Any AI scripter around ?

[motorsep]

The state of Doom 3 modding is pretty sad (while people still play and buy Doom 3, there aren't any new mods coming out and many of the old mods are abandoned).

So I am wondering if there are any modders who dwell on this forum worked with Doom 3 AI.

The question is if AI seen in my previous game, Steel Storm (http://store.steampowered.com/app/96200/), doable in Doom 3 without messing with C++ code.

[BielBdeLuna]

what features have the Steel Storm AI?
does it use objects or lists?

[motorsep]

I wish I knew

What it does it generates navigation grid made of cells of a fixed site, before player and AI spawns. It's purely a 2D system. It doesn't account for ramps or lifts or ladders. If an entity other than player occupies cell(s) those are marked as unavailable. AI simply probes around for free cells and moves enemies into free cells. Some basic steering is in place to "turn" around occupied cells. As AI finds player, they attack and they always track player as they move around. Of course there is a factor that doesn't allow them predict where player will be, otherwise player will never win

That's the gist of it.

[BielBdeLuna]

well there are multiple things here

- the AAS system should be more advanced that any grid out there ,and should take into account the reachabilities, therefore the ramps should also make into it, lift won't though, as well as ladders (although those could be added in)

- the AAS won't take into account the moving entities, that has to be worked out in real time

- is the turning on the centre of gravity of the enemy or the turn is done describing big circles with the centre out of the enemy?

- there is this concept of planning in AI that at the moment is quite impossible in AI scripting (as done in idTech X ) because the lack of lists, that should anticipate the player actions (F.E.A.R. had a system like this)

- the way you describe the AI seems to be pretty similar to what quake 1-2 monsters did, to always track the player position, with an added navigation scheme on top (that 2D grid you spoke about) tracking the player is what d3 monsters do all the time, so it should be totally doable in scripting (minus the 2D grid, but that's what the AAS is for which should be far more advanced)

- things that should require lists probably would be multi agent strategies, and multi target strategies per agent, the first should be interesting due you could find several enemies, and those could pin you while others flank you ( somewhat to what you're asked to do in the Brothers in Arms series ) but as I stated you might need lists for this

-also AAS makes enemies in reality blind because navigation is separated from decision making, only feeding it as input for decision making, therefore you don't know anything about your surroundings just how to navigate it, you don't know how tall is that wall, you just know how to navigate around, so tracing several lines should be the first steps towards a strategy, but without lists, this all goes quite forbidden quite quickly, another idea could be, adding a strategist scheme via c++ that could feed the scripting, but this is more laborious than having a simpler (much much much more simpler) AI scheme like the ones in D3.

- the AI schemes in D3 are FSM ( Finished State Machines ) which get bloated as you need more features from them, and doesn't facilitate the construction of different AI behaviour for different agent (all the enemies behave similarly or equally, and all agents never gain any capacity over time) there are other ways to produce AI scripting that discard the FSM scheme completely and get more real-time generated AI with far more advanced capabilities.

[motorsep]

- the AAS won't take into account the moving entities, that has to be worked out in real time

It actually would. There is dynamic obstacles avoidance system in Doom 3.

- is the turning on the centre of gravity of the enemy or the turn is done describing big circles with the centre out of the enemy?

It's just moving and adjusting turn angle. It's already in Doom 3's code (maybe not exposed to script).

- there is this concept of planning in AI that at the moment is quite impossible in AI scripting (as done in idTech X ) because the lack of lists, that should anticipate the player actions (F.E.A.R. had a system like this)

RAGE doesn't use planner either, but its AI is awesome

- things that should require lists probably would be multi agent strategies, and multi target strategies per agent, the first should be interesting due you could find several enemies, and those could pin you while others flank you ( somewhat to what you're asked to do in the Brothers in Arms series ) but as I stated you might need lists for this

No need to get things overcomplicated. If you can play SS:BR demo, you can "feel" the AI. It's quite good without having any advanced AI methods.

