Fog definition
// set global atmospheric fog effect in the scene.
// at the fog distance, there will be 63% visibility
fog {
fog_type 1 // 1=constant, 2=ground_fog
distance 10
color Gray // can also have 'filter' and 'transmit'
// (---turbulence---)
//turbulence <0.5, 0.5, 1.0>
//turb_depth 0.5
//omega 0.5
//lambda 2.0
//octaves 6
// (---ground fog---)
//fog_offset 0.5 // height of constant fog
//fog_alt 0.5 // at fog_offset+fog_alt: density=25%
}