--Function requires the same name as the file
local sound_entity = 963 --entity assigned to this lua file
local start_vol = 100 -- maximum sound volume
local trigger_zone = 1000-- action zone radius
local zone_segments = 20 -- create zone segments for each new location in the zone
local inzone=0

function m3waterfall_init(sound_entity)
end

function m3waterfall_main(sound_entity)
  --this code segment calculates the volume changes required as the player passes by the waterfall
  inc = (math.floor(trigger_zone / zone_segments))
  dist = GetPlayerDistance(sound_entity)
  new_dist = (math.floor(dist / inc))
  vol = start_vol - new_dist 
  if vol < 1 then
  vol = 1
  end
   
  if GetPlayerDistance(sound_entity) < trigger_zone and inzone == 0 then --player is in the active zone
	SetSoundVolume(vol)--this is where the volume changes based on the above calculation
	PlaySoundIfSilent(sound_entity, 0)
    --Prompt("new dist =  " .. new_dist .. "   inc =  " .. inc .."  vol =  " .. vol .." travel =  " .. (math.floor(dist)))
  end
  
  if GetPlayerDistance(sound_entity) > trigger_zone then --player has left the active zone
	StopSound(sound_entity, 0)
    inzone = 1
  end
  inzone = 0
end
 
--when the player has completed his walk past the waterfall i lose the background sound wav. that is
--attached to to start marker which is playing up until the time the player enters the area of the waterfall 
--but is lost when the player has passed the area of the waterfall lua file.