Next up: actually doing some work rather than babbling: Observing the behaviour of aliens according to the GUETE_* #defsFor these, I employed the modified g_ai.c file attached at the start of this thread, and start playing with the numbers.
One of the things to notice, is that you cannot really assign a distinct GUETE value to a type of 'behaviour'. This is a direct result from the fact that the values are adding/multiplying ontop of each other, so the actual behaviour is the sum of all the values. Some initial testing verified this, so instead I decided to try and get some general idea about what happens for extreme values of each of the defs. So I keep the standard values for all but one in each test. Then the next step is to find a 'best' value for each of them and combine them.
Then re-optimize each value with that new set of starting values etc,etc (which can be a work in progress forever).
The list of GUETE defs toyed with are:
GUETE_HIDE: default 60, the bonus(additive) score for being hidden at the end of the move. Double the bonus if there was no target.
GUETE_CLOSE_IN: default 20, the bonus(additive) score for closing in on any of the enemy soldiers. This is used as a 'don't dash to the enemy before shooting him' (bonus=GUETE_CLOSE_IN-move) and also as a bonus for ending up closer to the enemy soldiers at the end of your turn: score+= guete_close_in->integer * (1.0 - minDist / CLOSE_IN_DIST) (absolute distance as in 'it doesn't matter if it's 1000 steps away in pathing distance'. Also AI cheats here as it checks all entities, not just visible ones). close-in dist is set to 1200 in the defs and I didn't really touch that, minDist is the distance from the closest opponent.
GUETE_KILL: default 30, the bonus (additive) score for expecting to kill an entity with the shot you are considering to make.
GUETE_RANDOM: default 10, the randomizing bonus to an action. This is set to zero on all the tests in order to avoid skewed results.
GUETE_CIV_FACTOR: default 0.25 (or 25 in the cvar version), the (multiplicative) malus for shooting a civilian. This nerfs the base damage score because we're shooting a civilian.
even though I've cvar'ed other GUETE things, they are mostly about the civvies and the LUA AI, so ignore them.
I will be using 4 thresholds on each test: -1000, 0, default, 1000. This should tell us what behaviours are influenced from this tests. Observations are mainly a comparison between these 4 values.
My test map is the first one that pops-up in the skirmish: +africa small.
I observe the first 4 turns of the game without moving my units. Deviations from this only where otherwise mentioned
So, without further ado:
GUETE_HIDE (WARNING: if you're using trunk >=30780 or just dodon's patch in the following page, this observation goes out the window)
Right, default value is 60. This means that given a choice of expecting to deal less than 60 dmg OR hiding, the alien will opt to hide. That's a pretty harsh value I believe.
default(60): Well, the classic behaviour you all know. Aliens almost always opt to end up hidden. Bloodspiders don't dare attack me in fear of staying visible at the end of the turn (which ends up with them perma-hiding in a bungalow next to me). After 4 turns only one of my exposed squaddies is dead and about 4 civvies. Quite depressing.
-1000: madness! The aliens simply refuse to stay hidden. In the first turn 7 of them become visible, the 8th just didn't have enough TU's and appears at the 2nd turn. Since they don't seem so preoccupied with hiding behind a basket, their itchy trigger fingers produce (in the first 4 turns) 4 dead civvies and 6 of my squad members. A 7th is running around rumbling and the 8th is slightly injured. And that's with the 3 bloodspiders dashing from the other side of the map and one alien having no weapons on him after turn 2.
0: Splatter. 6 civvies dead and my whole squad at turn 4 (at turn 3 all were mad). I'd attribute the better killratios to the fact that the -1000 was hampering the alien movement by forcing them to end their turn in visible spots. The aliens don't seem to have any prefference to staying hidden or not (makes sense, bonus no longer applies).
