Add support for attached facedir/4dir nodes (#11432)

2 files changed, 36 insertions, 10 deletions

diff --git a/builtin/game/falling.lua b/builtin/game/falling.lua
index 01a7d60b8..f9d71c90a 100644
--- a/builtin/game/falling.lua
+++ b/builtin/game/falling.lua
@@ -466,15 +466,39 @@ local function drop_attached_node(p)
 	end
 end
 
-function builtin_shared.check_attached_node(p, n)
+function builtin_shared.check_attached_node(p, n, group_rating)
 	local def = core.registered_nodes[n.name]
 	local d = vector.zero()
-	if def.paramtype2 == "wallmounted" or
+	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
-		-- The fallback vector here is in case 'wallmounted to dir' is nil due
-		-- to voxelmanip placing a wallmounted node without resetting a
-		-- pre-existing param2 value that is out-of-range for wallmounted.
-		-- The fallback vector corresponds to param2 = 0.
+		-- 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
@@ -519,8 +543,9 @@ function core.check_single_for_falling(p)
 		end
 	end
 
-	if core.get_item_group(n.name, "attached_node") ~= 0 then
-		if not builtin_shared.check_attached_node(p, n) then
+	local an = core.get_item_group(n.name, "attached_node")
+	if an ~= 0 then
+		if not builtin_shared.check_attached_node(p, n, an) then
 			drop_attached_node(p)
 			return true
 		end
diff --git a/builtin/game/item.lua b/builtin/game/item.lua
index 1d1d52860..71126b0a7 100644
--- a/builtin/game/item.lua
+++ b/builtin/game/item.lua
@@ -240,8 +240,9 @@ function core.item_place_node(itemstack, placer, pointed_thing, param2,
 	end
 
 	-- Check if the node is attached and if it can be placed there
-	if core.get_item_group(def.name, "attached_node") ~= 0 and
-		not builtin_shared.check_attached_node(place_to, newnode) then
+	local an = core.get_item_group(def.name, "attached_node")
+	if an ~= 0 and
+		not builtin_shared.check_attached_node(place_to, newnode, an) then
 		log("action", "attached node " .. def.name ..
 			" cannot be placed at " .. core.pos_to_string(place_to))
 		return itemstack, nil