-also AAS makes enemies in reality blind because navigation is separated from decision making, only feeding it as input for decision making, therefore you don't know anything about your surroundings just how to navigate it, you don't know how tall is that wall, you just know how to navigate around, so tracing several lines should be the first steps towards a strategy, but without lists, this all goes quite forbidden quite quickly, another idea could be, adding a strategist scheme via c++ that could feed the scripting, but this is more laborious than having a simpler (much much much more simpler) AI scheme like the ones in D3.

That's no different than any other AI. There flying monsters, so there is a way to determine the height. Although I believe they just navigate until they reach the goal. But AAS has ledges and all that good stuff, so I am sure it's not a big deal to write a function that measures the height of the walls from the floor to the ledge. The question is how is it related to the AI in general and to the AI I need to make in particular ?

Note that somehow people think self-aware AI is awesome, but in reality it's faster and cheaper to have mix of prescripted events and hFSM to make fun and challenging AI than develop "correct" AI system that works as if it's a human/self-aware AI.

- the AI schemes in D3 are FSM ( Finished State Machines ) which get bloated as you need more features from them, and doesn't facilitate the construction of different AI behaviour for different agent (all the enemies behave similarly or equally, and all agents never gain any capacity over time) there are other ways to produce AI scripting that discard the FSM scheme completely and get more real-time generated AI with far more advanced capabilities.

FSM is easily organized into hFSM. Lists and anything else beyond FSm / hFSM is absolutely unnecessary at this point.

As I mentioned, AI in SS:BR is well received by people (a lot of folks thought it was too smart and tough; but I say it's just where it should be; maybe need slight tweaks and improvements but overall it's a perfect fit for the game), so there is no need to go a way beyond that. The goal is to recreate AI as-is (the "feel", not the exact code).

[BielBdeLuna]

It actually would. There is dynamic obstacles avoidance system in Doom 3.

is it robust enough?

It's just moving and adjusting turn angle. It's already in Doom 3's code (maybe not exposed to script).

turning is exposed and used in every character AI script

RAGE doesn't use planner either, but its AI is awesome

it is? what does Rage does diferent? how different it is from D3? there is a lot of animations in RAGE at there might be some cover, but there is also cover in d3

The question is how is it related to the AI in general and to the AI I need to make in particular ?

the idea was to comment on the limits of AAS, finding it useful it's up to you

FSM is easily organized into hFSM. Lists and anything else beyond FSm / hFSM is absolutely unnecessary at this point.

what do you refer as hFSM?

AI in SS:BR is well received by people

I don't see much of difference between the AI  in your game and the one in d3 imps so I guess you could start there

[motorsep]

I know what AAS can and can not do, and you could at least play the game before saying there is no difference between AI in SS:BR and Doom 3's imps :/

Imps don't move as dynamically as hovertanks in SS:BR, they don't dodge, they don't back away and then attack again. Imps are dumb as rocks. All they do is attack and jump occasionally to the side (so slow and without any timing that it's a useless evasive maneuver).

You can definitely prove me wrong on this one by setting camera to top down in Doom 3 and having several imps around you (with improved AI I suppose).

So meanwhile the original question stays open :/

[BielBdeLuna]

I have played the game that's the reason I stated that, and it was not meant as an insult.

so the enemies back up and dodge, ok you could add those behaviours to the imp AI script, and you're set! But this shouldn't be that big of a deal, this is an added behaviour, the general system remains the same

the general question doesn't remain open because I answered it:

The question is if AI seen in my previous game, Steel Storm (http://store.steampowered.com/app/96200/), doable in Doom 3 without messing with C++ code.

the answer is yes, it can be done, just need to look at the imp for starters and add those "new" behaviours you need

[motorsep]

so the enemies back up and dodge, ok you could add those behaviours to the imp AI script, and you're set!

But how? Isn't dodging a part of navigation, which is in C++?

What script event would I use to dodge and back away ? I know there is script even to look at player and I believe turn, but not dodge / move backward.

[solarsplace]

Hi

Dodging is driven from script.

There are several ways of doing it atucally. In simple terms:

You can have animation based dodge, or physics based force dodge for flying creatures.

Both in general simply use a timer and when next dodge time is up, the code says can i perform animation "left_dodge" without hitting an obstacle, if so play animation on channel legs.

Things like the lost soul don't play an animation but have a physics force applied to them to dive bomb or dive back. There is also a script event to move x units away from the player and move to entity.

