Minetest Game API
=================
GitHub Repo: https://github.com/minetest/minetest_game


Introduction
------------

The Minetest Game game offers multiple new possibilities in addition to the Luanti engine's built-in API,
allowing you to add new plants to farming mod, buckets for new liquids, new stairs and custom panes.
For information on the Luanti API, visit https://github.com/minetest/minetest/blob/master/doc/lua_api.txt
Please note:

 * [XYZ] refers to a section the Luanti API
 * [#ABC] refers to a section in this document
 * [pos] refers to a position table `{x = -5, y = 0, z = 200}`


Bucket API
----------

The bucket API allows registering new types of buckets for non-default liquids.

	bucket.register_liquid(
		"default:lava_source",   -- name of the source node
		"default:lava_flowing",  -- name of the flowing node
		"bucket:bucket_lava",    -- name of the new bucket item (or nil if liquid is not takeable)
		"bucket_lava.png",       -- texture of the new bucket item (ignored if itemname == nil)
		"Lava Bucket",           -- text description of the bucket item
		{lava_bucket = 1},       -- groups of the bucket item, OPTIONAL
		false                    -- force-renew, OPTIONAL. Force the liquid source to renew if it has
		                         -- a source neighbour, even if defined as 'liquid_renewable = false'.
		                         -- Needed to avoid creating holes in sloping rivers.
	)

The filled bucket item is returned to the player that uses an empty bucket pointing to the given liquid source.
When punching with an empty bucket pointing to an entity or a non-liquid node, the on_punch of the entity or node will be triggered.
The bucket API also allows registering buckets in other namespace using colon-prefixed itemname (i.e. ":cows:bucket_milk").


Beds API
--------

	beds.register_bed(
		"beds:bed",    -- Bed name
		def            -- See [#Bed definition]
	)

 * `beds.can_dig(bed_pos)` Returns a boolean whether the bed at `bed_pos` may be dug
 * `beds.read_spawns() `   Returns a table containing players respawn positions
 * `beds.kick_players()`  Forces all players to leave bed
 * `beds.skip_night()`   Sets world time to morning and saves respawn position of all players currently sleeping
 * `beds.day_interval`   Is a table with keys "start" and "finish". Allows you
   to set the period of the day (timeofday format). Default: `{ start = 0.2, finish = 0.805 }`.

### Bed definition

	{
		description = "Simple Bed",
		inventory_image = "beds_bed.png",
		wield_image = "beds_bed.png",
		tiles = {
			bottom = {'Tile definition'}, -- the tiles of the bottom part of the bed.
			top = {Tile definition} -- the tiles of the bottom part of the bed.
		},
		nodebox = {
			bottom = 'regular nodebox',     -- bottom part of bed (see [Node boxes])
			top = 'regular nodebox',        -- top part of bed (see [Node boxes])
		},
		selectionbox = 'regular nodebox',  -- for both nodeboxes (see [Node boxes])
		recipe = {                                         -- Craft recipe
			{"group:wool", "group:wool", "group:wool"},
			{"group:wood", "group:wood", "group:wood"}
		}
	}


Bones API
---------

An ordered list of listnames (default: "main", "craft") of the player inventory,
that will be placed into bones or dropped on player death can be looked up or changed
in `bones.player_inventory_lists`.

e.g. `table.insert(bones.player_inventory_lists, "backpack")`


Creative API
------------

Use `creative.register_tab(name, title, items)` to add a tab with filtered items.
For example,

	creative.register_tab("tools", "Tools", minetest.registered_tools)

is used to show all tools. Name is used in the sfinv page name, title is the
human readable title.

Creative provides `creative.is_enabled_for(name)`, which is identical in
functionality to the engine's `minetest.creative_is_enabled(name)`.
Its use is deprecated and it should also not be overriden.

The contents of `creative.formspec_add` is appended to every creative inventory
page. Mods can use it to add additional formspec elements onto the default
creative inventory formspec to be drawn after each update.

Group overrides can be used for any registered item, node or tool. Use one of
the groups stated below to pick which category it will appear in.

	node = 1      -- Appears in the Nodes category
	tool = 1      -- Appears in the Tools category
	craftitem = 1 -- Appears in the Items category


Chests API
----------

The chests API allows the creation of chests, which have their own inventories for holding items.

`default.chest.get_chest_formspec(pos)`

 * Returns a formspec for a specific chest.
 * `pos` Location of the chest node, e.g `{x = 1, y = 1, z = 1}`

`default.chest.chest_lid_obstructed(pos)`

 * Returns a boolean depending on whether or not a chest has its top obstructed by a solid node.
 * `pos` Location of the chest node, e.g `{x = 1, y = 1, z = 1}`

`default.chest.chest_lid_close(pn)`

 * Closes the chest that a player is currently looking in.
 * `pn` The name of the player whose chest is going to be closed

`default.chest.open_chests`

 * A table indexed by player name to keep track of who opened what chest.
 * Key: The name of the player.
 * Value: A table containing information about the chest the player is looking at.
   e.g `{ pos = {1, 1, 1}, sound = null, swap = "default:chest" }`

`default.chest.register_chest(name, def)`

 * Registers new chest
 * `name` Name for chest e.g. "default:chest"
 * `def`  See [#Chest Definition]

### Chest Definition

	description = "Chest",
	tiles = {
		"default_chest_top.png",
		"default_chest_top.png",
		"default_chest_side.png",
		"default_chest_side.png",
		"default_chest_front.png",
		"default_chest_inside.png"
	}, -- Textures which are applied to the chest model.
	sounds = default.node_sound_wood_defaults(),
	sound_open = "default_chest_open",
	sound_close = "default_chest_close",
	groups = {choppy = 2, oddly_breakable_by_hand = 2},
	protected = false, -- If true, only placer can modify chest.


