Altered AI physics?

H

hotsnot

Guest
hey i remember back like 5 or so months there was a vid showcasing HL2's "amazing nonscripted A.I." where Gordon wud push a table in front of the door, blocking enemies from the entrance. The combine soldiers, realzing that they cant get in through the door, lob a nade through a glass window and run. I tried it in the finished game and doesnt seem to work. anyone know why valve changed the feature? cuz now i put anything in front of the door and its just as easily pushed away when anyone enters.
 
It was a scripted sequence. No AI is smart enough to understand barricades that you throw up.
 
If you pushed the table there in the first place, it can be pushed away just as easily. Quite a simple solution, really.
 
actually they showcased it pretty convincing, just u throw a bunch of barricades from one side of a door, and the combine cant get in from the other side, so lob a grenade in. cant be that hard to program fi they can use barricades for cover rite? im just dissapointed u cant block enemy units from inside a house or something, and see how they wud react
 
When that video was released it wasn't implemented in HL2 yet, the movie shows what you could expect in HL2 when the game was finished but what you saw in the movie was scripted. I think they didn't put in in because it was to complex so it would cause a lot of bugs. And if they wanted too put it in we were probably still waiting for HL2.
 
Those are older than 5 months. Rather 20 months. Anyway, that was a scripted sequence.
 
oh damn thats a dissapointment :( oh well hope someone makes some uber podbots for cs to make up
 
Actually, i put a dresser drawer in front of one of the doors, and the soldiers couldn't get through, pretty cool actually.
 
I don't understand what was so hard to program about it. Just give soldier the AI the power to recognize:
1) openable doors
2) when a supposedly openable door won't open (is blocked) they first try it normally (to give the user the sense that they are finding out about the door), then they give it a kick (i.e. apply a physics force of a certain size)

It's not exactly rocket science. And in fact Valve implied that it was already working. The Combine Mechs even did cool things like look in the mail slot with a probe!
 
Actually, they kick the doors in. Good example is the Highway 17 where you enter the house seen in BINKs. I blocked both of the doors and they did kick the bastards in but never managed to actually get in as I had piled so much crap in front of them :p

I need to try to only block the front door and then wait for them to eitehr try to shoot me from the windows or come through the backdoor. No doubt they will do that.
 
I did that on Highway 17... only blocked the front entrance not realizing that there was a back one and they all piled in through the back door. Eventually though they did get the front door open too. Aggressive bastards.
 
they try to get to you, or they try to have their guns aimed at you... (they already do this)

If they can't do either, they try a diffrent way.... (they already do this)

they know where the should optimumly be able to go, and they know what is an object and what isn't. (this is apparently scripted, or they ahve preset routes/condition)

they also can calculate how much force is requried to move that object(s), and they know the options they have to exert force. (this could be easily implemented, considering they do alot of it on the phisic engine already)

heck, I could program the logic behind that.

BUT i don't think they could use other objects besides what you'd tell them is a usable object to exert force... you'd have to tell them taht barrales exert x ammount of force when blone up at x radius... and grenades so x ammount, and running does x ammount... I think a learning algorithim would work pretty well here.

lets just hope we can do that in the sdk
 
I've heard so many contradicting stories about AI, really, really makes you wonder if it malfunctions for some people's systems.
 
AI is swell on Combine but with your comrades, with your squad it's quite horrible. Those bastards run under fire too easily...not that anybody needs a group of people backing you up.
 
once we get the sdk, i'm goig to do some testing of things to see if the ai is as reactive as we all hope.
 
Another complaint about ai? wow. People just need to experiment just a like a few people did in this forum. Instead of coming on here saying omomgomgom111 where is the elleett Aii11. Go play and find out.
 
To answer to the poster actually that did happen to me...it was on coast. They couldn't push the door out cuse i had bunch of junk in it, they shot up the 2nd floor through the wall and window then they went around and used another door....If that is not enough for you then I dunno what is...Einstein?
 
