1.0.0.621: Stealth Bomber's Evasion(100) promotion does nothing?

Perkus

Prince
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Can someone explain to me what the Evasion(100) that every Stealth bomber starts with actually does? In XML, it sets the promotion field EvasionChange to 100. But it seems like this has no effect on anything. It doesn't make me immune to Interception, because when I air strike a Destroyer (which BTW supposedly has only a 40% interception chance), it fires back EVERY time. It doesn't reduce damage by 100% because I take damage EVERY time. To add to the confusion, there is a totally different, earnable, promotion called just "Evasion" (without the I). This is the only one you'll find anything about in the 'pedia. It says merely "reduced damage taken from Interception" by 50%. And it sets as different field, called 'InterceptionDefenseDamageModifier'. No matter how you slice it, Evasion(100) doesn't seem to work. They also give it to Guided Missiles, which are supposed to be un-interceptable. But Nuclear Missiles, which are also supposedly uninterceptable, have only Evasion I, which is "50". So are they interceptable half the time? Ok, I have yet to test missiles for this specifically. Maybe the stealth bomber never should have had this promotion, it's only intended for missiles?

Theory 1: Perhaps its reducing the damage I would otherwise be taking on the interception. But how much reduction is '100' then?
Theory 2: Perhaps it only works against actual enemy planes set on Intercept mode? I can't test it, because the AI will never build a plane, it seems. Any takers for testing this in multi-player?

At the very least, the bug is non-existent documentation...

Screenshot wouldn't help, save is heavily modded & somewhat obsolete.
 
From GlobalDefines.xml, the maximum evasion probability is 90%

Code:
<Row Name="MAX_EVASION_PROBABILITY">
	<Value>90</Value>
</Row>

Which is inline with my experience with Stealth Bombers (SB), that is, about 1 in 10 are intercepted. I've noticed that the Missile Cruiser (MC) tops out close to a 50% interception rate against my SB which leads me to believe the :c5rangedstrength: and :c5strength: are used in the interception calculation somehow, plus the difference between Evasion and Interception gets used somehow.

I don't think Evasion (100) will reduce the damage, but only guarantees that you will reach the maximum of 90%.

I play exclusively unmodded (more specifically, the units are unmodded, vanilla values)

EDIT: Also, I'm not convinced that EvasionChange=40 means a 40% change. I remember I did extensive Anti-Air analysis in Civ III and the relative strengths of the units mattered. Here's a link if you are interested in digging up the past (http://forums.civfanatics.com/showthread.php?t=76227)... granted, the details don't apply to Civ V, but maybe the method is similar...
 
Thanks, never noticed that global define before! But you find your stealth bombers evading 90% of the time? Against what units? I have a test save where I'm facing a bunch of destroyers and they seem to damage me almost, if not, every single time. Despite the fact that destroyers supposedly only have a 40% chance! Maybe this save is really bugged now due to all the mods...

Also, I've noticed I sometimes take damage from air strikes against units that have no interception capability anywhere near them. I bomb this Cavalry, and often take damage for some reason. The only thing nearby are a couple of cities. I have a map reveal mod, so I know there's no hidden intereceptor units nearby. I'm getting the impression that cities have a built-in interception chance also. This is also totally undocumented anywhere.

I'll go read your thread. In the same vein, I later found this detailed guide to Civ4 air combat:
http://www.civfanatics.com/civ4/strategy/air_combat.php
which made a few more things clear. I suspect many things were left exactly the same.
 
Actually, I stand corrected, I just ran a test with un-modded CiV 1.0.0.621

Stealth Bombers with Aluminum (53.33 :c5rangedstrength:) vs Destroyers on Ocean and Coast tiles (35 :c5strength: )
(Assuming a -50% Naval Penalty : 80 :c5rangedstrength: / 1.5 = 53.33 :c5rangedstrength: ) the results were as follows:

40 Sorties (40 Interceptions)
7 cases where Bomber takes 1 HP damage and delivers 4 HP to Destroyer
1 case where Bomber takes 1 HP damage and delivers 5 HP to Destroyer
4 cases where Bomber takes 2 HP damage and delivers 5 HP to Destroyer
4 cases where Bomber takes 2 HP damage and delivers 6 HP to Destroyer
3 cases where Bomber takes 1 HP damage and delivers 6 HP to Destroyer
14 cases where Bomber takes 2 HP damage and delivers 4 HP to Destroyer
6 cases where Bomber takes 2 HP damage and delivers 3 HP to Destroyer

Destroyers are intercepting 100% of the time.

