Negative Impale DPS on Dual Strike of Ambidexterity

[GoodOldMalk]

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What platform are you running Path of Building on?

Windows

What is the value from the calculation in-game?

PoE does not report impale DPS.

What is the value from the calculation in Path of Building?

Currently when using Dual Strike of Ambidexterity with a non-zero chance to impale PoB reports a negative impale DPS number if certain conditions are met, usually when less than 100% chance to impale is present.

The problem seems to be around this line in CalcOffence.lua:

PathOfBuilding/src/Modules/CalcOffence.lua

Lines 5541 to 5545 in e5efdfc

	if skillFlags.attack and skillData.doubleHitsWhenDualWielding and skillFlags.bothWeaponAttack then
	-- due to how its being combined
	output.ImpaleModifier = output.ImpaleModifier / 2
	end
	output.ImpaleDPS = output.impaleStoredHitAvg * ((output.ImpaleModifier or 1) - 1) * output.HitChance / 100 * skillData.dpsMultiplier

In line 5545, if ImpaleModifier is smaller than 1 the DPS becomes negative.

I believe the problem results from the following. In line 5036:

PathOfBuilding/src/Modules/CalcOffence.lua

Line 5036 in e5efdfc

output.ImpaleModifier = 1 + impaleDMGModifier

Adding 1 to impaleDMGModifier seems incorrect. The modifier can take values between 0 and 1, specially if the impale chance is lower than 100% and/or if not enough impale effect is stacked.

Similarly:

PathOfBuilding/src/Modules/CalcOffence.lua

Line 5545 in e5efdfc

output.ImpaleDPS = output.impaleStoredHitAvg * ((output.ImpaleModifier or 1) - 1) * output.HitChance / 100 * skillData.dpsMultiplier

If adding 1 to impaleDMGModifier is incorrect, then substracting 1 from ImpaleModifier should also be incorrect.

Normally the above operations would not result in a noticeable effect, since adding 1 and substracting 1 cancel each other, but because Dual Strike of Ambidexterity has the flags doubleHitsWhenDualWielding and bothWeaponAttack, the modifier gets halved to account for the dual strike effect:

PathOfBuilding/src/Modules/CalcOffence.lua

Line 5543 in e5efdfc

output.ImpaleModifier = output.ImpaleModifier / 2

This causes an imbalance in the equations and the negative DPS scenario.

I ignore what the correct calculation would look like, but if I had to guess it's probably better to calculate the output.ImpaleDPS for the main-hand and the off-hand separately, and if not possible, use the average between the main-hand and the off-hand.

How to reproduce the issue

No response

PoB for PoE1 build code

https://pobb.in/Rz44K7FGpysr

Screenshots

No response

[andyli00]

#8253 #8155 #7784 #5228

Found some potentially related issues regarding simultaneous attacks, will look into it further

As for this specific issue, it seems to be caused here:

PathOfBuilding/src/Modules/CalcOffence.lua

Lines 1873 to 1876 in 78aa5c1

	if skillData.doubleHitsWhenDualWielding then
	mainChance = mainChance / 10000
	offChance = offChance / 10000
	output[stat] = output.MainHand[stat] * mainChance + output.OffHand[stat] * offChance

When stat = ImpaleModifier, low enough impale chance (mainChance and offChance) can cause output[ImpaleModifier] to be lower than 1, which would be a negative multiplier.