It was a scripted sequence. No AI is smart enough to understand barricades that you throw up.
Click to expand...

i think it would be easy to progam.

if door = blocked by large object then ----> cant open.
 
And how many large objects are in the game? Also a stack would be considered a large object...And something in the hinges would be considered a large object! If you think about it, its a crap load to program just for a stupid feature, and after they open the door and move the stack of stuff out of the way they stand their anyhow since they can't see a way to get through it..It's not big deal.
 
I tried stacking a load of stuff at the doors to that bink house, they just opened the doors and it all moved out the way, almost instantly.
 
Beserker said:
Actually, they kick the doors in. Good example is the Highway 17 where you enter the house seen in BINKs. I blocked both of the doors and they did kick the bastards in but never managed to actually get in as I had piled so much crap in front of them :p

I need to try to only block the front door and then wait for them to eitehr try to shoot me from the windows or come through the backdoor. No doubt they will do that.
Click to expand...


Funny because i've tried the same thing, and they just kept running back and forth from both blocked doors, never kicking them in. I'm wondering if AI is dumbed down by the engine for slower CPU computers? or if it's just still a little buggy, and has a hard time choosing the right code paths.

One thing i've noticed that was rather dissapointing is that the AI will never thorw nades thru windows to flush you out if they cannot reach you. They might look thru them and fire at you, but if you hide, they never throw nades in. I think this woulda been a must do for the AI, but guess it isn't in.

Their flanking and cover is pretty well implemented, but even I still find them standing around sometimes just out in the open trying to die.

I for one can't wait for a accuracy/high hurt value mod for a Ultra-Violance type enemy


:thumbs:
 
Again, you don't need to make them know stuff about objects and so forth. All you need them to know is a binary "door opened?" response to their attempt to open an openable door. You then have them try to kick the door with a standard force. If "door opened?" still returns a "no" then go do something else.

The AI has been really hit or miss: sometimes some neat flanking stuff, sometimes inexplicably just standing out in the open or running out into obvious gunfire.
 
we11er said:
I tried stacking a load of stuff at the doors to that bink house, they just opened the doors and it all moved out the way, almost instantly.
Click to expand...
exactly, this is what i tried too. seems as if they can open the doors no matter what u put in front of them.
 
Do my eyes deceive me, or is there really another thread on this?
 
Actually on anticitizen once when soldiers were coming in through one door I blocked it with a locker they just went arround through another door. :D
 
Clavius said:
It was a scripted sequence. No AI is smart enough to understand barricades that you throw up.
Click to expand...

it wasnt scripted, valve said so, the cool AI was just removed from final game!
it probly just took to much CPU.
 
No it doesnt. AI need paths that mappers place so they can find you. If they dont place paths they wont find you. It's that simple.
 
Apos said:
Again, you don't need to make them know stuff about objects and so forth. All you need them to know is a binary "door opened?" response to their attempt to open an openable door. You then have them try to kick the door with a standard force. If "door opened?" still returns a "no" then go do something else.

The AI has been really hit or miss: sometimes some neat flanking stuff, sometimes inexplicably just standing out in the open or running out into obvious gunfire.
Click to expand...

Smart ai would know things about the door, like it's mass and be able to react with the phisics of the game to get the door open.

really good ai should also simulate dumb troops too ;)

I think they have a stat that controls their annoy-edness, if they are pissed off, they just charge you because their anger blinds their "thinking"... Certain troops are delegated "leader", and they don't get annoyed as easily so they are able to think better, and they can relay their thought to others. I thnk that when the ai is really smart, its because there is a leader around the troops.

(however, this is only speculation based on what little ai debuging i've found from the game)
 
m00b said:
No it doesnt. AI need paths that mappers place so they can find you. If they dont place paths they wont find you. It's that simple.
Click to expand...

thats basicly sums it up.. :cheers:
 
Mappers don't need to make paths, thats what pathfinding algorithms are for. Pathing maps, on the otherhand, can be made by mappers, but these can also be pre calculated/pre generated.
 
