Skybox (video games)

A skybox is a method of creating backgrounds to make a video game level appear larger than it really is.

Levels have to be processed at tremendous speeds, making it difficult to render vast skyscapes in real-time.

By careful alignment, a viewer in the exact middle of the skybox will perceive the illusion of a real 3D world around it, made up of those six faces.

This is often a good approximation of reality, where distant objects such as clouds, stars and even mountains appear to be stationary when the viewpoint is displaced by relatively small distances.

The source of a skybox can be any form of texture, including photographs, hand-drawn images, or pre-rendered 3D geometry.

Usually, these textures are created and aligned in 6 directions, with viewing angles of 90 degrees (which covers up the 6 faces of the cube).

In the game Half-Life 2, this effect was extensively used in showing The Citadel, a huge structure in the center of City 17.