Doors API
---------

The doors mod allows modders to register custom doors and trapdoors.

`doors.registered_doors[name] = Door definition` 
 * Table of registered doors, indexed by door name 

`doors.registered_trapdoors[name] = Trapdoor definition` 
 * Table of registered trap doors, indexed by trap door name 

`doors.register_door(name, def)`

 * Registers new door
 * `name` Name for door
 * `def`  See [#Door definition]

`doors.register_trapdoor(name, def)`

 * Registers new trapdoor
 * `name` Name for trapdoor
 * `def`  See [#Trapdoor definition]

`doors.register_fencegate(name, def)`

 * Registers new fence gate
 * `name` Name for fence gate
 * `def`  See [#Fence gate definition]

`doors.get(pos)`

 * `pos` A position as a table, e.g `{x = 1, y = 1, z = 1}`
 * Returns an ObjectRef to a door, or nil if the position does not contain a door

    ### Methods

        :open(player)   -- Open the door object, returns if door was opened
        :close(player)  -- Close the door object, returns if door was closed
        :toggle(player) -- Toggle the door state, returns if state was toggled
        :state()        -- returns the door state, true = open, false = closed

    the "player" parameter can be omitted in all methods. If passed then
    the usual permission checks will be performed to make sure the player
    has the permissions needed to open this door. If omitted then no
    permission checks are performed.

`doors.door_toggle(pos, node, clicker)`

 * Toggle door open or shut
 * `pos` Position of the door
 * `node` Node definition
 * `clicker` Player definition for the player that clicked on the door
 
### Door definition

	description = "Door description",
	inventory_image = "mod_door_inv.png",
	groups = {choppy = 2},
	model = "mod_door", -- (optional)
	-- Model name without a suffix ("big_door" not "big_door_a.obj", "big_door_b.obj")
	tiles = {"mod_door.png"}, -- UV map.
	-- The front and back of the door must be identical in appearence as they swap on
	-- open/close.
	recipe = craftrecipe,
	sounds = default.node_sound_wood_defaults(), -- optional
	sound_open = sound play for open door, -- optional
	sound_close = sound play for close door, -- optional
	gain_open = 0.3, -- optional, defaults to 0.3
	gain_close = 0.3, -- optional, defaults to 0.3
	protected = false, -- If true, only placer can open the door (locked for others)
	on_rightclick = function(pos, node, clicker, itemstack, pointed_thing), 
	-- optional function containing the on_rightclick callback, defaults to a doors.door_toggle-wrapper
	use_texture_alpha = "clip",

### Trapdoor definition

	description = "Trapdoor description",
	inventory_image = "mod_trapdoor_inv.png",
	nodebox_closed = {} -- Nodebox for closed model
	nodebox_opened = {} -- Nodebox for opened model
	-- (optional) both nodeboxes must be used, not one only
	groups = {choppy = 2},
	tile_front = "doors_trapdoor.png", -- the texture for the front and back of the trapdoor
	tile_side = "doors_trapdoor_side.png",
	-- The texture for the four sides of the trapdoor.
	-- The texture should have the trapdoor side drawn twice, in the lowest and highest
	-- 1/8ths of the texture, both upright. The area between is not used.
	-- The lower 1/8th will be used for the closed trapdoor, the higher 1/8th will be used
	-- for the open trapdoor.
	sounds = default.node_sound_wood_defaults(), -- optional
	sound_open = sound play for open door, -- optional
	sound_close = sound play for close door, -- optional
	gain_open = 0.3, -- optional, defaults to 0.3
	gain_close = 0.3, -- optional, defaults to 0.3
	protected = false, -- If true, only placer can open the door (locked for others)
	on_rightclick = function(pos, node, clicker, itemstack, pointed_thing) ,
	-- function containing the on_rightclick callback
	use_texture_alpha = "clip",

### Fence gate definition

	description = "Wooden Fence Gate",
	texture = "default_wood.png", -- `backface_culling` will automatically be
	                              -- set to `true` if not specified.
	material = "default:wood",
	groups = {choppy = 2, oddly_breakable_by_hand = 2, flammable = 2},
	sounds = default.node_sound_wood_defaults(), -- optional
	on_rightclick = function(pos, node, clicker, itemstack, pointed_thing)
	-- function containing the on_rightclick callback


Dungeon Loot API
----------------

The mod that places chests with loot in dungeons provides an API to register additional loot.

