[quote]So I parked a Gauss hog on the left bank of the archway that leads into the main battle, and got into the gunner's seat. I had a clear shot at the Scarab's leg joints (and turret gun) - but it couldn't touch me.

Until a Marine got into the driver's seat and took the hog down into the field of battle, and got me blowed up.
[/quote]
That's an excellent example of a stock AI cooperative behaviour which is helpful in 9 out of 10 cases - and then blows up in your face. This is definitely one case where a little careful scripting to modify standard behaviour could improve the user's experience, rather than degrade it. It's obvious that the level designer has deliberately provided a firing platform for the player to use, so the scripted effect could be neatly localised. Hindsight's a wonderful thing, though...

[quote]Same fight, a little later: I'm on a mongoose, driving, and I've got Joe Marine with a rocket launcher behind me. I drive up to the back of the Scarab, and there's a brute manning the plasma turret in the opening. Other than that brute, though, the way's clear; if we can kill him, I can jump up, run up the ramp, and take out the scarab with no more friendly deaths.

Except that Joe back there has decided that his only target is the knee joint - so he's firing straight up into the air (since we're UNDER a knee joint), instead of helping take out that stupid brute.

That stupid brute who kills us both, in short order. DOH!
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Yes, that one's very familiar. My best guess is that there are quite a few inhibitions built (or scripted) into friendly AI when it comes to targeting the Scarab, in an effort to keep friendly fire off the player during a boarding action. The best evidence I can offer for this is my own experience when trying to make use of the aforementioned firing platform. I'd drive the Gauss 'hog up and try to give my NPC gunner a good field of fire. Every time, after efficiently picking off enemies on deck, he'd then either refuse to fire or pump shot after shot into the concrete in a futile attempt to hit the lower leg joints (see the problem of sightline calculation mentioned in a previous reply). He simply wouldn't target the upper leg joints, or the top turret. In every case where I have been hit by friendly fire while on board the Scarab, it seemed to be because I was standing near an enemy NPC on the upper deck, who WILL most definitely be targeted by allies. I don't think NPCs are allowed to target the Scarab's bottom ramp platform at all, at least when the player is anywhere near it.

Here's another vehicle-related example which irks me. Like many people I decided that my best chance to beat Tsavo Highway on Legendary lay in 'jacking the first available Wraith at the earliest opportunity. As it happens, I really enjoy using the Wraith plasma mortar - a monster weapon which still takes skill and judgement to use - so I normally drive the Wraith all the way to the end of the level (and carry a fully loaded FRG on to The Storm as a bonus). If you return to the roadblock battle after 'jacking the Wraith, it's not too hard, and definitely worthwhile, to pick up a marine to man the Wraith's turret, though they seem to be very finicky about where they'll board from - front left wing only.

My gripe is this: after the roadblock battle is won and the Warthogs are dropped in, my gunner will often dismount and run off to man a 'hog. I've had this happen at the roadblock itself, just before entering the next cave, and just after it when I dismount briefly to scavenge FRG rounds. This is a clear exception to standard cooperative behaviour, and it seems so unnecessary.

Harking back to Narcogen's earlier comment about marines who rush ahead where you wish they'd hang back, the end-of-level encounter on Tsavo Highway is the most frustrating example I can think of. There I am, happily raining huge balls of plasma on the Brutes defending the roadblock, when a Warthog comes up behind me and a squad of marines dismount and charge past. My playing style is to avoid friendly kills, so I check my fire. The survivors race straight on over the hill and hurl themselves straight at the Brutes. It's such a senseless, futile waste of simulated human life. I don't demand or expect textbook armour-infantry cooperation from the AI, but it would be so nice if they had a behaviour which influenced them to hang back, or at least stay out of the tank's forward 90-degree sector.

[quote]How does damage work when you are in a vehicle? My impression is that small arms fire is less effective, you seem to gain some protection because you are in a vehicle. But vehicle weaponss and bigger weapons are just a deadly as being on foot, perhaps more so because the game seems to treat the entire vehicle as your body.

I've been killed easily by head on attacks from Ghosts when I was driving that Brute air boat thingy. The metal engine should have given me ample protection. It didn't.
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This is most likely an example of the general problem of collision detection discussed above. The simplified collision-geometry for the vehicle includes (or gains) an extension which encapsulates gunners, though perhaps not passengers, and the whole volume definitely does seem to be treated as a single entity for damage-calculation purposes in some cases.

