Random weather script

function StartWeather takes nothing returns nothing // This function can run at map init...
    call CleanWeatherWeights() // Prepares and clean the Weather script...
    call SetWeatherWeight(Northrend_Blizzard, 3.) // adds a weather type and its weight.
    call SetWeatherWeight(Rays_Of_Light, 5.)
    call SetWeatherWeight(Wind_Heavy, 8.)
    // if a weather has a higher weight, it will have more chances to happen than others.
    // this value is arbitrary...
endfunction

// Random weather changer, by moyack. 2008.
library RandomWeather initializer init
// Configuration section
globals
    private constant real    MinDur = 5. // minimum time that we have to wait between weathers
    private constant real    MaxDur = 15. // maximum time that we have to wait between weathers
endglobals
// End configuration section
globals
    // Weather Type Constants
    constant integer Ashenvale_Rain_Heavy    = 'RAhr'
    constant integer Ashenvale_Rain_Light    = 'RAlr'
    constant integer Dalaran_Shield          = 'MEds'
    constant integer Dungeon_Blue_Fog_Heavy  = 'FDbh'
    constant integer Dungeon_Blue_Fog_Light  = 'FDbl'
    constant integer Dungeon_Green_Fog_Heavy = 'FDgh'
    constant integer Dungeon_Green_Fog_Light = 'FDgl'
    constant integer Dungeon_Red_Fog_Heavy   = 'FDrh'
    constant integer Dungeon_Red_Fog_Light   = 'FDrl'
    constant integer Dungeon_White_Fog_Heavy = 'FDwh'
    constant integer Dungeon_White_Fog_Light = 'FDwl'
    constant integer Lordaeron_Rain_Heavy    = 'RLhr'
    constant integer Lordaeron_Rain_Light    = 'RLlr'
    constant integer Northrend_Blizzard      = 'SNbs'
    constant integer Northrend_Snow_Heavy    = 'SNhs'
    constant integer Northrend_Snow_Light    = 'SNls'
    constant integer Outland_Wind_Heavy      = 'WOcw'
    constant integer Outland_Wind_Light      = 'WOlw'
    constant integer Rays_Of_Light           = 'LRaa'
    constant integer Rays_Of_Moonlight       = 'LRma'
    constant integer Wind_Heavy              = 'WNcw'
    // End Weather type Constants...
    private boolean IsWeather = false
endglobals

private struct Weather // this is the struct that manages all the weather behavior
    private static rect R
    private static real total = 0.
    private static integer index = 0
    weathereffect w
    integer id
    real weight
    real chance
    
    private method onDestroy takes nothing returns nothing
        call RemoveWeatherEffect(.w)
    endmethod
    
    static method Clean takes nothing returns nothing
        local integer i = 1
        local Weather W
        loop
            exitwhen i > Weather.index
            set W = Weather(i)
            call W.destroy()
            set i = i+1
        endloop
        set Weather.index = 0
    endmethod
    
    static method Add takes integer id, real w returns nothing
        local integer i = 1
        local Weather W = Weather.allocate()
        set W.id = id
        set W.weight = w
        set W.w = AddWeatherEffect(Weather.R, id)
        call EnableWeatherEffect(W.w, false)
        set Weather.total = Weather.total + w
        set Weather.index = integer(W)
        loop
            exitwhen i > Weather.index
            set W = Weather(i)
            set W.chance = W.weight / Weather.total
            set i = i+1
        endloop
    endmethod
    
    static method Start takes nothing returns nothing
        local integer i = 1
        local real r = GetRandomReal(0,1)
        local real s = 0.
        local Weather W
        loop
            exitwhen i > Weather.index
            set W = Weather(i)
            exitwhen s <= r and r < s+W.chance
            set s = s+W.chance
            set i = i+1
        endloop
        call EnableWeatherEffect(W.w, true)
    endmethod
    
    static method Stop takes nothing returns nothing
        local integer i = 1
        local Weather W
        loop
            exitwhen i > Weather.index
            set W = Weather(i)
            call EnableWeatherEffect(W.w, false)
            set i = i+1
        endloop
    endmethod
    
    private static method onInit takes nothing returns nothing
        set Weather.R = GetWorldBounds()
    endmethod
endstruct

private function Loop takes nothing returns nothing
    local timer t = GetExpiredTimer()
    set IsWeather = not IsWeather
    if IsWeather then
        call Weather.Start()
    else
        call Weather.Stop()
    endif
    call PauseTimer(t)
    call TimerStart(t, GetRandomReal(MinDur, MaxDur), false, function Loop)
    set t = null
endfunction

private function init takes nothing returns nothing
    call TimerStart(CreateTimer(), GetRandomReal(MinDur, MaxDur), false, function Loop)
endfunction
// ==============
// user functions
// ==============
function SetWeatherWeight takes integer wid, real w returns nothing
    call Weather.Add(wid, w)
endfunction

function CleanWeatherWeights takes nothing returns nothing
    call Weather.Clean()
endfunction

endlibrary