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Author Topic: what does impact mitigation's elite effect actually do?  (Read 955 times)

Ruddygreat

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what does impact mitigation's elite effect actually do?
« on: September 15, 2021, 03:58:47 AM »

this is a pretty simple thing that i've veen wondering for a while - what does impact mitigation's elite effect, and by extenstion effectiveArmorBonus, actually do?

i've been assuming it adds flat armour that can't be stripped, but from some quick tests it definitely doesn't (reducing the damage of a heavy mauler by ~6 vs an 83% cr, otherwise stock eagle)
this leaves me with the assumption that it just adds 50 flat armour but doesn't show it in the ui, which is uhhhhhhhhhhhhhhhh let's just say not good

and for the bit actually relevant to effectiveArmorBonus (that should probably be somewhere else) - would reducing it cause any similar wierdness, or would it work as i assume it does (reducing armour for damage reduction but keeping the same hp)

or is this more fit for the modding questions thread? i dunno

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geminitiger

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Re: what does impact mitigation's elite effect actually do?
« Reply #1 on: September 15, 2021, 05:13:16 AM »

I hardly understand any of the elite bonuses  ;D
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hydremajor

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Re: what does impact mitigation's elite effect actually do?
« Reply #2 on: September 15, 2021, 05:35:24 AM »

I think what that means is that you get some damage reduction in combat ?

so basically the damage you should take is reduced by a flat 50 on all instances but can't go lower than 1 ?
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FooF

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Re: what does impact mitigation's elite effect actually do?
« Reply #3 on: September 15, 2021, 06:09:29 AM »

All ships have a residual 5% of total armor once armor is stripped so that weapons like Vulcans don’t murder hull. Considering an Eagle with 1000 armor, that 5% is 50 armor for hull. Elite Impact Mitigation basically doubles it so that’s it’s 100. Now, it does add 50 Armor for all damage calculations but it makes the most impact (pardon the pun) when calculating hull damage.
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Vanshilar

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Re: what does impact mitigation's elite effect actually do?
« Reply #4 on: September 15, 2021, 10:14:44 AM »

Eh there are two different bonuses at work here (a 3rd if you include the weapon/engine damage reduction):

1. -25% armor damage taken
2. (elite effect) +50 to armor for damage reduction calculation purposes

The way damage to armor/hull works in Starsector is that it goes through a damage reduction calculation, where the incoming damage D is multiplied by H / (H + A), where H is the weapon's hit strength, and A is the target's armor. So for example, if the incoming damage is 500, has a hit strength of 500, and the target's armor is 1000, then it'll end up doing 500 * 500 / (500 + 1000) = 167 damage.

The "damage reduction calculation" refers to the H / (H + A) part of the equation. It can have a minimum value of 0.15, i.e. if the hit strength is too low, it'll always do at least 15%. Generally for projectiles, the hit strength is equal to the damage per bullet, while for beams, the hit strength is half of the damage per second (note that for burst beams, you have to look at the DPS while the beam is on, not its average DPS -- this value can be found in weapon_data.csv).

Once the armor is stripped away, there is a 5% residual armor when a weapon hits hull, meaning that for damage reduction calculation purposes, the weapon will still count as if it's hitting armor, but at 5% of the armor's original value. So for a ship with 1000 base armor, it'll count as if there is still 5% or 50 armor for the damage reduction calculation. The original damage part (i.e. D) remains unchanged. The important thing to note here is that this means the kinetic/high explosive/fragmentation bonuses/penalties vs armor still apply toward H / (H + A), even though they do not apply to D. Hence HE will still do better vs hull than kinetic or frag, assuming the base damage is the same.

Impact mitigation does as what it says "on the carton". If the armor damage would have been 400 damage, after going through all the calculations, you'll only take 75% or 300 damage instead.

However, there seems to be an additional hidden effect: the incoming weapon's hit strength is also decreased by 25%. So if the weapon's hit strength is supposed to be 400, it'll end up being 300 for the damage reduction calculation.

The elite effect also does what it says "on the carton". When calculating H / (H + A), it'll add 50 to the armor. I have no idea if it decreases as the armor decreases or not (i.e. if it scales with the % armor remaining). However, it does not apply to residual armor, as far as I can tell. Once the armor is gone and the weapon is hitting hull, I don't see a difference whether the target has the elite effect or not.

