Snow

-- @author Quenty
-- Stick this guy in the StarterGui...

local Players = game:GetService("Players")
--Players.LocalPlayer.CameraMode = "Classic"
--Players.LocalPlayer.CameraMode = "LockFirstPerson"


-- You can use this to make it fall a lot...
local Configuration = {
	SnowModelName     = "ThatSnowRenderModel";
	SnowColor         = Vector3.new(1, 1, 1);
	SmallestFlakeSize = 8;-- Divided by 100
	LargestFlakeSize  = 15;
	MaxMoveX          = 5; -- Divided by 100
	MinMoveX          = -5;
	MaxMoveY          = 1;
	MinMoveY          = -12;
	MaxMoveZ          = 5;
	MinMoveZ          = -5;
	CyclesPerLifeMax  = 4;
	CyclesPerLifeMin  = 2;
	CycleLife         = 20;
	MaxTransparency   = 0.3;
	RangeX = 8;
	RangeY = 4;
	RangeZ = 8;

	-- QUICK EDITING STUFF HERE
	SnowAmountFactor = 3; -- Snowflakes made every frame. Double this, double lag, more snowflakes!
}

local function GetSnowModel()
	local Model = workspace:FindFirstChild(Configuration.SnowModelName)
	if not Model then
		Model = Instance.new("Camera", workspace)
		Model.Name = Configuration.SnowModelName
		Model.Archivable = false;
	end
	return Model
end

local function GetSnowflakeMovement()
	return Vector3.new(
		math.random(Configuration.MinMoveX, Configuration.MaxMoveX)/100,
		math.random(Configuration.MinMoveY, Configuration.MaxMoveY)/100,
		math.random(Configuration.MinMoveZ, Configuration.MaxMoveZ)/100
	)
end

local function GetRandomSnowflakePosition(LastValidPlace) --, CoordinateFrame)
	--[[return CFrame.new(LastValidPlace + Vector3.new(
			math.random(-Configuration.RangeX, Configuration.RangeX),
			math.random(-3, Configuration.RangeY),
			math.random(-Configuration.RangeZ, Configuration.RangeZ)
	) + Players.LocalPlayer.Character.Torso.CFrame.lookVector * 2)--]]
	return CFrame.new() + LastValidPlace:pointToWorldSpace(Vector3.new(
			math.random(-Configuration.RangeX, Configuration.RangeX),
			math.random(-3, Configuration.RangeY),
			math.random(-Configuration.RangeZ*2, 0)))
end

local SnowflakeQueue = {}

local function UpdateQueue()
	local HalfLife = Configuration.CycleLife;
	local MaxTransparency = Configuration.MaxTransparency
	--for Index, SnowFlake in pairs(SnowflakeQueue) do
	local Index = 1
	while Index <= #SnowflakeQueue do
		local SnowFlake = SnowflakeQueue[Index]

		local CycleTick = SnowFlake.CycleTick
		local Flake = SnowFlake.Flake
		if SnowFlake.Mode == 2 then
			SnowFlake.CyclesLeft = SnowFlake.CyclesLeft - 1
			if SnowFlake.CyclesLeft <= 0 then
				SnowFlake.Flake:Destroy()
				table.remove(SnowflakeQueue, Index)
			else
				SnowFlake.CycleTick = Configuration.CycleLife
				SnowFlake.Mode = 0
				Index = Index + 1
			end
		elseif SnowFlake.Mode == 0 then
			Flake.Transparency = (CycleTick/HalfLife)* MaxTransparency + (MaxTransparency)
			Flake.CFrame = Flake.CFrame + SnowFlake.MoveRate
			SnowFlake.CycleTick = CycleTick - 1
			if SnowFlake.CycleTick <= 0 then
				SnowFlake.Mode = 1
			end
			Index = Index + 1
		elseif SnowFlake.Mode == 1 then
			Flake.Transparency = (CycleTick/HalfLife)*MaxTransparency + (MaxTransparency)
			Flake.CFrame = Flake.CFrame + SnowFlake.MoveRate
			SnowFlake.CycleTick = CycleTick + 1
			if SnowFlake.CycleTick >= HalfLife then
				SnowFlake.Mode = 2
			end
			Index = Index + 1
		end
	end
end

local function MakeSnowFlake(Parent, InitialCFrame)
	local FlakeSize = math.random(Configuration.SmallestFlakeSize, Configuration.LargestFlakeSize)/100

	local Flake         = Instance.new("Part", Parent)
	Flake.Anchored      = true;
	Flake.CanCollide    = false;
	Flake.FormFactor    = "Custom";
	Flake.Size          = Vector3.new(1, 1, 1)
	Flake.Name          = "SnowFlake";
	Flake.BottomSurface = "Smooth";
	Flake.CFrame        = InitialCFrame
	Flake.Transparency  = 1;

