Light nodes, and a barrier.

4 different basic lights: off, and 3 intensities.
one broken light that will flicker (nodetimer based)

mods/nodes/init.lua

@@ -108,6 +108,85 @@ for _, v in pairs(nodes) do
 
 end
 
+-- barrier
+minetest.register_node("nodes:barrier", {
+	description = "Barrier",
+	pointable = true, -- make it easy to understand that it's a barrier
+	drawtype = "allfaces_optional",
+	tiles = {"itb_blank.png"},
+	sunlight_propagates = true,
+	paramtype = "light",
+	collision_box = {
+		type = "fixed",
+		-- oversized to prevent crawling through
+		fixed = {-1,-1,-1,1,1,1},
+	},
+})
+
+-- light fixtures
+for _, v in pairs({14, 11, 8, 0}) do
+	minetest.register_node("nodes:lamp_bar_" .. v, {
+		description = "A Lamp (" .. v .. ")",
+		light_source = v,
+		sunlight_propagates = true,
+		tiles = {"lamp_bar.png"},
+		paramtype = "light",
+		paramtype2 = "facedir",
+		drawtype = "nodebox",
+		node_box = {
+			type = "fixed",
+			fixed = {-1, 1/4, 1/4, 1, 1/2, 1/2},
+		},
+		groups = {node = 1},
+		on_rotate = screwdriver.rotate_simple()
+	})
+end
+
+minetest.register_node("nodes:lamp_bar_broken", {
+	description = "A Broken Lamp (flickering)",
+	light_source = 8,
+	sunlight_propagates = true,
+	tiles = {"lamp_bar.png"},
+	paramtype = "light",
+	paramtype2 = "facedir",
+	drawtype = "nodebox",
+	node_box = {
+		type = "fixed",
+		fixed = {-1, 1/4, 1/4, 1, 1/2, 1/2},
+	},
+	groups = {node = 1},
+	on_rotate = screwdriver.rotate_simple(),
+	on_timer = function(pos)
+		local node = minetest.get_node(pos)
+		minetest.set_node(pos, {name = "nodes:lamp_bar_broken_off", param2 = node.param2})
+	end,
+	on_construct = function(pos)
+		minetest.get_node_timer(pos):start(math.random(50)/10)
+	end,
+})
+
+minetest.register_node("nodes:lamp_bar_broken_off", {
+	description = "A Broken Lamp (flickering, off)",
+	sunlight_propagates = true,
+	tiles = {"lamp_bar.png"},
+	paramtype = "light",
+	paramtype2 = "facedir",
+	drawtype = "nodebox",
+	node_box = {
+		type = "fixed",
+		fixed = {-1, 1/4, 1/4, 1, 1/2, 1/2},
+	},
+	groups = {node = 1},
+	on_rotate = screwdriver.rotate_simple(),
+	on_timer = function(pos)
+		local node = minetest.get_node(pos)
+		minetest.set_node(pos, {name = "nodes:lamp_bar_broken", param2 = node.param2})
+	end,
+	on_construct = function(pos)
+		minetest.get_node_timer(pos):start(math.random(50)/10)
+	end,
+})
+
 -- panes
 --	iron_pane
 --	glass_pane