In WoW and other games, pathfinding is still "kind of a problem"
If you're not much of a computer programming person, this one might make your eyes glaze over a bit, but if you have any interest how the AI of videogame characters, including those in WoW, is programmed, this article about designing AI pathfinding is a terrific read. "Pathfinding" is a method of determining how NPCs move within a game world like Azeroth -- you and I can clearly see where the walls and bad guys are, and so we just have to press buttons to avoid either ingame, but NPCs (including pets and mobs) aren't quite that easy -- they need to be told clearly by programmers where they can go and how to get there. And when the rules they're given don't quite work, you get the funny seen above.
Many games use a "waypoint" system -- NPCs are given a series of paths around the space they can move in, and use those paths to determine where they can and can't go. The article argues for a "navigation mesh," a much looser definition of available space, which NPCs can then draw their own path across. It's a little technical, but it's cool to see the inner workings (and weaknesses) of Azeroth's code.
Of course, it's extremely unlikely that we'll ever really see the NPC pathfinding engine updated in WoW anyway -- Blizzard will update their system in certain places to fix things like exploits (and the occasional annoying escort quest, i.e. all of them), but there's no real need to update the whole system completely when there's so much content to be done. Hopefully videos like this will bring the problem to light, and in future games we'll see some better pathfinding. Someday, that NPC will know that it's easier to go around the pillar rather than trying to walk right through it.
Filed under: Analysis / Opinion, Cheats, Blizzard, Humor, Bosses, NPCs, Hardware






Reader Comments (Page 1 of 2)
Natalie Mootz Jul 30th 2008 3:46PM
Very amusing. The music is perfect.
SpaceDog Jul 30th 2008 6:44PM
I read your comment before watching the video and I knew exactly what the music was going to be. :)
Oh, and general question - what was the game where the cat kept running around the rock?
Zakk Jul 30th 2008 6:51PM
SpaceDog, I think that was Age of Conan. Not sure, but I think the little arrows are a part of the combat system in AoC.
Now somebody tell what that second game was. The one with the shotgun.
Dinnerbone Jul 30th 2008 7:06PM
That was Age of Conan, SpaceDog. I actually knew an AI designer for that game, who was responsible in part for the pathfinding - he refused to believe that it sucked. Hmm...
jurandr Jul 30th 2008 6:46PM
I enjoyed the Oblivion scenes. I actually come across pathfinding issues in that game on a daily basis. My favorite would be when I was in a ruin, and a bandit marauder was running at me, hugging the wall. All of a sudden, he turns, triggers his own trap, and then continues running at me. The distance between the trap trigger and the wall was probably about 50 feet... Oblivion's npc's also tend to walk into each other continuously unless you purposfully move them (character collision is enabled in that game)
Zakk Jul 30th 2008 6:49PM
I think the WoW issues are a lot more annoying than the issues of other games. In the others, the mob gets stuck or chooses a less than efficient path to you. In WoW, the damn things teleport through walls and run up stuff that's at a 90 degree angle. Neither are good, but at least the other games don't punish you for their system going crazy. I know once the pathfinding goes haywire it's kind of out of your control, so it's not so simple to minimize the pain of it, but it's still kind of annoying, and I'm gonna complain about =P
Oh, and I still love WoW (probably more than any other game), but it's not perfect.
Stigma Jul 31st 2008 8:37AM
The reason why bliz helps the mobs get to you in wow is to keep people from exploiting.
In games like eq people would find pathfinding issues with raid mobs and solo 40 man bosses because the mob could never get to them.
So take your pick a few bugged out mobs while questing, or people exploiting the game and soloing t6 content
Zakk Jul 31st 2008 2:15PM
Yeah, s'pose you're right, Stigma. Would kinda take the fun out if you could just hop up on a ledge and beat down on Kil'Jaeden.
Hurode Jul 30th 2008 7:13PM
My favorite part is in Gnomer, where the little non-Elite gnomes go on the 1" ledge on the -outside- of the pillar to get to you if the tank loses aggro or goes back and forth between them. At the part above the circle with the elevator.
Those who know the place I'm trying to describe know what I'm talking about. My tankadin is level 31 right now and has great fun in that part of the instance ^_^
Volomon Jul 30th 2008 7:21PM
You know technically this whole article isn't correct. Its not merely a pathfinding issue. Its has to do with the various environments. Such as the ledge the imp was stuck on probably isn't registered correctly in the game as a passable object. The ones where they get caught on a courner of another object they are probably clipping into the object and the AI believes they are WITHIN the object and are trying to find a way out but are looping the incorrect one.
The two of those are actually easy to fix, Blizzard's examples are correct, they should just clip through objects and ignore them when needed. Since you can't 100% be sure to check every terrain feature.
Dightkuz Jul 30th 2008 7:24PM
Ooh, I hate it so much when the mob dies on the side of a cliff where I cant reach and loot the corpse or dying inside the cliff where I cant reach it either. Indeed something Blizz should look into.
sizzle Jul 30th 2008 7:58PM
Not really a pathfinding issue, but if you walk around Darkshore, there are at least a few trees that if you get too close, will try and paw you.
DirtyPriest Jul 30th 2008 7:39PM
There are reasons why the pathfinding is done the way its done. Likely probably for improved server peformance. It's not exactly a highly critical issue especially in a game like this. If they wanted super duper hyper intelligent pathfinding they could have done so already. Blizzard does make RTS games in which pathfinding IS critical.
goliathsdkfz Jul 30th 2008 7:42PM
Whats the game at about 40 seconds in ?
Aaron Jul 30th 2008 7:57PM
The pathing in WoW is fantastic. Have you ever played EverQuest? I was blown away by how well WoW escort quests worked when I started playing this game.
Muse Jul 30th 2008 8:01PM
Same. I've done many dozen escort quests, and I've kept thinking "it's gonna bug, it's gonna bug, any minute now" but they never do. Sure, it's a slow walk sometimes, but they always get where they're going as long as I actually do the escorting part properly.
theRaptor Jul 30th 2008 10:36PM
WoW mostly doesn't have real pathfinding. They designed it so that it would be nearly impossible to glitch NPC's, because the NPC's just ignore most geometry. NPC's running through walls once they see you isn't a glitch, it is what is intended. The stuff that isn't intended is when NPC's aggro you through the floor/ceiling and you end up with half an instance ganking you (Hi Karazhan!).
zappo Jul 31st 2008 8:11AM
Yeah, I was actually trying to figure out what they were getting at with the WoW clip, then I realized that a troll came through the wall. I mean that's not a big deal, the mob got to where it was going! If you ever have played games where you try to pull a mob somewhere and then it gets stuck where you can't even attack it.. now that's annoying.
Thander Jul 31st 2008 1:15AM
The pathfinding in WoW is good enough. What I hate is the evade glitching. The quest where you have to kill the invasion point leader in hellfire comes to mind. I can't count how many times that guy evaded mid battle. Ranged or melee he always seems to evade mid battle more times than not. I always expect to have to kill him 3 times to finish the quest. It doesn't help with fast respawning mobs in the area.
Morganda Jul 31st 2008 9:02PM
I've had a couple of mobs lately that aggro on me, then take off running, then turn around and run back to hit me. It doesn't seem to be related to the landscape or architecture (some were on the flat, fairly clear parts of Badlands). It's truly bizzare.
There was one that I was blundered right up to that ran far enough away that it faded off my screen, and it never did come back - I think it leashed itself!