add the wandering "gas wisp" to light up some of the gas-filled caverns

mine_gas/init.lua

@@ -1,6 +1,8 @@
 local MP = minetest.get_modpath(minetest.get_current_modname())
 local S, NS = dofile(MP.."/intllib.lua")
 
+dofile(MP.."/wisp.lua")
+
 local gas_desc
 local gas_usage
 

mine_gas/wisp.lua

@@ -0,0 +1,77 @@
+local MP = minetest.get_modpath(minetest.get_current_modname())
+local S, NS = dofile(MP.."/intllib.lua")
+
+minetest.register_node("mine_gas:gas_wisp", {
+	description = S("Gas Wisp"),
+	_doc_items_longdesc = nil,
+	_doc_items_usagehelp = nil,
+	walkable = false,
+	diggable = false,
+	buildable_to = true,
+	drawtype = "plantlike",
+	waving = 1,
+	drowning = 1,
+	damage_per_second = 4,
+	post_effect_color = {a = 20, r = 20, g = 20, b = 250},
+	tiles = {{name = "mine_gas_wisp.png", animation =
+		{
+			type = "vertical_frames",
+			aspect_w = 16,
+			aspect_h = 16,
+			length = 1.5,
+		},
+	}},
+	light_source = 10,
+	use_texture_alpha = true,
+	groups = {not_in_creative_inventory=0},
+	paramtype = "light",
+	paramtype2 = "meshoptions",
+	place_param2 = 0,
+	-- * bit 4 (0x10, decimal 16) - Makes the plant mesh 1.4x larger
+	inventory_image = "mine_gas_wisp_inventory.png",
+	drop = {},
+	sunlight_propagates = true,
+	--on_blast = function() end, -- unaffected by explosions
+})
+
+minetest.register_abm({
+    label = "mine_gas:gas wisp movement",
+    nodenames = {"mine_gas:gas_wisp"},
+    neighbors = {"mine_gas:gas"},
+    interval = 1.0,
+    chance = 10,
+    catch_up = true,
+    action = function(pos, node)
+		local next_pos = {x=pos.x+math.random(1,3)-2, y=pos.y+math.random(1,3)-2, z=pos.z+math.random(1,3)-2}
+		local next_node = minetest.get_node(next_pos)
+		if next_node.name == "mine_gas:gas" then
+			minetest.swap_node(next_pos, node)
+			minetest.swap_node(pos, next_node)
+		end
+		pos = next_pos
+
+	end,
+})
+
+minetest.register_abm({
+    label = "mine_gas:gas wisp extinguish",
+    nodenames = {"mine_gas:gas_wisp"},
+    neighbors = {"air"},
+    interval = 10,
+    chance = 1,
+    catch_up = true,
+    action = function(pos, node)
+		for y = -1, 1 do
+			for x = -1, 1 do
+				for z = -1, 1 do
+					if minetest.get_node({x=pos.x+x, y=pos.y+y, z=pos.z+z}).name == "mine_gas:gas" then
+						-- there's gas adjacent, don't extinguish
+						return
+					end
+				end
+			end
+		end
+		-- no gas adjacent, extinguish
+		minetest.set_node(pos, {name="air"})
+	end,
+})