While a cube map by itself works great for a simple skybox, there are a few disadvantages that come with the simplicity. The effect only works well if the skybox is rendered
from the center of the cube, so anything that’s part of the skybox will always appear
to be at the same distance from viewers, no matter how far they travel. Since the
skybox is usually composed of prerendered textures, the scene is also necessarily
static, with clouds that don’t move. And depending on the viewer’s field of vision, the
cube map textures might need to be very high resolution to look good on the screen,
eating up a lot of texture memory and bandwidth.
Many modern games and applications usually work around these limitations by
complementing the traditional skybox technique with a separate 3D scene with its
own dynamic elements and clouds. This separate 3D scene will still be rendered
behind everything else; but the camera can also move around this separate scene
and elements inside that scene can be animated, giving the viewer the illusion of
being in a gigantic 3D world.