So basically its a collection of hard coded behaviors and tricks.

Cheers

[The Happy Friar]

EDIT: solarplace answered in less words.  :p

I have played the game that's the reason I stated that, and it was not meant as an insult.

You should, it's a fun game.  Coop is a lot of fun and the DLC is pretty darn hard.  I loved it!

But how? Isn't dodging a part of navigation, which is in C++?
What script event would I use to dodge and back away ? I know there is script even to look at player and I believe turn, but not dodge / move backward.

I could never get my head around AI scripts but I've modified them somewhat occasionally.  From looking at the Imp script, if the imp can't melee then it checks to see if it's in pain.  If it's in pain & the current time is greater or = the next dodge time, it tests the animation.  "testAnimMove" (from what I understand) has the engine check the bounding box of the animation (the whole thing).  If it's ok (ie no collisions in that space) then it randomly chooses a dodge animation (it tests both left & right).  So dodging itsn't in the AI or a special part, it's just a if/then/else statement somewhere in the script.

What the AI in SS:BR does is it doges w/o checking the animation because it doesn't run a dodge animation, it moves via code. That's also what Quake 2 does (never looked at Quake 1 code).  Q2 has the coder manually enter in the offset values for each animations movement.  A complete PITA. 

I took at a look at the caco AI & def & tested the model in game.  The Caco pain animation does make it move forward, but I can't find anywhere in the script that tells which direction/how far to move to dodge the player (which it does after getting in pain sometimes), so it must be in the code somewhere for flying monsters (IE don't stop flying at all).  The only thing that I can think of for flying is that the flying monsters have a pitch/roll/yaw value and when in pain the origin rotates up to this amount and keeps moving, and if you do a standard pain anim it runs the animation and rotates based on those values.

I would figure for a SS:BR type game in D3 you'd need to animate several different dodge distances and have it test those each time it calls for a dodge to get something similar.

[motorsep]

Doom 3 has animation driven AI, so I guess either hovertanks have to be flying monsters (but their code has no dodge functionality and it's all in C++), or they have to be standard creatures with dodge anims.

Next question is why doesn't Imp dodges properly/timely ?

[solarsplace]

Doom 3 has animation driven AI, so I guess either hovertanks have to be flying monsters (but their code has no dodge functionality and it's all in C++), or they have to be standard creatures with dodge anims.

You can easily add dodge to flying creatures. All you need to do is give them a physics force "blast" in a left or right direction from script. You could do this on a timer, or you could react to pain or you could react to enemy projectiles. It will require AI scripting of course, but its not that hard to implement. You don't need to write new systems in C++ to do that.

In fact a little physics push would look quite realistic for a hover tank perhaps?

Next question is why doesn't Imp dodges properly/timely ?

Keh? - Not totally sure of the question?

The imp spends most of its time waiting to do a "leap" attack and I'm not really sure dodge was properly implemented or it might only dodge one way I think I remember.

Bear in mind that a lot of the Doom3 AI scripts are a little "funky" in places and there are bugs. But obviously at the time id thought the behavior was just fine.

Cheers

[The Happy Friar]

Keh? - Not totally sure of the question?

The D3 id AI doesn't really dodge, it reacts to being damaged.  I'm not at my machine ATM but maybe the zombie police guys actually dodge.

I'm guessing what motorsep means by "dodge" is that the know the projecticle is heading their way so they get OUT of the way.  The imp doesn't know about the projecticle, he gets hit at least once & then decides if he should dodge (I want to say Q2 had some monsters that would detect if a projectile was heading their way and duck (stock Q2) or dodge (expansion pack) before they'd get hit).  The flying ones are the same way.

Maybe a check for projectiles could be made every couple game frames and if one is heading towards the AI position over several checks then it runs a dodge anim before it gets hit vs waiting until it gets hit.

[motorsep]

yeah, that's what I mean by dodging. In SS:BR if you use miniguns, AI would get hit and then dodge. However with projectiles, AI will dodge (I don't recall if it always dodges). I am not sure whether it detects projectiles, or detects what weapon player fired and the distance between player and AI and then it dodges (moves aside so it won't be hit).