Hmmm. I AM starting to wonder if the AI gets "dumbed down" on some systems. I have had the combine try MANY tactics to flush me out of houses I hide in (especially the one on the coast), and blocking doors does not usually stop them for long. I had them lob 'nades at me when I was hiding (and they could not see me), I have had them shoot at me through windows, search for other doors, try breaking the doors/blockades, etc. I have also had (in the prison) a guard on one end of the corridor shoot out boxes blocking other combine at the other end! I am not sure if this was accidental or not, but since I had not been anywhere near where he was shooting, it sure looked purposeful (and it really screwed me, because I was counting on keeping the other combine in that entrance blocked out.
 
Major - I haven't had any AI experiences quite to the level that you have, but I really do think there is a possibility that the AI is dumbed down on some computers. A lot of people complain and say FarCry's AI is better etc etc, but IMO they're both about the same, in fact HL2 might be a bit better than FarCry's in some regards as I felt FarCry was a bit OTT in some areas.
 
Lanthanide said:
Major - I haven't had any AI experiences quite to the level that you have, but I really do think there is a possibility that the AI is dumbed down on some computers. A lot of people complain and say FarCry's AI is better etc etc, but IMO they're both about the same, in fact HL2 might be a bit better than FarCry's in some regards as I felt FarCry was a bit OTT in some areas.
Click to expand...

That's why I wonder if it gets "dumbed down" on some systems. I am halfway through playing HL2 again, and I still think the AI is topnotch, and get realistic reactions by combine almost all of the time. But if you consider my system specs (Proc=AMD 64FX 53, RAM=2GB PC3200 DDR, HDD=2x120GB SATA 7200RPM 8MB cache drives in RAID 0, paired with a 9600XT video card), you will notice that I am over the top in all areas where AI might be affected (while limited by my videocard damn it!).

I think HL2 may have some ability to dynamically alter the amount of CPU cycles allocated to enemy decision making (I say enemy, because the squad AI seems less intelligent overall, and does not seem to get better on anyone's system) in order to preserve gamplay for those with older systems. We all know that the game scales exceptionally well in all graphics areas, so why not scale the AI as well?

If it is based on RAM or CPU, then those with more RAM or a better CPU may see more realistic reactions than those with 512 MB RAM, and an older AMD or P4. I would be interested in hearing if anyone with a great processor/lots of ram has had "dumb" AI consistenly, or if anyone with an almost too old processor and minimal ram has had thier AI perform well consistenly?
 
In Nova Propekt when you're trapped in that little area and get the three turrets and bunch of guys keep coming I blocked three of the entrances with boxes used the turrets on the last entrance and they couldn't make it through the *one box high* barracade and all just ran through the turrets and died. Neat that I could beat that section that way but in that case the AI was extremely dumb.. zombies can throw objects, which is cool, I don't understand why they could learn to move objects or climb over them.

Also I was disappointed in the gory death graphics, they just kind of fall over. Way back in like 1998 with Soldier of Forture you could hit a guy in the leg with a shotgun and blow his leg off or hit him in the stomach and all his guts would pour out on to the floor.

Also I noticed with sawblades that the zombies always get cut in two in the same place.

Also enemies don't clime ladders.

It seems like these things would be trival with the source engine... Oh well, there's always room for improvement I guess. It's still friggin cool.
 
It's due to ragdolls being the big new rage, so if you kill someone their body stays intact and flops to the ground. I personally prefer gibs (to some extent). Pity you can't have both, at least not right now - hit someone with a rocket and they explode into gibs, possibly with the top half of the body exploding and their legs remaining.

Would probably be a lot of work to create multiple limb rag-doll parts though and then determine which ones to use in any given situation.
 
Am I the only one that saw Rick talk about this sequence as if was already implimented into the A.I?

He said that the first Combine tried to open the door, while his partners simultaneously fired through the windows. The 2 events weren't related according to Rick. I do wonder if the 'door blocking' element was cut because the implimentation was buggy.

