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Author Topic: How does the AI work? (18 messages, Page 1 of 1)
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Rafeku
Joined: Sep 6, 2015

Shaddap, and go stealth BIATCH


Posted: Jan 15, 2016 08:32 AM    Msg. 1 of 18       
I actually wanted to put this on a off-topic, but I guess it can be kept here.
I've been playing Half-Life 2 and GMOD these days and one thing I can say about the source engine: The AI is crap. It's highly dependant of nodes when it's following the player, they get behind and keep standing like doors for almost no reason if you get too far. Enemies: when you are in their sight distance, they keep spraying their shots, only hitting a single bullet in 20 seconds(Considering playing the game on normal). Also they don't even try to dodge grenades. If they do, they're too slow.

Halo came in 2001 and the covenant AI is very effective(the humans are underwhelmed too easily...which I hate). They dodge grenades, cars, go behind cover when they feel this crap is getting real, go hunt you when YOU feel the crap is getting real, and etc.Tone this even more up when legendary.

HL2 launched in 2004 with its so glorious Source engine, mostly because it used Havok to help on physics, but the AI was still dumb. Can't help it but THIS makes Solid Snake feel dumb. Also they way source handles stuff is somewhat ineffective and resource intensive. Every stage is a room, the must be loaded separatedly. Sometimes those "rooms" are too small, and the loading takes sometime(depending on the map). But this is for another topic

So I kept wondering to myself: How does a game that came earlier, has a much superior AI, and pathfinding, while HL2 which is suposedly 3 years more "modern" has such a dumb and exploitable AI?


sparky
Joined: Jun 27, 2009

Jesus is a friend to the vindictive sociopath


Posted: Jan 15, 2016 09:49 AM    Msg. 2 of 18       
I am unfamiliar with Source Engine. The Blam! Scripting Engine is detailed in ways, and can be customized. I would presume that the Source Engine, being open-source, is detailed how you make it, and can be customized how you choose.


Super Flanker
Joined: Oct 5, 2012

The length of your life depends on my aim.


Posted: Jan 15, 2016 10:39 AM    Msg. 3 of 18       
Perhaps it's something as simple as monetary funding.

Halo had more funding in it it's conceptualization then the dudes at cs did.

Or more than likely Bungie was just far cleverer.
Edited by Super Flanker on Jan 15, 2016 at 10:46 AM


NeX
Joined: Apr 11, 2013


Posted: Jan 15, 2016 10:43 AM    Msg. 4 of 18       
Insurgency has very good AI and is a source game. I doubt its the engine's weakness and more likely developer faults.

Oh look who's back. Yay


Skidrow925
Joined: Mar 19, 2010

"ideological sense of respect and tact of a 5yo"


Posted: Jan 15, 2016 11:26 AM    Msg. 5 of 18       


I demand compensation for everything on my desk that just got covered in uh.. spit. we're going with spit. that's definitly spit.\



On the actual topic I'm inclined to agree that it's just a matter of poor design. Not to mention, the games are very different. Halo is very open, while Half-Life is more of a corridor (if that makes sense) and is more scripted imho.

Oh, and the insurgency AI are pretty stupid by the way.
Edited by Skidrow925 on Jan 15, 2016 at 11:28 AM


Halonimator
Joined: Dec 15, 2014

https://imgur.com/a/pVhmSgX


Posted: Jan 15, 2016 11:40 AM    Msg. 6 of 18       
Quote: --- Original message by: Rafeku
I actually wanted to put this on a off-topic, but I guess it can be kept here.
I've been playing Half-Life 2 and GMOD these days and one thing I can say about the source engine: The AI is crap. It's highly dependant of nodes when it's following the player, they get behind and keep standing like doors for almost no reason if you get too far. Enemies: when you are in their sight distance, they keep spraying their shots, only hitting a single bullet in 20 seconds(Considering playing the game on normal). Also they don't even try to dodge grenades. If they do, they're too slow.

Halo came in 2001 and the covenant AI is very effective(the humans are underwhelmed too easily...which I hate). They dodge grenades, cars, go behind cover when they feel this crap is getting real, go hunt you when YOU feel the crap is getting real, and etc.Tone this even more up when legendary.

HL2 launched in 2004 with its so glorious Source engine, mostly because it used Havok to help on physics, but the AI was still dumb. Can't help it but THIS makes Solid Snake feel dumb. Also they way source handles stuff is somewhat ineffective and resource intensive. Every stage is a room, the must be loaded separatedly. Sometimes those "rooms" are too small, and the loading takes sometime(depending on the map). But this is for another topic

So I kept wondering to myself: How does a game that came earlier, has a much superior AI, and pathfinding, while HL2 which is suposedly 3 years more "modern" has such a dumb and exploitable AI?


Because blam! use a more complex tree behavior and pathfinding?