1000: Aliens really love their hiding, as expected. This ofc has a drastic effect on their damage. 4 civvies dead, only one of my soldiers slightly injured. The pop-shoot-hide occassions are next to non-existent (compared to the default value). I'm guessing the aliens were so afraid of getting seen that they couldn't even get to a pop-shoot-cover position. Only in turns 3-4 one alien found a far-away cover that could produce a shooting spot next to it. Result: 2 hits with a pistol. All of the dead civvies are in areas I don't have vis on. Strange flukes: An alien is staying still and visible behind a fence, I guess he considers it hiding even though I have a 20% shot on him. I guess this implies hide may refer to (possibly exclusively) to cover. Need to revisit the code for that. Also: A bloodspider parked 2 tiles away from a soldier of mine (while visibleofc ) while dashing towards an empty bungalow next to the soldier (spider hid in there and staid there till end of test). I don't really know how this could've produce a max score, as it could've hidden on the other side of the bungalow. Maybe the hiding doesn't only refer to my team, but the civvies aswell (contrary to what I remember from the code).
Some general thoughts/notes:
*map design prolly affects aggressiveness penalty caused by the hiding bonus value.
*possibly nice heuristic because of the preference of aliens for pop-shoot-hide spots: explore such branches of the search tree first(prepBestAction checks these first against FighterBestAction), since they are likely to produce high-scores (so cutoffs prune the tree faster).
* aliens-shoot-through-walls happens a lot in this map, interesting.
* General observations: >0 values increasingly lower the lethality of the engagement. It does expose them to coutnerfire though. Values <0 increase the lethality, although in a much lower pace and are also counter-productive to the survivability of the alien. Stands to reason to ignore negative values.
*I suspect the best value is somewhere between 0 and 60, possibly around the 30's area. Needs real combat testing to really evaluate and it's really a matter of personal choice which battle style is preferred.
GUETE_CLOSE_INAs mentioned before, this value is both used for:
* Take shorter paths to the shooting spot (as the comments mention: don't run around the target before stabbing him)
* Force the aliens to get closer to the enemies (in cheat-o-vision) so the engagement can happen sooner or later (also should avoid searching for forgotten aliens in rooms with little vision).
default value (20): At round 4, the aliens have killed 4 civilians, slightly injured one of my soldiers. Most of the aliens have only crossed about half of the map, cept for spiders which are now hiding in the closeby bungalow
<ah... defeatfear theme kicks in. Taking 5 mins to headbang to it>
-1000:
The Ballad of Brave Sir Robin
Bravely bold Sir Robin rode forth from Camelot.
He was not afraid to die, O brave Sir Robin!
He was not at all afraid to be killed in nasty ways,
Brave, brave, brave, brave Sir Robin!
He was not in the least bit scared to be mashed into a pulp,
Or to have his eyes gouged out, and his elbows broken;
To have his kneecaps split, and his body burned away;
And his limbs all hacked and mangled, brave Sir Robin!
His head smashed in and his heart cut out
And his liver removed and his bowels unplugged
And his nostrils raped and his bottom burned off
And his pen--
Right, 4 rounds of the aliens running away to the furthest possible spot, blocking each other en route. 0 shots fired, funny to behold. Hiding was not affected as much (couldn't see many of em at end of turns), but that has probably something to do with the fact that the furthest edge of the map had a my line of vision almost completely covered with bungalows. I'd definitely expect them to totally ignore cover (or anything else for that matter) in favor to running away. Another thing I noticed is that reaction fire has nothing to do with the AI, from the looks of it, all leftover TU's on aliens are automatically used for RF (either that or they can always RF, don't know which).
0: 5 civilians dead, 1 squad member. Interesting things to point out is that this happened from pretty much 2-3 aliens, all ranged. After disabling ai with g_ai_kill, I took a strawl and found that the rest of the aliens were hidden in spots that could produce any shots within walking distance (this causes the BestfighterAction to return 0 and force PrepBestAction to stand still). Blood spiders seem to be completely useless at this value as they will never enter a range where they could reach their target. The aliens would also refuse to take a diagonal step ahead which would produce the same hiding spot, yet a closer range to shoot from. Apparently the hit % bonus is not strong enough to force this on it's own (rounding issue? this was observed on a pistol wielder).
