Basic questions about an escort/ambush mission concept

[Bahger]

Hey gents, it would save me much trial-and-error anguish if I could address the following issues in advance for a (quite promising, I think) idea I have for a mission:

Mission parameters:

- SP/coop, created in MP editing module using F2 framework

Concept:

- A marine unit must escort a truckload of civilians to a village from which they have recently been expelled by local militia on ethnic grounds.  A truce has been negotiated and the civs have been given permission to return.  However, the militia breaks its promise; the truck is blown to smithereens en route while escorted by the Marines and the fleeing occupants are cut down by militia forces targeting them from long range before withdrawing, their intention to draw the Marine unit into a fight in the well-defended village.

Issues:

- Which humans should I use as civilians, regular civs or disarmed local independents friendly to the West? Will I be able to create them as a group, have them mount the truck while the player watches and later have them flee from the explosion?

- I'm intending to use a mine or two to blow up the truck.  I think I know how to place it under the surface.  If there is a better, more spectacular way of doing this, though, like a daisy-chained string of explosions, could someone let me know?  I want a big bang but also survivors.

- I can use an Independent area trigger to get the militia to open fire on the truck after it has been destroyed but will there be a problem getting them to fire on Independents and not focus on the Marines?

- What is the best way to get the militia to pop smoke, break contact (rather than engage the Marines) and withdraw, so as to draw the angry Marines into a prepared defence at the village?

This might be a good mission if I can get some of this stuff properly organised.  Thanks!

[Wolfrug]

You're contending with Arma 2 AI here, which is usually not easy to strangle into doing "pre-scripted" things like these, but you can at least create a simulacrum of the desired events (and fudge the rest with radio comms and the like). But I really like the concept! I suggest you keep it fairly light scripting-wise, which means there will be a lot of unplanned things happening. The hardest will be, I think, to blow up the truck in "just the right way".

- Mines only apply to armored vehicles, not trucks, so you need to figure out another way. I suggest a simple trigger that spawns a an explosion under ground, coupled with a setdamage on the driver to make sure the truck isn't going to keep moving (this would be the most 'scripted' event in the mission). After that, the enemies would be given the green light to open up, and the people in the truck would be 'revealed' to them; that way it's more likely they'll target them. So:

First, the set-up: create a truck, name it e.g. truck1. Create a group of Independent-sided "foresters" etc (make sure they're hostile to OPFOR), and remove all their weapons. Name their group something, e.g. civgrp1 (civgrp1 = group this). Create any number of additional civilians and group them with the independent group - they'll be targeted all the same as long as there's an 'enemy' as the group leader. Now, create your ambushing group and name it something like e_grp1. Put it in position, and make sure they've got a clear line of fire to the road etc. Give them one waypoint, where the combat mode is set to "Hold Fire". This will make sure they don't open up too early.

Next, create a trigger, grouped to the civilian truck, Activated by: "Vehicle present" (this will make sure that even if the stupid AI manages to drive off-road, it'll still be hit), and place it on the ambush spot. Condition: this, On Activation:

Code: [Select]

nul= "Sh_120_HE" createvehicle (truck1 modeltoworld [0, 10, -2]); driver truck1 setdamage 1; {leader e_grp1 reveal _x} foreach units civgrp1; e_grp1 setcombatMode "YELLOW"
This will create a shell more or less in front/underneath the truck, which will hopefully (in my testing) disable it and let the civilians get out before blowing it up. You can try with different ammo classes and different model-to-world data to make it look just perfect. The driver of the truck is killed via script to make sure the truck doesn't go anywhere (make him a separate group). Then, as you can see, the civilians are all "revealed" to the enemy group leader and their combat mode is set to "fire at will". To make the slaughter even more complete, just give the civilians in the truck a single waypoint (from the start) which has them run into the enemy ambush location "in the confusion" and get themselves killed.

This is stage one. Stage two is getting the enemy insurgents to retreat back to the village. When do you want this to happen? This is what you put into the enemy group's first waypoint in the Condition field. Give them a second waypoint into the village where the combat mode is set to "Hold Fire", the Speed to Full and the Behaviour to Aware. This will HOPEFULLY make them retreat, but nothing is certain! Still, you can simply add a radio comment in the On Activation field of their first waypoint that says something like "the insurgents are falling back to the village! Pursue them!", even if this is not what's really happening

Anyway, as to this second condition: waiting for all the civilians to be dead is not safe, since the civs might decide to run in the opposite direction, take cover successfully or hide behind some terrain feature and so on. It might work once, but the next play-through it'll all be fudged. We want the retreat to happen after a first couple of moments of frantic shooting and burning trucks and chaos, so that the player as a minimum of time to react. The simplest way might be a timeout!

On the Insurgent's first waypoint, add the condition:

!alive truckdriver1

This is the trigger for the attack, and we know the truck driver will be dead since he's scripted to die (you should name the truckdriver of course). Now, above the condition field are three fields for "Timeout". These are the max, min and median times (in seconds) until the trigger activates -after- the condition has been fulfilled. So add something like max 60, min 30, med 45 into these, and the waypoint will be fulfilled and the enemy group move towards its next objective once the truck driver is dead & x amounts of seconds have passed (if they're all the same, then there's no random element of course).

