snow.lua

------------------------------
-- Happy Weather: Light Rain

-- License: MIT

-- Credits: xeranas
------------------------------

local snow = {}
snow.last_check = 0
snow.check_interval = 200
snow.chance = 0.2

-- Weather identification code
snow.code = "snow"

-- Manual triggers flags
local manual_trigger_start = false
local manual_trigger_end = false

-- Skycolor layer id
local SKYCOLOR_LAYER = "happy_weather_snow_sky"

snow.is_starting = function(dtime, position)
	if snow.last_check + snow.check_interval < os.time() then
		snow.last_check = os.time()
		if math.random() < snow.chance then
			return true
		end
	end

	if manual_trigger_start then
		manual_trigger_start = false
		return true
	end

	return false
end

snow.is_ending = function(dtime)
	if snow.last_check + snow.check_interval < os.time() then
		snow.last_check = os.time()
		if math.random() < 0.5 then
			return true
		end
	end

	if manual_trigger_end then
		manual_trigger_end = false
		return true
	end

	return false
end

local set_sky_box = function(player_name)
	local sl = {}
	sl.name = SKYCOLOR_LAYER
	sl.sky_data = {
		gradient_colors = {
			{r=0, g=0, b=0},
			{r=231, g=234, b=239},
			{r=0, g=0, b=0}
		}
	}
	skylayer.add_layer(player_name, sl)
end

snow.add_player = function(player)
	set_sky_box(player:get_player_name())
end

snow.remove_player = function(player)
	skylayer.remove_layer(player:get_player_name(), SKYCOLOR_LAYER)
end

-- Random texture getter
local choice_random_rain_drop_texture = function()
	local base_name = "happy_weather_light_snow_snowflake_"
	local number = math.random(1, 3)
	local extension = ".png"
	return base_name .. number .. extension
end

local add_particle = function(player)
	local offset = {
		front = 5,
		back = 2,
		top = 4
	}

	local random_pos = hw_utils.get_random_pos(player, offset)

	if hw_utils.is_outdoor(random_pos) then
		minetest.add_particle({
			pos = {x=random_pos.x, y=random_pos.y, z=random_pos.z},
			velocity = {x = math.random(-1,-0.5), y = math.random(-2,-1), z = math.random(-1,-0.5)},
			acceleration = {x = math.random(-1,-0.5), y=-0.5, z = math.random(-1,-0.5)},
			expirationtime = 2.0,
			size = math.random(0.5, 2),
			collisiondetection = true,
			collision_removal = true,
			vertical = true,
			texture = choice_random_rain_drop_texture(),
			playername = player:get_player_name()
		})
	end
end

local display_particles = function(player)
	if hw_utils.is_underwater(player) then
		return
	end

	add_particle(player)
end

local particles_number_per_update = 10
snow.render = function(dtime, player)
	for i=particles_number_per_update, 1,-1 do
		display_particles(player)
	end
end

snow.in_area = function(position)
	if hw_utils.is_biome_frozen(position) == false then
		return false
	end

	if position.y > -10 and position.y < 120 then
		return true
	end
	return false
end

snow.start = function()
	manual_trigger_start = true
end

snow.stop = function()
	manual_trigger_end = true
end

happy_weather.register_weather(snow)