Use proper method for getting OS time. Use per-server-session time offset to vary precipitation timing each server session

README.txt

@@ -1,4 +1,11 @@
-snowdrift 0.5.0 by paramat
-For Minetest 0.4.12 and later
-Depends default
-Licenses: Source code MIT. Media (textures) CC BY-SA (3.0)
+snowdrift 0.6.4 by paramat.
+For Minetest 0.4.16 and later. Compatible with Minetest 5.0.0.
+Depends: default.
+
+Licenses
+--------
+Source code: MIT by paramat.
+Media:
+Textures CC BY-SA (3.0) by paramat.
+Sounds CC BY (3.0) by inchadney.
+http://freesound.org/people/inchadney/sounds/58835/ 

init.lua

@@ -1,22 +1,39 @@
 -- Parameters
 
-local PRECSPR = 11 -- Time scale for precipitation variation in minutes
-local PRECOFF = 0.8 -- Precipitation noise threshold offset
-local PROCHA = 0.2 -- Per player per globalstep processing chance
-local FLAKES = 8 -- Snowflake density
-local DROPS = 16 -- Rainfall density
-local NISVAL = 39 -- Clouds RGB value at night
-local DASVAL = 175 -- Clouds RGB value in daytime
+local YWATER = 1 -- Normally set this to world's water level
+				-- Particles are timed to disappear at this y
+				-- Particles are not spawned for players below this y
+				-- Rain sound is not played for players below this y
+local YMIN = -48 -- Normally set this to deepest ocean
+local YMAX = 120 -- Normally set this to cloud level
+				-- Weather does not occur for players outside this y range
+local PRECTIM = 300 -- Precipitation noise 'spread'
+				-- Time scale for precipitation variation, in seconds
+local PRECTHR = 0.2 -- Precipitation noise threshold, -1 to 1:
+				-- -1 = precipitation all the time
+				-- 0 = precipitation half the time
+				-- 1 = no precipitation
+local FLAKLPOS = 32 -- Snowflake light-tested positions per 0.5s cycle
+				-- Maximum number of snowflakes spawned per 0.5s
+local DROPLPOS = 64 -- Raindrop light-tested positions per 0.5s cycle
+local DROPPPOS = 2 -- Number of raindrops spawned per light-tested position
+local RAINGAIN = 0.2 -- Rain sound volume
+local NISVAL = 39 -- Overcast sky RGB value at night (brightness)
+local DASVAL = 159 -- Overcast sky RGB value in daytime (brightness)
+local FLAKRAD = 16 -- Radius in which flakes are created
+local DROPRAD = 16 -- Radius in which drops are created
+
+-- Precipitation noise
 
 local np_prec = {
 	offset = 0,
 	scale = 1,
-	spread = {x = PRECSPR, y = PRECSPR, z = PRECSPR},
+	spread = {x = PRECTIM, y = PRECTIM, z = PRECTIM},
 	seed = 813,
 	octaves = 1,
 	persist = 0,
 	lacunarity = 2.0,
-	--flags = ""
+	flags = "defaults"
 }
 
 -- These 2 must match biome heat and humidity noise parameters for a world
@@ -29,7 +46,7 @@ local np_temp = {
 	octaves = 3,
 	persist = 0.5,
 	lacunarity = 2.0,
-	--flags = ""
+	flags = "defaults"
 }
 
 local np_humid = {
@@ -40,13 +57,17 @@ local np_humid = {
 	octaves = 3,
 	persist = 0.5,
 	lacunarity = 2.0,
-	--flags = ""
+	flags = "defaults"
 }
 
+-- End parameters
 
--- Stuff
+
+-- Some stuff
 
 local difsval = DASVAL - NISVAL
+local grad = 14 / 95
+local yint = 1496 / 95
 
 
 -- Initialise noise objects to nil
@@ -56,19 +77,43 @@ local nobj_humid = nil
 local nobj_prec = nil
 
 
+-- Player tables
+
+local handles = {}
+local skybox = {} -- true/false. To not turn off skyboxes of other mods
+
+
 -- Globalstep function
 