My example would be the encounter on the Ark which launches the vehicular-combat section of the level, just after the first terminal where you meet the shot-down marines. When the second wave of Brutes charge in on Prowlers, killing the turret gunners becomes a high priority, and they seem much more resistant to LAAG fire than you'd normally expect. Headshots don't seem to work reliably, either.

If I'm anywhere near right, this is a case where precise collision-detection has been sacrificed in order to keep the frame rate up. Game programming is full of trade-offs like that, you just can't avoid them, and have to strike compromises.

[quote]What if NPC's had two roles? Active and Passive.

You toggle their roles like you toggle between grenades (pre Halo 3). The toggle applies to all marines at the same time. Use the bottom of the dpad to toggle.

Active marines attack and try to drive, passive marines hang back and man guns.

Passive marines will not drive even if you get out and man the gun. If you switch from active to passive whilst being driven then the driver comes to a stop to let you use the laag as a sniper rifle.

What do you think?[/quote]

I think that's a really neat, elegant idea - congratulations. Obviously I haven't a clue whether that concept could easily be fitted into Bungie's (or anyone else's) AI scheme. I urge anyone who has the means to try this out, if they can spare the time and resources (and haven't already considered and rejected it). The trickiest point I can see at the moment is the question of scope - who obeys the order. Suppose you have two or more groups of Marines in one encounter and you (the level designer) want one group to hold a position while the other advances with the player. Here's another case where scripting might be used to beneficially modify a stock behaviour - the defensive group won't advance with the player, but they will retreat with him, or come forward as reinforcements (and obey commands) if the attacking group takes too many casualties.

The other obvious objection is on grounds of simplicity and accessibility - you want a default behaviour which will be as useful as possible to the novice or casual player, so he isn't forced to use this feature if he doesn't want to, or hasn't yet learned to. One possible solution might be to modify your active/passive behaviour categories slightly, so that active mode (the default) yields behaviour much like the current standard patterns. You'd need some kind of feedback to tell you which mode was selected, but this might not require a HUD indicator - a verbal acknowledgement from the ranking marine when you switch modes might be enough.

As I said, I like this idea a lot, but it's one which would really need gameplay testing, and very careful consideration of how it interacts with the scripting system.

(OldNick here: don't want to risk another temp-login until the previous one which I lost with the browser crash has expired)

To Red-Breast:

Thanks for contributing. Mass Effect certainly sounds tempting, and the reviews I've seen have been amazingly favourable, but the RPG element has me worried. I bought Unreal Tournament 2003 and abandoned it after only a few hours of play because I couldn't be bothered with the team-management system.

The command system you describe for Resident Evil 4 (with a flavour of Mass Effect's 'Take Cover' and 'Rally' commands, if they work the way I assume), sounds a lot like what WortJenkins is proposing for his 'T&R-like' concept, if I understand that correctly.

Let me describe what I'm thinking of; Default behaviour is for your squad to follow and react appropriately if threatened or attacked. Hit the command button in this state, and your squad stops and seeks cover appropriate to the threat level, without advancing past the forward limit of their current position, while you move ahead to scout or infiltrate. They won't move forward until one of three things happens:

a) you hit the command button again - in effect a 'Rally' command
b) you come under fire - they advance towards the sound of the guns and engage
c) they come under fire - they return fire and are free to advance if it's to their tactical advantage.

The 'Rally' command effectively throws them back into the default 'follow' mode, advancing to rejoin you by the most direct route. In the other two cases, the follow behaviour is prioritised below immediate tactical necessities.

In the original 'Truth and Reconciliation' ground engagements, scripting sets up something pretty close to this behaviour, with the marines' hold commands provided by the script, and the hold broken by the enemy seeing or firing on the player. You can, if you're careful, break the hold at a moment of your own choosing, but only by revealing yourself to the enemy. This command system would let you trigger the marines' advance while staying covert, then hit the enemy yourself from the rear or flank when they deployed to engage the marines. I like the sound of that.

I wonder how this would need to be modified when vehicles are involved? At the moment, sad to say, I don't have the time or energy to work through that, even in broad outline.