builtin/game/item_entity.lua

   1 -- Minetest: builtin/item_entity.lua
   2
   3 function core.spawn_item(pos, item)
   4         -- Take item in any format
   5         local stack = ItemStack(item)
   6         local obj = core.add_entity(pos, "__builtin:item")
   7         -- Don't use obj if it couldn't be added to the map.
   8         if obj then
   9                 obj:get_luaentity():set_item(stack:to_string())
  10         end
  11         return obj
  12 end
  13
  14 -- If item_entity_ttl is not set, enity will have default life time
  15 -- Setting it to -1 disables the feature
  16
  17 local time_to_live = tonumber(core.settings:get("item_entity_ttl")) or 900
  18 local gravity = tonumber(core.settings:get("movement_gravity")) or 9.81
  19
  20
  21 core.register_entity(":__builtin:item", {
  22         initial_properties = {
  23                 hp_max = 1,
  24                 physical = true,
  25                 collide_with_objects = false,
  26                 collisionbox = {-0.3, -0.3, -0.3, 0.3, 0.3, 0.3},
  27                 visual = "wielditem",
  28                 visual_size = {x = 0.4, y = 0.4},
  29                 textures = {""},
  30                 is_visible = false,
  31         },
  32
  33         itemstring = "",
  34         moving_state = true,
  35         physical_state = true,
  36         -- Item expiry
  37         age = 0,
  38         -- Pushing item out of solid nodes
  39         force_out = nil,
  40         force_out_start = nil,
  41
  42         set_item = function(self, item)
  43                 local stack = ItemStack(item or self.itemstring)
  44                 self.itemstring = stack:to_string()
  45                 if self.itemstring == "" then
  46                         -- item not yet known
  47                         return
  48                 end
  49
  50                 -- Backwards compatibility: old clients use the texture
  51                 -- to get the type of the item
  52                 local itemname = stack:is_known() and stack:get_name() or "unknown"
  53
  54                 local max_count = stack:get_stack_max()
  55                 local count = math.min(stack:get_count(), max_count)
  56                 local size = 0.2 + 0.1 * (count / max_count) ^ (1 / 3)
  57                 local def = core.registered_items[itemname]
  58                 local glow = def and def.light_source and
  59                         math.floor(def.light_source / 2 + 0.5)
  60
  61                 local size_bias = 1e-3 * math.random() -- small random bias to counter Z-fighting
  62                 self.object:set_properties({
  63                         is_visible = true,
  64                         visual = "wielditem",
  65                         textures = {itemname},
  66                         visual_size = {x = size + size_bias, y = size + size_bias},
  67                         collisionbox = {-size, -size, -size, size, size, size},
  68                         automatic_rotate = math.pi * 0.5 * 0.2 / size,
  69                         wield_item = self.itemstring,
  70                         glow = glow,
  71                 })
  72
  73         end,
  74
  75         get_staticdata = function(self)
  76                 return core.serialize({
  77                         itemstring = self.itemstring,
  78                         age = self.age,
  79                         dropped_by = self.dropped_by
  80                 })
  81         end,
  82
  83         on_activate = function(self, staticdata, dtime_s)
  84                 if string.sub(staticdata, 1, string.len("return")) == "return" then
  85                         local data = core.deserialize(staticdata)
  86                         if data and type(data) == "table" then
  87                                 self.itemstring = data.itemstring
  88                                 self.age = (data.age or 0) + dtime_s
  89                                 self.dropped_by = data.dropped_by
  90                         end
  91                 else
  92                         self.itemstring = staticdata
  93                 end
  94                 self.object:set_armor_groups({immortal = 1})
  95                 self.object:set_velocity({x = 0, y = 2, z = 0})
  96                 self.object:set_acceleration({x = 0, y = -gravity, z = 0})
  97                 self:set_item()
  98         end,
  99
 100         try_merge_with = function(self, own_stack, object, entity)
 101                 if self.age == entity.age then
 102                         -- Can not merge with itself
 103                         return false
 104                 end
 105
 106                 local stack = ItemStack(entity.itemstring)
 107                 local name = stack:get_name()
 108                 if own_stack:get_name() ~= name or
 109                                 own_stack:get_meta() ~= stack:get_meta() or
 110                                 own_stack:get_wear() ~= stack:get_wear() or
 111                                 own_stack:get_free_space() == 0 then
 112                         -- Can not merge different or full stack
 113                         return false
 114                 end
 115
 116                 local count = own_stack:get_count()
