Defense and Magic Defense Ratings = % Reduction

[mercurygerman]

I have to apologize ahead of time as even though I've tinkered with RPG Maker XP for years, I haven't done much in the way of scripting.  As this is my first script request, I hope my I can make everything easy to understand, and I'm sure it's an easy fix for some of you scripting gurus out there.  I'm going off memory here, so this is probably a little off, but the default battle algorithm in XP figures damage dealt by something like this:
     

  (Skill Power * Strength F ÷ 100)
- (Target Pdef * Pdef F ÷ 200)

Lately, I've been wanting the Defense and Magic Defense to have a much greater scaling effect.  I was wondering if there is a way to change the default battle battle algorithms (either by a script or modifying them directly) to make Defense and Magic Defense ratings reduce all damage taken by a *direct percentage*

For example, we have:

Arshes 
       
DF: 500
MDF: 100
Upcoming Damage = 1,000

If the incoming attack is physical, Arshes Defense Rating of 500 translates into 50% physical damage reduction, so he only receives 500 damage from that attack.  But if we say that 1,000 upcoming damage is magical, his 100 MDF rating translates into 10% magical damage reduction, so he only receives 900 damage.  I'm using 1,000 as a perfection reduction rating here, mainly because I use it as a cap for stats in my game.

Would this be a simple change or a major pain?  Is there anyone willing to help me out with this?  Thanks in advance!

 

[Prexus]

Very simple change.

Change these two lines in Game_Battler 3:

atk = [attacker.atk - self.pdef / 2, 0].max
self.damage = atk * (20 + attacker.str) / 20

to

self.damage = attacker.atk * (20 + attacker.str) / 20
self.damage -= self.damage * (self.pdef / 1000)

and then take this section:

power = skill.power + user.atk * skill.atk_f / 100
if power > 0
  power -= self.pdef * skill.pdef_f / 200
  power -= self.mdef * skill.mdef_f / 200
  power = [power, 0].max
end
# Calculate rate
rate = 20
rate += (user.str * skill.str_f / 100)
rate += (user.dex * skill.dex_f / 100)
rate += (user.agi * skill.agi_f / 100)
rate += (user.int * skill.int_f / 100)
# Calculate basic damage
self.damage = power * rate / 20

to this

power = skill.power + user.atk * skill.atk_f / 100
rate = 20
rate += (user.str * skill.str_f / 100)
rate += (user.dex * skill.dex_f / 100)
rate += (user.agi * skill.agi_f / 100)
rate += (user.int * skill.int_f / 100)
self.damage = power * rate / 20
if self.damage >= 0
  if skill.atk_f > 0
    self.damage -= self.damage * (self.pdef / 1000)
  else
    self.damage -= self.damage * (self.mdef / 1000)
  end
end

This also will ignore the effect if the skill has a negative power (heal) so heals aren't negatively modified by mdef.

It also determines if a skill is physical or magical the same way that the default system does, to determine whether or not to apply pdef or mdef.

 

[mercurygerman]

Thank you so much for the quick reply!  But I seem to be having some trouble.

I'm getting the oddest results on this.  When I plug these in, no damage reductions due to defense and magic defense are occurring...unless a character's stats are high enough to prevent *all* of the damage anyway, in which case the defenses are indeed applied.  At first I thought I had two scripts that were conflicting, but I tested this in a blank project and I'm getting the same results.

The way the formula should work is for every 10 points in defense (or magic defense), 1% of the incoming damage would be ignored.  I've tested these defense values at 100 (10% reduction), 500 (50% reduction), and 999 (99.9% reduction), yet all damage goes through anyway.  Would anyone else mind plugging these in real quick to see where I'm going wrong?  I'm sure I must be overlooking something...

 

[Atoa]

@mercurygerman
I found the error.
in the way it is, it first make the division, but since the value is an Integer, it don't consider decimals

so (500 / 1000) = 0

for physical attack try this

self.damage = attacker.atk * (20 + attacker.str) / 20
self.damage -= (self.damage * self.pdef) / 1000

But there's somethig that bothers me in the code for skills:
The Damage reduciton don't consider if the skill have both atk_f and int_f.
Even if it have both, the skill consider only the physical def.
And it completely ignore the  skill pdef_f and mdef_f

I think it would be better if it was like this:

power = skill.power + user.atk * skill.atk_f / 100
rate = 20
rate += (user.str * skill.str_f / 100)
rate += (user.dex * skill.dex_f / 100)
rate += (user.agi * skill.agi_f / 100)
rate += (user.int * skill.int_f / 100)
self.damage = power * rate / 20
if power > 0
  self.damage -= (self.damage * self.pdef * skill.pdef_f) / 100000
  self.damage -= (self.damage * self.mdef * skill.mdef_f) / 100000
end

 

[mercurygerman]

Nope.  That didn't seem to fix it either.  Here's how I tested.
I set up a skill (we'll call is "slam") to be physical:

SP 0      Power 1000  AT P 0  Evasion 0
Str 100  Dex 0          Agi  0  Int 0
Acc 100  PDef  100    Mdef 0  Variance 0


I set up a monster who would spam Slam over and over against a character
whose defense value I manipulated directly.  Here are my results:

Defense Value of  0    = 1050 Damage    (Should be 1050 due to 0% reduction)
Defense Value of 10    =  525 Damage    (This is 50% damage reduction,when it should be 1% reduction)
Defense Value of 20    =    o Damage    (100% reduction. Is this set to be on a scale of 1000 or 20?)
Defense Value of 50    = 75,075 Healing  (!)

Any ideas?

 

[Atoa]

Sorry, it was a small mess with the number of 0's ;D

Now it working fine

 

[mercurygerman]

Tested it and it works perfectly!  Thank you so much, Atoa!  I've wanted to implement this for such a long time, and now I can.  I worship the ground you walk upon!!  : )