The forum is a place to speak about our games, make suggestions, report bugs, and so on. To post a message, you need to be logged in.

BlckKnght


(killer user)
Last login: 10d 13h
Last forum reset: 98d 14h
Membership: 4365d 23h

A Guide to Avoiding Missiles

Message 1689, 3473d 10h ago.
In one of my recent games VP games (number 4126) there were three missile hits within a stretch of five turns (15, 17 and 19). In my judgment, the movement of all three missiles could have been predicted and then avoided (though to be fair, two of the missiles hit somebody other than their locked target).

I'm writing this post in the hope that it can help other players avoid missiles more successfully. The game rules explain how missiles move, but it can be difficult to use the explanation to predict the missile's path. Collision detection is an important sub-topic, since getting a missile to hit an asteroid (without hitting one yourself) is a good way to keep it from hitting you.

Missiles that are seeking towards a ship will zig-zag their thrusts towards their target. A nine thrust missile might seek with these moves: Thrust, Turn Right, Thrust, Thrust, Turn Left, Thrust, Thrust, Turn Right, Thrust (Bang!). Since a picture is worth a thousand words, here's what that looks like. (You'll need to copy and paste the URL to another browser window, since I can't embed the images.)

http://i476.photobucket.com/albums/rr128/BlckKnght/Diagonal.png

That seeking pattern isn't very efficient, since the 9 total thrust points the missile had took it only six hexes from it's starting point (three in the the direction of the original heading and three more 60 degrees to the right of that). The overall movement is along a "diagonal" composed of equal components in two of the main hex directions. The diagonal is shown as a red line in the image. There are three different diagonal directions, once of which happens to actually be horizontal (which is why I put the word diagonal in quotes initially).

Since not every missile starts out directly on a diagonal to its target, most of them will travel straight in one direction until they get to one and can start to zig-zag along it. If you break the distance from the missile to the target into two components aligned to the hex directions, the initial straight part of the thrust will be in the direction of the larger component. It's length will be the difference between the lengths of the components. To find out it's final position, count the moves and turns and stop when the missile's thrust is used up. Here's an image that shows both how a missile takes a straight course to reach a diagonal and also how to count the thrust.

http://i476.photobucket.com/albums/rr128/BlckKnght/Count.png

If a targeted ship has several choices of maneuvers that put its diagonal close to the missile's expected position, small differences in its movement can make a critical difference in where the missile ends up. This is because the missile will always turn so that it gets to the diagonal, even if is going to turn back soon after. Here's another image showing the different ways a missile might seek on a pair of targets that are five hexes from it (and just one hex from each other). If this was a standard 7 thrust missile, one target could be hit while the other could not.

http://i476.photobucket.com/albums/rr128/BlckKnght/TwoTargets.png

Once you can predict where a missile is going to thrust at, you need to know if it is going to hit anything before it gets there, such as an asteroid or another ship. This is where collision detection comes in. For collision detection, the pattern of thrusts described above isn't really important, just positions the missile will be in at the start and the end of the turn. All of the rules for missile collision detection also apply to fighter maneuvers, though some zero damage collisions can be ignored for them.

The official rules say that if the straight line path of a ship or missile crosses an asteroid hex it will collide, without saying exactly what it means to "cross" a hex. It should be obvious to everyone that flying through the middle of an asteroid hex will cause a collision, but what if you only pass through a smaller part? The only clearly defined "near-miss" case in the rules is that sliding directly along a hex-side causes a collision, but one that does not result in any damage to ships. The tricky cases are when a ship or missile cuts across the corner of an occupied hex, so that's what I'll try to explain.

My understanding of it works like this: A ship or missile could, in theory, cut from the midpoint of one hex-side to the midpoint of a neighboring hex-side without triggering a collision . If it were to cut off any more it would collide, any less and it won't. In actual gameplay, nothing can move through adjacent hex-sides since ships and missiles must start and end their moves in the center of a hex, but that is the limit on the amount you can cut from a corner. Here's an image showing what I mean by cutting more and less.

http://i476.photobucket.com/albums/rr128/BlckKnght/CuttingMoreorLess-1.png

A few last things about dodging missiles:

Some missiles can't be dodged, or can only be dodged by maneuvers that take you out of bounds or through an asteroid yourself. Those dodges are usually not worth it, since it's often better to let the missile hit you while you attack the enemy with your guns.

It is some times important to ignore a distant missile and let it come towards you. It's a lot more likely to hit something else when it's moving really fast.

If you're moving behind an asteroid, don't worry if the seeking algorithm will bring the missile to your exact location, since your cover will will make it blow up on its way in.

The best dodges are ones that make the missile hit or lock on to one of your opponents, or fail to lock onto anyone at all. The next best ones make the missile hit an asteroid or go out of bounds.

