Re: pathfinding refueling

[Peter Garrone <pgarrone at acay dot com dot au>]

On Thu, Dec 18, 2003 at 11:12:33PM -0500, Eric McDonald wrote:
> 
> OK, here are the scenarios. For the purposes of this discussion, I 
> have a couple working definitions:
> (1) Fuel-Material: Any material which must be consumed during 
> normal movement of a unit.
> (2) Range: The distance a unit can go, consuming a fuel-material, 
> before it must resupply that fuel-material.
> 
> And the scenarios are:
> (1) Suppose that a unit has just finished with combat and is now 
> low on two fuel-materials, fuel1 and fuel2. The unit is at point 
> A. The unit would like to move to point B. Destination C has an 
> available supply of fuel1, but no available fuel2. Destination D 
> has an available supply of fuel2, but no available fuel1. The unit 
> consumes fuel1 and fuel2 at the rate of 1 per move. The unit has 3 
> out of 10 fuel1 and 4 out of 8 fuel2. The distance from A to C is 
> 3, from A to D is 4, and C to D is 2.
>   Under your proposal, fuel2 would be regarded as the critical 
> fuel-material. However, because fuel1 is in a low supply 
> condition, either you would have to wait for the player to request 
> the destination again to override a safeguard (similar to the 
> existing behavior), or else you would have to ignore it under the 
> assumption that it would be replenished at the end of the turn. If 
> you ignored it, then you seem to suggest that the unit would be 
> directed towards destination D (because fuel2 has the shorter 
> range). However, in that case, the unit would never make it, 
> because it would run out of fuel1 first.
>   Under my proposal, I would make sure that the player was aware 
> of the fuel-materials situation by perhaps making him/her 
> re-request a destination. If given the re-request, then the 
> pathfinder would recognize that fuel1, not fuel2, was the most 
> critically needed, and would direct the unit towards destination 
> C, not D. The unit would arrive at C and refuel. After that, the 
> unit would still be in a predicament because it would have only 1 
> fuel2 left to reach D with, __not enough. However, it would have a 
> better chance at regaining mobility or just surviving because it 
> was able to replenish fuel1 (at least to some extent).
> 
> (2) Consider scenario 1 with the following modification. The unit 
> now has 6 out of 8 fuel2.
>   Under your proposal, the unit would attempt to reach destination 
> D (as in scenario 1) and would fail because it ran out of fuel1 
> first (as in scenario 1).
>   Under my proposal, the pathfinder would recognize that fuel1 was 
> the more critical and would attempt to reach destination C. The 
> unit would reach destination C, refuel, and then attempt to move 
> to B. Having only 3 of 8 fuel2, it would then divert to D (or 
> possibly a destination E, if E was within range, had available 
> fuel2, and was closer to B than D). There, it would refuel, and 
> then attempt to move onward to final destination B. In this 
> circumstance, my proposal is a clear win, because the unit 
> remains mobile and intact.
> 
> I have a few other scenarios in mind, but I am getting tired, so I 
> will leave them for another day (perhaps tomorrow).
> 
> Eric

These scenarios are not from any game in the library.
No rational game would have
separate sorts of extremely limited range fuels refueled from different
points like this. Nevertheless my following comments do apply to these
situations.

You would do better by creating a hypothetical situation from bellum
where both f and c are in short supply, some f is available at one spot,
some c at another, and an aircraft has to jump through calculation hoops
to work out what to do.

In such situations the player guides the unit to refueling points
(wo)manually and presses t for take. This sort of combat situation where
fuel etc is short should not be automated but it is the fun of the game
for the player to fix the situation directly by guiding the unit to
appropriate refueling points and allocating scarse resources as best
they can. 

But if the requirement were that all such situations should be
automated, then the approach I have advocated would be in error. But
that is not what I am trying to achieve anyway. I dont think its what
you would really like either, Eric.

No matter what situation you can postulate, I can always reply that the
player just does what is done now. But the approach I am outlining
simply reduces the micromanagement associated with
1) ferrying aircraft from point of production to the front.
2) combat situations where aircraft have to continuously get fuel almost
every turn.

I have spent hours on all these emails. I would rather just code up my
approach now thanks. Fat chance.
Peter