struct
FadetrueVolume reduction (fade-out) controlled by distance (fraction of audible distance).
FadestrueVolume reduction (fade-out) or increase (fade-in) controlled by zoom level.
floattrueHas to be in the range [-1.0, 1.0].
Positive values are used for night sounds, the volume of the sound is 1.0 when darkness = threshold, 0.0 when darkness = 0.0 and linearly interpolated in between.
Negative values are used for day sounds, the sound of the sound is 0.0 when darkness = -threshold, 1.0 when darkness = 1.0 and linearly interpolated in between.