dfcaverns/mine_gas/wisp.lua

local MP = minetest.get_modpath(minetest.get_current_modname())
local S, NS = dofile(MP.."/intllib.lua")

local wisp_desc
local wisp_usage

if minetest.get_modpath("doc") then
	wisp_desc = S("Mysterious blue flames may occasionally be found flickering on the edges of oil lakes, burning without oxygen and seeming to maintain their size as they drift about through the unbreathable atmosphere.")
	wisp_usage = S("Gas Wisps have no known use, and fortunately they are not hostile or very dangerous.")
end

minetest.register_node("mine_gas:gas_wisp", {
	description = S("Gas Wisp"),
	_doc_items_longdesc = wisp_desc,
	_doc_items_usagehelp = wisp_usage,
	walkable = false,
	is_ground_content = 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
					local node_name = minetest.get_node({x=pos.x+x, y=pos.y+y, z=pos.z+z}).name
					if node_name == "mine_gas:gas" or minetest.get_item_group(node_name, "flammable") > 0 then
						-- there's gas or a flammable adjacent, don't extinguish
						return
					end
				end
			end
		end
		-- no gas adjacent, extinguish
		minetest.set_node(pos, {name="air"})
	end,
})