Talk:Accuracy formula
From experience I think the chance of hitting an alien tends to be best if in an exact straight line (orthagonal or diagonal), and on the same level as it. This probably is explained by the misses that hit anyway, because you can miss slightly short and kneecap them, or long and hit them in the face, but I think this is less likely if you are at an oblique or acute angle (because there are less squares that are behind him you can scatter to, but still hit him - especially as you get further and further away so the aliens width becomes less of a factor). Equally with height, the further up you are, the less squares the fire can scatter to but still intersect with the alien.
Does this match up with other peoples experiences?
--Sfnhltb 12:59, 27 February 2007 (PST)
Hmm, I'm not sure what I'd say. In theory the "silhouette" wouldn't change much, if the angle were not a multiple of 45 degrees (that's what you mean, right?). I'm willing to bet that the engine is more influenced by things that might truncate values here and there, than anything else. And/or the interaction with exactly how they "draw" the "3D" target that the shot's trying to intersect. I'm sure it's crude but effective... but crude in what ways? shrug. - MikeTheRed 15:50, 28 February 2007 (PST)
Does the accuracy displayed in-game for the auto-fire apply to each individual shot or to all three shots?
- It applies to each individual shot. -NKF 22:39, 1 December 2008 (CST)
- Indeed. Note that the displayed "chance to hit" isn't really your chance to hit... It's more a measurement of the ranges of angles you can fire along. - Bomb Bloke 00:37, 2 December 2008 (CST)
- In Laser Squad Nemesis, that is explicit - units have a stat called "inaccuracy", defined as "The average deviation from true for a weapon shot, in degrees." Has anyone made tests in X-Com, what is the relation of distance to target and displayed and actual chance to hit? - Quantifier 05:14, 2 December 2008 (CST)
- Yes, this has been done. Arrow Quivershaft 08:49, 2 December 2008 (CST)
- As in "spread" of your shots, BB? Where bigger spread means, less accurate? -MikeTheRed 04:15, 2 December 2008 (CST)
What, exactly, happens when you miss? Does the game shift your aim by pivoting around the fire point or actually pick a random location in 3D that's close'ish to the target? It seems to me like it's the latter due to your ability to miss and shoot the ground right at your feet when shooting at nearby aliens. This doesn't seem to happen for farther away targets. Would this then suggest that aiming behind your target could potentially result in more hits on target due to more "misses" hitting? I haven't tried this tactic in practice.
- This is one of the unanswered questions, but the working hypothesis is that there is no specific hit/miss determination. That is, the game engine just fires the shot and introduces a random angular error. The maximum angular error is inversely proportional to the adjusted Chance to Hit. If the angular error is wide enough, the path of the shot no longer intersects the silhouette of the target defined by LOFTEMPS. Horizontal angular error seems to be greater than vertical angular error. But, most of this is conjecture. I was talking to Mike The Red about doing some histograms, analysing multiple shots with a wall of some vertical "destructible terrain" positioned behind a target. But we did not make any progress on that. Spike 14:13, 1 April 2011 (EDT)
- Seb76 has obtained the firing point from the executable. I have a reverse-engineering of the horizontal angle the game pivots around the fire point (cf. User_talk:Bomb_Bloke:Firing_Accuracy), but I haven't been able to convince Bomb Bloke that it's completely correct. (We disagree on how my formula graphs. It does exactly match the extreme bounds by construction.) I am getting empirically correct predictions in-game combining my horizontal accuracy formula with Blind_Spots_From_First_Principles. It's very nice being able to directly calculate the best possible ambush locations in a landed Supply ship :) Zaimoni 23:51, April 1, 2011 (CDT)
Height?
I've been testing a new terrain which has several 2 and 3 level buildings and one thing that I am noticing is that accuracy seems to be affected by differences in height. The terrain allows for long range gunfights between different heights and it has become common to see my elite soldiers hitting nearly all targets at the same height but missing close to half while firing at a different height. Hobbes 17:28, 28 February 2012 (EST)
- Units seem to have better accuracy vertically then they do horizontally, but as you get higher and higher above your target, their profile effectively gets smaller (eg, if you're directly above someone, all you're shooting at is their head).
- Though there may be more to it then this. Kneeling when standing directly next to an alien (forcing them to fire downwards at you) dramatically increases your life expectancy, way more then you'd expect it to. In fact kneeling increases the odds so dramatically in your favour that you could just about believe there's a bug in the firing engine somewhere.
- Shots are weighted (according to a bellcurve) so that they'll typically be closer to what you're shooting at, on average, then they could be. At 0% accuracy, you "can" fire anywhere up to half a radian to either the left or the right of the target - at 100%, you're still not guaranteed a hit, but you will never miss by MUCH (dunno what percentage you need to achieve "perfect" accuracy). This is why rookies are more likely to hit other team members then veterans are - because even if a vet misses, odds are his firing line is going to be closer to the alien then that of a rookie, so he has less chance of hitting anything that isn't directly between him and the target.
- But I digress. Vertically speaking, the angle range is much lower (though I haven't measured that one precisely yet - I just know it's smaller), but it may be that the same "weighting" isn't performed. This'd make height deviations much more important then they'd first appear as shot deviations would be less predictable. - Bomb Bloke (Talk/Contribs) 09:14, 1 March 2012 (EST)