The worst missile "dodges" are when you jump in front of a friendly missile, or even a missile you shot yourself, when it is seeking towards an enemy. Just say no to friendly fire!

Anyway, I hope this guide helps. If anything is unclear, please let me know and I'll try to add more clarification. I hope this helps VP players to plan better maneuvers in the future!

pier.

is pier

(schizo user)
"never give up"
Lives italy, near bologna
Last login: 2400d 8h
Last forum reset: never
Membership: 3574d 10h

A Guide to Avoiding Missiles

Message 1690, 3473d 8h ago. In reply to message 1689.
black, very nice guide

that match has been a crazy match, but whatever i think that only 2 missles could be avoided
the one who killed ozzman
the one who hitted me
for a strange joke of the destiny zal was damaged in manouvers and forced to move in a couple of exs to stay on the field, but there was the track of a missle locked on me that moved between those 2 ex, so >bang!< whatever !

i'm quite skilled to avoid missles, just i need to catch well how to broke em with the rocket cluster in case of emergency, i tried but with the following results :

zal42

is slightly photosynthetic

(ice user)
"carpe ichthae!"
Lives intermittently
Last login: 3339d 15h
Last forum reset: 3422d 11h
Membership: 3658d 1h

A Guide to Avoiding Missiles

Message 1691, 3473d 6h ago. In reply to message 1689.
Ahhh, that clear a lot of things up. Thanks!

Inertia applies to missiles just as to fighters, correct?

Also, I'm a little confused as to the order of battle events. Rocket clusters & inertial grenades can take out missiles, but their damage appears to happen last (i.e., after the missile's movement has finished.) So in the case of a missile heading straight at you, firing a rocket cluster won't destroy the missile if the missile would have hit you that turn (i.e., unless the missle ends its movement inside the explosion radius). Is that correct?

zal42

is slightly photosynthetic

(ice user)
"carpe ichthae!"
Lives intermittently
Last login: 3339d 15h
Last forum reset: 3422d 11h
Membership: 3658d 1h

A Guide to Avoiding Missiles

Message 1692, 3473d 6h ago. In reply to message 1690.
That was a fun, chaotic match.

BlckKnght


(killer user)
Last login: 10d 13h
Last forum reset: 98d 14h
Membership: 4365d 23h

A Guide to Avoiding Missiles

Message 1693, 3473d 5h ago. In reply to message 1691.
zal42 wrote:
Inertia applies to missiles just as to fighters, correct?

Yes, missiles have the same kind of inertia that fighters do. For each thrust they apply, they move one hex and gain two hexes worth of speed in the same direction. Using this fact you can plot out how a missile that is targeting you will move over several turns, though it can be tricky to do it all in your head.

Also, I'm a little confused as to the order of battle events. Rocket clusters & inertial grenades can take out missiles, but their damage appears to happen last (i.e., after the missile's movement has finished.) So in the case of a missile heading straight at you, firing a rocket cluster won't destroy the missile if the missile would have hit you that turn (i.e., unless the missle ends its movement inside the explosion radius). Is that correct?

You are correct that to shoot down an incoming missile you need to hit the hex that it will end it's turn on. If it's going to hit you right away, you won't be able to shoot it first. As for the overall order that a turn gets resolved in, the "Battle Log" page you can get to from each game lists each phase of the last few turns (and what happened during it). The order is:

1. Fighters move and consume fuel.
2. Fighters collide with asteroids (if any take lethal damage, they are left out of the shooting phases later).
3. Missiles seek their targets and blow up if they collide on anything (if they have no target, they move inertially and turn twice in a random direction).
4. Fighters shoot guns and launch new missiles.
5. Fighters fire rocket clusters and drop inertial grenades (these area of effect attacks can blow up missiles, like you were asking about).
6. Newly launched missiles check to see if they immediately have hit somebody.
7. Fighters blow up if they've taken too much damage, or gone out of bounds. If they went out of their own border, they retire. Missiles lock on to a target (not necessarily the same one they'd been locked on previously).
8. Points are given for kills and taken away for suicides, friendly fire kills and retiring.

BlckKnght


(killer user)
Last login: 10d 13h
Last forum reset: 98d 14h
Membership: 4365d 23h

A Guide to Avoiding Missiles

Message 1694, 3473d 4h ago. In reply to message 1690.
pier. wrote:
black, very nice guide

that match has been a crazy match, but whatever i think that only 2 missles could be avoided
the one who killed ozzman
the one who hitted me
for a strange joke of the destiny zal was damaged in manouvers and forced to move in a couple of exs to stay on the field, but there was the track of a missle locked on me that moved between those 2 ex, so >bang!< whatever !

Well, we can take a look at it: http://i476.photobucket.com/albums/rr128/BlckKnght/VPCollision.png

zal42's fighter (in blue) was moving out of bounds, and when he came back in bounds he got hit by the missile that was seeking on you (in red at the bottom of the screenshot) as you maneuvered to avoid an asteroid. zal42 had a maximum of three thrust, dual thrusters and light spinners. You had 5 thrust, power spinners and a single thruster (and very few armor points left).

