Add glow feature to signs, with three brightness levels

api.lua

@@ -4,6 +4,8 @@ local S = signs_lib.gettext
 
 local function get_sign_formspec() end
 
+signs_lib.glow_item = "basic_materials:energy_crystal_simple"
+
 signs_lib.lbm_restore_nodes = {}
 signs_lib.old_fenceposts = {}
 signs_lib.old_fenceposts_replacement_signs = {}
@@ -180,7 +182,7 @@ function signs_lib.delete_objects(pos)
 	end
 end
 
-function signs_lib.spawn_entity(pos, texture)
+function signs_lib.spawn_entity(pos, texture, glow)
 	local node = minetest.get_node(pos)
 	local def = minetest.registered_items[node.name]
 	if not def or not def.entity_info then return end
@@ -229,6 +231,10 @@ function signs_lib.spawn_entity(pos, texture)
 		end
 	end
 
+	if glow ~= "" then
+		obj:set_properties({glow = tonumber(glow * 5))
+	end
+
 	if yaw then
 		obj:set_rotation({x = pitch, y = yaw, z=0})
 
@@ -247,14 +253,15 @@ function signs_lib.spawn_entity(pos, texture)
 	end
 end
 
-function signs_lib.set_obj_text(pos, text)
+function signs_lib.set_obj_text(pos, text, glow)
 	local split = signs_lib.split_lines_and_words
 	local text_ansi = Utf8ToAnsi(text)
 	local n = minetest.registered_nodes[minetest.get_node(pos).name]
 	signs_lib.delete_objects(pos)
 	-- only create sign entity for actual text
 	if text_ansi and text_ansi ~= "" then
-		signs_lib.spawn_entity(pos, signs_lib.make_sign_texture(split(text_ansi), pos) )
+		signs_lib.spawn_entity(pos,
+				signs_lib.make_sign_texture(split(text_ansi), pos), glow)
 	end
 end
 
@@ -707,6 +714,12 @@ function signs_lib.rightclick_sign(pos, node, player, itemstack, pointed_thing)
 end
 
 function signs_lib.destruct_sign(pos)
+	local meta = minetest.get_meta(pos)
+	local glow = meta:get_string("glow")
+	if glow ~= "" then
+		local num = tonumber(glow)
+		minetest.add_item(pos, ItemStack(signs_lib.glow_item .. " " .. num))
+	end
 	signs_lib.delete_objects(pos)
 end
 
@@ -720,6 +733,24 @@ local function make_infotext(text)
 	return table.concat(lines2, "\n")
 end
 
+function signs_lib.glow(pos, node, puncher)
+	local tool = puncher:get_wielded_item()
+	if tool:get_name() == signs_lib.glow_item then
+		local meta = minetest.get_meta(pos)
+		local glow = tonumber(meta:get_string("glow"))
+		if not glow then
+			glow = 1
+		elseif glow < 3 then
+			glow = glow + 1
+		else
+			return -- already at brightest level
+		end
+		tool:take_item()
+		puncher:set_wielded_item(tool)
+		meta:set_string("glow", glow)
+	end
+end
+
 function signs_lib.update_sign(pos, fields)
 	local meta = minetest.get_meta(pos)
 
@@ -737,7 +768,9 @@ function signs_lib.update_sign(pos, fields)
 
 	meta:set_string("text", text)
 	meta:set_string("infotext", ownstr..make_infotext(text).." ")
-	signs_lib.set_obj_text(pos, text)
+
+	local glow = meta:get_string("glow")
+	signs_lib.set_obj_text(pos, text, glow)
 end
 
 function signs_lib.can_modify(pos, player)

standard_signs.lua

@@ -16,6 +16,10 @@ signs_lib.register_sign("default:sign_wall_wood", {
 	allow_onpole_horizontal = true,
 	allow_yard = true,
 	use_texture_alpha = "clip",
+	on_punch = function(pos, node, puncher, pointed_thing)
+		signs_lib.glow(pos, node, puncher)
+		return signs_lib.update_sign
+	end
 })
 
 signs_lib.register_sign("default:sign_wall_steel", {