I’ve learned that video game ‘clipping’ is caused by high velocity, thin colliders, and too-slow physics updates. Why are terrain surfaces in most 3D video games paper-thin? Why isn’t terrain given extra fill/thickness inside and under it to prevent ‘falling through the map into the void’?

Question

I could see why you might not want to fill under the terrain in a game that features things like underground caves, but thin terrain seems to be present in a huge majority of 3D games (even those without underground features) and is not engine-specific. Why is terrain almost always a fragile piece of origami that’s so easily punctured?

In: Technology

Answer 1

I’ve seen a bunch of answers here that are quite difficult to understand, so I’ll take a stab at it.

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You have to keep in mind that although a 3D video game gives the illusion of being similar to real life, it is completely different. Everything is done with math, resulting in something that feels like real life.

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Visually, the game is just a camera that can move around and look at 3D graphics. This camera can go anywhere, and go right through any rendered object.

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A 3D graphic is just some edges put together. When you think about it, even in real life you can only ever see the outside edges of an object. Yes, in real life there’s stuff inside, but a visual rendering is just some pixels to look at; there’s nothing beyond the edges you see. That’s why any 3D object or “terrain” is paper thin. What’s it gonna be filled with? Atoms? What would you see when you went inside it? Blackness? Visually, thickness doesn’t really exist.

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The system of collisions (and other physics) has to be programmed in. A simplified way of thinking about a system that stops the camera from moving through an object is telling the computer: “Hey, if the camera’s position tries to go within the space taken up by that object, stop it! Push it back or something!” and this is where some of the more advanced answers about extensive collision systems with hardcore math come in.

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So a collision in a video game is only as good as the system that prevents you from moving through an area you don’t wanna move through. You can collide with an invisible wall just the same as how you can collide with an object. It’s just a bunch of numbers and visuals, there’s no terrain or thickness at all.

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TL;DR Minecraft blocks are hollow dude

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Edit: This is from a programmer’s perspective, I’m not a game dev or a graphics engineer, but I believe this is an accurate explanation.