Anyway, let's move on to what I
expect was one of the biggest challenges in developing the game: the
TA: Is it amazing? It's creaky and
Well it looks amazing from my end,
since there's a metric ton of characters all doing it at once.
TA: The dwarves themselves mostly move
around with A*, with the regular old street-distance heuristic. The
tricky part is that it can't really call A* if they don't know they
can get there in advance, or it'll end up flooding the map and
killing the processor.
(Ed. note: see here)
Sometimes in commercial
projects the developers do a bit of cheating, and predefine travel
TA: Yeah, that's the hard part. We
can't really predefine areas beyond very basic notions because fluids
can zip by and block them off, or they can mine a floor out. All it
does now, and this isn't ideal, is keep connected component numbers.
So if a dwarf is standing in "2", they know they can't get
to "3" and don't bother trying. However, they assume they
can get to any other "2", and will A* those paths. There
are still a few failures, but it's fixable.
There's a price to pay for that though,
on a few levels. First, it's a pain to maintain. If a fluid occupies
a square, it has to update. If a fluid flows through a passageway and
cuts it in half, it has to reindex one or both sides. There are other
ways to think about handling it, like keeping track of some sort of
rectangles or something, and pathing on those, but the memory cost is
The memory cost here is large, and it's
also a speed burden. There are probably a ton of better ways to do
it, it's just a very hard problem.
And all of this taking
place over potentially many Z-levels too.
TA: In a 480x480xZ map. Or even a
768x768xZ at max settings.
And there's another huge downside to it
that I have to cope with, and that's the mode of travel. A dwarf
walks; a dwarf does not fly. For a flying creature, the path
components are meaningless. So flying creatures are much dumber than
dwarves, and dwarves are already kinda dumb.
I still stand by the adjective
"amazing" though, based on how watching a dwarf make his
away around the world, then suddenly disappear because he took an
unforeseen shortcut over a hillside, is a cool experience.
TA: Yeah, it's nice that they can solve
an arbitrary labyrinth of your own design, and they'll pick the best
possible path, generally. There are some exceptions, like mining
where they can mine from multiple sides, and don't try them all.
At its most complex, running Dwarf
Fortress is like having an ant farm. You look in, and
these little bearded guys are roaming all around, each with his own
agenda. It's fascinating to watch for its own sake.
TA: Somebody modded their dwarves into
antmen [laughs]. I even have a few people that went as far as
donating, and they don't even play. They just like to check out the