Make light blocks `buildable_to`

mods/CORE/mcl_util/init.lua

@@ -34,7 +34,6 @@ function mcl_util.mcl_log (message, module, bypass_default_logger)
 	end
 end
 
-
 function mcl_util.file_exists(name)
 	if type(name) ~= "string" then return end
 	local f = io.open(name)
@@ -704,8 +703,10 @@ assert(not close_enough(test_eh,test_eh_diff))
 assert(not close_enough(test_nt, test_nt_diff)) --no floats involved here
 
 --tests for properties_changed
-local test_properties_set1={collisionbox = {-0.35,0,-0.35,0.35,0.8,0.35}, eye_height = 0.65, nametag_color = { r = 225, b = 225, a = 225, g = 225 }}
+local test_properties_set1 = {collisionbox = {-0.35, 0, -0.35, 0.35, 0.8, 0.35}, eye_height = 0.65,
-local test_properties_set2={collisionbox = {-0.35,0,-0.35,0.35,0.8,0.35}, eye_height = 1.35, nametag_color = { r = 225, b = 225, a = 225, g = 225 }}
+	nametag_color = {r = 225, b = 225, a = 225, g = 225}}
+local test_properties_set2 = {collisionbox = {-0.35, 0, -0.35, 0.35, 0.8, 0.35}, eye_height = 1.35,
+	nametag_color = {r = 225, b = 225, a = 225, g = 225}}
 
 local test_p1, _ = props_changed(test_properties_set1, test_properties_set1)
 local test_p2, _ = props_changed(test_properties_set1, test_properties_set2)
@@ -729,6 +730,243 @@ function mcl_util.set_bone_position(obj, bone, pos, rot)
 	end
 end
 
