michael breaker
Hey everyone, this week on Video Game Tuesday we are back with the second in a series of posts about things that have been around for many years. This is all about part 2 of my blog about the use of artificial intelligence (AI) in video games.
Well, last time we talked about AI in general and some of the things it's done to actually make video games possible. This week we're going to talk about something more basic: pathfinding. Pathfinding, or Monte Carlo tree search as some call it, is what most games need, but sometimes it doesn't work.
How to search the tree?: This term is a reference to a programming tree of actions and responses to input, essentially a series of if/then statements applied to game coding. Suppose a player is facing an enemy and chooses to jump. It might be something like, “Did the player jump?” If yes, then “Did the player jump before the attack started?” If yes… etc. This series of logical questions allows the system to decide what to do next in a given situation. This is most often used for pathfinding in games.
In Assassin's Creed, for example, if a player is detected in a restricted area, enemies become hostile, alert, and begin searching for the player. Enemies may jump a bit, climb down ladders, or climb stairs as they search around for you. However, at no point can you start walking through the air to reach the player or move directly to your location without being seen by the player.
That's what pathfinding means. This is extremely complex programming, and most players don't really realize how much effort goes into creating good, reliable pathfinding that can handle almost any terrain and obstacles without resorting to outright cheating like the air walking example above.
However, sometimes things get overlooked. In that case, pathfinding can yield interesting results. Atheon and the Templars in Destiny 1's Vault of Glass raid are a prime example. When the raid first started, Atheon and the Templars were the first raid bosses. The developers overlooked a small hole in the pathfinding logic that allowed players to be pushed off ledges or tricked, completely abusing the system to get interesting results. Bungie never fully recovered from that mistake, and the effects can be seen in other bosses in Destiny 1 and Destiny 2. Bungie really doesn't want something as basic as that to happen again.
But this is just an obvious example of pathfinding. Sometimes it's a little more abstract, like in Castlevania: Portrait of Ruin's almost post-story zone, Lair of Evil. At the bottom of the gauntlet of nasty monsters is an encounter with a creature called a doppelganger. And the gimmick of that battle is to copy all of the currently equipped equipment of Jonathan the Vampire Hunter or Charlotte the Witch, depending on who you're copying.
If it copies Jonathan and he uses the Illusion Fist weapon with no sub-weapons equipped, all the boss can do is walk or trot towards you and not actually fight at all. The reason is that Phantom Fist has no attack animations, so you can't fight bosses. It's a very easy way to defeat certain bosses.
That’s it for this week’s Video Game Tuesday!