`dungeon_loot.register(def)`

 * Registers one or more loot items
 * `def` Can be a single [#Loot definition] or a list of them

`dungeon_loot.registered_loot`

 * Table of all registered loot, not to be modified manually

### Loot definition

	name = "item:name",
	chance = 0.5,
	-- ^ chance value from 0.0 to 1.0 that the item will appear in the chest when chosen
	--   Due to an extra step in the selection process, 0.5 does not(!) mean that
	--   on average every second chest will have this item
	count = {1, 4},
	-- ^ table with minimum and maximum amounts of this item
	--   optional, defaults to always single item
	y = {-32768, -512},
	-- ^ table with minimum and maximum heights this item can be found at
	--   optional, defaults to no height restrictions
	types = {"desert"},
	-- ^ table with types of dungeons this item can be found in
	--   supported types: "normal" (the cobble/mossycobble one), "sandstone"
	--   "desert" and "ice"
	--   optional, defaults to no type restrictions


Fence API
---------

Allows creation of new fences with "fencelike" drawtype.

`default.register_fence(name, item definition)`

 Registers a new fence. Custom fields texture and material are required, as
 are name and description. The rest is optional. You can pass most normal
 nodedef fields here except drawtype. The fence group will always be added
 for this node.

### fence definition

	name = "default:fence_wood",
	description = "Wooden Fence",
	texture = "default_wood.png",
	material = "default:wood", -- `nil` if you don't want the recipe
	groups = {choppy = 2, oddly_breakable_by_hand = 2, flammable = 2},
	sounds = default.node_sound_wood_defaults(),


Walls API
---------

The walls API allows easy addition of stone auto-connecting wall nodes.

walls.register(name, desc, texture, mat, sounds)
^ name = "walls:stone_wall". Node name.
^ desc = "A Stone wall"
^ texture = "default_stone.png"
^ mat = "default:stone". Used to auto-generate crafting recipe.
^ sounds = sounds: see [#Default sounds]

All walls will be connected to any nodes with one of the following groups:
 * `wall`
 * `stone`
 * `fence`
 * `wall_connected`


Farming API
-----------

The farming API allows you to easily register plants and hoes.

`farming.register_hoe(name, hoe definition)`
 * Register a new hoe, see [#hoe definition]

`farming.register_plant(name, Plant definition)`
 * Register a new growing plant, see [#Plant definition]

`farming.registered_plants[name] = definition`
 * Table of registered plants, indexed by plant name

### Hoe Definition


	{
		description = "",                      -- Description for tooltip
		inventory_image = "unknown_item.png",  -- Image to be used as wield- and inventory image
		max_uses = 30,                         -- Uses until destroyed
		material = "",                         -- Material for recipes
		recipe = {                             -- Craft recipe, if material isn't used
			{"air", "air", "air"},
			{"", "group:stick"},
			{"", "group:stick"},
		}
	}

### Plant definition

	{
		description = "",                      -- Description of seed item
		harvest_description = "",              -- Description of harvest item
		                                       -- (optional, derived automatically if not provided)
		inventory_image = "unknown_item.png",  -- Image to be used as seed's wield- and inventory image
		steps = 8,                             -- How many steps the plant has to grow, until it can be harvested
		-- ^ Always provide a plant texture for each step, format: modname_plantname_i.png (i = stepnumber)
		minlight = 13,                         -- Minimum light to grow
		maxlight = default.LIGHT_MAX           -- Maximum light to grow
		can_grow = function(pos)               -- Сalled every growth tick to check if the plant can grow, returns bool
		                                       -- (optional, checks for wet soil by default)
	}


Fire API
--------

Add group flammable when registering a node to make fire seek for it.
Add it to an item to make it burn up when dropped in lava or fire.
New node def property:

`on_burn(pos)`

 * Called when fire attempts to remove a burning node.
 * `pos` Position of the burning node.

 `on_ignite(pos, igniter)`

  * Called when Flint and steel (or a mod defined ignitor) is used on a node.
    Defining it may prevent the default action (spawning flames) from triggering.
  * `pos` Position of the ignited node.
  * `igniter` Player that used the tool, when available.


Give Initial Stuff API
----------------------

`give_initial_stuff.give(player)`

^ Give initial stuff to "player"

`give_initial_stuff.add(stack)`

^ Add item to the initial stuff
^ Stack can be an ItemStack or a item name eg: "default:dirt 99"
^ Can be called after the game has loaded

`give_initial_stuff.clear()`

^ Removes all items from the initial stuff
^ Can be called after the game has loaded

`give_initial_stuff.get_list()`

^ returns list of item stacks

`give_initial_stuff.set_list(list)`

^ List of initial items with numeric indices.

`give_initial_stuff.add_from_csv(str)`

^ str is a comma separated list of initial stuff
^ Adds items to the list of items to be given


Player API
----------

The player API can register player models and update the player's appearance.

* `player_api.globalstep(dtime, ...)`
	* The function called by the globalstep that controls player animations.
	  You can override this to replace the globalstep with your own implementation.
	* Receives all args that minetest.register_globalstep() passes

* `player_api.register_model(name, def)`
	* Register a new model to be used by players
	* `name`: model filename such as "character.x", "foo.b3d", etc.
	* `def`: see [#Model definition]
	* Saved to player_api.registered_models

* `player_api.registered_models[name]`
	* Get a model's definition
	* `name`: model filename
	* See [#Model definition]

* `player_api.set_model(player, model_name)`
	* Change a player's model
	* `player`: PlayerRef
	* `model_name`: model registered with `player_api.register_model`

* `player_api.set_animation(player, anim_name, speed)`
	* Applies an animation to a player if speed or anim_name differ from the currently playing animation
	* `player`: PlayerRef
	* `anim_name`: name of the animation
	* `speed`: keyframes per second. If nil, the default from the model def is used