Anyway, it's in the Valve info thread. Am I the only one that saw Rick talk about this sequence as if was already implemented into the A.I?

He said that the first Combine tried to open the door, while his partners simultaneously fired through the windows. The 2 events weren't related according to Rick. Perhaps the 'door blocking' element existed, but was cut because the implementation was buggy.

Anyway, it's in the Valve info thread.
 
Lanthanide said:
Pity you can't have both, at least not right now - hit someone with a rocket and they explode into gibs, possibly with the top half of the body exploding and their legs remaining..
Click to expand...

Agreed, but I have seen a few things in HalfLife2 which came close (or at least amazed me). In Ravenholm, I was up on a rooftop overlooking an alley of zombies with asplodable barrels. When I blew up one, it started a chain reaction of all of them going up, and one of the last things that happened was that one of the zombies got blown in half, with his legs gone (across the street), but his top half (torso, plus head with plush headcrab acessory attached) kept moving!!! His top tried to crawl away until I blew the headcrap off him (leaving a pretty nasty looking deadguy half). I have not seen anything that cool in ANY game, EVER. I do miss Gibs tho, and it would be nice if we would more breakpoints per enemy than just 1 (I never tried the saw with a combine, so I do not know if they even have a breakpoint). But it is possible that they took this out because the computation required to do this would have made the game unplayable for many.
 
Yes, AI is CPU-dependent.

It takes a significant amount of cpu-crunching to handle things like pathing, etc. On slower cpus, cpu time spent on AI would definately be one of the first things reduced.

AI isn't just "there", its a pretty complicated and involved process that requires constant input about the environment and evaluations about the situation.
 
I bet money that both the ai and the phisics are dynamically changed based on the processsor. there is no way they could do both at the same time on an 800mhz proc and still maintain even a mere 5fps count.

I have a 2.8 pentium4, my roommate has a 3.4pentium4, (both prescott) and my mom has a 700mhz amd durron. I will try out my tests on all these computers to see if it actually does affect what they do. I have a big list of things to test for when I actully have time. (I plan to durring christmas break)

There are any number of ways that they could dumb down the ai to run quicker... such as lowering the range taht they take into account objects (aka, lowering their field of view when looking for cover, or alternate routes/fireing positions). Or lowering the ammount of data they save on the game world (ie, what they remember). Or changeing the rate taht they take in certain non critical data (like, how offten to look for cover, on a per frame basis). Or even running less effective but less intesive ai contructs (maybe even ported some from the first game ?). Or even skipping certain ai routines all together.

Even more, this could be dynamically changed based on the current frames per second or processor load, but I bet taht would lead to some inconsistant gameplay (but it would lead to thigns that we've seen now)..

ALSO, GOOD AI doesn't necisarily mean that ALL troops are SMART. they could definately have created ones that are smarter then others, perhaps changing the above parameters on a per charicter or per roll (leader/brute/scardycat..) basis.

the resistance might have GOOD AI, but they might all simply be very DUMB. (note, the bit about not staying put was a design malfunction, not necisarily attributed to bad ai).

Also, with things that are hghly chaotic and intately unpredicable, such as ai, the concept of emmergant behavior arrises. they might have the cappabilities to do cool stuff if the cercumsttances arise, but it might also flop to be somethign dull.
(for instance, the apperance that the two combine are actively working togeter to get you out of a room like in the demos, might simply have emerged from that situation, one chose to open the door, and the other chose to shoot at you through teh window. These actions could very well have arrissen from independet decissions by both npcs, but have been effectively working together due to the cercumstances, as they deffinately appeared that way.)

Or EVERYTHING could be scripted and prerouted... but considering the size of the game, that would take ALOT of scripting. And where would all the fun be in that?
 
I have had a lot of success and fun with the AI (especially on Highway 17). Although I haven't seen anything as cool as in the BINK video (they also took out a lot of traps from that part of the game...oh well), I do have this one really cool video I recorded of some pretty sweet, unscripted AI, i'll upload it later when the attach files thing is working....
 
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