From 512847f8f615bd9904d8c5d0d1c0d4a0012587c1 Mon Sep 17 00:00:00 2001
From: trans_soup <>
Date: Sun, 22 Oct 2023 22:13:46 +0200
Subject: [PATCH] improve placement of leveled nodes.

they now stack when placed on top of each other, even if there's a node
in the position above the targetted stack.
---
 mods/bg_api/leveled_node.lua | 48 +++++++++++++++++++++++++++++++++---
 1 file changed, 44 insertions(+), 4 deletions(-)

diff --git a/mods/bg_api/leveled_node.lua b/mods/bg_api/leveled_node.lua
index ce8752a..b0e378b 100644
--- a/mods/bg_api/leveled_node.lua
+++ b/mods/bg_api/leveled_node.lua
@@ -4,6 +4,12 @@ local function is_same_kind (pos, kindname)
 	return kindname and node_kindname and kindname == node_kindname
 end
 
+local function transfer_levels (source, target, max)
+	local max_diff = max - target
+	local diff = math.min(max_diff, source)
+	return source - diff, target + diff
+end
+
 local function stack_attempt (pos, source_level)
 	local node = minetest.get_node(pos)
 	local def = minetest.registered_nodes[node.name]
@@ -12,11 +18,10 @@ local function stack_attempt (pos, source_level)
 	local level_max = def.level_max
 	local kindname = def.kindname
 
-	local max_diff = level_max - def.level
-	local diff = math.min(max_diff, source_level)
+	local source_level, target_level = transfer_levels(source_level, def.level, level_max)
 
-	minetest.swap_node(pos, {name = kindname .. "_" .. (def.level + diff)})
-	return source_level - diff
+	minetest.swap_node(pos, {name = kindname .. "_" .. (target_level)})
+	return source_level
 end
 
 function blockgame.check_for_stacking (pos)
@@ -43,6 +48,40 @@ end
 
 
 
+local function on_place (itemstack, placer, pointed)
+	local function fallback_to_default ()
+		return minetest.item_place(itemstack, placer, pointed)
+	end
+
+	local placed_def = minetest.registered_items[itemstack:get_name()]
+	if not placed_def.level_max then return fallback_to_default() end
+
+	if not is_same_kind(pointed.under, placed_def.kindname) then return fallback_to_default() end
+
+	local above = pointed.under + vector.new(0, 1, 0)
+	local is_top = above == pointed.above
+	if not is_top then return fallback_to_default() end
+
+	local above_node = minetest.get_node(above)
+
+	local target_node = minetest.get_node(pointed.under)
+	local target_def = minetest.registered_items[target_node.name]
+	if target_def.level_max == target_def.level then return fallback_to_default() end
+
+	local source_level, target_level = transfer_levels(placed_def.level, target_def.level, placed_def.level_max)
+	if source_level > 0 and above_node.name ~= "air" then return fallback_to_default() end
+
+	local left_over = stack_attempt(pointed.under, placed_def.level)
+	if above_node.name == "air" then
+		minetest.set_node(pointed.above, {name = target_def.kindname .. "_" .. left_over})
+	end
+	itemstack:set_count(itemstack:get_count() - 1)
+
+	return itemstack
+end
+
+
+
 local function register_layer (kindname, def, level, modname)
 	local def = blockgame.naive_deep_copy(def)
 	def.level = level
@@ -60,6 +99,7 @@ local function register_layer (kindname, def, level, modname)
 	end
 
 	def.on_construct = blockgame.check_for_stacking
+	def.on_place = on_place
 	def.after_place_node = blockgame.check_for_stacking
 	def.after_land = blockgame.check_for_stacking