 117                 local total_count = stack:get_count() + count
 118                 local max_count = stack:get_stack_max()
 119
 120                 if total_count > max_count then
 121                         return false
 122                 end
 123                 -- Merge the remote stack into this one
 124
 125                 local pos = object:get_pos()
 126                 pos.y = pos.y + ((total_count - count) / max_count) * 0.15
 127                 self.object:move_to(pos)
 128
 129                 self.age = 0 -- Handle as new entity
 130                 own_stack:set_count(total_count)
 131                 self:set_item(own_stack)
 132
 133                 entity.itemstring = ""
 134                 object:remove()
 135                 return true
 136         end,
 137
 138         enable_physics = function(self)
 139                 if not self.physical_state then
 140                         self.physical_state = true
 141                         self.object:set_properties({physical = true})
 142                         self.object:set_velocity({x=0, y=0, z=0})
 143                         self.object:set_acceleration({x=0, y=-gravity, z=0})
 144                 end
 145         end,
 146
 147         disable_physics = function(self)
 148                 if self.physical_state then
 149                         self.physical_state = false
 150                         self.object:set_properties({physical = false})
 151                         self.object:set_velocity({x=0, y=0, z=0})
 152                         self.object:set_acceleration({x=0, y=0, z=0})
 153                 end
 154         end,
 155
 156         on_step = function(self, dtime, moveresult)
 157                 self.age = self.age + dtime
 158                 if time_to_live > 0 and self.age > time_to_live then
 159                         self.itemstring = ""
 160                         self.object:remove()
 161                         return
 162                 end
 163
 164                 local pos = self.object:get_pos()
 165                 local node = core.get_node_or_nil({
 166                         x = pos.x,
 167                         y = pos.y + self.object:get_properties().collisionbox[2] - 0.05,
 168                         z = pos.z
 169                 })
 170                 -- Delete in 'ignore' nodes
 171                 if node and node.name == "ignore" then
 172                         self.itemstring = ""
 173                         self.object:remove()
 174                         return
 175                 end
 176
 177                 if self.force_out then
 178                         -- This code runs after the entity got a push from the is_stuck code.
 179                         -- It makes sure the entity is entirely outside the solid node
 180                         local c = self.object:get_properties().collisionbox
 181                         local s = self.force_out_start
 182                         local f = self.force_out
 183                         local ok = (f.x > 0 and pos.x + c[1] > s.x + 0.5) or
 184                                 (f.y > 0 and pos.y + c[2] > s.y + 0.5) or
 185                                 (f.z > 0 and pos.z + c[3] > s.z + 0.5) or
 186                                 (f.x < 0 and pos.x + c[4] < s.x - 0.5) or
 187                                 (f.z < 0 and pos.z + c[6] < s.z - 0.5)
 188                         if ok then
 189                                 -- Item was successfully forced out
 190                                 self.force_out = nil
 191                                 self:enable_physics()
 192                                 return
 193                         end
 194                 end
 195
 196                 if not self.physical_state then
 197                         return -- Don't do anything
 198                 end
 199
 200                 assert(moveresult,
 201                         "Collision info missing, this is caused by an out-of-date/buggy mod or game")
 202
 203                 if not moveresult.collides then
 204                         -- future TODO: items should probably decelerate in air
 205                         return
 206                 end
 207
 208                 -- Push item out when stuck inside solid node
 209                 local is_stuck = false
 210                 local snode = core.get_node_or_nil(pos)
 211                 if snode then
 212                         local sdef = core.registered_nodes[snode.name] or {}
 213                         is_stuck = (sdef.walkable == nil or sdef.walkable == true)
 214                                 and (sdef.collision_box == nil or sdef.collision_box.type == "regular")
 215                                 and (sdef.node_box == nil or sdef.node_box.type == "regular")
 216                 end
 217
 218                 if is_stuck then
 219                         local shootdir
 220                         local order = {
 221                                 {x=1, y=0, z=0}, {x=-1, y=0, z= 0},
 222                                 {x=0, y=0, z=1}, {x= 0, y=0, z=-1},
 223                         }
 224
 225                         -- Check which one of the 4 sides is free
 226                         for o = 1, #order do
