Add MC-like falling nodes

mods/ENTITIES/mcl_falling_nodes/description.txt

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+Falling node entities, Minecraft-style

mods/ENTITIES/mcl_falling_nodes/init.lua

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+minetest.register_entity(":__builtin:falling_node", {
+	initial_properties = {
+		visual = "wielditem",
+		visual_size = {x = 0.667, y = 0.667},
+		textures = {},
+		physical = true,
+		is_visible = false,
+		collide_with_objects = false,
+		collisionbox = {-0.5, -0.5, -0.5, 0.5, 0.5, 0.5},
+	},
+
+	node = {},
+	meta = {},
+
+	set_node = function(self, node, meta)
+		self.node = node
+		self.meta = meta or {}
+		self.object:set_properties({
+			is_visible = true,
+			textures = {node.name},
+		})
+	end,
+
+	get_staticdata = function(self)
+		local ds = {
+			node = self.node,
+			meta = self.meta,
+		}
+		return minetest.serialize(ds)
+	end,
+
+	on_activate = function(self, staticdata)
+		self.object:set_armor_groups({immortal = 1})
+		
+		local ds = minetest.deserialize(staticdata)
+		if ds and ds.node then
+			self:set_node(ds.node, ds.meta)
+		elseif ds then
+			self:set_node(ds)
+		elseif staticdata ~= "" then
+			self:set_node({name = staticdata})
+		end
+	end,
+
+	on_step = function(self, dtime)
+		-- Set gravity
+		local acceleration = self.object:getacceleration()
+		if not vector.equals(acceleration, {x = 0, y = -10, z = 0}) then
+			self.object:setacceleration({x = 0, y = -10, z = 0})
+		end
+		-- Turn to actual node when colliding with ground, or continue to move
+		local pos = self.object:getpos()
+
+		-- Portal check
+		local np = {x = pos.x, y = pos.y + 0.3, z = pos.z}
+		local n2 = minetest.get_node(np)
+		if n2.name == "mcl_portals:portal_end" then
+			-- TODO: Teleport falling node. 
+			self.object:remove()
+			return
+		end
+
+		-- Position of bottom center point
+		local bcp = {x = pos.x, y = pos.y - 0.7, z = pos.z}
+		-- Avoid bugs caused by an unloaded node below
+		local bcn = minetest.get_node_or_nil(bcp)
+		local bcd = bcn and minetest.registered_nodes[bcn.name]
+
+		-- TODO: At this point, we did 2 get_nodes in 1 tick.
+		-- Figure out how to improve that (if it is a problem).
+
+		if bcn and (not bcd or bcd.walkable or
+				(minetest.get_item_group(self.node.name, "float") ~= 0 and
+				bcd.liquidtype ~= "none")) then
+			if bcd and bcd.leveled and
+					bcn.name == self.node.name then
+				local addlevel = self.node.level
+				if not addlevel or addlevel <= 0 then
+					addlevel = bcd.leveled
+				end
+				if minetest.add_node_level(bcp, addlevel) == 0 then
+					self.object:remove()
+					return
+				end
+			elseif bcd and bcd.buildable_to and
+					(minetest.get_item_group(self.node.name, "float") == 0 or
+					bcd.liquidtype == "none") then
+				minetest.remove_node(bcp)
+				return
+			end
+			local nd = minetest.registered_nodes[n2.name]
+			if n2.name == "mcl_portals:portal_end" then
+				-- TODO: Teleport falling node. 
+
+			elseif nd and nd.buildable_to == true then
+				-- Replace destination node if it's buildable to
+				minetest.remove_node(np)
+				-- Run script hook
+				for _, callback in pairs(minetest.registered_on_dignodes) do
+					callback(np, n2)
+				end
+				if minetest.registered_nodes[self.node.name] then
+					minetest.add_node(np, self.node)
+					if self.meta then
+						local meta = minetest.get_meta(np)
+						meta:from_table(self.meta)
+					end
+				end
+			else
+				-- Drop the *falling node* as an item if the destination node is NOT buildable to
+				local drops = minetest.get_node_drops(self.node.name, "")
+				for _, dropped_item in pairs(drops) do
+					minetest.add_item(np, dropped_item)
+				end
+			end
+			self.object:remove()
+			minetest.check_for_falling(np)
+			return
+		end
+		local vel = self.object:getvelocity()
+		if vector.equals(vel, {x = 0, y = 0, z = 0}) then
+			local npos = self.object:getpos()
+			self.object:setpos(vector.round(npos))
+		end
+	end
+})

mods/ENTITIES/mcl_falling_nodes/mod.conf

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+name = mcl_falling_nodes