Missile Targeting

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RonaldX
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Missile Targeting

#1 Post by RonaldX » Sun May 16, 2010 3:35 am

The concept behind this came to me while reading the Battle Tactics page, but this is a tangent so I started a new thread.

Obviously direct fire weapons are targeted at a visible enemy, are fired, and immediately strike the target. Missiles, however, have a transit time, speed, etc. They exist in space for several turns before hitting an enemy, during which time they can be shot down or perhaps evaded.

Obviously a missile launcher can't target a stealthed enemy.. but what if an enemy ship goes into stealth or is destroyed by direct fire before the missile gets there? Does it acquire a new target (this technology is 20 years old even for us), or just self-destruct? Is a unit prevented from going into stealth while a missile is heading for it? Can the target of a missile be changed while the missile is in-flight? Do missiles have their own detection rating?

Due to the time-delayed nature of missiles, I think a set of rules for their behavior needs to be hashed out. I'm particularly concerned about their response to stealth, as a highly stealthy ship could make itself nearly immune to missiles depending on how they function.

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Krikkitone
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Re: Missile Targeting

#2 Post by Krikkitone » Sun May 16, 2010 11:50 pm

Well I think that

1. Missile should Not have their own detection range, they should be reliant on the rest of the fleet
2. If the target of a missile is no longer detectable by the fleet, then they will travel to the nearest detectable target.
3. The player cannot change the target of a missile midflight...Rule#2 should be the only way a missile changes target
4. Once launched, the Missile should have NO Range Limitations, just to keep things simple.

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Re: Missile Targeting

#3 Post by RonaldX » Mon May 17, 2010 2:37 am

I more or less agree with all of those.

So the questions that remain are:

1) If a missile loses its target while "in flight", and there are no other enemies detected, what happens to it? Does it target a friendly, does it sit around in acquisition mode until a target shows up (or it runs out of fuel), or does it self-destruct? This is important because it will determine whether a single ship can exploit stealth to dodge missiles indefinately or not.

2) Are missiles going to be of varying speed? I think that even if missiles have different speeds, the slowest missile should still be faster than the fastest ship. PD should be able to buy time by red-shifting, but they shouldn't be able to do it indefinately.

3) I'm not completely sold on "in flight" missiles having unlimited range.. I agree that they should be able to chase a fleeing enemy outside the range of the launcher, but depending on whether they simply self-destruct if there are no targets or else stay in acquisition mode until a new target becomes available, there needs to be some kind of time limit to how long the missile sticks around for.

I'll try to summarize my concern here..

Attacker asteroid ship has high stealth, and whenever the defenders fire missiles at it, it ducks into an asteroid belt and disappears. There are no other enemy ships. The missiles either self destruct, or else sit around waiting for the asteroid ship to come out and play. By doing this, they can continue to be a threat and will move closer and closer every time the asteroid ship preforms an action and reveals itself. This isn't necessarily bad, but if missiles have a time limit, then the asteroid ship could simply sit still until they expire (same situation if they self-destruct), and then come out.. This kind of silly cat-and-mouse tactic to waste enemy ammunition is boring and extremely slow-paced. If missiles don't have a time limit, the defender could just fill the system with missiles that would sit around indefinately, and auto-acquire any enemy that entered the system as reinforcements, or a future invasion force. Enough time pumping missiles into the system and reloading and you could make systems into virtual minefields.

These are kind of extreme examples requiring quite a bit more micromanagement than is desired from the player, but the strategies are supported by the mechanics.

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Re: Missile Targeting

#4 Post by Krikkitone » Mon May 17, 2010 6:07 pm

RonaldX wrote:I more or less agree with all of those.