I do recall an earlier time when it worked as I originally described. Unfortunately, I don't have any saves. But I can confirm Destroyers and Missile Cruisers intercept 100% of the time vs stealth bombers. It would be handy if I could see the odds before hand and predicted damage like I can with land unit bombarding. It would save me actually having to make the bombing runs.

EDIT: I did notice that during this test that when I start the war bombarding a destroyer, not officially declaring war via diplomacy, that the destroyer never intercepts. After the surprise attack though, it functions normally. This knowledge may be handy when selecting the target of opportunity to start your air campaign.
 
Destroyers are intercepting 100% of the time.

Thanks, that's good to know that I'm not seeing things over here!

I do recall an earlier time when it worked as I originally described.

Perhaps. Maybe they broke or changed it in .62 / .621 ? I wouldn't know because I won all my early games by conquest without getting that far.

It would be handy if I could see the odds before hand and predicted damage like I can with land unit bombarding. It would save me actually having to make the bombing runs.

That's the mod I'm putting together is going to do, that's why I need to understand this stuff in such depth. I should have something ready for testing in another day or two. Most of it works now, I'm just working on interception damage. I have to estimate/fake much of the functions because there is no built in calls to do what is needed. Unfortunately I'm having a lot of trouble figuring out how air combat is *supposed* to work, because of all the bugs and obsolete or incomplete documentation. The 'pedia at one point refers to an "Advanced Combat" section. There is no such entry! At least as far as I could find. I know the full manual covers it, but it doesn't say anything more than the 'pedia, as I recall.

EDIT: I did notice that during this test that when I start the war bombarding a destroyer, not officially declaring war via diplomacy, that the destroyer never intercepts. After the surprise attack though, it functions normally. This knowledge may be handy when selecting the target of opportunity to start your air campaign.

There a number of bugs I've seen when I declare war via air attack. I haven't spotted the lack of interception, but it doesn't surprise me. I doubt it's by design, either. I've noticed that the animations often don't play, and damage just happens. If you really want some fun, experiment with Guided Missiles. They're totally FUBAR in my experience...
 
Destroyers are intercepting 100% of the time.
My experience has been that Stealth Bombers take damage from *anything* they bomb. That coupled with the fact that you can't promote them makes it seem like regular Bombers are always preferable unless you have an Oil shortage.
 
The Stealth Bomber non-promotion is clearly a bug I *hope* they've been made well aware of by now. They have the same set of promotions available as Bombers. They actually do earn experience, they just never prompt for promotion with it.
 
That's the mod I'm putting together is going to do, that's why I need to understand this stuff in such depth. I should have something ready for testing in another day or two. Most of it works now, I'm just working on interception damage. I have to estimate/fake much of the functions because there is no built in calls to do what is needed. Unfortunately I'm having a lot of trouble figuring out how air combat is *supposed* to work, because of all the bugs and obsolete or incomplete documentation. The 'pedia at one point refers to an "Advanced Combat" section. There is no such entry! At least as far as I could find. I know the full manual covers it, but it doesn't say anything more than the 'pedia, as I recall.

Let me know if you need help, I'd be more than happy to do some testing on air bombardments actual damage vs how much damage your mod says it should do...
 
@BomberEscort:
In your 40 Sorties (40 Interceptions) table, what was the health of both units during those attacks? Were they always at full health, or all over the place? And how did you do so many tests without going crazy anyway? It takes me 2-3 minutes to reload a late game save, and the game crashes on every 2nd reload! :cry: Needless to say, it's hellish for me to get enough sample data quickly. Yours is *very* valuable. Ideally I need similar samples (from anyone reading) against SAMs / AAGs / MCs / Fighters / Jet Fighters as well. I don't know how many of those it's possible to even get the AI to make! And vs. cities, if they are indeed responsible for my "phantom interceptions."
 