* `player_api.set_textures(player, textures)`
	* Sets player textures
	* `player`: PlayerRef
	* `textures`: array of textures. If nil, the default from the model def is used

* `player_api.set_textures(player, index, texture)`
	* Sets one of the player textures
	* `player`: PlayerRef
	* `index`: Index into array of all textures
	* `texture`: the texture string

* `player_api.get_animation(player)`
	* Returns a table containing fields `model`, `textures` and `animation`
	* Any of the fields of the returned table may be nil
	* `player`: PlayerRef

* `player_api.player_attached`
	* A table that maps a player name to a boolean
	* If the value for a given player is set to true, the default player animations
	  (walking, digging, ...) will no longer be updated, and knockback from damage is
	  prevented for that player
	* Example of usage: A mod sets a player's value to true when attached to a vehicle

### Model Definition

	{
		animation_speed = 30,           -- Default animation speed, in keyframes per second
		textures = {"character.png"},   -- Default array of textures
		animations = {
			-- [anim_name] = {
			--   x = <start_frame>,
			--   y = <end_frame>,
			--   collisionbox = <model collisionbox>, -- (optional)
			--   eye_height = <model eye height>,     -- (optional)
			--   -- suspend client side animations while this one is active (optional)
			--   override_local = <true/false>
			-- },
			stand = ..., lay = ..., walk = ..., mine = ..., walk_mine = ..., -- required animations
			sit = ... -- used by boats and other MTG mods
		},
		-- Default object properties, see lua_api.txt
		visual_size = {x = 1, y = 1},
		collisionbox = {-0.3, 0.0, -0.3, 0.3, 1.7, 0.3},
		stepheight = 0.6,
		eye_height = 1.47
	}


TNT API
-------

`tnt.register_tnt(definition)`

^ Register a new type of tnt.

 * `name` The name of the node. If no prefix is given `tnt` is used.
 * `description` A description for your TNT.
 * `radius` The radius within which the TNT can destroy nodes. The default is 3.
 * `damage_radius` The radius within which the TNT can damage players and mobs. By default it is twice the `radius`.
 * `sound` The sound played when explosion occurs. By default it is `tnt_explode`.
 * `disable_drops` Disable drops. By default it is set to false.
 * `ignore_protection` Don't check `minetest.is_protected` before removing a node.
 * `ignore_on_blast` Don't call `on_blast` even if a node has one.
 * `tiles` Textures for node
  * `side`  Side tiles. By default the name of the tnt with a suffix of `_side.png`.
  * `top`  Top tile. By default the name of the tnt with a suffix of `_top.png`.
  * `bottom` Bottom tile. By default the name of the tnt with a suffix of `_bottom.png`.
  * `burning` Top tile when lit. By default the name of the tnt with a suffix of `_top_burning_animated.png".

`tnt.boom(position[, definition])`

^ Create an explosion.

* `position` The center of explosion.
* `definition` The TNT definion as passed to `tnt.register` with the following addition:
 * `explode_center` false by default which removes TNT node on blast, when true will explode center node.

`tnt.burn(position, [nodename])`

^ Ignite node at position, triggering its `on_ignite` callback (see fire mod).
If no such callback exists, fallback to turn tnt group nodes to their
"_burning" variant.
  nodename isn't required unless already known.

To make dropping items from node inventories easier, you can use the
following helper function from 'default':

default.get_inventory_drops(pos, inventory, drops)

^ Return drops from node inventory "inventory" in drops.

* `pos` - the node position
* `inventory` - the name of the inventory (string)
* `drops` - an initialized list

The function returns no values. The drops are returned in the `drops`
parameter, and drops is not reinitialized so you can call it several
times in a row to add more inventory items to it.


`on_blast` callbacks:

Both nodedefs and entitydefs can provide an `on_blast()` callback

`nodedef.on_blast(pos, intensity)`
^ Allow drop and node removal overriding
* `pos` - node position
* `intensity` - TNT explosion measure. larger or equal to 1.0
^ Should return a list of drops (e.g. {"default:stone"})
^ Should perform node removal itself. If callback exists in the nodedef
^ then the TNT code will not destroy this node.

`entitydef.on_blast(luaobj, damage)`
^ Allow TNT effects on entities to be overridden
* `luaobj` - LuaEntityRef of the entity
* `damage` - suggested HP damage value
^ Should return a list of (bool do_damage, bool do_knockback, table drops)
* `do_damage` - if true then TNT mod wil damage the entity
* `do_knockback` - if true then TNT mod will knock the entity away
* `drops` - a list of drops, e.g. {"wool:red"}


Node drops:

When a node is detonated it is removed according to the following rules.
1. If `on_blast` is defined, that is called.
2. Else if the node has group `flammable` it is replaced with a fire node.
3. Else the dropped items are retrieved and it is replaced with air.

The parameter `_tnt_loss` in any item definition can be set to a number to
effect that "one in X" of these drops will be lost during an explosion.
For example `_tnt_loss = 2` would cause 50% of items to disappear.
The default is to not lose any items, which is equivalent to `_tnt_loss = 0`.

Screwdriver API
---------------

The screwdriver API allows you to control a node's behaviour when a screwdriver is used on it.
To use it, add the `on_screwdriver` function to the node definition.

