Why Tears of the Kingdom’s physics are so mind-blowing
05.10.2023 - 19:19
/ polygon.com
Back in May, the gameplay clip that had everyone talking was of a lava bridge in The Legend of Zelda: Tears of the Kingdom. Developers were impressed by the game’s robust physics engine, noting that getting something like this to work in a game is an incredibly difficult task.
But why is that?
I interviewed two game developers about working with gameplay physics, and what Tears of the Kingdom does that makes it stand out from other games.
If you play games you probably have an idea of what I mean when I say “physics” but it’s worth going over the fundamentals because, like most aspects of game development, the more you think about physics the more complicated it gets and the more miraculous it seems.
The game programming flex of all time. pic.twitter.com/id2K5uE5mz
In games, anything that moves is basically either a canned animation, or a physics object.
“[Physics] covers things like collision, movement, acceleration, even character controls,” software engineer Cole Wardell told me. “A lot of it is trying to solve these very complex equations in a way that is both fast and does not cause a lot of error.”
Game physics are tough because there’s a lot of math going on to make us believe that a digital rock is falling to the digital ground in a way that doesn’t break our immersion.
As an immersive sim, Tears of the Kingdom’s physics are trickier than most. The interactions that the player can cause are incredibly complex. Wardell points to a door that is pulled open by chains attached to rotating tires.
NOPE FUCK THAT THIS PHYSICS ENGINE IS BLACK MAGIC. <a href=«https://twitter.com/hashtag/TearsOfTheKingdom?src=hash&ref_src=» https:>#TearsOfTheKingdom
<a href=«https://twitter.com/hashtag/Zelda?src=hash&ref_src=» https:>#Zelda <a href=«https://twitter.com/hashtag/NintendoSwitch?src=hash&ref_src=» https:>#NintendoSwitch pic.twitter.com/HMi0wITRI7
In most games, something like this pulley system would be a canned animation, or the points where the chain attaches and their effect on the door would be faked in some way.
“But later on in that, in that dungeon,” Wardell said, “you’re given just wheels, and the chains are hanging there, and you have to build it yourself.” After expermenting with the door, he was able to find other ways to lift it by attaching the hanging chains to different points.
“That bridge and the chain are really the same thing,” Wardell said. “Because if you think about it, all of them are a bunch of segments connected by hinges. That’s how ropes are done in a game engine.”
A functional video game rope or chain isn’t a continuous object — it’s basically tons of segments, and when one of them moves, the others react. That can easily create a, ha, chain reaction where the whole thing freaks