add ambience sounds and helper function

.luacheckrc

@@ -3,7 +3,8 @@ std = "min+minetest"
 unused_args = false
 
 globals = {
-	"scifi_nodes"
+	"scifi_nodes",
+	"minetest"
 }
 
 read_globals = {
@@ -13,7 +14,6 @@ read_globals = {
 	"stairsplus",
 	"xpanes",
 	"screwdriver",
-	"minetest",
 	"mesecon",
 	"unifieddyes",
 	"letters",

README.md

@@ -49,6 +49,9 @@ CC BY 3.0
 
 CC0
 * scifi_nodes_digicode.ogg https://freesound.org/people/benjaminharveydesign/sounds/315921/
+* scifi_nodes_ambience_fan.ogg https://freesound.org/people/itinerantmonk108/sounds/554430/
+* scifi_nodes_ambience_vent.ogg https://freesound.org/people/kentspublicdomain/sounds/324665/
+* scifi_nodes_ambience_engine.ogg https://freesound.org/people/firestorm185/sounds/423221/
 
 
 # Contributors:

ambience.lua

@@ -0,0 +1,73 @@
+
+-- currently playing sounds per mapblock
+-- mapblock_pos[number]
+local currently_playing = {}
+
+-- clear the currently playing tracker every few seconds
+local function clear_currently_playing()
+    currently_playing = {}
+    minetest.after(5, clear_currently_playing)
+end
+minetest.after(5, clear_currently_playing)
+
+-- mapblock resolution
+local function get_key(pos)
+    return minetest.pos_to_string(vector.round(vector.divide(pos, 16)))
+end
+
+local function add_currently_playing(pos, value)
+    local key = get_key(pos)
+    local count = currently_playing[key]
+    if not count then
+        -- new entry
+        count = value
+    else
+        -- update entry
+        count = count + value
+    end
+    currently_playing[key] = count
+end
+
+-- limit plaing sounds per mapblock
+local function can_play(pos)
+    local count = currently_playing[get_key(pos)]
+    return not count or count < 10
+end
+
+-- register ambience sounds with node-timer
+function scifi_nodes.register_ambience(nodename, soundname, opts)
+    assert(opts)
+    opts.interval = opts.interval or 60
+
+    local function play(pos)
+        minetest.sound_play(soundname ,{
+            max_hear_distance = opts.max_hear_distance or 16,
+            pos = pos,
+            gain = opts.gain or 0.7
+        })
+    end
+
+    minetest.override_item(nodename, {
+        on_timer = function(pos)
+            local timer = minetest.get_node_timer(pos)
+
+            if not can_play(pos) then
+                -- too many sounds playing, recheck again soon
+                timer:start(2)
+                return
+            end
+
+            -- increment usage count
+            add_currently_playing(pos, 1)
+            play(pos)
+
+            -- restart timer
+            timer:start(opts.interval)
+        end,
+        on_construct = function(pos)
+            play(pos)
+            local timer = minetest.get_node_timer(pos)
+            timer:start(opts.interval)
+        end
+    })
+end

init.lua

@@ -20,6 +20,7 @@ if minetest.get_modpath("default") then
 	dofile(MP.."/chest.lua")
 end
 
+dofile(MP.."/ambience.lua")
 dofile(MP.."/plants.lua")
 dofile(MP.."/models.lua")
 dofile(MP.."/nodes.lua")

nodes.json

@@ -25,7 +25,13 @@
         "texture_name": "white2"
     },
     "engine": {
-        "description": "Engine"
+        "description": "Engine",
+        "ambience": {
+            "scifi_nodes_ambience_engine": {
+                "interval": 16.1,
+                "gain": 2.0
+            }
+        }
     },
     "wall": {
         "description": "metal wall"
@@ -58,7 +64,12 @@
         "description": "transparent vent",
         "texture_name": "vent2",
         "texture_modifier": "^[makealpha:33,33,33",
-        "drawtype": "glasslike"
+        "drawtype": "glasslike",
+        "ambience": {
+            "scifi_nodes_ambience_vent": {
+                "interval": 4.2
+            }
+        }
     },
     "stripes": {
         "description": "hazard stripes",
@@ -261,7 +272,12 @@
         "light": 5
     },
     "fan": {
-        "description": "Fan"
+        "description": "Fan",
+        "ambience": {
+            "scifi_nodes_ambience_fan": {
+                "interval": 7
+            }
+        }
     },
     "ppllght": {
         "description": "Purple wall light",

nodes.lua

@@ -537,7 +537,8 @@ for name, def in pairs(nodes) do
 	end
 
 	-- register node
-	minetest.register_node("scifi_nodes:"..name, node_def)
+	local nodename = "scifi_nodes:" .. name
+	minetest.register_node(nodename , node_def)
 
 	-- unified dyes registration
 	if def.colorable and has_unifieddyes_mod then
@@ -574,6 +575,13 @@ for name, def in pairs(nodes) do
 		})
 	end
 
+	if def.ambience then
+		for soundname, opts in pairs(def.ambience) do
+			print(dump(opts))
+			scifi_nodes.register_ambience(nodename, soundname, opts)
+		end
+	end
+
 	-- advtrains platform registration
 	if has_advtrains_mod and def.advtrains_platform then
 		advtrains.register_platform("scifi_nodes", "scifi_nodes:" .. name)