Improve Route Finder to Consider Territory Effects

beelee

@redrum yea i know the paratrooper thing doesn't alway's take a legal route. As alkexr alluded to, it's not hard to edit and do the move thing

prastle

@beelee control click

Frostion

@redrum @Cernel We could just rewrite the current description of the Bugs category to say "Report bugs and usability issues related to the game engine, maps and mods here"? Remember that casual players might never drop by Github. We are lucky if they drop by here

Cernel

@frostion This is up to the developers ( @redrum @LaFayette @RoiEX @ssoloff ) to decide, but I think usability should be divided into usability feature requests and usability bugs too, and I would consider this a bug. I think the engine should always successfully select one of the shortest possible routes, or at least never preferring an impossible one over a possible one, like here, without using Ctrl being mandatory.

redrum

@alkexr PR to have route finding check for territory effects: https://github.com/triplea-game/triplea/pull/3664

Cernel

@redrum Cool. I see/assume this works for infinite movement. Also, I seem to recall the existent regular route finder (normal impassable or hostile units blocking etc.) works only for movement 2 units, but it is not necessarily correct for movement 3 or more, but I'm not sure if this is the case?

redrum

@cernel Feel free to test it out: https://github.com/triplea-game/triplea/releases/tag/1.9.0.0.10898

Generally, it treats the territory effect not allowed to enter as if that territory is impassible for any units in that list for route finding purposes. Route finder takes a bunch of different things into account such as impassible, restricted, territory effects, neutrals, enemy, and AA. I doubt its perfect and if you have some simple examples where it does poorly then I'm glad to make additional improvements.

Cernel

@redrum Ah so you reworked the entire router finder, not just expanded it for the territory effects only?

For now, I tested on 1.9.0.0.10874 with the horsearchers of 270BC and I can confirm that the old router finder would try impossibly to move 2 through a blocker when it could move 3 to the target territory.

Cernel

@redrum Using 1.9.0.0.10898 do this:

Skip all until Parthia.

Edit 1 horsearcher in Gazaca.

Edit out all units in Seleucia.

I see there are 2 issues:

If you try to move directly from Gazaca to Hatra, the route finder fails (try to go through
Ninive).
If you ctrl your path from Gazaca through Ctesiphon, Seleucia, Hatra, the move is given as invalid as "Cannot blitz out of a battle further into enemy territory", since you would be starting from hostile, but I believe this move should be allowed, as you are first stepping into a friendly territory (Ctesiphon), and you can actually do it if you first move to Cteshipon, then do the rest of the movement, manually in two steps (on the same phase). I'm not actually sure if when starting movement in a hostile territory you are supposed to be unable to enter an enemy owned territory for all the movement or only for the territory you immediately move out, so being possible by stepping through a friendly territory in between but, one way of the other, this should work the same if you do it with ctrl or manually in multiple steps (I think this movement should be legal, but not entirely sure).

If, additionally to the edits above, you also edit out all existent units in Gazaca and make the territory owned by Parthia, then issue number 2 is not present anymore, but the number 1 is still there.

Cernel

@redrum What I'm saying is that I believe, in the case you pictured at that pull, that if there would be no territories effects in the map, but East Methedras would be just impassable or blocked by enemy units, then that movement would not have been handled correctly, as well, as the old routefinde would try to go through East Methedras in any case.

I'm not sure, but what I recall is that, even in the supported cases (blockers etc.), the old routefinder would find the right route only if it is one amongst the shortest paths.

So, for example, the case posted at the first post, of going from Isengard to Gap of Rohan was already supported for blockers etc., but the case you posted of of going from Isengard to Westfold, avoiding the shortest route, was not supported generally, also for the supported items, not just relatively to the totally not supported territory effects. Practically, only movement 2 units were fully supported, not 3 or more.

So, what I'm thinking is that this change rather than expanding the route finder support to territory effects, now it handles such things differently and better than how more common items (regular impassable, blockers...) are currently supported.

Cernel

@Panther Since I see you around right now, question:

I know that it is not possible to go from A to B if A is hostile and B is enemy owned (the case of contested territories in Axis & Allies 1914).

But is it possible to go from A to C through B (A->B->C) if A is hostile, C is enemy owned and B is friendly?

Currently, the engine allows you to do so in two steps, but disallows you to do so in a single step, using Ctrl, and I'm wondering about the intended behaviour, reinterpreting the rules for multiple movement units.

