Bifalgorithm post

How can a game like GTA load an entire city without showing you a loading screen every five minutes? Simple answer, it doesn't load the entire city. That would destroy your memory budget. A huge open world can contain roads, buildings, textures, cars, pedestrians, audio, animations, and thousands of other assets. There's no reason to keep all of that in RAM when the player can only see a tiny part of the world. So instead, the game uses something called world streaming. Imagine the entire map divided into smaller regions or tiles. The game only keeps the regions around the player loaded in memory. Everything far away stays on storage. Now you start driving. As you move toward a new part of the city, the game begins loading those regions before you reach them. At the same time, areas far behind you can be removed from memory, so the world around you is constantly being built and destroyed as you move through it. But now there's a problem. Imagine you're driving down the highway at 120 miles per hour. If the game only loads what's immediately around you, you could reach the next area before the SSD finishes loading it. So the engine tries to predict where you're going. If you're moving quickly north, it can start streaming more of the world to the north. The faster you move, the further ahead it needs to prepare. And if you suddenly make a U-turn, the priorities change. Assets behind your new direction become more important, while unnecessary loading requests can be deprioritized or canceled. But what about buildings you can see miles away? Surely those are loaded. Kind of. Games use something called level of detail or LOD. A building far away doesn't need detailed windows, interiors, signs, or high resolution textures. From that distance, you couldn't see them anyway. So the game loads a much simpler version. As you get closer, that building gets replaced with increasingly detailed models and, when you're right next to it, the highest quality version can finally be loaded. The same idea applies to textures, shadows, vegetation, cars, and even pedestrians. Now we need to control memory. The console only has a fixed amount of RAM, so think of memory like a backpack. Every time a new area goes into the backpack, something you no longer need has to come out. The engine constantly decides what should stay, what should load next, and what can safely be removed. This is also why fast SSDs became such a big deal for modern open-world games. Older hard drives were much slower at fetching new assets. Developers sometimes had to hide loading behind long corridors, elevators, narrow passages, or other tricks that slowed the player down. With modern SSDs, assets can be pulled from storage much faster, making aggressive world streaming much more practical. So when you drive across a massive open world city, the entire map isn't secretly sitting in memory. The game is constantly loading what you're about to see, simplifying what's far away and deleting what you've already left behind. The illusion is that the whole city exists at once. The engineering trick is making sure you never notice that it doesn't.

How can a game like GTA load an entire city without showing you a loading screen every five minutes? Simple answer, it doesn't load the entire city. That would…