Add the group attached_node

Nodes in this group will be dropped as items if the node under them or the node in the wallmounted direction is not walkable.

diff --git a/builtin/falling.lua b/builtin/falling.lua
index 3912727c32605a6cf28811014f8fa8737b6fe3e9..903c5dfd0c6b281dbe2eec83478ea979d6d77026 100644 (file)
--- a/builtin/falling.lua
+++ b/builtin/falling.lua
@@ -91,6 +91,48 @@ function spawn_falling_node(p, nodename)
        obj:get_luaentity():set_node(nodename)
 end
 
+function drop_attached_node(p)
+       local nn = minetest.env:get_node(p).name
+       minetest.env:remove_node(p)
+       for _,item in ipairs(minetest.get_node_drops(nn, "")) do
+               local pos = {
+                       x = p.x + math.random(60)/60-0.3,
+                       y = p.y + math.random(60)/60-0.3,
+                       z = p.z + math.random(60)/60-0.3,
+               }
+               minetest.env:add_item(pos, item)
+       end
+end
+
+function check_attached_node(p, n)
+       local def = minetest.registered_nodes[n.name]
+       local d = {x=0, y=0, z=0}
+       if def.paramtype2 == "wallmounted" then
+               if n.param2 == 0 then
+                       d.y = 1
+               elseif n.param2 == 1 then
+                       d.y = -1
+               elseif n.param2 == 2 then
+                       d.x = 1
+               elseif n.param2 == 3 then
+                       d.x = -1
+               elseif n.param2 == 4 then
+                       d.z = 1
+               elseif n.param2 == 5 then
+                       d.z = -1
+               end
+       else
+               d.y = -1
+       end
+       local p2 = {x=p.x+d.x, y=p.y+d.y, z=p.z+d.z}
+       local nn = minetest.env:get_node(p2).name
+       local def2 = minetest.registered_nodes[nn]
+       if def2 and not def2.walkable then
+               return false
+       end
+       return true
+end
+
 --
 -- Some common functions
 --
@@ -108,6 +150,13 @@ function nodeupdate_single(p)
                        nodeupdate(p)
                end
        end
+       
+       if minetest.get_node_group(n.name, "attached_node") ~= 0 then
+               if not check_attached_node(p, n) then
+                       drop_attached_node(p)
+                       nodeupdate(p)
+               end
+       end
 end
 
 function nodeupdate(p)

diff --git a/builtin/item.lua b/builtin/item.lua
index 0f8dcff1fbc2192de307c8d35ff8cbd02a7c2432..9352a43fcf8f24025e6906a37d3edf1831ca6265 100644 (file)
--- a/builtin/item.lua
+++ b/builtin/item.lua
@@ -181,6 +181,13 @@ function minetest.item_place_node(itemstack, placer, pointed_thing)
                end
        end
 
+       -- Check if the node is attached and if it can be placed there
+       if not check_attached_node(place_to, newnode) then
+               minetest.log("action", "attached node " .. def.name ..
+                       " can not be placed at " .. minetest.pos_to_string(place_to))
+               return
+       end
+
        -- Add node and update
        minetest.env:add_node(place_to, newnode)
 

diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index e32efc6df888cb257d9713a582ac073cba4e2705..08619b72afa2e774166b52011760a0f97262c113 100644 (file)
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -457,6 +457,9 @@ Special groups
 - fall_damage_add_percent: damage speed = speed * (1 + value/100)
 - bouncy: value is bounce speed in percent
 - falling_node: if there is no walkable block under the node it will fall
+- attached_node: if the node under it is not a walkable block the node will be
+                  dropped as an item. If the node is wallmounted the
+                  wallmounted direction is checked.
 
 Known damage and digging time defining groups
 ----------------------------------------------

diff --git a/games/minimal/mods/default/init.lua b/games/minimal/mods/default/init.lua
index 5f4d8e06348ce019a4b2c51d081cabab1063e27f..9900b98a5076683cbd3d2a246483b4d4a6dd6e90 100644 (file)
--- a/games/minimal/mods/default/init.lua
+++ b/games/minimal/mods/default/init.lua
@@ -837,7 +837,7 @@ minetest.register_node("default:junglegrass", {
        wield_image = "default_junglegrass.png",
        paramtype = "light",
        walkable = false,
-       groups = {snappy=3},
+       groups = {snappy=3,attached_node=1},
        sounds = default.node_sound_leaves_defaults(),
 })
 
@@ -1106,7 +1106,7 @@ minetest.register_node("default:torch", {
                wall_bottom = {-0.1, -0.5, -0.1, 0.1, -0.5+0.6, 0.1},
                wall_side = {-0.5, -0.3, -0.1, -0.5+0.3, 0.3, 0.1},
        },
-       groups = {choppy=2,dig_immediate=3},
+       groups = {choppy=2,dig_immediate=3,attached_node=1},
        legacy_wallmounted = true,
        sounds = default.node_sound_defaults(),
 })
@@ -1127,7 +1127,7 @@ minetest.register_node("default:sign_wall", {
                --wall_bottom = <default>
                --wall_side = <default>
        },
-       groups = {choppy=2,dig_immediate=2},
+       groups = {choppy=2,dig_immediate=2,attached_node=1},
        legacy_wallmounted = true,
        sounds = default.node_sound_defaults(),
        on_construct = function(pos)
@@ -1495,7 +1495,7 @@ minetest.register_node("default:sapling", {
        wield_image = "default_sapling.png",
        paramtype = "light",
        walkable = false,
-       groups = {snappy=2,dig_immediate=3},
+       groups = {snappy=2,dig_immediate=3,attached_node=1},
        sounds = default.node_sound_defaults(),
 })