And the first Half-Life has better Ai than the sequel... some youtube: https://www.youtube.com/watch?v=zXjk2jKd_xo&list=PLDmcwfn8y0lMtlqcpUhggk0FB1EC2i3iB
Edited by Halonimator on Jan 15, 2016 at 11:59 AM


Skidrow925
Joined: Mar 19, 2010

"ideological sense of respect and tact of a 5yo"


Posted: Jan 15, 2016 12:13 PM    Msg. 7 of 18       
Quote: --- Original message by: Halonimator

Quote: --- Original message by: Rafeku
I actually wanted to put this on a off-topic, but I guess it can be kept here.
I've been playing Half-Life 2 and GMOD these days and one thing I can say about the source engine: The AI is crap. It's highly dependant of nodes when it's following the player, they get behind and keep standing like doors for almost no reason if you get too far. Enemies: when you are in their sight distance, they keep spraying their shots, only hitting a single bullet in 20 seconds(Considering playing the game on normal). Also they don't even try to dodge grenades. If they do, they're too slow.

Halo came in 2001 and the covenant AI is very effective(the humans are underwhelmed too easily...which I hate). They dodge grenades, cars, go behind cover when they feel this crap is getting real, go hunt you when YOU feel the crap is getting real, and etc.Tone this even more up when legendary.

HL2 launched in 2004 with its so glorious Source engine, mostly because it used Havok to help on physics, but the AI was still dumb. Can't help it but THIS makes Solid Snake feel dumb. Also they way source handles stuff is somewhat ineffective and resource intensive. Every stage is a room, the must be loaded separatedly. Sometimes those "rooms" are too small, and the loading takes sometime(depending on the map). But this is for another topic

So I kept wondering to myself: How does a game that came earlier, has a much superior AI, and pathfinding, while HL2 which is suposedly 3 years more "modern" has such a dumb and exploitable AI?


Because blam! use a more complex tree behavior and pathfinding?

And the first Half-Life has better Ai than the sequel... some youtube: https://www.youtube.com/watch?v=zXjk2jKd_xo&list=PLDmcwfn8y0lMtlqcpUhggk0FB1EC2i3iB
Edited by Halonimator on Jan 15, 2016 at 11:59 AM



Edited by Skidrow925 on Jan 15, 2016 at 12:14 PM


Rafeku
Joined: Sep 6, 2015

Shaddap, and go stealth BIATCH


Posted: Jan 15, 2016 04:15 PM    Msg. 8 of 18       
You see, none of this you people are seeing happening here is scripted, everything is done by the AI decisions and bla bla. That was at the presentation of Half-Life 2 back in 2003.

One of the biggest problems that I have with it's AI, are simple pathfinding and being able to jump(which they just don't) For example, you're walking and you find yourself in place where you have to jump, without other way around and you have an NPC following you. You can go down, the NPC will be there looking into nothingness without knowing what to do. Unless the map is noded, they sometimes will find a way around. But they just dont jump. Same problem happens in irregular terrain, they just get lost easily when you're going uphill, even with nodes.

That probally why Insurgency NPCs are bad, but I don't own the game to say anything, I just saw some videos to see how is the game.


Skidrow925
Joined: Mar 19, 2010

"ideological sense of respect and tact of a 5yo"


Posted: Jan 15, 2016 10:14 PM    Msg. 9 of 18       
Quote: --- Original message by: Rafeku
You see, none of this you people are seeing happening here is scripted, everything is done by the AI decisions and bla bla. That was at the presentation of Half-Life 2 back in 2003.

One of the biggest problems that I have with it's AI, are simple pathfinding and being able to jump(which they just don't) For example, you're walking and you find yourself in place where you have to jump, without other way around and you have an NPC following you. You can go down, the NPC will be there looking into nothingness without knowing what to do. Unless the map is noded, they sometimes will find a way around. But they just dont jump. Same problem happens in irregular terrain, they just get lost easily when you're going uphill, even with nodes.

That probally why Insurgency NPCs are bad, but I don't own the game to say anything, I just saw some videos to see how is the game.


Trust me, insurgency AI only win because RPG


Rafeku
Joined: Sep 6, 2015

Shaddap, and go stealth BIATCH


Posted: Jan 16, 2016 03:58 PM    Msg. 10 of 18       
lol.

But back on topic, I just wanna know how the AI on halo works, how it does stuff. If anyone knows of course


A Juicy Frank
Joined: Oct 28, 2013


Posted: Jan 16, 2016 05:31 PM    Msg. 11 of 18       
I remember being somewhat interested in the way halo's ai pathfinds when I was looking for ways to infulence how a BSP's "pathfinding surfaces" (pathfinding nodes) are created to better optimize ai movement to firing positions. The best way to see it all in action would be spawning ai in sapien and running various debug commands after selecting the encounter and watch what they do. Images:







This modacity thread I found discussed the question I had (unfortunately concluding that we just don't have enough resources or knowledge in the area to achieve those goals). I didn't really read much into what they referenced as I'd just moved on to other experiments, but you may definitely find some of it interesting.

