Place trapdoors upside-down when placed at top

mods/ITEMS/mcl_doors/init.lua

@@ -664,6 +664,32 @@ function mcl_doors:register_trapdoor(name, def)
 				punch(pos)
 			end),
 		}},
+		on_place = function(itemstack, placer, pointed_thing)
+			local p0 = pointed_thing.under
+			local p1 = pointed_thing.above
+			local param2 = 0
+
+			local placer_pos = placer:getpos()
+			if placer_pos then
+				param2 = minetest.dir_to_facedir(vector.subtract(p1, placer_pos))
+			end
+
+			local finepos = minetest.pointed_thing_to_face_pos(placer, pointed_thing)
+			local fpos = finepos.y % 1
+
+
+			local origname = itemstack:get_name()
+			if p0.y - 1 == p1.y or (fpos > 0 and fpos < 0.5)
+					or (fpos < -0.5 and fpos > -0.999999999) then
+				param2 = param2 + 20
+				if param2 == 21 then
+					param2 = 23
+				elseif param2 == 23 then
+					param2 = 21
+				end
+			end
+			return minetest.item_place(itemstack, placer, pointed_thing, param2)
+		end,
 		on_rightclick = on_rightclick,
 	})