EDIT: What I meant is if you have a unit that can move 2 during Combat Move, would such a unit starting in a hostile land territory be able to move 2 spaces first into a friendly land territory and then into an enemy owned land territory? Or is this just a case not covered by any rulesets?

redrum

@cernel Actually I think I have a much simpler example of your first point (which is way more common than the contested territories as very few maps allow that).

Skip to Parthia
Edit out units in Seleucia and Hatra
Try moving Horse Archer in Ctesiphon to Amida

It should favor going Ctesiphon -> Seleucia -> Hatra -> Amida as that is a legal move that you can make using waypoints. But it tries to move through Ninive because that is shorter even though there are units blocking.

Cernel

@redrum Right, and what I understand is that, now, if Ninive would have a territory effect impeding access to horsearchers, the router finder would work fine, instead. So now the routerfinder behaves differently (better) for territory effects than for the rest, and I think this is not really good. Either the router finder for the territory effects should be dumbed down to behave like the rest or the rest should be made to behave like it, is my suggestion.

Cernel

Another unsupported item is canals. For example, open World At War and edit a German battleship in 116 Sea Zone and try to move to 109 Sea Zone: it will try to go there directly, getting blocked by the canal, while it should select the path through 104 Sea Zone (if we edited a submarine in, also going through 115 Sea Zone would be valid, but I think 104 Sea Zone should be preferred anyways, as friendly).

redrum

@cernel correct as right now impassible, restricted, and terrain are treated as more hard stops then reduce number of moves then enemy units, AA, etc. I'm guessing this was designed primarily for 1-2 move units not 3+.

Cernel

@redrum Yep what I'm saying is that even having all supporting only 2 movement units might be better than having some supporting infinite and some other supporting only 2. Otherwise having the routefinder behaving one way when I deal with impassable territory effects and another way when I deal with regular impassable or blockers may be just confusing. Of course, the best would be having all supporting infinite, tho really the only added item is movement 3, as movement 4 land units are almost inexistent.

Panther

@cernel said in Improve Route Finder to Consider Territory Effects:

@Panther Since I see you around right now, question:

I know that it is not possible to go from A to B if A is hostile and B is enemy owned (the case of contested territories in Axis & Allies 1914).

But is it possible to go from A to C through B (A->B->C) if A is hostile, C is enemy owned and B is friendly?

Currently, the engine allows you to do so in two steps, but disallows you to do so in a single step, using Ctrl, and I'm wondering about the intended behaviour, reinterpreting the rules for multiple movement units.

EDIT: What I meant is if you have a unit that can move 2 during Combat Move, would such a unit starting in a hostile land territory be able to move 2 spaces first into a friendly land territory and then into an enemy owned land territory? Or is this just a case not covered by any rulesets?

@Cernel Though I am focussed on wwII and not really a wwI expert, I think I can answer your question:
In AA1914 OOB land units can only move one space. From the rules: "Land units that begin the turn in contested territories can only be moved to territories that at the beginning of the turn were either controlled by your power or contained units belonging to your power."
In Larry Harris' 1914 "Potential Tournament Rules" land units usualy may move two spaces. But as the rules say: "Land units that begin their turn in contested territories can only be moved to an adjacent territory. That territory must have at the beginning of the turn either been controlled by the moving power or contained units belonging to that power. Such land units can also be moved by transport, in which case they may either be transported to a territory within range that meets those same requirements or remain at sea."
So it looks like your scenario is not possible in AA1914.

Cernel

@panther Yeah I know that the situation never happens. The question was rather what you think would be the case if, like:

I would take WWII Global and add the possibility of having an allied power, having units in my territories, that becomes enemy, thus I may start a turn of mine with hostile units in a land territory of mine.
I would take WWI 1914 and, for example, add a "cavalry" unit that moves 2 during combat move (not necessarily a bad decision).

I guess this is a blind spot that should be decided by TripleA, and documented, as it actually already matters for quite a number of games, so the rules should be defined.

Panther

@cernel Ah, ok, couldn't have guessed that from your initial question that I read as rules question.
Searching for sort of analogies in the rules we have the "Sea Units starting in hostile seazones" rules, that allow to move from a hostile seazone, simply to escape combat or to initiate combat elsewhere.

So concerning land units I would tend to let the player decide to let them either stay and engage the enemy troops or to move to an adjacent territory during combat move phase.

In case the territory has become hostile due to the player's proximate action, I would allow two steps. (Analogy: Load transport in hostile seazone exception, when the seazone has just become hostile due to proximate DOW by the transport's owning power).
In case the territory has become hostile at some time between the power's turns, I would only allow one step in analogy to the 1914 rules.

Just some ideas of course.