@BomberEscort:
In your 40 Sorties (40 Interceptions) table, what was the health of both units during those attacks? Were they always at full health, or all over the place? And how did you do so many tests without going crazy anyway? It takes me 2-3 minutes to reload a late game save, and the game crashes on every 2nd reload! :cry: Needless to say, it's hellish for me to get enough sample data quickly. Yours is *very* valuable. Ideally I need similar samples (from anyone reading) against SAMs / AAGs / MCs / Fighters / Jet Fighters as well. I don't know how many of those it's possible to even get the AI to make! And vs. cities, if they are indeed responsible for my "phantom interceptions."

One full-health Stealth Bomber attack per full-health Destroyer, then record the results, and move on to the next full-health v full-health attack (No Social Policies, Wonder, or Terrain bonuses on combat). Once all the SBs attacked, I reloaded the save. All destroyers were spaced with two hexes between them and the nearest Destroyer (not including the hexes the Destroyers occupied) to minimize any "interference" from multiple destroyers trying to intercept (when I had them closer, sometimes two destroyers would fire on the bomber, but never more than two, sometimes this changed the data and sometimes it didn't... But no worries, none of that data is in this table).

I created a scenario using default 1.0.0.621 rules, duel map, America and England, placed one city each and gave them both access to enough Aluminium to be used for their units and then placed SBs in the American capital and English Destroyers around it (was MCs at one time, that's why England has Aluminum). Declare war via diplomacy and save. Reload, then after my 5 bombers do their stuff, I reload and start again. Takes 3-5 seconds to load and maybe a minute to run it, but all that is on the map is what I need for the testing, nothing more (if I could remember how to turn off the animations, then it would go much faster. 75% of the time is watching the SB fly to and from the target)

Pertaining to the data...

Is 40 sorties enough?
Do you need more or less to be statistically signifigant?
Does this info agree with what is coming out of your mod?

Also, I can run some sorties against the city of London since it is within my range and post that data too. 40 sorties took me about 10 minutes (including running the sim, recording the data, and formatting it; the online posting took a few minutes more)

EDIT:
I chose SB v Destroyers because they're the closest I could get to an even battle with an evasion unit (40 :c5rangedstrength: ) versus an interception unit (35 :c5strength: ). I also thought this would allow the best testing of:

AIR_STRIKE_SAME_STRENGTH_MIN_DEFENSE_DAMAGE (2 HP)
AIR_STRIKE_SAME_STRENGTH_POSSIBLE_EXTRA_DEFENSE_DAMAGE (0-1 HP Extra)
INTERCEPTION_SAME_STRENGTH_MIN_DAMAGE (4 HP)
INTERCEPTION_SAME_STRENGTH_POSSIBLE_EXTRA_DAMAGE (0-2 HP Extra)

I'm wondering if it would help to set the extra damage to zero and see how that would affect the data. At the best, that would nail down the formula for interception damage/air strike damage. Then the values could be returned to default and any deviation from the original data could be used to extrapolate the extra damage part of the formula.

Also, if anyone is considering using any unit with PROMOTION_WEAK_RANGED (I.e - Fighter/Zero/Jet Fighter) to test, be aware that the tool tip says they have a 50% penalty on ranged attacks (air strikes) but in the XML it's actually a 75% penalty. I noticed this originally when my Fighter sorties were doing less damage than I though they should. Upon investigating, I discovered the error. I communicated this to Thalassicus, so it's in his UP mod, but those using default 1.0.0.621 for testing will have wrong tooltip info...

Questions
Does Interception use the :c5strength: or :c5rangedstrength: of the defending unit
Why can units without interception capability intercept aircraft some of the time (only in Cities)?
What is the effect of multiple interception capable units overlapping the target?
 
