how this game renders millions of objects using 1 trick

本站添加: 2026-06-02

[00:00:00]I was playing Satisfactory recently when I hit one of those moments where you just stop and stare. Hundreds of conveyor belts, thousands of buildings, millions of iron plates sliding around, and my PC was still alive. Barely, but still alive. So, I started wondering, how does any factory game actually do this? Because it's not just Satisfactory, Factorio, Mindustry, Dyson Sphere Program, all have this problem.

[00:00:25]Millions of objects, all moving, all simulated, all on screen at once. Turns out, there's one trick sitting underneath almost everything you see in those games. It's the same trick used to render grass, particles, and basically everything that appears in huge numbers.

[00:00:41]Let's take a look at it. However, before we see the solution, let's first look at the problem.

[00:00:46]So, the problem with conveyor belts is the numbers. Unlike trees or buildings, which just sit there, conveyor belts are covered in items, moving items. And in a big enough factory, you're talking millions of them on screen at the same time. Millions of objects means millions of positions to track, millions of physics calculations, millions of individual properties. If the game treated every single iron plate as its own unique project, your PC would burst into flames before you even reached mid-game. So, instead of rendering and creating mechanics for each individual item, these games use something called GPU instancing. The game isn't tracking a million individual iron plates, it's tracking the belt. Where it starts, where it ends, how fast it's moving.

[00:01:31]From that, it calculates where items would be, spaces them out, and stamps copies of the same mesh along the path.

[00:01:37]They're not real objects living in the world, just visual copies. And when you go to pick something up, the game just approximates which item you're pointing at based on your position on the belt, instantly creates the object, and removes it from the GPU.

[00:01:50]GPU instancing isn't some trick Satisfactory invented, it's basically everywhere. And once you know about it, you cannot unsee it. Open world games like Ghost of Tsushima or Elden Ring use it to render grass. Instead of simulating thousands of individual blades, the engine keeps one in memory and copies it across the entire landscape with slight rotation and color offsets so that they don't look identical. Football games use it to render thousands of fans in the background. Most of them are the same five or six people instanced across the entire stadium with tiny color and animation offsets so they don't all look like clones of each other. So, basically, almost nothing you see in huge numbers in a game is a real individual object. They're all copies, the same mesh rendered over and over in slightly different spots with the GPU, not the CPU, doing the heavy lifting.

[00:02:41]There's also another trick that you've definitely experienced without realizing it. It's called level of detail. Every game uses this. Red Dead Redemption, Fortnite, Roblox. It doesn't matter how different they look, they all do it. And it's a simple idea. When an object is far away from the camera, you can't really see the detail on it. This mimics real life as our eyes lose detail the further away we get. So, why bother rendering it at full quality? The game swaps in a lower poly, simpler version of the model the further away it gets.

[00:03:12]Fewer vertices and fewer triangles means less work for the GPU. Then, as you walk closer, it quietly swaps back to the high detail version right before you would even notice the difference. In a factory game, this matters a lot because your camera is constantly pulling back to see the whole base. If every machine on the far end of your factory was rendering at full detail, you'd never hit a stable frame rate.

[00:03:35]Here's another one you might have actually noticed if you played Satisfactory long enough. Build walls around part of your factory and your FPS goes up. And that's because of the optimization method called culling.

[00:03:46]The game is constantly checking several aspects. What can the camera actually see right now? Anything outside the camera's view, behind you, around the corner, inside a closed room, gets skipped entirely. The GPU doesn't render it. The walls trick works because when you surround buildings with walls, the culling system can prove that the interior is completely hidden. So, it stops drawing. Less to draw, more frames per second.

[00:04:11]So, the next time you're running through your factory watching 10,000 iron plates zoom past you on a belt, you will know the truth. Those items aren't real objects in the real world. They are data living inside a texture being read by a shader, drawn exactly where they need to be for almost zero processing cost. The game isn't simulating all of that. It's just very convincingly lying to you about it. If you want to go deeper into how Satisfactory was actually built, I have a video on the full development story. Go check that out, and if you like this one, subscribe for more.