+---Return a function to use in `on_place`.
+---
+---Allow to bypass the `buildable_to` node field in a `on_place` callback.
+---
+---You have to make sure that the nodes you return true for have `buildable_to = true`.
+---@param func fun(node_name: string): boolean Return `true` if node must not replace the buildable_to node which have `node_name`
+---@return fun(itemstack: ItemStack, placer: ObjectRef, pointed_thing: pointed_thing, param2: integer): ItemStack?
+function mcl_util.bypass_buildable_to(func)
+	--------------------------
+	-- MINETEST CODE: UTILS --
+	--------------------------
+
+	local function copy_pointed_thing(pointed_thing)
+		return {
+			type  = pointed_thing.type,
+			above = pointed_thing.above and vector.copy(pointed_thing.above),
+			under = pointed_thing.under and vector.copy(pointed_thing.under),
+			ref   = pointed_thing.ref,
+		}
+	end
+
+	local function user_name(user)
+		return user and user:get_player_name() or ""
+	end
+
+	-- Returns a logging function. For empty names, does not log.
+	local function make_log(name)
+		return name ~= "" and minetest.log or function() end
+	end
+
+	local function check_attached_node(p, n, group_rating)
+		local def = core.registered_nodes[n.name]
+		local d = vector.zero()
+		if group_rating == 3 then
+			-- always attach to floor
+			d.y = -1
+		elseif group_rating == 4 then
+			-- always attach to ceiling
+			d.y = 1
+		elseif group_rating == 2 then
+			-- attach to facedir or 4dir direction
+			if (def.paramtype2 == "facedir" or
+				def.paramtype2 == "colorfacedir") then
+				-- Attach to whatever facedir is "mounted to".
+				-- For facedir, this is where tile no. 5 point at.
+
+				-- The fallback vector here is in case 'facedir to dir' is nil due
+				-- to voxelmanip placing a wallmounted node without resetting a
+				-- pre-existing param2 value that is out-of-range for facedir.
+				-- The fallback vector corresponds to param2 = 0.
+				d = core.facedir_to_dir(n.param2) or vector.new(0, 0, 1)
+			elseif (def.paramtype2 == "4dir" or
+				def.paramtype2 == "color4dir") then
+				-- Similar to facedir handling
+				d = core.fourdir_to_dir(n.param2) or vector.new(0, 0, 1)
+			end
+		elseif def.paramtype2 == "wallmounted" or
+			def.paramtype2 == "colorwallmounted" then
+			-- Attach to whatever this node is "mounted to".
+			-- This where tile no. 2 points at.
+
+			-- The fallback vector here is used for the same reason as
+			-- for facedir nodes.
+			d = core.wallmounted_to_dir(n.param2) or vector.new(0, 1, 0)
+		else
+			d.y = -1
+		end
+		local p2 = vector.add(p, d)
+		local nn = core.get_node(p2).name
+		local def2 = core.registered_nodes[nn]
+		if def2 and not def2.walkable then
+			return false
+		end
+		return true
+	end
+
+	return function(itemstack, placer, pointed_thing, param2)
+		-------------------
+		-- MINETEST CODE --
+		-------------------
+		local def = itemstack:get_definition()
+		if def.type ~= "node" or pointed_thing.type ~= "node" then
+			return itemstack
+		end
+
+		local under = pointed_thing.under
+		local oldnode_under = minetest.get_node_or_nil(under)
+		local above = pointed_thing.above
+		local oldnode_above = minetest.get_node_or_nil(above)
+		local playername = user_name(placer)
+		local log = make_log(playername)
+
+		if not oldnode_under or not oldnode_above then
+			log("info", playername .. " tried to place"
+				.. " node in unloaded position " .. minetest.pos_to_string(above))
+			return itemstack
+		end
+
+		local olddef_under = minetest.registered_nodes[oldnode_under.name]
+		olddef_under = olddef_under or minetest.nodedef_default
+		local olddef_above = minetest.registered_nodes[oldnode_above.name]
+		olddef_above = olddef_above or minetest.nodedef_default
+
+		if not olddef_above.buildable_to and not olddef_under.buildable_to then
+			log("info", playername .. " tried to place"
+				.. " node in invalid position " .. minetest.pos_to_string(above)
+				.. ", replacing " .. oldnode_above.name)
+			return itemstack
+		end
+
+		---------------------
+		-- CUSTOMIZED CODE --
+		---------------------
+
+		-- Place above pointed node
+		local place_to = vector.copy(above)
+
+		-- If node under is buildable_to, check for callback result and place into it instead
+		if olddef_under.buildable_to and not func(oldnode_under.name) then
+			log("info", "node under is buildable to")
+			place_to = vector.copy(under)
+		end
+
+		-------------------
+		-- MINETEST CODE --
+		-------------------
+
+		if minetest.is_protected(place_to, playername) then
+			log("action", playername
+				.. " tried to place " .. def.name
+				.. " at protected position "
