This component defines special rendering effects.
Background defines the sky colors and textures.
LocalFog simulate natural fog.
Note that depths (in
FogCoordinate.depth) are sensible
only in the [0, 1] range (like allowed by the specification),
and are not affected by the
(also following the spec). Effectively, this means that
does not substitute the mere distance to the eye in the fog equation.
Instead, it specifies directly the fog intensity.
I understand that this is the intention of the spec, although the wording
is clumsy (not saying directly what "implicit depth" is —
fog input distance or fog output intensity).