This is based on testing with a stock Eagle, with the player as officer, testing with skills ranged spec (i.e. no impact mitigation), impact mitigation, or impact mitigation + elite bonus, and with the ship having base armor (1000), heavy armor (1400), or heavy armor + armored weapon mounts (1500). It also had blast doors and reinforced bulkheads for extra hull but I don't think they affect the damage reduction calculations. The weapon used for testing is the Target Practice mod's harpoon ship, firing harpoons which do 750 HE damage each. The test results, against full armor and against bare hull (i.e. with only residual armor remaining), with the conditions of ranged spec (i.e. no impact mitigation), impact mitigation, or impact mitigation with elite bonus as the columns, were:

Nothing: 899 / 725 | 595 / 718 | 581 / 718
Heavy Armor: 775 / 716 | 501 / 706 | 491 / 706
Heavy + Armored Mount: 749 / 715 | 482 / 703 | 473 / 703

Hope it makes sense despite the formatting. Basically, what I described above fits the data perfectly; the harpoon does 1500 damage and has 1500 hit strength vs armor, which drops to 750 damage and 1500 hit strength vs hull, but once there's impact mitigation, the hit strength becomes 1125 instead. On the armor side, it's fixed as 1000/1400/1500 when full and 50/70/75 when stripped, regardless of if there's impact mitigation or its elite effect.
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Ruddygreat

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Re: what does impact mitigation's elite effect actually do?
« Reply #5 on: September 17, 2021, 02:24:49 AM »

Eh there are two different bonuses at work here (a 3rd if you include the weapon/engine damage reduction):

1. -25% armor damage taken
2. (elite effect) +50 to armor for damage reduction calculation purposes

The way damage to armor/hull works in Starsector is that it goes through a damage reduction calculation, where the incoming damage D is multiplied by H / (H + A), where H is the weapon's hit strength, and A is the target's armor. So for example, if the incoming damage is 500, has a hit strength of 500, and the target's armor is 1000, then it'll end up doing 500 * 500 / (500 + 1000) = 167 damage.

The "damage reduction calculation" refers to the H / (H + A) part of the equation. It can have a minimum value of 0.15, i.e. if the hit strength is too low, it'll always do at least 15%. Generally for projectiles, the hit strength is equal to the damage per bullet, while for beams, the hit strength is half of the damage per second (note that for burst beams, you have to look at the DPS while the beam is on, not its average DPS -- this value can be found in weapon_data.csv).

Once the armor is stripped away, there is a 5% residual armor when a weapon hits hull, meaning that for damage reduction calculation purposes, the weapon will still count as if it's hitting armor, but at 5% of the armor's original value. So for a ship with 1000 base armor, it'll count as if there is still 5% or 50 armor for the damage reduction calculation. The original damage part (i.e. D) remains unchanged. The important thing to note here is that this means the kinetic/high explosive/fragmentation bonuses/penalties vs armor still apply toward H / (H + A), even though they do not apply to D. Hence HE will still do better vs hull than kinetic or frag, assuming the base damage is the same.

Impact mitigation does as what it says "on the carton". If the armor damage would have been 400 damage, after going through all the calculations, you'll only take 75% or 300 damage instead.

However, there seems to be an additional hidden effect: the incoming weapon's hit strength is also decreased by 25%. So if the weapon's hit strength is supposed to be 400, it'll end up being 300 for the damage reduction calculation.

The elite effect also does what it says "on the carton". When calculating H / (H + A), it'll add 50 to the armor. I have no idea if it decreases as the armor decreases or not (i.e. if it scales with the % armor remaining). However, it does not apply to residual armor, as far as I can tell. Once the armor is gone and the weapon is hitting hull, I don't see a difference whether the target has the elite effect or not.

This is based on testing with a stock Eagle, with the player as officer, testing with skills ranged spec (i.e. no impact mitigation), impact mitigation, or impact mitigation + elite bonus, and with the ship having base armor (1000), heavy armor (1400), or heavy armor + armored weapon mounts (1500). It also had blast doors and reinforced bulkheads for extra hull but I don't think they affect the damage reduction calculations. The weapon used for testing is the Target Practice mod's harpoon ship, firing harpoons which do 750 HE damage each. The test results, against full armor and against bare hull (i.e. with only residual armor remaining), with the conditions of ranged spec (i.e. no impact mitigation), impact mitigation, or impact mitigation with elite bonus as the columns, were:

Nothing: 899 / 725 | 595 / 718 | 581 / 718
Heavy Armor: 775 / 716 | 501 / 706 | 491 / 706
Heavy + Armored Mount: 749 / 715 | 482 / 703 | 473 / 703

Hope it makes sense despite the formatting. Basically, what I described above fits the data perfectly; the harpoon does 1500 damage and has 1500 hit strength vs armor, which drops to 750 damage and 1500 hit strength vs hull, but once there's impact mitigation, the hit strength becomes 1125 instead. On the armor side, it's fixed as 1000/1400/1500 when full and 50/70/75 when stripped, regardless of if there's impact mitigation or its elite effect.

ty for the explanation!
ngl i probably just asked the question badly, i already knew about all the armour mechanic stuff, i was mainly wondering if it applied to the minimum armour value (which it doesn't, so the elite effect is ~useless lmao)
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RustyCabbage!