So the questions that remain are:

1) If a missile loses its target while "in flight", and there are no other enemies detected, what happens to it? Does it target a friendly, does it sit around in acquisition mode until a target shows up (or it runs out of fuel), or does it self-destruct? This is important because it will determine whether a single ship can exploit stealth to dodge missiles indefinately or not.
I'd say sit around in acquisition mode*
RonaldX wrote: 2) Are missiles going to be of varying speed? I think that even if missiles have different speeds, the slowest missile should still be faster than the fastest ship. PD should be able to buy time by red-shifting, but they shouldn't be able to do it indefinately.
I do agree that slowest missile should be faster than fastest ship... at a particular tech level (if there is a Big enough gap in tech then you should be able to outrun enemy missiles... but it would have to be a big gap, of a level that wouldn't likely occur in an actual game.)
RonaldX wrote: 3) I'm not completely sold on "in flight" missiles having unlimited range.. I agree that they should be able to chase a fleeing enemy outside the range of the launcher, but depending on whether they simply self-destruct if there are no targets or else stay in acquisition mode until a new target becomes available, there needs to be some kind of time limit to how long the missile sticks around for.

I'll try to summarize my concern here..

Attacker asteroid ship has high stealth, and whenever the defenders fire missiles at it, it ducks into an asteroid belt and disappears. There are no other enemy ships. The missiles either self destruct, or else sit around waiting for the asteroid ship to come out and play. By doing this, they can continue to be a threat and will move closer and closer every time the asteroid ship preforms an action and reveals itself. This isn't necessarily bad, but if missiles have a time limit, then the asteroid ship could simply sit still until they expire (same situation if they self-destruct), and then come out.. This kind of silly cat-and-mouse tactic to waste enemy ammunition is boring and extremely slow-paced. If missiles don't have a time limit, the defender could just fill the system with missiles that would sit around indefinately, and auto-acquire any enemy that entered the system as reinforcements, or a future invasion force. Enough time pumping missiles into the system and reloading and you could make systems into virtual minefields.

These are kind of extreme examples requiring quite a bit more micromanagement than is desired from the player, but the strategies are supported by the mechanics.
*Good point.. I was thinking more of an 'in battle' turn limit. So a Missile would self destruct on the same time schedule that 'reloading' occurs. (ie in between turns)

Another limit for the 'virtual minefield', the missile can only be launched if there is a valid target (you should probably be unable to target your own ships) so the enemy would have to cooperate.

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Re: Missile Targeting

#5 Post by Bigjoe5 » Mon May 17, 2010 7:36 pm

Having missiles lose their target when it goes stealthy brings up a lot of potential problems and abuses. I'd say that if a missile is fired and its target becomes stealthy, the missile should continue to track the target until it hits. This avoids any weird stealth abuse issues.
Krikkitone wrote:(you should probably be unable to target your own ships)
Why? IMO, targeting your own ships/planets/etc. should be fair game, and could be useful to set up a clever ruse, for example if the player's ships are disguised as pirate ships, or ships belonging to another empire.
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Re: Missile Targeting

#6 Post by Geoff the Medio » Mon May 17, 2010 7:52 pm

RonaldX wrote:2) Are missiles going to be of varying speed?
Yes, speed is one of the properties of a missile that can be defined in ship part definitions. These properties currently include: damage, rate of fire per battle turn, range from which missiles can be fired, speed of missile, stealth of missle, health of missle, number of missiles carried by a ship with the part.
3) I'm not completely sold on "in flight" missiles having unlimited range..
Assuming the target is visible, the current plan is for missiles to have no range limits after they are launched.
Bigjoe5 wrote:...if a missile is fired and its target becomes stealthy, the missile should continue to track the target until it hits. This avoids any weird stealth abuse issues.
That's not practical, because it would require the client to know where the stealthy ship is, so that it can direct the missiles to that location, but clients don't know the locations of ships they don't have visibility of.

The simplest solution for missiles whose target is no longer visible to the missiles' owner, whether due to stealth effects or the target being destroyed or leaving the map, would be to remove those missiles from the battle map. tzlaine may have something else in mind, but I can't find any record of us discussing that issue specifically.