+local os_time_0 = os.time()
+local t_offset = math.random(0, 300000)
+
+local timer = 0
+
 minetest.register_globalstep(function(dtime)
-	for _, player in ipairs(minetest.get_connected_players()) do
-		-- Randomise and spread processing load
-		if math.random() > PROCHA then
+	timer = timer + dtime
+	if timer < 0.5 then
 		return
 	end
 
+	timer = 0
+
+	for _, player in ipairs(minetest.get_connected_players()) do
+		local player_name = player:get_player_name()
 		local ppos = player:getpos()
+		-- Point just above player head, to ensure precipitation when swimming
+		local pposy = math.floor(ppos.y) + 2
+		if pposy >= YMIN and pposy <= YMAX then
 			local pposx = math.floor(ppos.x)
-		local pposy = math.floor(ppos.y)
 			local pposz = math.floor(ppos.z)
+			local ppos = {x = pposx, y = pposy, z = pposz}
+
+			-- Heat, humidity and precipitation noises
+
+			-- Time in seconds.
+			-- Add the per-server-session random time offset to avoid identical behaviour
+			-- each server session.
+			local time = os.difftime(os.time(), os_time_0) - t_offset
 
 			local nobj_temp = nobj_temp or minetest.get_perlin(np_temp)
 			local nobj_humid = nobj_humid or minetest.get_perlin(np_humid)
@@ -76,26 +121,30 @@ minetest.register_globalstep(function(dtime)
 
 			local nval_temp = nobj_temp:get2d({x = pposx, y = pposz})
 			local nval_humid = nobj_humid:get2d({x = pposx, y = pposz})
-		local nval_prec = nobj_prec:get2d({x = os.clock() / 60, y = 0})
+			local nval_prec = nobj_prec:get2d({x = time, y = 0})
+
+			-- Default Minetest Game biome system:
+			-- Frozen biomes below heat 35
+			-- deserts below line 14 * t - 95 * h = -1496
+			-- h = (14 * t + 1496) / 95
+			-- h = 14/95 * t + 1496/95
+			-- where 14/95 is gradient and 1496/95 is 'y-intersection'
+			-- h - 14/95 * t = 1496/95
+			-- so area above line is
+			-- h - 14/95 * t > 1496/95
 
-		-- Biome system: frozen biomes below heat 35,
-		-- deserts below humidity 20
 			local freeze = nval_temp < 35
-		local precip = nval_prec > (nval_humid - 50) / 50 + PRECOFF
+			local precip = nval_prec > PRECTHR and
+				nval_humid - grad * nval_temp > yint
 
-		-- Check if player is outside
-		local outside = minetest.get_node_light(ppos, 0.5) == 15
-
-		-- Occasionally reset player sky
-		if math.random() < 0.05 then
-			if precip then
-				-- Set overcast sky
+			-- Set sky
+			if precip and not skybox[player_name] then
+				-- Set overcast sky only if normal
 				local sval
 				local time = minetest.get_timeofday()
 				if time >= 0.5 then
 					time = 1 - time
 				end
-
 				-- Sky brightness transitions:
 				-- First transition (24000 -) 4500, (1 -) 0.1875
 				-- Last transition (24000 -) 5750, (1 -) 0.2396
@@ -104,59 +153,87 @@ minetest.register_globalstep(function(dtime)
 				elseif time >= 0.2396 then
 					sval = DASVAL
 				else
-					sval = math.floor(NISVAL + ((time - 0.1875) / 0.0521) * difsval)
+					sval = math.floor(NISVAL +
+						((time - 0.1875) / 0.0521) * difsval)
+				end
+				player:set_sky({r = sval, g = sval, b = sval + 16, a = 255},
+					"plain", {}, false)
+				skybox[player_name] = true
+			elseif not precip and skybox[player_name] then
+				-- Set normal sky only if skybox
+				player:set_sky({}, "regular", {}, true)
+				skybox[player_name] = nil
 			end
 