1000: 7 civvies dead and all of my squad on round 4. Hiding feature seems non-existent too. I did see aliens move away from my soldiers which probably means they were getting closer to a civvie. Ah, that's the perp, the code rewards total distance closing in AFTER shooting, and the distance is to any non-member (so civvies were the case). That'd explain most of the civvies dying first.
Some general thoughts/notes:
* positive values definitely help agression&map completion by bringing the enemies closer to you, which also helps them explore more of the map. Negative values could be used only in strange cases (hunts) or a simplistic civvie behaviour (I believe civvie AI uses a similar method, not sure since I've only glanced at it 3 days ago). Also this value does influence the hiding behaviour since at high enough values it can overshadow it. I don't believe though we should ever investigate such high values. From this simplistic check I found that the default value looks ok. It's high enough to progressively bring the enemies towards you, but it's not large enough to overshadow shooting stuff or hiding. If someone wants to further experiment with this value, I'd suggest the 20-60 range (at 60 we interfere with hiding a lot) with a focus on the 20-30 range (remember, we're cutting in the agression by preferring a dash instead of a shot). Bear in mind that the large close_in bonus happens AFTER the shot, before that it works as a malus:
Before: max(guete_close_in->integer - move, 0)
After: guete_close_in->integer * (1.0 - minDist / CLOSE_IN_DIST)
Bear in mind that I intend to modify the 2nd part by factoring in the path distance (try to avoid having them stuck behind the hull of ships)
GUETE_KILLA simple additive score boost that rewards killing a target. Default value of 30, which gets an additional bonus if the target was in reaction-fire mode (GUETE_REACTION_ELIMINATION). The extra bonus should make agression to RF'ers prefferable, but would make this test a lot harder (aliens dying), so I don't put RF on, and as such I take the reaction_elimination out of the picture.
default(30): Using the 4 civvies dead & 1 squad member that seems to be the result of the previous tests
-1000: 3 civilians dead and one injured squaddie. Interesting to mention that the alienn that landed the hit on my squaddie immediatelly switched fire to a harder target. One would expect that there should be 0 deaths with this value (I did), but then I remembered that the dmg score also factors in the hit %. So those deaths were probably the 'lucky' hits.
0: Interesting results. Only 2 civilian kills and one heavily injured soldier. I can't really explain the result, someone care to repeat this test and see what he finds? Supposedly this value would make the aliens ignore whether they'd kill someone or not and make them go for raw dps. Instead, I get minimal dps&deaths. Will have to repeat myself sometime.
1000: 2 civvie deaths and some melee enemies sitting next to my soldiers visible, doing nothing. This gets weirder by the moment. Redid the test, same results. Maybe I need to see this with a cleared head at a later time.
*Bloodspiders/melle heavily influenced by this metric, at least in the negative values where they just freeze up.
*Initially i thought that this could be used in order to make snipers prefer larger distances. Then I realized that this would make them useless at close-range, unless the value is somehow tied to the weapon (so we could theoretically force a weapon change?)
* due to the probabilistic nature of when this metric is applied, it's not that easy to weigh it without repeated tests. I can only go as far as to say that this *should* affect how flims a shot the aliens are allowed to take when a possible kill is involved (might partly explain why aliens somtimes prefer to take shots to civvies further away, despite the civ-target nerf. The other reason ofc being the large base dmg because of the lack of armor).
GUETE_CIV_FACTORThis is a multiplicative malus that is directly applied to the damage expected, right before it becomes the base score for this action: dmg *= (guete_civ_factor->integer)/100.0
Please note that the original value is a float, but I switched it to an integer and added the "/100" part. I'll still consider -1000 and +1000 (rather than -100 and +100) since it still makes sense to check for extreme ranges first.
default(25): Copy/pasta from previous examples, 4 civvies dead and one squaddie
-1000: 2 civvies dead (??!!) and one squaddie. The 2nd civ death was a collateral from a grenade launcher, the first one I believe was because the civ was in the line of fire. Other than that there were civs sitting right next to the aliens and were completely ignored.