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Re: Missile Targeting

#7 Post by Bigjoe5 » Mon May 17, 2010 8:44 pm

Geoff the Medio wrote:That's not practical, because it would require the client to know where the stealthy ship is, so that it can direct the missiles to that location, but clients don't know the locations of ships they don't have visibility of.
Then calculations for the missile's trajectory should be done server-side and relayed to the client. Having missiles detonate when their target becomes stealthy would open the door to a lot of balance/abuse issues that I don't think anybody wants to deal with.
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Re: Missile Targeting

#8 Post by Geoff the Medio » Mon May 17, 2010 10:42 pm

Bigjoe5 wrote:Then calculations for the missile's trajectory should be done server-side and relayed to the client.
That's not possible due to latency issues. Simulation time steps are about 60 per second, if I recall correctly. The client(s) and server run several seconds of battle simulation in parallel between updates to the clients from the server. This includes missile trajectories, fighters movement and shooting, and ship movement and shooting.
Having missiles detonate when their target becomes stealthy would open the door to a lot of balance/abuse issues that I don't think anybody wants to deal with.
An alternative would be to have the missiles continue on a straight-line trajectory if their target is lost.

Another option would be to go to the missile's target's last known position, where the missiles would detonate. Having to track the latest known position of all enemy ships might be more trouble than it's worth, though.

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Re: Missile Targeting

#9 Post by pd » Mon May 17, 2010 11:05 pm

Geoff the Medio wrote: An alternative would be to have the missiles continue on a straight-line trajectory if their target is lost.
This sounds good to me. Would it still be possible to hit the stealthy target "accidently" with those missiles?

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Re: Missile Targeting

#10 Post by RonaldX » Mon May 17, 2010 11:12 pm

To assist in this, I'm going to give a real brief synopsis of how a real guided missile works.

A guided missile is composed of:

1) Warhead
2) Engine
3) Flight System
4) Targeting System

The first two are self-explanatory. We upgrade those through making new payload types and faster engines. The flight system is how the missile maneuvers, either vectored thrusting or mechanical flaps, wings, canards, whatever, that get the warhead pointed in the right direction. This is really irrelevant to the game, we assume that a missile can turn to follow a target, the "how" isn't really important.

The targeting system is going to be one of three types:
1) A true "guided" missile is going to follow radiation. This can be thermal, infrared, radar, laser, etc. So you can have either the launcher (or a 3rd party) draw a line to the target and the missile follow the line. In this case either the ship doing the shooting or some other ship in the fleet needs to act as a spotter. As long as they can see the target, the missile will track towards it and eventually hit it. In other words, the missile needs a spotter.
2) A "guided" missile can also be of the "fire and forget" variety, where the targeting system is contained within the missile itself. It is designed to either "home in" on radiation generated by the target (for example a heat-seeking missile), or through a radar system, or IFF tagging (identification friend-or-foe, where the missile will go for anything it finds not broadcasting a "friend" signal). In this case the missile is going to have it's own ability to detect the target.
3) A "guided" missile can also be guided by destination coordinates, much like artillery. You can pick a location and program the missile (or the missile will do it's own calculations) to move to that location and detonate.

What happens if the target disappears before you get to it, either because it is destroyed or goes into stealth, is going to depend on what kind of targeting system we're assuming the missiles to have.

-A tag-guided missile is going to stop tracking, but the propulsion is still going, so it will go into a straight line until a new target is designated or it runs out of fuel.
-A fire-and-forget missile is going to chase the target as long as it can find it. If it can't find it, it's going to go in a straight line until it finds another target, or it runs out of fuel.
-A destination-guided missile will get to the target location and detonate.

I think it might be best to go with the 2nd option. Missiles without a target will go in a straight line on their current heading. They should still impact a stealthed ship if the ship hasn't moved, because their targeting computer is still going to register that as the last valid target location. If that ship isn't there because it has been destroyed or has moved, the missiles continue to go in a straight line until they leave the combat map. If at any time before they leave the combat area a new enemy is detected, they will turn and acquire the new enemy.

This keeps missiles from being useless right away, as they will hang around for a few combat turns before leaving the combat map, but also prevents them from sticking around indefinately. A stealthy ship is going to have to keep moving or else be blown up by the missiles it was trying to avoid.