The move you made was the only one that would avoid getting splattered on the asteroid you started out next to. I remember that my initial thought was that you couldn't get away safely, but after some consideration I worked out where you could reach. Having a good guess at your ending position, I could then calculate where the missile seeking you would be likely to end up. If it had not hit zal42 first, it would have gone well out of bounds and self destructed.

zal42 definitively needed to make two thrusts in the left-down direction to stay in bounds, but it was the third thrust that put him into the missile's final path. If he'd stopped after just two I'm pretty sure he'd have been safe (but it would have been a very close call). He could also have used his third thrust to move one hex up, putting him well clear of the missile's path (though when making the move it would look like he was moving into it's path instead).

As I look at the moves, I think I understand what he was trying to do, and it makes perfect sense even though it didn't work. The purpose of his move was to get into range so that he could fire his rocket cluster at the missile's starting location. Unfortunately, the missile wasn't there any more due to the phase order (which I explained in my other post on this thread, replying to his questions).

BlckKnght


(killer user)
Last login: 10d 13h
Last forum reset: 98d 14h
Membership: 4365d 23h

A Guide to Avoiding Missiles

Message 2046, 3156d 8h ago. In reply to message 1689.
I just decided to bump this topic back to the first page, since it can be useful for some of the newer VP players. To make this post not entirely without substance, here's an image showing the one-turn intercept range of 7-thrust (in red) and 9-thrust (yellow) berserk missiles:

http://i476.photobucket.com/albums/rr128/BlckKnght/DumbMissileRisk2.png

BlckKnght


(killer user)
Last login: 10d 13h
Last forum reset: 98d 14h
Membership: 4365d 23h

A Guide to Avoiding Missiles

Message 2264, 2534d 7h ago. In reply to message 1689.
Another bump and another addition:

One thing I failed to mention in the other posts is that just like ships, missiles have velocity that carries over from turn to turn. When launched, a missile gets the equivalent of one thrust from its firer's position (so it's one hex ahead of the nose of the ship, and its velocity is two hexes more in that direction). And just like a fighter, each time a missile thrusts, it adds two hexes to the velocity it carries into the next turn.

The seeking behavior I described in the earlier posts is always performed from the missile's future position, that is, from the end of its velocity vector at the start of a given turn.

To understand this, it can help a lot to look at a missile's movement on the turn after it happens (using the "Toggle view" button), as the VP interface will show both the original velocity the missile had, and its final position (and the initial and final positions of its target, for good measure). Here's a screenshot of that kind of view that I took from game 6680, where AshayRey misjudged the course of a missile, and as a consequence got hit by it rather than it being blown up by his inertial grenade.

http://i476.photobucket.com/albums/rr128/BlckKnght/VPmissileseeking-1.png

AshayRey's fighter (with blue exhaust) is up near the top (under a bunch of clutter). He started at rest where the center of the grenade explosion is, and he moved two hexes up and to the left. Almost any two-hex other leftward movement would have been safe from the missile, but not that one.

The missile that hits him is the one who's original position is shown translucently at the lower left. That missile was fired on the previous turn by sfatula (shown in yellow doing a 180 spin to shoot another missile at somebody else).

The dotted line indicates the missile's original momentum vector, and the solid lines represents the missile and ships' actual movement. I've added text showing how to count out the moves the missile took while seeking. Note that there are seven moves, so the 7-thrust missile can make it. I've also added an outline in red showing the missile's "kill zone", where it can seek for a definite hit on its target (it might also collide with you if you are outside of the zone, but only if you put yourself in its path). This is the same "maple leaf" shape as the image I posted previously in this thread.

As always, I'll be happy to answer any questions that still exist.

AshayRey

is a VP addict

(ice user)
"Please don't move if i shoot at you"
Lives in my cockpit
Last login: 2044d 21h
Last forum reset: 2167d 18h
Membership: 3415d 14h

A Guide to Avoiding Missiles

Message 2265, 2533d 23h ago. In reply to message 2264.
If i get it right then you start calculating the missiles trajectory from it's end point of the dotted line. But must i take in account that the mikssile has already a velocity or must i do the calculations from this point as if the missile was stationary at that point. If this is the case then the 7 points maple leaf figure is always the same size every turn and that will ease prediction ten fold.

BlckKnght


(killer user)
Last login: 10d 13h
Last forum reset: 98d 14h
Membership: 4365d 23h

A Guide to Avoiding Missiles

Message 2266, 2533d 3h ago. In reply to message 2265.
AshayRey wrote:
If i get it right then you start calculating the missiles trajectory from it's end point of the dotted line. But must i take in account that the mikssile has already a velocity or must i do the calculations from this point as if the missile was stationary at that point. If this is the case then the 7 points maple leaf figure is always the same size every turn and that will ease prediction ten fold.

