UFO Flight Patterns
(Zaimoni: Some working notes. This plausibly should be moved to mainline when sufficiently detailed. While I do use MISSIONS.DAT notation to index the UFOs, this does not belong there.)
Common observations:
- In spite of the game having precomputed trig functions at 1/8 ° resolution, the "turning points" are not nearly so densely packed. (I suspect a sparse latitude-longitude grid, or an explicit valid list somewhere.) It should be possible to identify the precise intermediate destination in-game, at least when it's near the equator and not at the same latitude. UFOs are notably slower at turning points.
- When a UFO leaves its target region, it's leaving for good.
- The next "turning point" (or landing site, as the case may be) is only generated when the current one is reached.
- I have not been able to get a Retaliation mission scheduled when a UFO is shot down at the second or later "turning points". Scheduling is very unreliable even then, and is not a strict matter of either speed or accuracy.
Retaliation searching UFOs
- Searching Retaliation UFOs (before BattleShip) fly slow. With XComUtil craft, it may be possible to shoot them down with a Skyranger.
- Searching Retalation Battleships merely fly "normally".
- needless to say, the sequence will abort if the UFO finds your base.
I am tentatively assuming that the number of turning points is fixed, but that they may not necessarily be visible to the naked eye because of practical colinearity.
Research 0/0
- These do not land.
- Four turning points, leave.
Research 1/0
- Four turning points, land, leave.
Research 2/0
- Four turning points, land, two turning points, land, leave
Terror 0/0
- three turning points, land, three turning points, land, leave
Terror 1/0
- two turning points, land, leave
Terror 2/0
- These do not land (??? need more samples to document variability between instances ???)
- two turning points, leave
Retaliation 0/0
- These do not land.
- five turning points, leave. (Didn't get a clear sample)
Retaliation 1/*
- These do not land.
- seven turning points, leave. The 1/0 I observed to count this did a very tight zigzag pattern...it would have touched any base in about 2/3rds of the nation of South Africa, and just about any base in Madagascar. This may be fluky, though. 1/1 is the same format, but the one I observed was not a tight-weave.
Retaliation 2/0
- These do not land.
- eight turning points, leave.
One thing i've noticed that might help: searching Battleships on retaliation missions tend to overfly the base that they are looking for. This could be just coincidence but i've seen it happen a few times. Could the turning points be related to the location of the base?
Hobbes 16:12, 6 January 2007 (PST)
The Retaliation 1/0 I observed was zigzagging across where I had done two shootdowns, so that's entirely possible. The 1/1 was more generalized.
Zaimoni 6:48, 7 Jan 2007 (CST)
Zaimoni, anything you can do to predict where and when something might land, given your insights, would help. Are there specific speeds and/or distances associated with each leg? I guess it's less relevant with Terror (aimed at a city) and Retaliation searches, and Supply is often (always?) aimed at an existing base. But with Research it could be useful. Players sometimes want to catch a UFO just as it lands, to save flytime/fuel and/or daylight. In my experience though it's pretty random and basically hard to predict, even with reloading, as you say.
Could you benefit from a logger program that collects data overnight, or does it seem so highly variable that it's anybody's guess when a Research might land? - MikeTheRed 17:09, 10 January 2007 (PST)