-				player:set_sky({r = sval, g = sval, b = sval + 16, a = 255}, "plain", {})
-			else
-				-- Reset sky to normal
-				player:set_sky({}, "regular", {})
+			-- Stop looping sound.
+			-- Stop sound if head below water level.
+			if not precip or freeze or pposy < YWATER then
+				if handles[player_name] then
+					minetest.sound_stop(handles[player_name])
+					handles[player_name] = nil
 				end
 			end
 
-		if precip and outside then
-			-- Precipitation
+			-- Particles and sounds.
+			-- Only if head above water level.
+			if precip and pposy >= YWATER then
 				if freeze then
-				-- Snowfall
-				for flake = 1, FLAKES do
+					-- Snowfall particles
+					for lpos = 1, FLAKLPOS do
+						local lposx = pposx - FLAKRAD +
+							math.random(0, FLAKRAD * 2)
+						local lposz = pposz - FLAKRAD +
+							math.random(0, FLAKRAD * 2)
+						if minetest.get_node_light(
+								{x = lposx, y = pposy + 10, z = lposz},
+								0.5) == 15 then
+							-- Any position above light-tested position is also
+							-- light level 15.
+							-- Spawn Y randomised to avoid particles falling
+							-- in separated layers.
+							-- Random range = speed * cycle time
+							local spawny = pposy + 10 + math.random(0, 10) / 10
+							local extime = math.min((spawny - YWATER) / 2, 10)
+
 							minetest.add_particle({
-						pos = {
-							x = pposx - 32 + math.random(0, 63),
-							y = pposy + 10 + math.random(0, 4),
-							z = pposz - 26 + math.random(0, 63)
-						},
-						vel = {
-							x = 0.0,
-							y = -2.0,
-							z = -1.0
-						},
-						acc = {x = 0, y = 0, z = 0},
-						expirationtime = 12,
+								pos = {x = lposx, y = spawny, z = lposz},
+								velocity = {x = 0, y = -2.0, z = 0},
+								acceleration = {x = 0, y = 0, z = 0},
+								expirationtime = extime,
 								size = 2.8,
-						collisiondetection = false,
+								collisiondetection = true,
+								collision_removal = true,
 								vertical = false,
-						texture = "snowdrift_snowflake" .. math.random(1, 4) .. ".png",
+								texture = "snowdrift_snowflake" ..
+									math.random(1, 12) .. ".png",
 								playername = player:get_player_name()
 							})
 						end
+					end
 				else
-				-- Rainfall
-				for flake = 1, DROPS do
+					-- Rainfall particles
+					for lpos = 1, DROPLPOS do
+						local lposx = pposx - DROPRAD +
+							math.random(0, DROPRAD * 2)
+						local lposz = pposz - DROPRAD +
+							math.random(0, DROPRAD * 2)
+						if minetest.get_node_light(
+								{x = lposx, y = pposy + 10, z = lposz},
+								0.5) == 15 then
+							for drop = 1, DROPPPOS do
+								local spawny = pposy + 10 + math.random(0, 60) / 10
+								local extime = math.min((spawny - YWATER) / 12, 2)
+								local spawnx = lposx - 0.4 + math.random(0, 8) / 10
+								local spawnz = lposz - 0.4 + math.random(0, 8) / 10
+
 								minetest.add_particle({
-						pos = {
-							x = pposx - 8 + math.random(0, 16),
-							y = pposy + 6 + math.random(0, 4),
-							z = pposz - 8 + math.random(0, 16)
-						},
-						vel = {
-							x = 0.0,
-							y = -8.0,
-							z = 0.0
-						},
-						acc = {x = 0, y = 0, z = 0},
-						expirationtime = 2,
+									pos = {x = spawnx, y = spawny, z = spawnz},
+									velocity = {x = 0.0, y = -12.0, z = 0.0},
+									acceleration = {x = 0, y = 0, z = 0},
+									expirationtime = extime,
 									size = 2.8,
-						collisiondetection = false,
+									collisiondetection = true,
+									collision_removal = true,
 									vertical = true,
 									texture = "snowdrift_raindrop.png",
 									playername = player:get_player_name()
@@ -164,5 +241,50 @@ minetest.register_globalstep(function(dtime)
 							end
 						end
 					end
+					-- Start looping sound
+					if not handles[player_name] then
+						local handle = minetest.sound_play(
+							"snowdrift_rain",
+							{
+								to_player = player_name,
+								gain = RAINGAIN,
+								loop = true,
+							}
+						)
+						if handle then
+							handles[player_name] = handle
+						end
+					end
+				end
+			end
+		else
+			-- Player outside y limits.
+			-- Stop sound if playing.
+			if handles[player_name] then
+				minetest.sound_stop(handles[player_name])
+				handles[player_name] = nil
+			end
+			-- Set normal sky if skybox
+			if skybox[player_name] then
+				player:set_sky({}, "regular", {}, true)
+				skybox[player_name] = nil
+			end
+		end
+	end
+end)
+
+
+-- On leaveplayer function
+
+minetest.register_on_leaveplayer(function(player)
+	local player_name = player:get_player_name()
+	-- Stop sound if playing and remove handle
+	if handles[player_name] then
+		minetest.sound_stop(handles[player_name])
+		handles[player_name] = nil
+	end
+	-- Remove skybox bool if necessary
+	if skybox[player_name] then
+		skybox[player_name] = nil
 	end
 end)