Ah, you've mastered the art of scenario creation, that would certainly help make this more efficient. I've never even fired up that tool so far. I'm still gathering my courage to take another swing at using the FireTuner.

Yeah, the tooltip is fixed in Unofficial Patch. I wasn't even aware it was wrong until this came up in another thread.

40 samples is more than enough, the accuracy of this is not going to be that high anyway unless it becomes obvious what the formulas are exactly. The combat odds panel doesn't show any decimal places, and the game typically rounds down dropping fractions, so the estimates already shown are *really* coarse. I thought about adding in one decimal place for the air combat, but it's not available for the ranged/melee damage anyway, and so far I doubt I can get that level of accuracy, so I wasn't going to bother.

Right now what little I have to work with is rather strange. I tried working it out last night with these 2 pieces data, one mine, one yours:

-- SB Str 38(?) vs Des Str 60.5, 0.63 ratio, 2.5 attack dmg, 2.5 avg interception damage
-- SB Str 40(?) vs Dest Str 35, 1.14 ratio, 4.2 attack dmg, 1.7 avg interception damage

Even the worst case interceptions (using Fighters) will only do about 4-5 dmg. The observed same strength interception damage appears to be around 1.8. The two global defines you mentioned should be making it around 5.0 (400 + ((300-100)/2)/100 to account for the supposed rounding down). Obviously it's nowhere close to that. So it's either not using those values at all, or there is a divisor of about 2.8. By playing around with those 2 values we should be able to find out if they're even used.

I don't even trust that the stated penalties vs. land/naval units are actually being applied properly. I won't know until I can get data vs. units without such a penalty (Bomber vs. AA gun/SAM). I figured that if I gifted AA units to CityStates I'd be able to test against them. But scenario creation would be a lot easier.

As far as what is used for anti-air defensive strength, I've been assuming that it's just like vs. non-air ranged attacks, i.e. ranged naval units defend using their melee strength, but ranged land units defend using their ranged strength! Which could also be wrong, of course.

I didn't think it was possible to be intercepted more than once per sortie? You've seen this? That goes against the documentation, as well as the API functions, where there is the concept of "Best Interceptor", suggesting that only one could ever be chosen.

Right now I have a bug in the code somewhere to track down, then I'll try to get some more data to play with.
 
I didn't think it was possible to be intercepted more than once per sortie? You've seen this? That goes against the documentation, as well as the API functions, where there is the concept of "Best Interceptor", suggesting that only one could ever be chosen.

I've seen the animation for interception play twice. Once for the target destroyer and once for a destroyer that is next to it. It is hard to tell if any extra damage was done though. Just to make sure, I separated them, since the Destroyer's interception range is 2 (not sure about this, but I know it isn't larger than 2).
 
Interestingly, if 4.2 attack dmg is AD and 1.7 avg interception damage is ID then:

ID/AD = 0.404

The destroyer inteception = 40

I wonder, is it a coincidence?
 
More Data:
====================================================
SB (80 :c5rangedstrength: ) vs MSAM (66.8 :c5strength: ) - MSAM on Grassland has Al; SB has Al

6/3 - 2 cases : 6 damage done to MSAM; 3 damage done to SB
4/2 - 6 cases
5/2 - 3 cases
3/2 - 3 cases
3/1 - 1 case
2/2 - 1 case
5/3 - 4 cases
4/3 - 2 cases
3/3 - 3 cases
5/1 - 2 cases

4.14 damage done to MSAM/2.29 damage done to SB
====================================================
Fighter (28.57 :c5rangedstrength: ) vs MSAM - vs MSAM (66.8 :c5strength: ) - MSAM on Grassland has Al; Fighter has Oil
(For 28.57 :c5rangedstrength: explanation - see EDIT at the end of this post)
(For 66.8 :c5strength: explanation - see EDIT at the end of this post)
(I anticipated that the MSAM would clobber the Fighter)

3/3 - 4 cases
3/2 - 2 cases :3 damage done to MSAM, 2 damage done to fighter
2/3 - 2 cases
3/1 - 2 cases
1/2 - 4 cases
2/2 - 4 cases

