Got bored this past afternoon and decided to find the math involved for projectile penetration through armor as I couldn't find any recent sources showing the raw equations. Here's what I found in
The graph shows percent probability of penetration on the vertical axis and a variable (ammo penetration value by default) on the horizontal. The
d value is the armor durability percentage, the
a value is the armor's "protection value," which I believe is ten times the armor class, and the
p value is the ammo pen, which you can pull off of
100 - x if you want the chance to block the projectile.
Interestingly, the probability is defined piecewise, depending on how far an indicator function (
h in the graph) is above the ammo's penetration value.
What surprised me most was how much durability affected the chance to pen. Try setting
p to a constant (e.g. 45, which usually wouldn't pen level 6 at all), and let
d = x: The chance increases dramatically as the armor falls below half.
Obviously, there's a lot more to the system — ricochet chance, fragmentation chance, armor damage, blunt damage, etc. I'm excited to look into these soon. Oh, and if anyone has the armor class resistance values (I think from a file called
global.json), that data would be greatly appreciated.