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Re: what does impact mitigation's elite effect actually do?
« Reply #6 on: September 17, 2021, 06:24:10 AM »

One minor point: when it comes to residual armor, the elite effect still occurs, but only up to 50 armor. Thus, the elite effect has no impact on residual armor for any ship with over 1000 armor, but for less armored ships it does do a little (probably not worthwhile in the end, but non-zero).

e.g. an armor stripped IM+ Condor has 25 armor, which would be treated as 50 for damage calculations.

Thaago

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Re: what does impact mitigation's elite effect actually do?
« Reply #7 on: September 17, 2021, 09:42:10 AM »

One minor point: when it comes to residual armor, the elite effect still occurs, but only up to 50 armor. Thus, the elite effect has no impact on residual armor for any ship with over 1000 armor, but for less armored ships it does do a little (probably not worthwhile in the end, but non-zero).

e.g. an armor stripped IM+ Condor has 25 armor, which would be treated as 50 for damage calculations.

I thought that got changed this version and they were properly stacking? Or am I misremembering?
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Vanshilar

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Re: what does impact mitigation's elite effect actually do?
« Reply #9 on: September 17, 2021, 12:09:59 PM »

One minor point: when it comes to residual armor, the elite effect still occurs, but only up to 50 armor. Thus, the elite effect has no impact on residual armor for any ship with over 1000 armor, but for less armored ships it does do a little (probably not worthwhile in the end, but non-zero).

e.g. an armor stripped IM+ Condor has 25 armor, which would be treated as 50 for damage calculations.

Huh that's interesting! Yes I tested with a Medusa (300 base armor) against the Target Practice's harpoons (750 HE damage) and this is how it works -- it does 742 damage normally (matching the D * H / (H + A) of 750 * 1500 / (1500 + 15)), 740 damage with Impact Mitigation (matching 750 * 1125 / (1125 + 15)), and 718 damage with Impact Mitigation elite (matching 750 * 1125 / (1125 + 50)).

Incidentally when I changed the Medusa's armor to 25, the first shot against it was as if it had 75 armor, not 50. So at full armor, the elite effect adds 50, while when armor is gone, the elite effect gives a floor of 50, for damage reduction calculation purposes. I have no idea what happens once the armor starts taking damage (i.e. if it's a flat +50 or if it scales (decreases) as armor decreases), nor what happens when some armor cells are still present but others are gone (i.e. hitting hull on some cells but not others). But this at least gives what happens at full armor and when armor is gone.

this leaves me with the assumption that it just adds 50 flat armour but doesn't show it in the ui, which is uhhhhhhhhhhhhhhhh let's just say not good

Impact Mitigation doesn't actually affect the amount of armor that's present, and thus it wouldn't show up in the UI. Rather, it adjusts the numbers H and A of the D * H / (H + A) damage reduction calculation. So for example even though the elite effect says it adds 50 armor for damage reduction, your ship still has whatever base armor is shown in the UI.
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Thaago

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Re: what does impact mitigation's elite effect actually do?
« Reply #10 on: September 17, 2021, 01:42:52 PM »

Huh, TIL. I might run a few tests on enforcers or another high armor ship to double check but those numbers seem right to me. Surprising!
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Vanshilar

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Re: what does impact mitigation's elite effect actually do?
« Reply #11 on: September 17, 2021, 06:42:41 PM »

Huh, TIL. I might run a few tests on enforcers or another high armor ship to double check but those numbers seem right to me. Surprising!

I know! I didn't think to test Impact Mitigation until this thread came up. Turns there are two "hidden" effects that aren't documented in the game, on the wiki, nor anywhere else that I'm aware of:

1. Impact Mitigation reduces the weapon's hit strength by 25% for damage reduction calculation.

2. Impact Mitigation's elite effect does not directly add to residual armor. (I.e., if the base armor was 1400, then the residual armor will be 70, not 70+50 = 120, nor (1400+50)/20 = 72.5). Rather, if the residual armor is less than 50, then it'll set a minimum of 50 for the damage reduction calculation.

The latter may be important if your ship has weak armor, i.e. is a frigate for example. A Tempest for example has a base armor of 200, and thus a residual armor of 10. That means that a tactical laser, which does 75 DPS and thus a hit strength of 37.5, would do 75 * 37.5 / (37.5 + 10) = 59.2 DPS against it. But if the Tempest has Impact Mitigation, then it would do only 75 * 37.5 / (37.5 + 50) = 32.1 DPS, or 54% of the original damage (damage cut almost in half). So it can do a lot to make weak ships more survivable.