2.05 damage done to MSAM/2.22 damage done to fighter
====================================================

EDIT:

OK, I just did some testing for WEAK_RANGED. I gave the Catapult, Cannon, and Arty the promo. Here are the stats:

Default Catapult 4 :c5strength: / 14 :c5rangedstrength:
Default Cannon 10 :c5strength: / 26 :c5rangedstrength:
Default Artillery 16 :c5strength: / 32 :c5rangedstrength:

(these are the stats displayed on the panel with no mention of a penalty)
WEAK Catapult 4 :c5strength: / 8 :c5rangedstrength:
WEAK Cannon 10 :c5strength: / 14.85 :c5rangedstrength:
WEAK Artillery 16 :c5strength: / 18.28 :c5rangedstrength:

All of these are :c5rangedstrength: / 1.75, I would've thought they would've been :c5rangedstrength: * 0.25...

Based on this information. The Fighter bombards at 28.57 :c5rangedstrength:
For the record, I'd prefer they left it as the tooltip claims (-50%), then they would be more like flying artillery (33.33 :c5rangedstrength: )

What's strange is on the same map I have an enemy MSAM that has a -33% terrain penalty and a -50% resource penalty and it's displayed as 6.8 :c5strength: (40 / 1.83 = 21.86), so for those penalties it must be doing it as 40 * (1 - 0.83) = 6.8 :c5strength: . Isn't that odd that penalties are calculated two different ways? Is there a reason for this that anyone can think of?

Based on this information what would the true defense be for a MSAM on Grasslands with a 100% bonus vs aircraft? (EDIT 66.8 :c5rangedstrength: - see below)

EDIT2:

MSAM attacked by a Helicopter:
base 40 :c5strength:
-33% for Grassland
-50% Resource Penalty
+15% Flanking
+100% vs Helicopters

Displayed on Panel is 52.8 :c5strength: (40 * (1 - 0.33 - 0.5 + 0.15 + 1)) = 52.8 :c5strength:

So, to answer the original question (40 * (1 - 0.33 + 1)) = 66.8 :c5rangedstrength:
 
Re: coincidence - probably, but you never know. Yeah, I've noticed those Fighters don't really seem to be attacking as if they're really at 12.5 strength, which is why I wrote that I don't trust those penalties are even being applied. Interception is really weak even in worst cases. I'll gnosh on the data a little later, thanks!
 
Re: coincidence - probably, but you never know. Yeah, I've noticed those Fighters don't really seem to be attacking as if they're really at 12.5 strength, which is why I wrote that I don't trust those penalties are even being applied. Interception is really weak even in worst cases. I'll gnosh on the data a little later, thanks!

WEAK_RANGED works, the only issue is it doesn't display on the panel. It comes directly off of :c5rangedstrength: (see post #14 above)

Also, I have corrected post #4 to correctly show the SB ranged attack based on this new information
(I.e - Assuming a -50% Naval Penalty : 80 :c5rangedstrength: / 1.5 = 53.33 :c5rangedstrength: )

I think the important thing here is when an air unit with WEAK_RANGED is bombarding to remember that it is taken out of the strength before that information is passed to the panel.
 
Further results... It appears when a unit that has an interception chance is bombarded directly, the interception rate is 100%. For Destroyers (40%) vs Fighters, where a Frigate exists one hex away from the Destroyer and is the target of the bombardment, the results for Fighter interception by the destroyer are remarkably close to the interception rate of the destroyer (40%)... Hopefully you're still working on this Perkus :)
 
I've discovered why the first attack to initate a war with missile or fighter units is not subject to interception. It appears that the first attack is treated as a 'Bombard' and not an 'Air Strike'. I discovered this when I changed the XP for an 'Air Strike' to 8XP. When the fighter performed a first strike that prosecuted the war, it was awarded 'Bombard' XP. All subsequent attacks we awarded 'Air Strike' XP. A subtle difference, but represents the value of a surprise air attack accurately.
 
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