How "chance to not consume ammo" works (Explanation)
- Thread starter Samrux
- Start date
All Seeing Eye
Eye of Cthulhu
Created an account simply for this mathematical conversation. I wanted to educate you all on how to simplify this but it has already been said already.
I just checked the gamepedia and calculating the tip (from gamepedia information ) gives an 1 - 0.34*0.8*0.75*0.8 = 83,68% chance to not consumme ammo, without the box, and 86.944 % with the box.
Simplifing the matters through calculating the chance to actually use ammo instead of not using ammo is the way to go, but that has already been said so, yeh.
If somebody is interested in putting it in more graphical words: For every item there is, the game rolls a number and ONLY if EVERY roll fails than ammo gets consumed.
If someone is interested in that kind of game problems Sacred 2 is the game to grab. Its pure math and calculating for every littel tiny bit there is, but other games have the same problems and mechanics as well. 30% + 30% evasion in dota translates into 1-0.7*0.7 = 51 % not to get hit.
Random facts:
1 Magic Quiver = 20 %
+ Potion = 34 %
+ Box = 48.8 %
Vortex Beater = 66% ( actually i wondering if they mean 2/3 instead of .66 and the tooltip is mismatched )
+ Potion = 72.8 %
+ Box = 78.24%
+ Breastplate = 83.68 %
+ Headgear = 86.944 %
As you can see 20% chance to not consume ammo later effectively translates into an 3% increase, which is not that big.
This can get even more obvious when stacking higher numbers. A shield with 70 % chance to block melee attacks and the buff to block melee attacks with a 70 % makes in total 1-0.3*0.3 = 91%. So the Mega big buff of 70 % of blocking an attack effectively translates into an 21% increase ( Like, would you ever equip an item which says it increases your block chance by 21 % if you already have 70 % ??? )
My advice: Stick to a single high % and leave it at that because "Slots" and "Buffs" and "Inventory Space" and "Gear you wear Space" are created all equally and are limited.
Here is the ultimate example:
-All slots are equal
-Your Dps is 50dmg/sec
-1 Bullet per second
-Enemy has 500 health ( lets ignore armor for now)
- For simplicity we say every bullet hits the target ( Clorophyte Bullets, Positioning, etc )
Case 1: - 50 % not to consume ammo
- 50 % not to consume ammo
= average of 2.5 bullets used ( 10 bullets in 10 second and 2.5 of them getting actually used up )
Case 2 : - 50 % not to consume ammo
- add 25 dps ( doesnt matter how we do it )
= 3.333 bullets used per enemy ( 75 dps kills an 500 hp enemy in 6.666 seconds and uses 6.666 bullets from which 50%, so 3.333 actually get used up.) ( to be ingame correct it needs 7 bullets and 7 seconds and uses an average of 3.5 bullets)
Difference: 3.333 (3.5) seconds of time, 1.3 (1.5) more bullets used
So in the above case the same % to not consume ammo is better than the % of increased dps if you want to preserve the bullets. The % in increased dps has to be 1.333 (1.4) times higher than the same % of not consumming ammo perk, buffs,slots, etc ... .
Example: 25% increase in dps is better than an 18% to not consume ammo, but worse than 19% ( the breaking even point is 18.7546% ).
Unlucky enough the armor reduction is flat number ( its an SUBSTRACTION not an DIVISON) which means we do different amount of dps versus different enemies with different armor, which means we need to evaluate our dps against different enemies first and than look if it actually worth it to get the % dps increase or the % of not consumming ammo.
You cant achieve 100% btw, like never. All chances are handled pretty much the same except 0% and 100 %
All the above only works if there is an INDEPENDENT roll for every chance slot, buff, reforge ( there is no ammo reforge but dps reforge). If things get ADDED or SUBSTRACTED it gets messier because as we all know that changing the order in an only * operation doesnt matter but it starts to matter when there are *+,*- or */ operations.
It all comes down to how the game is coded.
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Nope, for the game its all the same. A 500/1000 is the same as 1/2.
And its 50/100 not 100/50.
You must be fun at parties
i'm pretty sure that thats how crits work, too. it makes high crit build somewhat difficult
Pretty sure what's how crits work?