I wonder what other skills have these hidden or undocumented effects.
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FooF

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Re: what does impact mitigation's elite effect actually do?
« Reply #12 on: September 17, 2021, 07:26:28 PM »

Color me surprised. For an Elite effect that is...really underwhelming. When it was +150, it was a huge boon to bare hull but since it has no real effect on Cruisers and above, its pretty meh. I mean, it's no better or worse than +30 seconds of CR for a lot of ships but Elite skills that don't do much are kind of duds in my book.

I probably won't bother with it any more.
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Alex

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Re: what does impact mitigation's elite effect actually do?
« Reply #13 on: September 17, 2021, 07:50:51 PM »

1. Impact Mitigation reduces the weapon's hit strength by 25% for damage reduction calculation.

Hmm, where are you getting that info? I'm pretty positive this isn't the case. I mean, maybe I'm missing something that's staring me in the face? But I'm looking at the skill definition and I don't see it.

2. Impact Mitigation's elite effect does not directly add to residual armor. (I.e., if the base armor was 1400, then the residual armor will be 70, not 70+50 = 120, nor (1400+50)/20 = 72.5). Rather, if the residual armor is less than 50, then it'll set a minimum of 50 for the damage reduction calculation.

Ahh, interesting! I'm trying to remember if I was actively aware of that at some point, but regardless, I certainly wasn't keeping that in mind when changing the value from 150 to 50. Made a note to have a look; that's really weak.

I thought that got changed this version and they were properly stacking? Or am I misremembering?

(Edit: hmm, I don't remember changing this - and looking at the code, it's evidently not been changed - so maybe you're thinking of something else?)
« Last Edit: September 17, 2021, 07:52:45 PM by Alex »
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Vanshilar

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Re: what does impact mitigation's elite effect actually do?
« Reply #14 on: September 17, 2021, 09:16:49 PM »

Hmm, where are you getting that info? I'm pretty positive this isn't the case. I mean, maybe I'm missing something that's staring me in the face? But I'm looking at the skill definition and I don't see it.

Yeah I was surprised because it wasn't anywhere in ImpactMitigation.java (so maybe it's something in the part of the code that actually does the damage reduction calculation? but I have no idea where that is), but it's through testing.

For example, taking an Eagle (1000 base armor), assign the player character to it, no skills. I used Target Practice mod's harpoon ship to fire a bunch of harpoon missiles (750 HE damage) at my Eagle.

Without any skills, the Eagle takes 899 armor damage on the first hit, then after armor is gone, it takes 725 (or 726) damage per hit to hull. This fits with the D * H / (H + A) calculation. So far so good.

With Impact Mitigation, the Eagle takes 595 armor damage on the first hit, then after armor is gone, it takes 716 (or 717) damage per hit to hull. This doesn't fit with -25% armor damage taken, which would predict 675 armor damage on the first hit, and 725 (or 726) damage to hull. However, it fits perfectly with -25% armor damage taken and the weapon's hit strength decreasing from 1500 to 1125. Every other data point in my post above (where I tested Eagle with nothing, with Impact, or with Impact + Elite, and ship with nothing (1000 armor), heavy armor (1400 armor), or heavy armor + armored weapon mount (1500 armor)) conforms with this as well, along with my testing using Medusa with stock base armor (300) and setting the base armor to 25. I can't think of any other explanation that makes the numbers work out other than that the hit strength is also reduced by 25% if the target has Impact Mitigation. (Maybe Target Practice's harpoon-firing drones does something funky in the code if there's Impact Mitigation, but I hope not.)

Actually, just tested this using sim Onslaught. TPC, 250 energy damage, vs my Eagle. No skills, it does 49 damage on the first hit against full armor, pretty much the predicted 50 damage accounting for rounding. With Impact Mitigation, it does 29 damage. The -25% armor damage taken predicts that it should've done 37.5 damage instead, but if the hit strength is also decreased from 250 to 187.5, the predicted damage is 29.6, which fits the observed data.

I only use utility mods, no faction mods, so I don't think it's coming from any of the mods. I can give a full modlist if you get different numbers.

Ahh, interesting! I'm trying to remember if I was actively aware of that at some point, but regardless, I certainly wasn't keeping that in mind when changing the value from 150 to 50. Made a note to have a look; that's really weak.

I don't know if a residual armor of 50 is particularly weak. It means no effect for ships with a base armor of 1000 or above, but helps out all other ships once their armor is gone.

On the other hand, a residual armor of 150 is really strong, since it's "as if" the ship originally had a base armor of 3000. A pulse laser (hit strength 100) does 67% damage to a residual armor of 50, but 40% damage to a residual armor of 150. So a residual armor of 150 pretty much means the attacker needs to rely on armor-breakers like Heavy Blaster or HIL even when the armor is gone.
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