builtin/game/falling.lua

   1 -- Minetest: builtin/item.lua
   2
   3 --
   4 -- Falling stuff
   5 --
   6
   7 core.register_entity(":__builtin:falling_node", {
   8         initial_properties = {
   9                 visual = "wielditem",
  10                 visual_size = {x = 0.667, y = 0.667},
  11                 textures = {},
  12                 physical = true,
  13                 is_visible = false,
  14                 collide_with_objects = false,
  15                 collisionbox = {-0.5, -0.5, -0.5, 0.5, 0.5, 0.5},
  16         },
  17
  18         node = {},
  19
  20         set_node = function(self, node)
  21                 self.node = node
  22                 self.object:set_properties({
  23                         is_visible = true,
  24                         textures = {node.name},
  25                 })
  26         end,
  27
  28         get_staticdata = function(self)
  29                 return core.serialize(self.node)
  30         end,
  31
  32         on_activate = function(self, staticdata)
  33                 self.object:set_armor_groups({immortal = 1})
  34
  35                 local node = core.deserialize(staticdata)
  36                 if node then
  37                         self:set_node(node)
  38                 elseif staticdata ~= "" then
  39                         self:set_node({name = staticdata})
  40                 end
  41         end,
  42
  43         on_step = function(self, dtime)
  44                 -- Set gravity
  45                 local acceleration = self.object:getacceleration()
  46                 if not vector.equals(acceleration, {x = 0, y = -10, z = 0}) then
  47                         self.object:setacceleration({x = 0, y = -10, z = 0})
  48                 end
  49                 -- Turn to actual sand when collides to ground or just move
  50                 local pos = self.object:getpos()
  51                 local bcp = {x = pos.x, y = pos.y - 0.7, z = pos.z} -- Position of bottom center point
  52                 local bcn = core.get_node(bcp)
  53                 local bcd = core.registered_nodes[bcn.name]
  54                 -- Note: walkable is in the node definition, not in item groups
  55                 if not bcd or bcd.walkable or
  56                                 (core.get_item_group(self.node.name, "float") ~= 0 and
  57                                 bcd.liquidtype ~= "none") then
  58                         if bcd and bcd.leveled and
  59                                         bcn.name == self.node.name then
  60                                 local addlevel = self.node.level
  61                                 if not addlevel or addlevel <= 0 then
  62                                         addlevel = bcd.leveled
  63                                 end
  64                                 if core.add_node_level(bcp, addlevel) == 0 then
  65                                         self.object:remove()
  66                                         return
  67                                 end
  68                         elseif bcd and bcd.buildable_to and
  69                                         (core.get_item_group(self.node.name, "float") == 0 or
  70                                         bcd.liquidtype == "none") then
  71                                 core.remove_node(bcp)
  72                                 return
  73                         end
  74                         local np = {x = bcp.x, y = bcp.y + 1, z = bcp.z}
  75                         -- Check what's here
  76                         local n2 = core.get_node(np)
  77                         local nd = core.registered_nodes[n2.name]
  78                         -- If it's not air or liquid, remove node and replace it with
  79                         -- it's drops
  80                         if n2.name ~= "air" and (not nd or nd.liquidtype == "none") then
  81                                 core.remove_node(np)
  82                                 if nd.buildable_to == false then
  83                                         -- Add dropped items
  84                                         local drops = core.get_node_drops(n2.name, "")
  85                                         for _, dropped_item in pairs(drops) do
  86                                                 core.add_item(np, dropped_item)
  87                                         end
  88                                 end
  89                                 -- Run script hook
  90                                 for _, callback in pairs(core.registered_on_dignodes) do
  91                                         callback(np, n2)
  92                                 end
  93                         end
  94                         -- Create node and remove entity
  95                         if core.registered_nodes[self.node.name] then
  96                                 core.add_node(np, self.node)
  97                         end
  98                         self.object:remove()
  99                         nodeupdate(np)
 100                         return
 101                 end
 102                 local vel = self.object:getvelocity()
 103                 if vector.equals(vel, {x = 0, y = 0, z = 0}) then
 104                         local npos = self.object:getpos()
 105                         self.object:setpos(vector.round(npos))
 106                 end
 107         end
 108 })
 109
 110 function spawn_falling_node(p, node)
 111         local obj = core.add_entity(p, "__builtin:falling_node")
 112         obj:get_luaentity():set_node(node)
 113 end
 114
 115 function drop_attached_node(p)
 116         local nn = core.get_node(p).name
 117         core.remove_node(p)
 118         for _, item in pairs(core.get_node_drops(nn, "")) do
 119                 local pos = {
 120                         x = p.x + math.random()/2 - 0.25,
 121                         y = p.y + math.random()/2 - 0.25,
 122                         z = p.z + math.random()/2 - 0.25,
 123                 }
 124                 core.add_item(pos, item)
 125         end
 126 end
 127
 128 function check_attached_node(p, n)
 129         local def = core.registered_nodes[n.name]
 130         local d = {x = 0, y = 0, z = 0}
 131         if def.paramtype2 == "wallmounted" then
 132                 -- The fallback vector here is in case 'wallmounted to dir' is nil due
 133                 -- to voxelmanip placing a wallmounted node without resetting a
 134                 -- pre-existing param2 value that is out-of-range for wallmounted.