	local Mesh = Instance.new("SpecialMesh", Flake)
	Mesh.MeshType    = "FileMesh"
	Mesh.MeshId      = "http://www.roblox.com/asset/?id=1185246"
	Mesh.TextureId   = "http://www.roblox.com/asset/?id=1361097"
	Mesh.VertexColor = Configuration.SnowColor;
	Mesh.Scale       = Vector3.new(FlakeSize, FlakeSize, FlakeSize)

	local SnowFlake = {}
	SnowFlake.Flake = Flake;
	SnowFlake.CycleTick = Configuration.CycleLife
	SnowFlake.CyclesLeft = math.random(Configuration.CyclesPerLifeMin, Configuration.CyclesPerLifeMax)
	SnowFlake.MoveRate = GetSnowflakeMovement()
	SnowFlake.Mode = 0
	table.insert(SnowflakeQueue, SnowFlake)
end

local function CheckPlayer(Player)
	--- Makes sure a player has all necessary components.
	-- @return Boolean If the player has all the right components

	return Player and Player:IsA("Player") and Player:IsDescendantOf(Players)
end


local function CheckCharacter(Player)
	-- Makes sure a character has all the right "parts"

	if CheckPlayer(Player) then
		local Character = Player.Character;

		if Character then

			return Character.Parent
				and Character:FindFirstChild("Humanoid")
				and Character:FindFirstChild("HumanoidRootPart")
				and Character:FindFirstChild("Torso")
				and Character:FindFirstChild("Head")
				and Character.Humanoid:IsA("Humanoid")
				and Character.Head:IsA("BasePart")
				and Character.Torso:IsA("BasePart")
				and true
		end
	else
		warn("[CheckCharacter] - Character Check failed!")
	end

	return nil
end




local FindPartOnRayWithIgnoreList = workspace.FindPartOnRayWithIgnoreList

local function AdvanceRaycast(RayTrace, IgnoreList, TransparencyThreshold, IgnoreCanCollideFalse, TerrainCellsAreCubes, MaximumCastCount, CustomCondition)
	-- @param TransparencyThreshold The transparency a part can be for it to be counted. For example, if TransparencyThreshold is 0.25, and a part is 0.24 transparency then it will be counted as solid, otherwise if it
	--                              is 0.26 then it will be counted as transparent.
	--                              If you don't want to hit transparent parts, then you can set it to -math.huge.
	--                              TransparencyThreshold should not be above 1, probably.
	-- @param [CustomCondition] A function that can be defined to create a custom condition (such as making sure a character is hit)
	-- CustomCondition(HitObject, Position)
			-- @return boolean If true, then it will automatically abort the cycle and return.

	assert(type(MaximumCastCount) == "number", "MaximumCastCount is not a number")
	assert(type(TransparencyThreshold) == "number", "TransparencyThreshold must be a number")

	--print(TransparencyThreshold)

	local ContinueCasting = true;
	local CastCount = 0

	local function CastAttempt(NewRayTrace)
		-- print("Cast attempt " .. CastCount)

		if CastCount >= MaximumCastCount then
			return
		else
			CastCount = CastCount + 1
		end

		local Object, Position = FindPartOnRayWithIgnoreList(workspace, NewRayTrace, IgnoreList, TerrainCellsAreCubes)

		if Object and Position then
			if CustomCondition and CustomCondition(Object, Position) then
				-- print("Custom override")
				return Object, Position
			elseif IgnoreCanCollideFalse and Object.CanCollide == false then
				IgnoreList[#IgnoreList+1] = Object

				--print("Hit something cancollide false", Object:GetFullName())
				return CastAttempt(NewRayTrace)
			elseif TransparencyThreshold and Object.Transparency >= TransparencyThreshold then
				IgnoreList[#IgnoreList+1] = Object

				--print("Hit something transparent false", Object:GetFullName())
				return CastAttempt(NewRayTrace)
			else
				return Object, Position
			end
		else
			--print("Just didn't hit anything")
			return
		end
	end

	local DirectionUnit = RayTrace.Direction.unit
	local Magnitude = RayTrace.Direction.magnitude
	local CastedMagnitude = 0

	--game:GetService("Debris"):AddItem(
	-- lib.DrawRay(RayTrace, BrickColor.new("Bright orange"))
	--, 2)

	while CastedMagnitude < Magnitude do
		local ToCastMagnitude = Magnitude - CastedMagnitude

		if ToCastMagnitude > 999.5 then
			ToCastMagnitude = 999
		end

		local WaysAlongPath = RayTrace.Origin + (DirectionUnit * CastedMagnitude)
		local NewRayTrace = Ray.new(WaysAlongPath, DirectionUnit * ToCastMagnitude)
		local Object, Position = CastAttempt(NewRayTrace)