https://en.wikipedia.org/wiki/A*_search_algorithm - A* search algorithm
http://slideplayer.com/slide/1406867/ - integration of ai and level design
https://web.archive.org/web/20151123201443/http://electronics.howstuffworks.com/halo2-ai.htm - In the mind of the enemy: halo 2 ai
http://webcache.googleusercontent.com/search?q=cache:A9mOmvRKGFUJ:https://www.aaai.org/Papers/AIIDE/2005/AIIDE05-040.ppt+&cd=3&hl=en&ct=clnk&gl=us - general spatial competence .ppt



Some links looked gibbed. Fixing.
Edited by A Juicy Frank on Jan 16, 2016 at 06:30 PM


Skidrow925
Joined: Mar 19, 2010

"ideological sense of respect and tact of a 5yo"


Posted: Jan 16, 2016 06:59 PM    Msg. 12 of 18       
Woah woah woah woah woah, how dis you get the firing position letters to show up? (if its in the links I suppose ill find it later, on the phone)


A Juicy Frank
Joined: Oct 28, 2013


Posted: Jan 16, 2016 07:14 PM    Msg. 13 of 18       
Cereal Killer showed up one day with the button combo. V+M.


http://forum.halomaps.org/index.cfm?page=topic&topicID=45792
Quote: --- Original message by: The Cereal Killer

Found this old thread: http://forum.halomaps.org/index.cfm?page=topic&topicID=41753

Tonight I found that the key combination in Sapien to toggle labels on the firing positions as shown is V+M

That's all. Thanks for stopping by.
Edited by The Cereal Killer on Apr 14, 2014 at 01:11 AM


Skidrow925
Joined: Mar 19, 2010

"ideological sense of respect and tact of a 5yo"


Posted: Jan 16, 2016 07:34 PM    Msg. 14 of 18       
And he NEVER FRIGGEN TOLD ME!?!?!?

TCK dun goofed. Although that's probably the mist helpful thing ever. I think I may go through and see what other keybinds I can find at some point.


A Juicy Frank
Joined: Oct 28, 2013


Posted: Jan 16, 2016 08:50 PM    Msg. 15 of 18       
My memory is severely fuzzy about this, but I think I remember someone stating they messed with Sapien's executable or something in order to find hotkeys that would be accepted for actions long ago. They noted that most functions were disabled outright for our version of Sapien (non Bungie), and that one function of particular interest was still enabled but would crash when used. The function supposedly allowed us to select a unit in the game window and physically control that unit just as we do in the main game. Apparently it was how Bungie created 'recorded animations' from within Sapien while working on the scenario.


My level of understanding is nowhere near what's needed to effectively find (much less re-enable) any of these functions, if that wasn't already obvious. We may just need our Blam! gods to shed some light on this stuff in time. If you've got the time, I'd take a look into OS' source for anything regarding Sapien to see if there's any useful information in there.


Halonimator
Joined: Dec 15, 2014

https://imgur.com/a/pVhmSgX


Posted: Jan 18, 2016 02:56 PM    Msg. 16 of 18       
starting wth c++ basic ai (edited snake source code)



with a* pathfinding!


Rafeku
Joined: Sep 6, 2015

Shaddap, and go stealth BIATCH


Posted: Jan 21, 2016 12:42 PM    Msg. 17 of 18       
I have to read this a bit later, most of it is geek stuff, gotta read carefully. and I remember reading an article about Halo 2 AI, told in the simplistic manner. Well good thing I've opened something useful here.


NeX
Joined: Apr 11, 2013


Posted: Jan 21, 2016 12:46 PM    Msg. 18 of 18       
Quote: --- Original message by: Halonimator
starting wth c++ basic ai (edited snake source code)

http://i66.tinypic.com/208usya.jpg

with a* pathfinding!



If you don't have a decent grasp of data structures and algorithms (especially if you're using c++), you are biting off quite a bit.

I found a good explanation of pretty simple procedural pathfinding algorithms on stackoverflow, copypasta'd here.

Even the simplest AI will need one of the two below, and I mean simple as in "16 bit mario"


Dijkstra:
It has one cost function, which is real cost value from source to each node: f(x)=g(x).
It finds the shortest path from source to every other node by considering only real cost.




A* search:
It has two cost function.

g(x): same as Dijkstra. The real cost to reach a node x.
h(x): approximate cost from node x to goal node. It is a heuristic function. This heuristic function should never overestimate the cost. That means, the real cost to reach goal node from node x should be greater than or equal h(x). It is called admissible heuristic.
The total cost of each node is calculated by f(x)=g(x)+h(x)

A* search only expands a node if it seems promising. It only focuses to reach the goal node from the current node, not to reach every other nodes. It is optimal, if the heuristic function is admissible.

So if your heuristic function is good to approximate the future cost, than you will need to explore a lot less nodes than Dijkstra.
Edited by NeX on Jan 21, 2016 at 12:47 PM

 

 
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