`on_rotate(pos, node, user, mode, new_param2)`

 * `pos` Position of the node that the screwdriver is being used on
 * `node` that node
 * `user` The player who used the screwdriver
 * `mode` screwdriver.ROTATE_FACE or screwdriver.ROTATE_AXIS
 * `new_param2` the new value of param2 that would have been set if on_rotate wasn't there
 * return value: false to disallow rotation, nil to keep default behaviour, true to allow
 	it but to indicate that changed have already been made (so the screwdriver will wear out)
 * use `on_rotate = false` to always disallow rotation
 * use `on_rotate = screwdriver.rotate_simple` to allow only face rotation


Sethome API
-----------

The sethome API adds three global functions to allow mods to read a players home position,
set a players home position and teleport a player to home position.

`sethome.get(name)`

 * `name` Player who's home position you wish to get
 * return value: false if no player home coords exist, position table if true

`sethome.set(name, pos)`

 * `name` Player who's home position you wish to set
 * `pos` Position table containing coords of home position
 * return value: false if unable to set and save new home position, otherwise true

`sethome.go(name)`

 * `name` Player you wish to teleport to their home position
 * return value: false if player cannot be sent home, otherwise true

Spawn API
---------

The spawn mod takes care of deciding the position of new and respawning players
in the world and has an API to modify its behavior.

`spawn.get_default_pos()`
* Gets the default spawn position as decided by a biome-dependent algorithm.
* This is not influenced by settings like "static_spawnpoint" or "engine_spawn".
* return value: a vector or `nil` on failure

`spawn.add_suitable_biome(biome)`:
* Adds a biome to the list of allowed biomes for the above algorithm.
* `biome`: Name of a registered biome

`spawn.register_on_spawn(func)`:
* Registers a callback to be called when a player (re-)spawns. This can be used
  to intercept the normal logic to e.g. respawn a player at his bed.
* `func`: `function(player, is_new)` with arguments
  - `player`: ObjectRef
  - `is_new`: true if the player is joining the server for the first time
  - return value: true to skip all other spawn logic, false or nil otherwise

When a player (re-)spawns the following order is executed:
1. All spawn callbacks in order of registration.
2. If no result, teleport player to `spawn.get_default_pos()`.
3. If that fails, spawning is left up to engine.


Sfinv API
---------

It is recommended that you read this link for a good introduction to the
sfinv API by its author: https://rubenwardy.com/minetest_modding_book/en/chapters/sfinv.html

### sfinv Methods

**Pages**

* sfinv.set_page(player, pagename) - changes the page
* sfinv.get_page(player) - get the current page name. Will never return nil
* sfinv.get_homepage_name(player) - get the page name of the first page to show to a player
* sfinv.register_page(name, def) - register a page, see section below
* sfinv.override_page(name, def) - overrides fields of an page registered with register_page.
    * Note: Page must already be defined, (opt)depend on the mod defining it.
* sfinv.set_player_inventory_formspec(player) - (re)builds page formspec
             and calls set_inventory_formspec().
* sfinv.get_formspec(player, context) - builds current page's formspec

**Contexts**

* sfinv.get_or_create_context(player) - gets the player's context
* sfinv.set_context(player, context)

**Theming**

* sfinv.make_formspec(player, context, content, show_inv, size) - adds a theme to a formspec
    * show_inv, defaults to false. Whether to show the player's main inventory
    * size, defaults to `size[8,8.6]` if not specified
* sfinv.get_nav_fs(player, context, nav, current_idx) - creates tabheader or ""

### sfinv Members

* pages - table of pages[pagename] = def
* pages_unordered - array table of pages in order of addition (used to build navigation tabs).
* contexts - contexts[playername] = player_context
* enabled - set to false to disable. Good for inventory rehaul mods like unified inventory

### Context

A table with these keys:

* page - current page name
* nav - a list of page names
* nav_titles - a list of page titles
* nav_idx - current nav index (in nav and nav_titles)
* any thing you want to store
    * sfinv will clear the stored data on log out / log in

### sfinv.register_page

sfinv.register_page(name, def)

def is a table containing:

* `title` - human readable page name (required)
* `get(self, player, context)` - returns a formspec string. See formspec variables. (required)
* `is_in_nav(self, player, context)` - return true to show in the navigation (the tab header, by default)
* `on_player_receive_fields(self, player, context, fields)` - on formspec submit.
* `on_enter(self, player, context)` - called when the player changes pages, usually using the tabs.
* `on_leave(self, player, context)` - when leaving this page to go to another, called before other's on_enter

### get formspec

Use sfinv.make_formspec to apply a layout:

	return sfinv.make_formspec(player, context, [[
		list[current_player;craft;1.75,0.5;3,3;]
		list[current_player;craftpreview;5.75,1.5;1,1;]
		image[4.75,1.5;1,1;gui_furnace_arrow_bg.png^[transformR270]
		listring[current_player;main]
		listring[current_player;craft]
		image[0,4.25;1,1;gui_hb_bg.png]
		image[1,4.25;1,1;gui_hb_bg.png]
		image[2,4.25;1,1;gui_hb_bg.png]
		image[3,4.25;1,1;gui_hb_bg.png]
		image[4,4.25;1,1;gui_hb_bg.png]
		image[5,4.25;1,1;gui_hb_bg.png]
		image[6,4.25;1,1;gui_hb_bg.png]
		image[7,4.25;1,1;gui_hb_bg.png]
	]], true)

See above (methods section) for more options.