		-- game:GetService("Debris"):AddItem(
		--	lib.DrawRay(NewRayTrace, BrickColor.new("Bright green"))
		--, 2)

		if Object then
			return Object, Position
		end

		CastedMagnitude = CastedMagnitude + ToCastMagnitude

		if CastCount >= MaximumCastCount then
			print("[AdvanceRaycast] - Reached maximum cast count @ " .. CastCount .. "; MaximumCastCount = " .. MaximumCastCount)
			return nil
		end
	end
end

local SnowModel = GetSnowModel()
SnowModel:ClearAllChildren()

local LocalPlayer = Players.LocalPlayer
--[[
local function SetupCharacter(Character)
	local IgnoreList = {}
	local LastValidPlace = nil --Players.LocalPlayer.Character.Torso.Position
	while not CheckCharacter(LocalPlayer) and Character == LocalPlayer.Character do
		wait()
	end

	while CheckCharacter(LocalPlayer) and Character == LocalPlayer.Character do
		--if Character:FindFirstChild("Torso") then

			local NewRay = Ray.new(Torso.Position + Vector3.new(0, 3, 0), Vector3.new(0, 100, 0))
			local Hit, Position =  AdvanceRaycast(NewRay, IgnoreList, 0.001, true, true, 5)
			if not Hit then
				LastValidPlace = Torso.Position
			--else
				--print("Inside")
			end
			if LastValidPlace then
				MakeSnowFlake(SnowModel, GetRandomSnowflakePosition(LastValidPlace))
			end
		--end
		UpdateQueue()
		wait()
	end
end

if LocalPlayer.Character then
	SetupCharacter(LocalPlayer.Character)
end

LocalPlayer.CharacterAdded:connect(SetupCharacter)--]]

local LastValidPlace
local IgnoreList = {SnowModel, LocalPlayer.Character}
local LastClean = tick()

local function CleanIgnoreList()
	if LastClean + 5 <= tick() then
		IgnoreList = {SnowModel, LocalPlayer.Character}
		LastClean = tick()
	end
end

local function DrawRay(Ray, Color, Parent)
	--- Draw's a ray out (for debugging)
	-- Credit to Cirrus for initial code.

	Parent = Parent or workspace

	local NewPart = Instance.new("Part", Parent)

	NewPart.FormFactor = "Custom"
	NewPart.Size       = Vector3.new(0.2, Ray.Direction.magnitude, 0.2)

	local Center = Ray.Origin + Ray.Direction/2
	-- lib.DrawPoint(Ray.Origin).Name = "origin"
	-- lib.DrawPoint(Center).Name = "Center"
	-- lib.DrawPoint(Ray.Origin + Ray.Direction).Name = "Destination"

	NewPart.CFrame     = CFrame.new(Center, Ray.Origin + Ray.Direction) * CFrame.Angles(math.pi/2, 0, 0) --* GetCFramePitch(math.pi/2)
	NewPart.Anchored   = true
	NewPart.CanCollide = false
	NewPart.Transparency = 0.5
	NewPart.BrickColor = Color or BrickColor.new("Bright red")
	NewPart.Name = "DrawnRay"

	Instance.new("SpecialMesh", NewPart)

	return NewPart
end


while true do
	local Camera = workspace.CurrentCamera
	if Camera then
		-- Check to make sure we're next extending through a roof or something...
		local ExtensionRay = Ray.new(Camera.CoordinateFrame.p,
			Camera.CoordinateFrame:vectorToWorldSpace(Vector3.new(0, 0, -Configuration.RangeZ))
			)
		local Hit, Position =  AdvanceRaycast(ExtensionRay, IgnoreList, 0.001, true, true, 5)
		if not Hit then
			-- Extend by mid range.
			local NewRay = Ray.new((Camera.CoordinateFrame * CFrame.new(0, 0, -Configuration.RangeZ)).p, Vector3.new(0, 100, 0))
			local Hit, Position =  AdvanceRaycast(NewRay, IgnoreList, 0.001, true, true, 5)
			if not Hit then
				LastValidPlace = Camera.CoordinateFrame
			end
		end

		if LastValidPlace then
			for Index = 1, Configuration.SnowAmountFactor do
				MakeSnowFlake(SnowModel, GetRandomSnowflakePosition(LastValidPlace, Camera.CoordinateFrame))
			end
		end
	end
	UpdateQueue()
	CleanIgnoreList()
	wait(0.03)
end