 227                                 local cnode = core.get_node(vector.add(pos, order[o])).name
 228                                 local cdef = core.registered_nodes[cnode] or {}
 229                                 if cnode ~= "ignore" and cdef.walkable == false then
 230                                         shootdir = order[o]
 231                                         break
 232                                 end
 233                         end
 234                         -- If none of the 4 sides is free, check upwards
 235                         if not shootdir then
 236                                 shootdir = {x=0, y=1, z=0}
 237                                 local cnode = core.get_node(vector.add(pos, shootdir)).name
 238                                 if cnode == "ignore" then
 239                                         shootdir = nil -- Do not push into ignore
 240                                 end
 241                         end
 242
 243                         if shootdir then
 244                                 -- Set new item moving speed accordingly
 245                                 local newv = vector.multiply(shootdir, 3)
 246                                 self:disable_physics()
 247                                 self.object:set_velocity(newv)
 248
 249                                 self.force_out = newv
 250                                 self.force_out_start = vector.round(pos)
 251                                 return
 252                         end
 253                 end
 254
 255                 node = nil -- ground node we're colliding with
 256                 if moveresult.touching_ground then
 257                         for _, info in ipairs(moveresult.collisions) do
 258                                 if info.axis == "y" then
 259                                         node = core.get_node(info.node_pos)
 260                                         break
 261                                 end
 262                         end
 263                 end
 264
 265                 -- Slide on slippery nodes
 266                 local def = node and core.registered_nodes[node.name]
 267                 local keep_movement = false
 268
 269                 if def then
 270                         local slippery = core.get_item_group(node.name, "slippery")
 271                         local vel = self.object:get_velocity()
 272                         if slippery ~= 0 and (math.abs(vel.x) > 0.1 or math.abs(vel.z) > 0.1) then
 273                                 -- Horizontal deceleration
 274                                 local factor = math.min(4 / (slippery + 4) * dtime, 1)
 275                                 self.object:set_velocity({
 276                                         x = vel.x * (1 - factor),
 277                                         y = 0,
 278                                         z = vel.z * (1 - factor)
 279                                 })
 280                                 keep_movement = true
 281                         end
 282                 end
 283
 284                 if not keep_movement then
 285                         self.object:set_velocity({x=0, y=0, z=0})
 286                 end
 287
 288                 if self.moving_state == keep_movement then
 289                         -- Do not update anything until the moving state changes
 290                         return
 291                 end
 292                 self.moving_state = keep_movement
 293
 294                 -- Only collect items if not moving
 295                 if self.moving_state then
 296                         return
 297                 end
 298                 -- Collect the items around to merge with
 299                 local own_stack = ItemStack(self.itemstring)
 300                 if own_stack:get_free_space() == 0 then
 301                         return
 302                 end
 303                 local objects = core.get_objects_inside_radius(pos, 1.0)
 304                 for k, obj in pairs(objects) do
 305                         local entity = obj:get_luaentity()
 306                         if entity and entity.name == "__builtin:item" then
 307                                 if self:try_merge_with(own_stack, obj, entity) then
 308                                         own_stack = ItemStack(self.itemstring)
 309                                         if own_stack:get_free_space() == 0 then
 310                                                 return
 311                                         end
 312                                 end
 313                         end
 314                 end
 315         end,
 316
 317         on_punch = function(self, hitter)
 318                 local inv = hitter:get_inventory()
 319                 if inv and self.itemstring ~= "" then
 320                         local left = inv:add_item("main", self.itemstring)
 321                         if left and not left:is_empty() then
 322                                 self:set_item(left)
 323                                 return
 324                         end
 325                 end
 326                 self.itemstring = ""
 327                 self.object:remove()
 328         end,
 329 })