license.txt

@@ -2,7 +2,7 @@ License of source code
 ----------------------
 
 The MIT License (MIT)
-Copyright (C) 2014-2016 paramat
+Copyright (C) 2017 paramat
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of this
 software and associated documentation files (the "Software"), to deal in the Software
@@ -22,3 +22,70 @@ DEALINGS IN THE SOFTWARE.
 
 For more details:
 https://opensource.org/licenses/MIT
+
+
+License of media (textures)
+---------------------------
+
+Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)
+Copyright (C) 2017 paramat
+
+You are free to:
+Share — copy and redistribute the material in any medium or format.
+Adapt — remix, transform, and build upon the material for any purpose, even commercially.
+The licensor cannot revoke these freedoms as long as you follow the license terms.
+
+Under the following terms:
+
+Attribution — You must give appropriate credit, provide a link to the license, and
+indicate if changes were made. You may do so in any reasonable manner, but not in any way
+that suggests the licensor endorses you or your use.
+
+ShareAlike — If you remix, transform, or build upon the material, you must distribute
+your contributions under the same license as the original.
+
+No additional restrictions — You may not apply legal terms or technological measures that
+legally restrict others from doing anything the license permits.
+
+Notices:
+
+You do not have to comply with the license for elements of the material in the public
+domain or where your use is permitted by an applicable exception or limitation.
+No warranties are given. The license may not give you all of the permissions necessary
+for your intended use. For example, other rights such as publicity, privacy, or moral
+rights may limit how you use the material.
+
+For more details:
+http://creativecommons.org/licenses/by-sa/3.0/
+
+
+License of media (sounds)
+-------------------------
+
+Attribution 3.0 Unported (CC BY 3.0)
+Copyright (C) 2008 inchadney
+
+You are free to:
+Share — copy and redistribute the material in any medium or format.
+Adapt — remix, transform, and build upon the material for any purpose, even commercially.
+The licensor cannot revoke these freedoms as long as you follow the license terms.
+
+Under the following terms:
+
+Attribution — You must give appropriate credit, provide a link to the license, and
+indicate if changes were made. You may do so in any reasonable manner, but not in any way
+that suggests the licensor endorses you or your use.
+
+No additional restrictions — You may not apply legal terms or technological measures that
+legally restrict others from doing anything the license permits.
+
+Notices:
+
+You do not have to comply with the license for elements of the material in the public
+domain or where your use is permitted by an applicable exception or limitation.
+No warranties are given. The license may not give you all of the permissions necessary
+for your intended use. For example, other rights such as publicity, privacy, or moral
+rights may limit how you use the material.
+
+For more details:
+http://creativecommons.org/licenses/by/3.0/