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

Lets simplify the issue and think in 2D, with two triangles that can be at any place and any rotation.

A triangle is made of 3 points (vertices). It’s actually quite computationally difficult to determine if a point is inside another polygon.

But a triangle is also made of 3 lines. Lines are much easier for computers to work with; they can tell if a pair of lines intersect quite quickly, so most collision systems are checking if lines intersect.

The issue is that if an object moves too fast it can be on one side of another object’s collision line on one frame and on the other side the next frame.

Because none of the lines are intersecting, the system doesn’t detect a collision.