### Customising themes

Simply override this function to change the navigation:

	function sfinv.get_nav_fs(player, context, nav, current_idx)
		return "navformspec"
	end

And override this function to change the layout:

	function sfinv.make_formspec(player, context, content, show_inv, size)
		local tmp = {
			size or "size[8,8.6]",
			theme_main,
			sfinv.get_nav_fs(player, context, context.nav_titles, context.nav_idx),
			content
		}
		if show_inv then
			tmp[4] = theme_inv
		end
		return table.concat(tmp, "")
	end


Stairs API
----------

The stairs API lets you register stairs and slabs and ensures that they are registered the same way as those
delivered with Minetest Game, to keep them compatible with other mods.

The following node attributes are sourced from the recipeitem:
 * use_texture_alpha
 * sunlight_propagates
 * light_source
 * If the recipeitem is a fuel, the stair/slab is also registered as a fuel of proportionate burntime.

`stairs.register_stair(subname, recipeitem, groups, images, description, sounds, worldaligntex)`

 * Registers a stair
 * `subname`: Basically the material name (e.g. cobble) used for the stair name. Nodename pattern: "stairs:stair_subname"
 * `recipeitem`: Item used in the craft recipe, e.g. "default:cobble", may be `nil`
 * `groups`: See [Known damage and digging time defining groups]
 * `images`: See [Tile definition]
 * `description`: Used for the description field in the stair's definition
 * `sounds`: See [#Default sounds]
 * `worldaligntex`: A bool to set all textures world-aligned. Default false. See [Tile definition]

`stairs.register_slab(subname, recipeitem, groups, images, description, sounds, worldaligntex)`

 * Registers a slab
 * `subname`: Basically the material name (e.g. cobble) used for the slab name. Nodename pattern: "stairs:slab_subname"
 * `recipeitem`: Item used in the craft recipe, e.g. "default:cobble"
 * `groups`: See [Known damage and digging time defining groups]
 * `images`: See [Tile definition]
 * `description`: Used for the description field in the slab's definition
 * `sounds`: See [#Default sounds]
 * `worldaligntex`: A bool to set all textures world-aligned. Default false. See [Tile definition]

`stairs.register_stair_inner(subname, recipeitem, groups, images, description, sounds, worldaligntex, full_description)`

 * Registers an inner corner stair
 * `subname`: Basically the material name (e.g. cobble) used for the stair name. Nodename pattern: "stairs:stair_inner_subname"
 * `recipeitem`: Item used in the craft recipe, e.g. "default:cobble", may be `nil`
 * `groups`: See [Known damage and digging time defining groups]
 * `images`: See [Tile definition]
 * `description`: Used for the description field in the stair's definition with "Inner" prepended
 * `sounds`: See [#Default sounds]
 * `worldaligntex`: A bool to set all textures world-aligned. Default false. See [Tile definition]
 * `full_description`: Overrides the description, bypassing string concatenation. This is useful for translation. (optional)

`stairs.register_stair_outer(subname, recipeitem, groups, images, description, sounds, worldaligntex, full_description)`

 * Registers an outer corner stair
 * `subname`: Basically the material name (e.g. cobble) used for the stair name. Nodename pattern: "stairs:stair_outer_subname"
 * `recipeitem`: Item used in the craft recipe, e.g. "default:cobble", may be `nil`
 * `groups`: See [Known damage and digging time defining groups]
 * `images`: See [Tile definition]
 * `description`: Used for the description field in the stair's definition with "Outer" prepended
 * `sounds`: See [#Default sounds]
 * `worldaligntex`: A bool to set all textures world-aligned. Default false. See [Tile definition]
 * `full_description`: Overrides the description, bypassing string concatenation. This is useful for translation. (optional)

```
stairs.register_stair_and_slab(subname, recipeitem, groups, images, desc_stair, desc_slab,
	sounds, worldaligntex, desc_stair_inner, desc_stair_outer)
```

 * A wrapper for stairs.register_stair, stairs.register_slab, stairs.register_stair_inner, stairs.register_stair_outer
 * Uses almost the same arguments as stairs.register_stair
 * `desc_stair`: Description for stair nodes. For corner stairs 'Inner' or 'Outer' will be prefixed unless
 	`desc_stair_inner` or `desc_stair_outer` are specified, which are used instead.
 * `desc_slab`: Description for slab node
 * `desc_stair_inner`: Description for inner stair node
 * `desc_stair_outer`: Description for outer stair node


Xpanes API
----------

Creates panes that automatically connect to each other

`xpanes.register_pane(subname, def)`

 * `subname`: used for nodename. Result: "xpanes:subname" and "xpanes:subname_{2..15}"
 * `def`: See [#Pane definition]

### Pane definition

	{
		textures = {
			"texture for front and back",
			(unused),
			"texture for the 4 edges"
		}, -- More tiles aren't supported
		groups = {group = rating}, -- Uses the known node groups, see [Known damage and digging time defining groups]
		sounds = SoundSpec,        -- See [#Default sounds]
		recipe = {{"","","","","","","","",""}}, -- Recipe field only
		use_texture_alpha = true, -- Optional boolean (default: `false`) for colored glass panes
	}


Raillike definitions
--------------------

The following nodes use the group `connect_to_raillike` and will only connect to
raillike nodes within this group and the same group value.
Use `minetest.raillike_group(<Name>)` to get the group value.

| Node type             | Raillike group name
|-----------------------|---------------------
| default:rail          | "rail"
| tnt:gunpowder         | "gunpowder"
| tnt:gunpowder_burning	| "gunpowder"

Example:
If you want to add a new rail type and want it to connect with default:rail,
add `connect_to_raillike=minetest.raillike_group("rail")` into the `groups` table
of your node.