Samrux
Santa Claus
No.
W1K
Witch
Crits are additive, every crit bonus you get through accessories and prefixes is added directly to the weapon's crit chance. However, I believe the idea is the same when it comes to ranged weapons crit chances, as the weapon and the ammo's crit chance are two different chances resolved indipendently, so you would calculated the total chance the same way as ammo reduction.
MorningSTAR-αΩ
Official Terrarian
The Phantasm, combined with the Ammo potion, box, Magic Quiver and Vortex armor grants and 1 in 10 chance of actually consuming the ammo huh?
So basically Phantasm is best bow
So basically Phantasm is best bow
I just tested this out. I shot 100 Musket Balls from a The Undertaker (no prefix) at a Target Dummy. I had no armor on, but had a Lucky Sniper Scope, Lucky Destroyer Emblem, Lucky Eye of the Golem, Lucky Fishron Wings, and Precise DPS Meter. I had no buffs.
The Undertaker and the Musket Balls both displayed a crit chance of 50%, matching what I calculated from my accessories and the base 4% chance.
After firing all 100 shots and tallying the number of crits and the number of noncrits, they were both even at exactly 50 of each. Therefore, I'm going to stick with my previous belief that ammo crit chance is meaningless.
Samrux
Santa Claus
It already was! Plus, its moderate rate of fire, the multiple arrows it shoots per row, and the ghostly arrows that are fired in sequence upon sustaining fire on an enemy, basically made it ridiculously ammo-efficient to begin with. I was AMAZED to also see that "66% chance to not consume ammo" in the tooltip.The Phantasm, combined with the Ammo potion, box, Magic Quiver and Vortex armor grants and 1 in 10 chance of actually consuming the ammo huh?
So basically Phantasm is best bow
Go home, Tsunami.
I'd do five different rounds of 100 bullets each, just to be sure. Random chance sure is random, but with a large enough group, it gets flattened out of the equation.
SzGamer227
Spazmatism
*raises hand* Aren't the last two ammo consumption calculations inaccurate since they have multiple items all providing the 20% conservation bool? Afaik the Chlorophyte Helmet, Magic Quiver, Ammo Box, and Conservation Potion would overlap the same way the Shroomite Breastplate and Chlorophyte Helmet don't stack. I don't see why they would use separate bools anyways. @W1K?
MegaMage314 🌳
Living Tree
Maybe they don't cancel each other out because they aren't armor pieces?
SzGamer227
Spazmatism
I don't think they would have a separate boolean value for "armor 20% ammo reduction" and "non-armor 20% ammo reduction." :l
I wouldn't know for sure, though.
W1K
Witch
Magic Quiver uses its own bool which is also used to check the other effects of the accessory. Ammo Box and the potion also each have their own buffs related to their buffs
SzGamer227
Spazmatism
- There is a 0.5 chance (1 - 0.5) to consume ammo with the Megashark.
- There is a 0.8 chance (1 - 0.2) to consume ammo with the Shroomite Breastplate
- There is a 0.8 chance (1 - 0.2) to consume ammo with the Ammo Box
- Since all of those events have to occur together, one after the other, for the ammo to not be consumed, we multiply them: 0.5 x 0.8 x 0.8 = 0.32 (32% is the chance to use the ammo)
- Finally, to convert this from consuming to preserving ammo, we do 1 - 0.32 = 0.68
= 68% chance to save ammo
Concluding that, with a 50% chance, a 20% chance, and another 20% chance, the final chance to not consume ammo is, in fact, 68%
Why would they bother rolling many times more than necessary? I doubt they roll multiple times for each shot fired, all you have to do is multiply the chance to use ammo from all your gear once and then roll once per shot.
W1K
Witch
It does roll multiple times in the source codes, once for every different ammo-reserving variable.
Samrux
Santa Claus
That's just how it works. It has nothing to do with efficiency; your computer can handle thousands of quick calculations like these in an instant, so it makes no difference at all. And you can't simply multiply them together, as I explained.
SzGamer227
Spazmatism
This is why there's a guide here on how it actually works, because a lot of people make this same assumption.
All you have to do is read the first couple paragraph to figure out what's up, and just let the guide do the explaining.