I believe that is Ben's script but I am not sure.
Just from glancing at the script it appears there is no instruction in it to turn the fog off.
;Artificial Intelligence Script
; by xplosys
desc = Simple Night Vision
; LICENSE
; Feel free to use, pass along, alter this script in
; any way you please. If you figure out a better way
; to accomplish this or specifically learn a way to
; effectively use the same key for the ON and OFF key
; please pass it on to myself and everyone else.
;
; USAGE
; Place a light anywhere in your leve and change it
; to dynamic (static=No). Name it night_Vision or
; another name to make it different from other lights
; in your level and assign this script as it's Main
; AI script. This script uses the N key to turn on
; night vision and the M key to turn it off.
;
; You can use any keys you like by changing the value
; of "scancodekeypressed" in the script to match the
; value of any key. You can change the lighting by
; changing the values of ambience and ambiencegreen.
;
; SETUP
; This script assumes that your ambience levels are
; set at zero in your level. If not, you should
; change the values for ambience in the "state=2"
; line to match the values of your level, so when the
; goggles are turned off, the lighting returns to the
; default value of your level.
;Header
;Triggers
:state=0:state=1
:state=1,scancodekeypressed=49:fog=1,fogred=255,foggreen=255,fogblue=255,state=2
:state=2,scancodekeypressed=50:fog=0,fogred=0,foggreen=0,fogblue=0,state=0
;End of Script
As you can see I modified xplosys' night vision script and now you can use this script to turn the fog on and off.
You can change the keys to turn it on/off and the types of fog as well.
I don't know how useful this will be but there it is.
