Unified custom falling checks

docs/ideas.txt

@@ -67,10 +67,6 @@ IDEAS: Possible future additions/improvements to the game
 		- Upconvert dirt to humus nearby?
 		- Rushes to reeds to windchimes?
 
-- Rework falling_node (or build alternative) with customizability
-	- Allow lode rods, ladders to hang from ceilings?
-	- Add on_fall_check hook, hook in check_single_for_falling
-
 - A pure white concrete material?
 	- Use crude glass for recipe?  Flow wet concrete into crude
 	  glass from above?

docs/issues-code.txt

@@ -141,9 +141,6 @@ ISSUES-CODE: Issues related to code quality and APIs
   modified copy of another definition, e.g. for planted eggcorns copying
   dirt, door panels copying original materials, etc.
 
-- Add an on_falling_check handler to replace check_single_for_falling custom
-  hook in writing, and possibly other places.
-
 - Should we create "recipe groups" to make it easier to specify
   equivalent recipes for hint purposes?
 

mods/nc_api/item_support_falling.lua

@@ -13,9 +13,16 @@ function minetest.check_single_for_falling(pos, ...)
 		if not def then return n end
 		return (not (def and def.groups and def.groups.support_falling)) and n or nil
 	end
-	local function helper(...)
+	local function helper(fell, ...)
 		minetest.get_node_or_nil = gnon
-		return ...
+		if not fell then
+			local node = minetest.get_node(pos)
+			local def = minetest.registered_nodes[node.name] or {}
+			if def.on_falling_check then
+				return def.on_falling_check(pos, node)
+			end
+		end
+		return fell, ...
 	end
 	return helper(csff(pos, ...))
 end

mods/nc_items/hooks.lua

@@ -129,25 +129,6 @@ function minetest.item_drop(item, player, ...)
 	return helper(olddrop(item, player, ...))
 end
 
-local oldfallcheck = minetest.check_single_for_falling
-function minetest.check_single_for_falling(pos, ...)
-	local function helper(...)
-		if minetest.get_node(pos).name ~= modname .. ":stack" then return ... end
-		local stack = nodecore.stack_get(pos)
-		local below = {x = pos.x, y = pos.y - 1, z = pos.z}
-		if minetest.get_node(below).name == modname .. ":stack" then
-			stack = nodecore.stack_add(below, stack)
-			if stack:is_empty() then
-				minetest.remove_node(pos)
-			else
-				nodecore.stack_set(pos, stack)
-			end
-			return ...
-		end
-	end
-	return helper(oldfallcheck(pos, ...))
-end
-
 local oldlog = minetest.log
 function minetest.log(...)
 	local args = {...}

mods/nc_items/node.lua

@@ -70,6 +70,19 @@ minetest.register_node(modname .. ":stack", {
 		after_dig_node = pezdispense,
 		on_settle_item = function(pos, _, stack)
 			return nodecore.stack_add(pos, stack)
+		end,
+		on_falling_check = function(pos)
+			local stack = nodecore.stack_get(pos)
+			local below = {x = pos.x, y = pos.y - 1, z = pos.z}
+			if minetest.get_node(below).name == modname .. ":stack" then
+				stack = nodecore.stack_add(below, stack)
+				if stack:is_empty() then
+					minetest.remove_node(pos)
+				else
+					nodecore.stack_set(pos, stack)
+				end
+				return false
+			end
 		end
 	})
 

mods/nc_writing/node.lua

@@ -50,20 +50,14 @@ for i = 1, #nodecore.writing_glyphs do
 					return raw .. "\n" .. desc
 				end
 				return raw
+			end,
+			on_falling_check = function(pos, node)
+				local dp = vector.add(pos, nodecore.facedirs[node.param2].b)
+				if not nodecore.writing_writable(dp, nil, true) then
+					minetest.remove_node(pos)
+					return true
+				end
+				return false
 			end
 		})
 end
-
-local oldcsff = minetest.check_single_for_falling
-function minetest.check_single_for_falling(pos, ...)
-	local node = minetest.get_node_or_nil(pos)
-	if not node then return oldcsff(pos, ...) end
-	if minetest.get_item_group(node.name, "alpha_glyph") ~= 0 then
-		local dp = vector.add(pos, nodecore.facedirs[node.param2].b)
-		if not nodecore.writing_writable(dp, nil, true) then
-			minetest.remove_node(pos)
-			return true
-		end
-	end
-	return oldcsff(pos, ...)
-end