add on_sound node support and example.

api.lua

@@ -18,7 +18,7 @@ end
 
 mobs = {
 	mod = "redo",
-	version = "20241001",
+	version = "20241002",
 	spawning_mobs = {},
 	translate = S,
 	invis = minetest.global_exists("invisibility") and invisibility or {},
@@ -4794,13 +4794,27 @@ if settings:get_bool("mobs_can_hear") ~= false then
 					def.loudness = def.gain - (bit * def.distance)
 
 					-- run custom on_sound function if heard
-					if def.loudness > 0 then
-						ent.on_sound(ent, def)
-					end
+					if def.loudness > 0 then ent.on_sound(ent, def) end
 				end
 			end
 		end
 
+		-- find nodes that can hear up to 8 blocks away
+		local dist = min(def.max_hear_distance, 8)
+		local ps = minetest.find_nodes_in_area(
+				vector.subtract(def.pos, dist),
+				vector.add(def.pos, dist), {"group:on_sound"})
+
+		if #ps > 0 then
+
+			for n = 1, #ps do
+
+				local ndef = minetest.registered_nodes[minetest.get_node(ps[n]).name]
+
+				if ndef and ndef.on_sound then ndef.on_sound(ps[n], def) end
+			end
+		end
+
 		return old_sound_play(spec, param, eph)
 	end
 end

api.txt

@@ -357,6 +357,14 @@ enhance mob functionality and have them do many interesting things:
       'max_hear_distance' max distance sound can be heard from source.
 
 
+Hearing Nodes
+-------------
+
+If a node has the {on_sound = 1} group and an on_sound() function set as above then
+nodes within 8 blocks of a sound will be activated and the function run.  Check the
+"mobs:hearing_vines" node as an example which has mesecons support when active.
+
+
 Internal Variables
 ------------------
 

crafts.lua

@@ -421,3 +421,57 @@ minetest.register_craft({
 	recipe = "mobs:meatblock_raw",
 	cooktime = 30
 })
+
+-- hearing vines (if mesecons active it acts like blinkyplant)
+
+local mod_mese = minetest.get_modpath("mesecons")
+
+minetest.register_node("mobs:hearing_vines", {
+	description = S("Hearing Vines"),
+	drawtype = "firelike",
+	waving = 1,
+	tiles = {"mobs_hearing_vines.png"},
+	inventory_image = "mobs_hearing_vines.png",
+	wield_image = "mobs_hearing_vines.png",
+	paramtype = "light",
+	sunlight_propagates = true,
+	walkable = false,
+	buildable_to = true,
+	groups = {snappy = 3, flammable = 3, attached_node = 1, on_sound = 1},
+	sounds = mobs.node_sound_leaves_defaults(),
+	selection_box = {
+		type = "fixed", fixed = {-6 / 16, -0.5, -6 / 16, 6 / 16, -0.25, 6 / 16},
+	},
+	on_sound = function(pos, def)
+		minetest.set_node(pos, {name = "mobs:hearing_vines_active"})
+	end
+})
+
+minetest.register_node("mobs:hearing_vines_active", {
+	description = S("Active Hearing Vines"),
+	drawtype = "firelike",
+	waving = 1,
+	tiles = {"mobs_hearing_vines_active.png"},
+	inventory_image = "mobs_hearing_vines_active.png",
+	wield_image = "mobs_hearing_vines_active.png",
+	paramtype = "light",
+	sunlight_propagates = true,
+	walkable = false,
+	buildable_to = true,
+	light_source = 1,
+	damage_per_second = 4,
+	drop = "mobs:hearing_vines",
+	groups = {snappy = 3, flammable = 3, attached_node = 1, not_in_creative_inventory = 1},
+	sounds = mobs.node_sound_leaves_defaults(),
+	selection_box = {
+		type = "fixed", fixed = {-6 / 16, -0.5, -6 / 16, 6 / 16, -0.25, 6 / 16},
+	},
+	on_construct = function(pos)
+		minetest.get_node_timer(pos):start(1)
+		if mod_mese then mesecon.receptor_on(pos) end
+	end,
+	on_timer = function(pos)
+		minetest.set_node(pos, {name = "mobs:hearing_vines"})
+		if mod_mese then mesecon.receptor_off(pos) end
+	end
+})

mod.conf

@@ -1,4 +1,4 @@
 name = mobs
 description = Adds a mob api for mods to add animals or monsters etc.
-optional_depends = default, tnt, invisibility, lucky_block, cmi, toolranks, pathfinder, player_api, mtobjid, visual_harm_1ndicators, mcl_sounds
+optional_depends = default, tnt, invisibility, lucky_block, cmi, toolranks, pathfinder, player_api, mtobjid, visual_harm_1ndicators, mcl_sounds, mesecons
 min_minetest_version = 5.0