Well, yes and no.

The seeking works from the end of the velocity vector, and that's the only extent to which it takes velocity into account in determining how to thrust. So yes, the maple leaf shaped area is the same size every turn (though the size is larger for 9-thrust missiles than 7-thrust ones). The area will be rotated if the missile doesn't start facing towards the top of the map, but that's the only way it changes other than moving to be centered on the future position.

But that doesn't quite mean that original position and velocity are irrelevant once you know where the velocity vector ends. The missile's trajectory (shown by a solid line on the image), is from the missile's original position to the position the seeking ended. This is what you need to check to see if the missile will hit something (such as an asteroid or fighter) on the way in.

And if the missile doesn't hit anything during the current turn, the thrust it performed while seeking adds more velocity to the missile, just like fighter thrusts do (two hexes of velocity per hex of thrust). So if you're trying to figure out where a missile will end up more than one turn out in time, you will need to pay attention to the missile's velocity. If its seeking towards your fighter, you may be able to pick your movement location to guarantee that the missile will fly out of bounds on a following turn, or more rarely, trick it into locking on to somebody else!

AshayRey

is a VP addict

(ice user)
"Please don't move if i shoot at you"
Lives in my cockpit
Last login: 2044d 21h
Last forum reset: 2167d 18h
Membership: 3415d 14h

A Guide to Avoiding Missiles

Message 2267, 2532d 20h ago. In reply to message 2266.
So for me, i will print a maple leaf in various directions and on scale. Cut it out, hold it over the missile and if i am outside this then i will be safe. (from the missile anyway )

BlckKnght


(killer user)
Last login: 10d 13h
Last forum reset: 98d 14h
Membership: 4365d 23h

A Guide to Avoiding Missiles

Message 2268, 2532d 9h ago. In reply to message 2267.
AshayRey wrote:
So for me, i will print a maple leaf in various directions and on scale. Cut it out, hold it over the missile and if i am outside this then i will be safe. (from the missile anyway )


That would work, though it might be a bit of a pain. I usually do the counting method, rather than using the maple leaf chart in actual gameplay, because its useful even when the missile has no chance of reaching you in one turn (it tells you where the seeking stops).

Here's another screenshot from that same game, which illustrates what I mean.

http://i476.photobucket.com/albums/rr128/BlckKnght/VPMissilediversion.png

On this turn, a missile was seeking towards me, but due to our diverging velocity vectors we were not going to end up very close together. If you wanted to place a maple-leaf chart on here, you'd orient it with the long center part of the leaf pointing down-left and the step pointing up-right, centered on the bottom right corner of this image. Because it doesn't tell you much, I've left it off the image.

Anyway, my maneuver on this turn was an attempt to get the missile to lock on to sfatula (the yellow team fighter on the left), rather than me. I wasn't successful because he didn't move the way I had anticipated, but it wasn't a bad effort. It would have worked if he'd moved to get a good shot at me with his guns.

Here's how to understand the image. First, just pay attention to the missile on the bottom right, and my fighter on the top. I've drawn in a dotted cyan line showing the "diagonal" from the position I moved to, and counted out the missile's seeking moves (and drew them in with a solid line). The missile's moves were: (1) Turn Right, (2) Thrust, (3) Turn Right, (4) Thrust, (5) Thrust, (6) Turn Left, (7) Thrust. It ended facing the up-left direction, which was what I wanted it to do (if it had been facing just up, it never would have been able to see sfatula).

Now, look at the yellow, green and red lines I drew in concentric arcs in front of the missile's final position, and see where sfatula and I ended up on them. Those lines each show an area that is at an equal distance from the missile (counted in hexes). The yellow ones are where there was nothing to lock on to. Green is where it found a target and red means the more distant target that wasn't considered. My hope was that sfatula would have moved into the area where I've placed an orange box. If he had, he would have been closer to the missile than me, and so it would have started chasing him on the next turn. I'm not sure what would have happened if he'd been on the green arc, as I think that missiles choose randomly between fighters that are at the same distance (but I may be wrong about that).

Copyright

It is understood that in submitting material (like suggestions, comments and proposals on our games) on this forum you are giving up any copyright claims, allowing us at takeaplay.net to freely display, copy, distribute, alter, transform, and build on this material, for the purpose of improving our site and games. We cannot guarantee that all proposals and requests will be developed, of course. In addition, we cannot guarantee that your contribution will be credited esplicitly, though we usually try to do that. However, we intend to keep the forum publicly available, so other players will always be able to know how and when you contributed to this site's growth. It is understood that we will make use of your suggestions to improve the site to the best of our abilities and time available. Your contributions will be rewarded with big smiles, , warm hugs, and no money.