In the On Activation field of the trigger, you can also fudge some smoke grenades and such, for instance:

nul = "SmokeGrenade" createvehicle getpos this

"this" when written inside the On Activation field of a waypoint always refers to the one the waypoint belongs to - in this case the Insurgent leader (whoever he is). Of course there's no telling where he'll be at the time of the retreat, so the shell might land at a stupid place, but there's little you can do unless you're going to add a veeery complicated algorithm for figuring out where the insurgents are in relation to the marines and then pop shells in the intervening space. It's just eye candy anyway. You can add more smokes by doing stuff like:

nul = "SmokeGrenade" createvehicle (getpos (units group this select 1));

Which will pop a smoke at the feet of "number one" of the group as well, whoever that will be. Using named soldiers here is not very good, since they might have been killed in the intervening time.

As to making them ignore the marines and focus on the civilians: not much you can do there I'm afraid unless you want to completely skew everything (e.g. make the marines setCaptive or something) - why wouldn't the insurgents focus their fire on the most dangerous thing on the battlefield if they're getting shot up? Anyway, most of the civilians will probably be cut down and killed during the first couple of seconds anyway, so it should be good. You -can- of course use things like doTarget to try to make sure the civilians are targeted first, but I think the general confusion, explosion, shooting etc. should be enough in this situation.

Having tested this, I'd also like to suggest you remove any RPG-soldiers from the ambushing insurgents, since they might just blow up the truck the moment they're given the all-clear, not giving the civilians enough time to get out. Also, the shell I used (M1A1 HE shell) is pretty powerful, but currently explodes underground which makes it a bit less deadly - you might want to experiment with different types, but keep in mind that missiles will fly off if spawned in the air!

Anyway, it's a complicated situation to pull off, but I think you can do it - but please don't expect the scripted sequence to be the same every time, or even 50% of the time That's Arma 2 for you, I'm afraid!

Do tell me if there's something that doesn't work out for you. Added to the post is my test mission, which works - more or less You can load it up in the editor and check it out (no marines in that mission, and in a randomly placed location).

Good luck!

Wolfrug out.

[Bahger]

This is fantastic, Wolfrug, thank you so much for lending me your time and expertise!  Not only will your contribution make this a much better-designed mission, it will also provide me with an invaluable lesson in ArmA 2 editing techniques.

I'm going to load up your test mission and, even though I'm out tonight, test it in the next 48 hours.  

If you would like formally to co-author this mission with me, I'd be honored.

Meanwhile here are a few preliminary thoughts:

-  I agree with you about excessive scripting.  It's one thing to choreograph cool things, another to introduce the probability of instability, chaos and unreplayability.

-  Did you make your mission in the MP editing module?  Did you see in my post where I mentioned making this with the F2 MP framework so that the mission would have coop as well as SP functionality?  I'm going to load your sample mission into the MP missions folder or somehow copy the content so that I can then layer in the pre-made F2 scripts for MP and use the pre-made Shacktac templates for Marine force structures and armament (one Rifle Squad/three fire teams, approx).  Does this make sense to you?  If not, I will settle for making the mission in the SP editor for SP only.

-  I'm going to work on starting the mission on the move, with the player, the squad commander, in the gunner's perch of a HumVee with .50 cal.  I'm thinking of having the Marine Rifle squad all embarked on HumVees and deployed off-road, slightly behind the civilian truck.  The briefing will have established that they are to escort the civs to their village per the terms of the (rather tenuous) ceasefire.  Putting the player in the gunner's perch (for overwatch/SA) will give him a good view of the coming explosion and massacre.

-  I need to find suitable terrain to provide two villages with a road between them in enough open space that the convoy can have gotten up to speed when it is attacked.  Obviously I need to find good ambush placement for the enemies.

-   I will have the player's commander, in the village behind, where they set off from, see the smoke from the explosion and radio the player, asking for a SITREP.  The player's message in reply will say they've been ambushed, that unarmed civs have been massacred and that he wants to go after the perpetrators, who have withdrawn after committing their cowardly act.  He is ANGRY, the response emotional.  His commander tells him to calm down, that following the enemy might be leading his men into a carefully-prepared trap and orders him to hold, to defend the site against further attack and to wait for medics to arrive to deal with the casualties.  I will see if there are dedicated mobile med units in A2 that I can then script to come out.  The trick here will be to prevent the player from charging off without orders, in other words to script things so that the player-commanded units HAVE to hold until ordered to proceed.  Once the medics get to the site, which needs to be quickly, the final phase of the mission can be triggered:

-  The commander authorises the player to assault the village ahead and to go after the perps.  This village will be very well-defended, with static defenses etc., as, indeed, the whole purpose of the attack on civilians was to lead the Marines into a trap, handing the bad guys a huge propaganda victory.

-  To add one final wrinkle, I'm considering creating a squad of partisan troops loyal to Blue, outraged by the massacre of their fellow-countrymen, eager for revenge.  I would give the commander a name and a "personality" via direct radio contact with the player.  I would want him to agree to place his small, motorised force at the player's disposal but do not know how to trigger this event.  Either the player will be able to deploy the partisan squad like he can deploy his own, or if that is unwieldy I would have the partisan commander tell the player that he knows the terrain well and can find a flanking route to assault the village from the woods.  I would then try to coordinate his assault with the player's actions.

-  The mission would end when the player and/or partisan group has cleared the village.

-  If done properly, this mission might engage the player emotionally as well as exercise his tactical muscles in the village assault.

-  One more thing; can you advise me how to do radio messages that show up in dialogue boxes on the side of the HUD, as stock radio messages do?  In my last mission I used mid-screen dialogue captions and it wasn't quite appropriate for radio comms.

I really appreciate your guidance.  Let me know what you think when you get a moment.