Experienced Points

Experienced Points
What Makes the Technology in Grand Theft Auto V So Great

Shamus Young | 20 Jan 2015 15:00
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Experienced Points GTA V

So last week I said that Grand Theft Auto V has amazing technology but frequently fails at game design fundamentals. A couple of people wanted to know more about what makes the technology so great. Okay then. Let's talk about that.

What we're not talking about is "graphics". Lots of games have nice graphics. Many games look just as nice as GTA V in screenshots. Having nice graphics is always appreciated, but it's not all that rare and it's certainly not what sets GTA apart.

First, let's look at what makes sandbox games hard in general before I talk about what makes GTA V amazing.

Games have assets. The 3D models that make up the characters in the scene. The textures that cover their surface. The animations that make them move. The audio files of all the dialog and sound effects. The scenery. The background music. This stuff takes up a lot of space. A typical game gets to have loading screens where the game unloads all the old stuff it's not going to use anymore and loads in all the assets it's going to need in the coming area. A sandbox game has to do that in real time, while you're running around looking at other assets. It's the difference between moving into an empty apartment and moving into an apartment while the previous resident is also moving out. It's a lot more complex.

A non-sandbox game gets to put walls around the play area. The buildings in the distance can be simple boxes with nothing inside, because the player can't jump over this one-meter hedge to reach them. You can have high-detail areas where the player will travel, and low-detail areas where they can't. In a sandbox game, everything has to be done at the highest possible detail level because the player can go anywhere, and they will notice if they walk up to a building and it looks blurry and barren. Worst of all, the "play area" tends to be massive. So not only does everything need to be more densely packed with detail, but that detail needs to stretch to the horizon instead of just covering a small area.

A non-sandbox game can put walls in the way to block line-of-sight. If the game slows down when the factory and warehouse buildings are visible at the same time, the level designer can throw a wall or a hill between the two so the game never has to draw both at once. In a sandbox game, all bets are off. You can't throw random mountains in the middle of a city, and urban buildings aren't big enough that you can count on them to control lines of sight. Sure, if I'm standing right in front of the bank I can't see the apartment buildings behind it, but if I drive one block away then the bank and apartments are both visible, and therefore the game needs to be able handle both.

A non-sandbox gets to have choke points where it can do background loading. (It's like a soft loading screen.) Once the player enters the docks area, the game knows it's time to load the inside of the warehouse where they will be going, and the designers can make the walk to the warehouse take long enough that by the time the player reaches it, all the loading will be done. In a sandbox game, all bets are off. The player might parachute in. They might approach fast-moving by vehicle. There aren't predictable choke points where the game can safely add assets. The game basically needs to be able to load stuff at a moment's notice, and it needs to keep stuff ready "just in case".

What happens is that urban sandbox games end up relying heavily on Level of Detail. Every asset - every building, every car, every city block - needs to have multiple versions. One version of the corner store is a simple box that looks acceptable from a kilometer away. Another version has the proper shape of the building and looks okay from a hundred meters or so. Another version is the full-detail model with moving doors, stuff on the shelves, advertisements in the windows, and graffiti all over one side of the building. The entire game world ends up being one big loading zone where the game is constantly replacing low-detail stuff with high-detail stuff in front of you and doing the opposite behind you.

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