3 is a stun. Tried it with (3) and (0003) as listed in the database.

That didnt work, just kept rolling 0 damage and not applying the state (had a.atk stat set to 20 and b.def set to 1, so should always apply). Tried both with and without using the semicolons. Any help appreciated.

Edit - is it possible to use note tag instead of damage formula box to accomplish the desired effect?
xcom

#30 Sep 15, 2019, 05:38 AM Source

Hello!

I can do just about anything with MV, but this combat coding has me feeling like my 6 year old trying to understand how algebra works....

I am trying to turn (for fun) a old Grail Quest: Choose Your Own Adventure RPG book into a free to play MV game. I would like the combat in the game to mimic how it worked in the RPG book.

So like this:

1) Roll 2D6 (so generate a random number between 2 to 12)
2) To HIT you opponent you need to roll higher than the weapon ATK value. (So if the ATK is 6, to hit you need to get a number higher than 6.)
3) The DAMAGE done is equal to the DMG value of the weapon plus every point above the ATK value of what your just rolled. (So if the ATK value of the weapon used was a 6, and you rolled an 8, and the weapon has a DMG value of the weapon is 2, then you did 4 points of DMG.)
4) Then deduct the DEFENSE value of any armor worn (if any at all) from the damage, to get the final damage done. (So if 4 DMG was done from the weapon, but the opponent has a DEFENSE value of 1, then only 3 points of total DMG is done!)

So basically:
IF ROLLED RESULT < ATTACK VALUE then MISSED
IF ROLLED RESULT > ATTACK VALVE then ((ROLLED RESULT - ATTACK VALUE) + WEAPON DAMAGE) - DEFENSE VALUE = FINAL DAMAGE DONE

EXAMPLE:
Rolled a 8 ((8 rolled - 6 ATK) + 2 DMG) - 1 DEF = 3 total damage to opponent

I was thinking of just eventing the combat if I couldn't figure out how to make it work through the normal combat system.
J-G

#31 Oct 18, 2019, 08:10 PM Source

I'm having issues with my formula. No matter what I do they always yield me 0 damage.
Example of formula used
((8/16) * (level+a.mat)) * 6
I've used variations of this with and without the brackets as well and still a 0
Aloe Guvner

#32 Oct 18, 2019, 08:59 PM Source

@J-G in your formula, you've written "level".
Whose level? a or b?
J-G

#33 Oct 18, 2019, 09:00 PM Source

Sorry I left that out. It's a's level
Aloe Guvner

#34 Oct 18, 2019, 09:05 PM Source
If it's a's level then you need to write "a.level" otherwise it doesn't know who's level.

So the formula would be
Code:
(a.level + a.mat) * 3
Because of course "(8/16) * 6" simplifies to just 3
J-G

#35 Oct 18, 2019, 09:06 PM Source

Yeah, just tried it lol didn't realize I was leaving the "a." Part out haha now it works. Thanks so much
Nofx670

#36 Oct 20, 2019, 06:53 AM Source

Hi I'm after 2 things one has already been asked but didn't get a reply

Is it possible to change a variable with a damage formula so I can make a skill that gets stronger the more it's used?

Also is it possible to make a formula that does damage to an enemy and inflicts a state on the party aswell? I tried

A. Addstate(poison) ; && a. Atk * 4 - b. Def * 2

Any help would be much appreciated
Engr. Adiktuzmiko

#37 Oct 20, 2019, 11:15 AM Source

@Nofx670 -

1) Yes, if its a game variable just do

$gameVariables.set(ID,value)

or if it isnt a GV, just do variable_name = value

before the actual damage part of the formula.

2) Yes, you are almost right, but the code to add state afaik is a.addState(State ID) not Addstate(state name)

Also dont write && after the ;... You dont need &&
Nofx670

#38 Oct 20, 2019, 03:43 PM Source

Engr. Adiktuzmiko said:
@Nofx670 -

1) Yes, if its a game variable just do

$gameVariables.set(ID,value)

or if it isnt a GV, just do variable_name = value

before the actual damage part of the formula.

2) Yes, you are almost right, but the code to add state afaik is a.addState(State ID) not Addstate(state name)

Also dont write && after the ;... You dont need &&

I've tried both of those but they come back with no damage or states inflicted and don't change the variable when I check the debug window
Silva

#39 Oct 20, 2019, 05:24 PM Source
Your above message may have been typed by phone and I appreciate that predictive keyboards make writing code difficult, but if not you need to be careful of the case your typing in. You have a lot of upper case letters where you should be using lower case - this means that the engine isn't recognising the properties and is instead returning undefined, this won't give you any errors in the console because it's expected behaviour. This is likely the reason there's no damage.

Regarding setting the game variable, the correct code is
Code:
$gameVariables.setValue(id, value); // eg. $gameVariables.setValue(1, 200); // Set variable 1's value to 200
I can see no reason that the state codes should not work, unless there has been an error before hand and the damage formula has stopped evaluating. Ideally you want something that looks like this
Code:
a.addState(4); $gameVariables.setValue(1, 200); a.atk * 4 - b.def * 2;
Nofx670

#40 Oct 20, 2019, 06:06 PM Source
Silva said:
Your above message may have been typed by phone and I appreciate that predictive keyboards make writing code difficult, but if not you need to be careful of the case your typing in. You have a lot of upper case letters where you should be using lower case - this means that the engine isn't recognising the properties and is instead returning undefined, this won't give you any errors in the console because it's expected behaviour. This is likely the reason there's no damage.

Regarding setting the game variable, the correct code is

Code:
$gameVariables.setValue(id, value); // eg. $gameVariables.setValue(1, 200); // Set variable 1's value to 200

I can see no reason that the state codes should not work, unless there has been an error before hand and the damage formula has stopped evaluating. Ideally you want something that looks like this

Code:
a.addState(4); $gameVariables.setValue(1, 200); a.atk * 4 - b.def * 2;
Yea sorry that was predicted txt

When typed in the skills box it is correct but still neither seem to work. If I remove the set variables or add state code it works and does basic damage.

I'm wondering if the add state command isn't working because I'm trying to effect the 2 separate targets with the 1 formula.

Thank you for your help