Default sounds
--------------

Sounds inside the default table can be used within the sounds field of node definitions.

 * `default.node_sound_defaults()`
 * `default.node_sound_stone_defaults()`
 * `default.node_sound_dirt_defaults()`
 * `default.node_sound_sand_defaults()`
 * `default.node_sound_wood_defaults()`
 * `default.node_sound_leaves_defaults()`
 * `default.node_sound_glass_defaults()`
 * `default.node_sound_metal_defaults()`


Default constants
-----------------

`default.LIGHT_MAX`  The maximum light level (see [Node definition] light_source)


GUI and formspecs
-----------------

`default.get_hotbar_bg(x, y)`

 * Get the hotbar background as string, containing the formspec elements
 * x: Horizontal position in the formspec
 * y: Vertical position in the formspec

`default.gui_bg`

 * Deprecated, remove from mods.

`default.gui_bg_img`

 * Deprecated, remove from mods.

`default.gui_slots`

 * Deprecated, remove from mods.

`default.gui_survival_form`

 * Entire formspec for the survival inventory

`default.get_furnace_active_formspec(fuel_percent, item_percent)`

 * Get the active furnace formspec using the defined GUI elements
 * fuel_percent: Percent of how much the fuel is used
 * item_percent: Percent of how much the item is cooked

`default.get_furnace_inactive_formspec()`

 * Get the inactive furnace formspec using the defined GUI elements


Leafdecay
---------

To enable leaf decay for leaves when a tree is cut down by a player,
register the tree with the default.register_leafdecay(leafdecaydef)
function.

If `param2` of any registered node is ~= 0, the node will always be
preserved. Thus, if the player places a node of that kind, you will
want to set `param2 = 1` or so.

The function `default.after_place_leaves` can be set as
`after_place_node of a node` to set param2 to 1 if the player places
the node (should not be used for nodes that use param2 otherwise
(e.g. facedir)).

If the node is in the `leafdecay_drop` group then it will always be
dropped as an item.

`default.register_leafdecay(leafdecaydef)`

`leafdecaydef` is a table, with following members:
	{
		trunks = {"default:tree"}, -- nodes considered trunks
		leaves = {"default:leaves", "default:apple"},
			-- nodes considered for removal
		radius = 3, -- radius to consider for searching
	}

Note: all the listed nodes in `trunks` have their `on_after_destruct`
callback overridden. All the nodes listed in `leaves` have their
`on_timer` callback overridden.


Dyes
----

Minetest Game dyes are registered with:

    groups = {dye = 1, color_<color> = 1},

To make recipes that will work with dyes from many mods, define them using the
dye group and the color groups.

Dye color groups:

 * `color_white`
 * `color_grey`
 * `color_dark_grey`
 * `color_black`
 * `color_red`
 * `color_pink`
 * `color_orange`
 * `color_brown`
 * `color_yellow`
 * `color_green`
 * `color_dark_green`
 * `color_blue`
 * `color_cyan`
 * `color_violet`
 * `color_magenta`

Example of one shapeless recipe using the dye group and a color group:

	minetest.register_craft({
		type = "shapeless",
		output = "<mod>:item_yellow",
		recipe = {"<mod>:item_no_color", "group:dye,color_yellow"},
	})


Trees
-----

 * `default.grow_tree(pos, is_apple_tree)`
  * Grows a mgv6 tree or apple tree at pos

 * `default.grow_jungle_tree(pos)`
  * Grows a mgv6 jungletree at pos

 * `default.grow_pine_tree(pos)`
  * Grows a mgv6 pinetree at pos

 * `default.grow_new_apple_tree(pos)`
  * Grows a new design apple tree at pos

 * `default.grow_new_jungle_tree(pos)`
  * Grows a new design jungle tree at pos

 * `default.grow_new_pine_tree(pos)`
  * Grows a new design pine tree at pos

 * `default.grow_new_snowy_pine_tree(pos)`
  * Grows a new design snowy pine tree at pos

 * `default.grow_new_acacia_tree(pos)`
  * Grows a new design acacia tree at pos

 * `default.grow_new_aspen_tree(pos)`
  * Grows a new design aspen tree at pos

 * `default.grow_bush(pos)`
  * Grows a bush at pos

 * `default.grow_acacia_bush(pos)`
  * Grows an acaia bush at pos

 * `default.grow_pine_bush(pos)`
  * Grows a pine bush at pos

 * `default.grow_blueberry_bush(pos)`
  * Grows a blueberry bush at pos

 * `default.on_grow_failed(pos)`
  * Reset the node timer to 300 seconds, used as default callback when the growth of a sapling fails

 * `default.sapling_growth_defs`
  * Table that contains all the definitions for the growable saplings, see `default.register_sapling_growth`

 * `default.register_sapling_growth(name, def)`
  * Register a new sapling growth configuration. Useful to add custom sapling and trees to the game in a compact way.
	default.register_sapling_growth(
		"default:sapling", -- Name of the sapling
		{
			can_grow = default.can_grow, -- Function called to determine whether the sapling can grow, should return a boolean 
			on_grow_failed = default.on_grow_failed, -- Function called when the growth fails
			grow = function(pos) -- Function called when the growth has success. This should replace the sapling with a tree.
		}
	)

 * `default.grow_sapling(pos)`
  * Attempt to grow a sapling at the given position. Useful as on_timer callback.