 135                 -- The fallback vector corresponds to param2 = 0.
 136                 d = core.wallmounted_to_dir(n.param2) or {x = 0, y = 1, z = 0}
 137         else
 138                 d.y = -1
 139         end
 140         local p2 = vector.add(p, d)
 141         local nn = core.get_node(p2).name
 142         local def2 = core.registered_nodes[nn]
 143         if def2 and not def2.walkable then
 144                 return false
 145         end
 146         return true
 147 end
 148
 149 --
 150 -- Some common functions
 151 --
 152
 153 function nodeupdate_single(p)
 154         local n = core.get_node(p)
 155         if core.get_item_group(n.name, "falling_node") ~= 0 then
 156                 local p_bottom = {x = p.x, y = p.y - 1, z = p.z}
 157                 local n_bottom = core.get_node(p_bottom)
 158                 local d_bottom = core.registered_nodes[n_bottom.name]
 159                 -- Note: walkable is in the node definition, not in item groups
 160                 if d_bottom and
 161                                 (core.get_item_group(n.name, "float") == 0 or
 162                                         d_bottom.liquidtype == "none") and
 163                                 (n.name ~= n_bottom.name or (d_bottom.leveled and
 164                                         core.get_node_level(p_bottom) < core.get_node_max_level(p_bottom))) and
 165                                 (not d_bottom.walkable or
 166                                         d_bottom.buildable_to) then
 167                         n.level = core.get_node_level(p)
 168                         core.remove_node(p)
 169                         spawn_falling_node(p, n)
 170                         return true
 171                 end
 172         end
 173
 174         if core.get_item_group(n.name, "attached_node") ~= 0 then
 175                 if not check_attached_node(p, n) then
 176                         drop_attached_node(p)
 177                         return true
 178                 end
 179         end
 180
 181         return false
 182 end
 183
 184 -- This table is specifically ordered.
 185 -- We don't walk diagonals, only our direct neighbors, and self.
 186 -- Down first as likely case, but always before self. The same with sides.
 187 -- Up must come last, so that things above self will also fall all at once.
 188 local nodeupdate_neighbors = {
 189         {x = -1, y = -1, z = 0},
 190         {x = 1, y = -1, z = 0},
 191         {x = 0, y = -1, z = -1},
 192         {x = 0, y = -1, z = 1},
 193         {x = 0, y = -1, z = 0},
 194         {x = -1, y = 0, z = 0},
 195         {x = 1, y = 0, z = 0},
 196         {x = 0, y = 0, z = 1},
 197         {x = 0, y = 0, z = -1},
 198         {x = 0, y = 0, z = 0},
 199         {x = 0, y = 1, z = 0},
 200 }
 201
 202 function nodeupdate(p)
 203         -- Round p to prevent falling entities to get stuck.
 204         p = vector.round(p)
 205
 206         -- We make a stack, and manually maintain size for performance.
 207         -- Stored in the stack, we will maintain tables with pos, and
 208         -- last neighbor visited. This way, when we get back to each
 209         -- node, we know which directions we have already walked, and
 210         -- which direction is the next to walk.
 211         local s = {}
 212         local n = 0
 213         -- The neighbor order we will visit from our table.
 214         local v = 1
 215
 216         while true do
 217                 -- Push current pos onto the stack.
 218                 n = n + 1
 219                 s[n] = {p = p, v = v}
 220                 -- Select next node from neighbor list.
 221                 p = vector.add(p, nodeupdate_neighbors[v])
 222                 -- Now we check out the node. If it is in need of an update,
 223                 -- it will let us know in the return value (true = updated).
 224                 if not nodeupdate_single(p) then
 225                         -- If we don't need to "recurse" (walk) to it then pop
 226                         -- our previous pos off the stack and continue from there,
 227                         -- with the v value we were at when we last were at that
 228                         -- node
 229                         repeat
 230                                 local pop = s[n]
 231                                 p = pop.p
 232                                 v = pop.v
 233                                 s[n] = nil
 234                                 n = n - 1
 235                                 -- If there's nothing left on the stack, and no
 236                                 -- more sides to walk to, we're done and can exit
 237                                 if n == 0 and v == 11 then
 238                                         return
 239                                 end
 240                         until v < 11
 241                         -- The next round walk the next neighbor in list.
 242                         v = v + 1
 243                 else
 244                         -- If we did need to walk the neighbor, then
 245                         -- start walking it from the walk order start (1),
 246                         -- and not the order we just pushed up the stack.
 247                         v = 1
 248                 end
 249         end
 250 end
 251
 252 --
 253 -- Global callbacks
 254 --
 255
 256 function on_placenode(p, node)
 257         nodeupdate(p)
 258 end
 259 core.register_on_placenode(on_placenode)
 260
 261 function on_dignode(p, node)
 262         nodeupdate(p)
 263 end
 264 core.register_on_dignode(on_dignode)
 265
 266 function on_punchnode(p, node)
 267         nodeupdate(p)
 268 end
 269 core.register_on_punchnode(on_punchnode)