The problem will be requiring a check with the server to see if the missiles are overlapping a stealthed ship when they get to that destination point.

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Re: Missile Targeting

#11 Post by Geoff the Medio » Mon May 17, 2010 11:15 pm

How "real" guided missiles work is irrelevant, because this is game and not reality, and future space missiles can work any way we want or need them to for balance and/or implementation reasons.
pd wrote:Would it still be possible to hit the stealthy target "accidently" with those missiles?
I don't know how tzlaine plans to handle missiles passing the location of ship they are not targeting, or detonating near but not "on" a ship, stealthy or otherwise.

I would guess that missiles won't have any "area of effect damage" so would not actually damage anything they are not tracking (targeting and that is visible) at the time of detonation.

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Re: Missile Targeting

#12 Post by Bigjoe5 » Mon May 17, 2010 11:18 pm

There are a couple of other solutions as well, though I can't say I'm particularly fond of either of them, or any that have been suggested thus far...

- The player could retain some sort of "partial" tactical visibility while his missiles are on route to a target of which he doesn't have full tactical visibility. The client would display the location of the vessel, but the player would not be able to select it as a target for weapons.

- The player could lose visibility of any missiles which are en route to a target of which he does not have tactical visibility. The server would calculate the trajectory of the missiles, but it would not be relayed to the client.

Remember that tactical visibility may be able to be lost without galaxy map visibility being lost - in other words, the player might be able to lose knowledge of a ship's location on the tactical map without losing the knowledge of whether or not the ship is in the system. Because of this, there may have to be two special cases for losing visibility of an object: one for when tactical visibility is lost either due to an increase in stealth or an increase in distance from a player-owned detector, and one for when galaxy map visibility of a ship is lost, which can only occur due to an increase in stealth (since galaxy map distance is always equal to 0 when two ships are in the same system).
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Re: Missile Targeting

#13 Post by RonaldX » Tue May 18, 2010 12:14 am

Geoff the Medio wrote:How "real" guided missiles work is irrelevant, because this is game and not reality,
True. The description, at any rate, was only posted to assist in determining the preferred behavioral archetype for these specific projectiles.
- The player could lose visibility of any missiles which are en route to a target of which he does not have tactical visibility. The server would calculate the trajectory of the missiles, but it would not be relayed to the client.
This is actually a pretty solid idea. The missile then becomes literally "fire and forget", and would have it's own AI about chasing targets and re-acquiring new targets if the first one is destroyed while the missile is en route.

This does, however, have some pretty huge implications as a balance to stealth, since an LR ship only needs to be in range of a high-stealth scout for one turn to virtually guarantee a kill. I'd prefer this to highly stealthy ships being able to shake off missiles at will, though.

Edit: On second thought, I'd actually prefer that the missiles just go into a straight line until you either detect a new target or the leave the system map. It's ugly that stealth ships can shake missiles easily, but it adds more tactical interest and gives players a reason to invest in SR weaponry as an anti-stealth weapon. I would also be fine if they simply did not detonate or impact on a stealthed ship that they couldn't detect but flew right on past it instead. That way you don't need to worry about the hassle of collision checks with stealthed units or anything on the fly. Make SR the preferred weapon for combatting stealth and you give it an interesting role in the battle. SR vs Stealth, and LR vs PD, create some interesting tactical options for the clever player without needing heavy micromanagement.

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Re: Missile Targeting

#14 Post by pd » Tue May 18, 2010 11:59 am

RonaldX wrote:I'd prefer this to highly stealthy ships being able to shake off missiles at will, though.
I don't think it's that easy. There's not an on/off switch for stealth. From my understanding, for a ship to vanish of the screen due to it's stealth, the enemy detector would need to be destroyed or out of range.

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Re: Missile Targeting

#15 Post by RonaldX » Tue May 18, 2010 11:29 pm

I was more referring to ships being able to duck into or out of areas on the battle map that increase stealth, such as an asteroid field.

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