Carts
-----

	carts.register_rail(
		"mycarts:myrail", -- Rail name
		nodedef,          -- standard nodedef
		railparams        -- rail parameter struct (optional)
	)

	railparams = {
		on_step(obj, dtime), -- Event handler called when
		                     -- cart is on rail
		acceleration, -- integer acceleration factor (negative
		              -- values to brake)
	}

	The event handler is called after all default calculations
	are made, so the custom on_step handler can override things
	like speed, acceleration, player attachment. The handler will
	likely be called many times per second, so the function needs
	to make sure that the event is handled properly.


Key API
-------

The key API allows mods to add key functionality to nodes that have
ownership or specific permissions. Using the API will make it so
that a node owner can use skeleton keys on their nodes to create keys
for that node in that location, and give that key to other players,
allowing them some sort of access that they otherwise would not have
due to node protection.

To make your new nodes work with the key API, you need to register
two callback functions in each nodedef:


`on_key_use(pos, player)`
 * Is called when a player right-clicks (uses) a normal key on your
 * node.
 * `pos` - position of the node
 * `player` - PlayerRef
 * return value: none, ignored

The `on_key_use` callback should validate that the player is wielding
a key item with the right key meta secret. If needed the code should
deny access to the node functionality.

If formspecs are used, the formspec callbacks should duplicate these
checks in the metadata callback functions.


`on_skeleton_key_use(pos, player, newsecret)`

 * Is called when a player right-clicks (uses) a skeleton key on your
 * node.
 * `pos` - position of the node
 * `player` - PlayerRef
 * `newsecret` - a secret value(string)
 * return values:
 * `secret` - `nil` or the secret value that unlocks the door
 * `name` - a string description of the node ("a locked chest")
 * `owner` - name of the node owner

The `on_skeleton_key_use` function should validate that the player has
the right permissions to make a new key for the item. The newsecret
value is useful if the node has no secret value. The function should
store this secret value somewhere so that in the future it may compare
key secrets and match them to allow access. If a node already has a
secret value, the function should return that secret value instead
of the newsecret value. The secret value stored for the node should
not be overwritten, as this would invalidate existing keys.

Aside from the secret value, the function should retun a descriptive
name for the node and the owner name. The return values are all
encoded in the key that will be given to the player in replacement
for the wielded skeleton key.

if `nil` is returned, it is assumed that the wielder did not have
permissions to create a key for this node, and no key is created.

`default.register_craft_metadata_copy(ingredient, result)`
----------------------------------------------------------

This function registers a shapeless recipe that takes `ingredient`
and `result` as input and outputs `result`.

The metadata of the input `result` is copied to the output `result`.


Log API
-------

Logs action of the player with a node at a certain position.
By default only actions of real players are logged.
Actions of non-players (usually machines) are logged only when
setting `log_non_player_actions` is enabled.
A player is considered non-player if `player:is_player()` returns
`false` or `player.is_fake_player` is truthy. The use of
`is_fake_player` is an unofficial standard between mods.
These non-players are marked by the content of `is_fake_player`
(if it is a string) or a "*" in brackets after the player name in
the log.

`default.log_player_action(player, ...)`

 * `player`        The player who performed the action
 * `message_parts` Any mumber of message parts describing the action
                   in 3rd person singular present tense. It can also
                   contain a `pos` which is logged as "(X,Y,Z)"

`default.set_inventory_action_loggers(def, name)`

 * hooks the callbacks `on_metadata_inventory_move`,
   `on_metadata_inventory_put` and `on_metadata_inventory_take`
   that log corresponding actions
 * after logging the action, the original callback (if any) is called
 * `def`     See [Node definition]
 * `name`    Description of the node in the log message


Weather API
-----------

The weather mod will constantly adjust weather effects seen by the player
(that is: cloud parameters, shadow intensity, bloom and volumetric lighting).
These can be influenced using this API.

#### `weather.get = function(player)`

* Returns the current weather effects seen by the player.
  It returns a table with two keys:
  * `clouds`:   A table (or `nil`) with cloud data following the same format as used for `player:set_clouds()`.
  * `lighting`: A table (or `nil`) with lighting data following the same format as used for `player:set_lighting()`.
* `player`: ObjectRef of the relevant player
* You can override this function to change the weather effects by simply returning different values.
  Setting `clouds` or `lighting` in the result table to `nil` will *prevent* those from changing.

Utilities
---------

`default.dig_up(pos, node, digger, max_height)`

 * Find all nodes above `pos` that is the same, then dig them all
 * `max_height`	Maximum number of nodes to iterate. Default: 100
