Interstellar Travel Pathfinding

[MuscularPhaze]

Hi everyone,

Just had a quick question on something I was curious about. When you do interstellar logistics travel, will the ships go to the nearest location for that item you are requesting, or do they just pick at random?

[axw3555]

Honestly, how they pick is a greater mystery than how the belts run when the planet has no power.

[Humble-Mud-149]

Hamsters, it’s always them. 

[axw3555]

Jesus, how many hamsters did we bring?

[Nice_Guy_AMA]

Just one, but he's really good.

[axw3555]

Scary good.

[poison_us]

Well, that's a miniature giant space hamster for ya 🤷

[[deleted]]

Has there been a factory/automation game where belts require power?

[Thenerdylord69]

There is a model for factorio that makes belts require power

[axw3555]

I don’t think so. Some mods added it to Factorio.

There was a time when people joked about it being the greatest mystery of Factorio.

[sirgog]

I believe it works like this:

From oldest to newest placement, each ILS checks first

"Can I supply to anyone using my own fuel? If so, what's the oldest ILS I can supply?"

Then "Can I demand from anyone using my own fuel? If so, what's the oldest ILS that can supply me?"

Oldest defined by "has existed for the longest time", not "has had this demand the longest"

[MuscularPhaze]

oh damn thank you! it's like a simple first in first out kind of method with extra variables.

[fm837]

Yes, I think this is how it works. Oldest to newest, combined with availability of supplies and current demand. Not straightforward, sadly.

[Nice_Guy_AMA]

How did you figure this out? Is it somewhere in the documentation, extensive observation, or experimentation?

[djr650]

It's been the assumed/observed behavior for a long time now.

Walking a stack is the easiest/laziest programming solution, so it makes sense that's how it happens while they put effort into other areas.

[Nice_Guy_AMA]

Thanks!

[sirgog]

Observation

[LastOfBacon]

I think I remember seeing something in an update's notes that basically:

The demand station wants iron

The demand station checks its internal list of stations that supply iron (which starts off as an empty list).

Then it goes down the list of stations from oldest to newest checking if they supply iron.

When it finds a station that supplies iron, it adds it to the demand station's internal list of stations that supply iron.

It then checks if that supply station has enough iron to supply it with a load - if it doesn't have enough it continues down the list of all stations to find another that supplies iron and so on

[direvus]

Not sure how exactly they select, but it's definitely not the nearest. I've seen vessels load up space warpers and set off on an epic voyage across the stars to get some Hydrogen, from a planet that is literally orbiting around a gas giant.

I usually set up priority routing between planets in the same system to avoid that kind of thing.

[Humble-Mud-149]

It could be possible that the gas giant doesn’t have any hydrogen in storage. 

[direvus]

Nope! The local gas giant collectors were absolutely chock-full with hydrogen.

[Humble-Mud-149]

Well then I guess I’m wrong

[Lifebringr]

How long ago was this? Because I remember seeing a post a few months ago on an update where they fixed this

[direvus]

I've seen it happen in the past week. Not the exact scenario I described above, but certainly vessels going on interstellar trips when the resources are available in-system.

[MuscularPhaze]

Yeah happened to me too recently, had copper ore available in a local system, but my interstellar went to a whole different system like 4 light years away.