0: 0 civvies and 3 squaddies dead (damn that alien with that plasma grenade launcher). This time no civvies were in the line of fire. Despite the difference of the results, I'd say this was a fluke. Both this and the previous example should be identical, since it's multiplicative and makes the aliens totally avoid targeting civvies
1000: lots of kills, that guy with the bazooka got a monsterkill. Only behavior worth to mention here is that at no occasion would an alien pick try and shoot a squaddie of mine instead of me. There was an occasion where I received direct fire, and that was from an alien that closed-in, and from his hiding spot he could only reach my squaddie.
notes:
*This is a pretty clear-cut case. It handles how willing are the aliens to shoot at civilians. This indirectly affects other behaviour by letting civ-shooting get in the way of doing other things (like shooting your squad).
* I believe the original value of 25 (0.25 in #defs) is too large. I'd reccomend looking to something closer to 0.15, maybe less. Remember, most civ hits are kills, so the dmg (how many hp's do civvies have?) will usually get the kill bonus (I don't know if the auto-RF makes civvies flagged as RF. That'd also add the RF eradication bonus ontop). So, if a civvie has 50 health, that's 80 base score for certain hits, which can easily overshadow aggression towards your team in many occasions.
OVERALL & NOTES:* From those simple tests, it's obvious that the GUETE values don't just affect dramatically the efficiency&behaviour of the aliens as a combat group, but also the bloodspider/melee as a race/outfit. Values that may look nice for ranged units will probably be not so much for the melee ones, and vice-versa. One more reason for creating individual/race-specific sets of GUETE values (apart from the 'nice feature' aspect of it). I suspect that the various degrees of long-ranged and short-ranged weapon wielders have a similar, yet not so dramatic, effect. Example: there's no reason for a sniper to get any positive bonus from the close_in at the absolute-distance calculation. Maybe we could go as far as to say this should be a malus for him.
* Fine tuning these values to perfection is probably going to have an inverse square relationship of time spent and performance boost. Still, it should be considered an ongoing sport, even past the initial large-gain period. Should be especially honored when something significant changes in the game (new races/weapons and combat mechanics).
* Changing the numeric values the one way examined here. Another way to go about it is to transform the additive effect of most of the to multiplicative. This will create another interesting set of values that can easily be better or worse.
* Changing the base dmg weight to the score (apply some kind of multiplication at the end) can be of equal importance as the GUETE values. This needs to be tested and tuned accordingly (TODO).
* Noticed that aliens will toss the sole (melee) weapon they have. We should get them to avoid doing that in general, and/or take into account that in the next turn they will have to spend TU's to re-equip a weapon. If we force them to make sure they re-equip a weapon at the same turn (or stop considering a weapon if they an't), we don't need to do the avoiding part.
If someone wants to help, I'd appreciate:*people to repeat those tests and evaluate/comment.
* Maybe some kind of a fixed small/med map where spawnlocations&numbers&equipment are also fixed. That way we can compare the results without needing many repetitions and deviations due to the randomness of the skirmish.
On a semi-relevant notice (aliens-shoot through walls):
"dmg = vis * (fd->damage[0] + fd->spldmg[0]) * fd->shots * shots;". This is the base dmg calculation. See the vis variable? that's a G_ActorVis() returns 0.0-1.0. I have also noticed that the shoot-through-walls happens a lot more often in maps with objects that for some reason you can see through at some point (the huts of africa for example). The huts is also the example where the aliens tend to futily shoot up. Maybe there is a disparity between visibility and shooting lines that confuses the AI and makes it shoot through ubreakable & semi-transparent objects? Glass for example work fine here, but hut walls don't. Maybe it's an issue with the definition of the wall itself? I can't really say much since I have no idea what happens outside of g_ai.c. I could start printing out the vis&dmg values and wait to see the results when a wall-shooting occurs.
Finally, I have to add, that I'll probably need someone to review any/all the code I write. I've been java-spoiled for the past decade or so, and I'm really terribad with having 'free()' in my mind
I also have forgotten every single performance coding tip I ever knew.
I'm also terribad with handling svn access. So me playing with commit without someone holding my hand can be a bad idea.