+				.. minetest.pos_to_string(place_to))
+			minetest.record_protection_violation(place_to, playername)
+			return itemstack
+		end
+
+		local oldnode = minetest.get_node(place_to)
+		local newnode = {name = def.name, param1 = 0, param2 = param2 or 0}
+
+		-- Calculate direction for wall mounted stuff like torches and signs
+		if def.place_param2 ~= nil then
+			newnode.param2 = def.place_param2
+		elseif (def.paramtype2 == "wallmounted" or
+			def.paramtype2 == "colorwallmounted") and not param2 then
+			local dir = vector.subtract(under, above)
+			newnode.param2 = minetest.dir_to_wallmounted(dir)
+			-- Calculate the direction for furnaces and chests and stuff
+		elseif (def.paramtype2 == "facedir" or
+			def.paramtype2 == "colorfacedir" or
+			def.paramtype2 == "4dir" or
+			def.paramtype2 == "color4dir") and not param2 then
+			local placer_pos = placer and placer:get_pos()
+			if placer_pos then
+				local dir = vector.subtract(above, placer_pos)
+				newnode.param2 = minetest.dir_to_facedir(dir)
+				log("info", "facedir: " .. newnode.param2)
+			end
+		end
+
+		local metatable = itemstack:get_meta():to_table().fields
+
+		-- Transfer color information
+		if metatable.palette_index and not def.place_param2 then
+			local color_divisor = nil
+			if def.paramtype2 == "color" then
+				color_divisor = 1
+			elseif def.paramtype2 == "colorwallmounted" then
+				color_divisor = 8
+			elseif def.paramtype2 == "colorfacedir" then
+				color_divisor = 32
+			elseif def.paramtype2 == "color4dir" then
+				color_divisor = 4
+			elseif def.paramtype2 == "colordegrotate" then
+				color_divisor = 32
+			end
+			if color_divisor then
+				local color = math.floor(metatable.palette_index / color_divisor)
+				local other = newnode.param2 % color_divisor
+				newnode.param2 = color * color_divisor + other
+			end
+		end
+
+		-- Check if the node is attached and if it can be placed there
+		local an = minetest.get_item_group(def.name, "attached_node")
+		if an ~= 0 and
+			not check_attached_node(place_to, newnode, an) then
+			log("action", "attached node " .. def.name ..
+				" cannot be placed at " .. minetest.pos_to_string(place_to))
+			return itemstack
+		end
+
+		log("action", playername .. " places node "
+			.. def.name .. " at " .. minetest.pos_to_string(place_to))
+
+		-- Add node and update
+		minetest.add_node(place_to, newnode)
+
+		-- Play sound if it was done by a player
+		if playername ~= "" and def.sounds and def.sounds.place then
+			minetest.sound_play(def.sounds.place, {
+				pos = place_to,
+				exclude_player = playername,
+			}, true)
+		end
+
+		local take_item = true
+
+		-- Run callback
+		if def.after_place_node then
+			-- Deepcopy place_to and pointed_thing because callback can modify it
+			local place_to_copy = vector.copy(place_to)
+			local pointed_thing_copy = copy_pointed_thing(pointed_thing)
+			if def.after_place_node(place_to_copy, placer, itemstack,
+				pointed_thing_copy) then
+				take_item = false
+			end
+		end
+
+		-- Run script hook
+		for _, callback in ipairs(minetest.registered_on_placenodes) do
+			-- Deepcopy pos, node and pointed_thing because callback can modify them
+			local place_to_copy = vector.copy(place_to)
+			local newnode_copy = {name = newnode.name, param1 = newnode.param1, param2 = newnode.param2}
+			local oldnode_copy = {name = oldnode.name, param1 = oldnode.param1, param2 = oldnode.param2}
+			local pointed_thing_copy = copy_pointed_thing(pointed_thing)
+			if callback(place_to_copy, newnode_copy, placer, oldnode_copy, itemstack, pointed_thing_copy) then
+				take_item = false
+			end
+		end
+
+		if take_item then
+			itemstack:take_item()
+		end
+		return itemstack
+	end
+end
+
 --[[Check for a protection violation in a given area.
 --
 -- Applies is_protected() to a 3D lattice of points in the defined volume. The points are spaced

mods/ITEMS/mcl_core/nodes_misc.lua

@@ -262,6 +262,8 @@ for i = 0, 14 do --minetest.LIGHT_MAX
 		walkable = false,
 		light_source = i,
 		drop = "",
+		buildable_to = true,
+		node_placement_prediction = "",
 		inventory_image = "mcl_core_light_" .. i .. ".png",
 		wield_image = "mcl_core_light_" .. i .. ".png",
 		sunlight_propagates = true,
@@ -272,6 +274,9 @@ for i = 0, 14 do --minetest.LIGHT_MAX
 			itemstack:set_name("mcl_core:light_" .. ((i == 14) and 0 or i + 1))
 			return itemstack
 		end,
+		on_place = mcl_util.bypass_buildable_to(function(node_name)
+			return string.match(node_name, "^mcl_core:light_(%d+)$")
+		end),
 		after_place_node = function(pos, placer, itemstack, pointed_thing)
 			if placer == nil then
 				return