Lua Modding API Reference

This is lua_api.txt nicely formated: I did not write this

This page was last updated 23/April/2017.
See doc/lua_api.txt for the latest version (in plaintext).
Generated using a Python script.

Table of Contents

Introduction

Content and functionality can be added to Minetest 0.4 by using Lua scripting in run-time loaded mods.

A mod is a self-contained bunch of scripts, textures and other related things that is loaded by and interfaces with Minetest.

Mods are contained and ran solely on the server side. Definitions and media files are automatically transferred to the client.

If you see a deficiency in the API, feel free to attempt to add the functionality in the engine and API. You can send such improvements as source code patches to celeron55@gmail.com.

This page was last updated 23/April/2017.
See doc/lua_api.txt for the latest version (in plaintext).
Generated using a Python script.

Programming in Lua

If you have any difficulty in understanding this, please read Programming in Lua.

Startup

Mods are loaded during server startup from the mod load paths by running the init.lua scripts in a shared environment.

Paths

Games

Games are looked up from:

where gameid is unique to each game.

The game directory contains the file game.conf, which contains these fields:

name = <Human-readable full name of the game>

e.g.

name = Minetest

The game directory can contain the file minetest.conf, which will be used to set default settings when running the particular game. It can also contain a settingtypes.txt in the same format as the one in builtin. This settingtypes.txt will be parsed by the menu and the settings will be displayed in the "Games" category in the settings tab.

Games can provide custom main menu images. They are put inside a menu directory inside the game directory.

The images are named $identifier.png, where $identifier is one of overlay,background,footer,header. If you want to specify multiple images for one identifier, add additional images named like $identifier.$n.png, with an ascending number $n starting with 1, and a random image will be chosen from the provided ones.

Mod load path

Generic:

In a run-in-place version (e.g. the distributed windows version):

On an installed version on Linux:

Mod load path for world-specific games

It is possible to include a game in a world; in this case, no mods or games are loaded or checked from anywhere else.

This is useful for e.g. adventure worlds.

This happens if the following directory exists:

$world/game/

Mods should be then be placed in:

$world/game/mods/

Modpack support

Mods can be put in a subdirectory, if the parent directory, which otherwise should be a mod, contains a file named modpack.txt. This file shall be empty, except for lines starting with #, which are comments.

Mod directory structure

mods
|-- modname
|   |-- depends.txt
|   |-- screenshot.png
|   |-- description.txt
|   |-- settingtypes.txt
|   |-- init.lua
|   |-- models
|   |-- textures
|   |   |-- modname_stuff.png
|   |   `-- modname_something_else.png
|   |-- sounds
|   |-- media
|   `-- <custom data>
`-- another

modname

The location of this directory can be fetched by using minetest.get_modpath(modname).

depends.txt

List of mods that have to be loaded before loading this mod.

A single line contains a single modname.

Optional dependencies can be defined by appending a question mark to a single modname. Their meaning is that if the specified mod is missing, that does not prevent this mod from being loaded.

screenshot.png

A screenshot shown in the mod manager within the main menu. It should have an aspect ratio of 3:2 and a minimum size of 300×200 pixels.

description.txt

A File containing description to be shown within mainmenu.

settingtypes.txt

A file in the same format as the one in builtin. It will be parsed by the settings menu and the settings will be displayed in the "Mods" category.

init.lua

The main Lua script. Running this script should register everything it wants to register. Subsequent execution depends on minetest calling the registered callbacks.

minetest.setting_get(name) and minetest.setting_getbool(name) can be used to read custom or existing settings at load time, if necessary.

models

Models for entities or meshnodes.

textures, sounds, media

Media files (textures, sounds, whatever) that will be transferred to the client and will be available for use by the mod.

Naming convention for registered textual names

Registered names should generally be in this format:

"modname:<whatever>" (<whatever> can have characters a-zA-Z0-9_)

This is to prevent conflicting names from corrupting maps and is enforced by the mod loader.

Example

In the mod experimental, there is the ideal item/node/entity name tnt. So the name should be experimental:tnt.

Enforcement can be overridden by prefixing the name with :. This can be used for overriding the registrations of some other mod.

Example: Any mod can redefine experimental:tnt by using the name

:experimental:tnt

when registering it. (also that mod is required to have experimental as a dependency)

The : prefix can also be used for maintaining backwards compatibility.

Aliases

Aliases can be added by using minetest.register_alias(name, convert_to) or `minetest.register_alias_force(name, convert_to).

This will make Minetest to convert things called name to things called convert_to.

The only difference between minetest.register_alias and minetest.register_alias_force is that if an item called name exists, minetest.register_alias will do nothing while minetest.register_alias_force will unregister it.

This can be used for maintaining backwards compatibility.

This can be also used for setting quick access names for things, e.g. if you have an item called epiclylongmodname:stuff, you could do

minetest.register_alias("stuff", "epiclylongmodname:stuff")

and be able to use /giveme stuff.

Textures

Mods should generally prefix their textures with modname_, e.g. given the mod name foomod, a texture could be called:

foomod_foothing.png

Textures are referred to by their complete name, or alternatively by stripping out the file extension:

Texture modifiers

There are various texture modifiers that can be used to generate textures on-the-fly.

Texture overlaying

Textures can be overlaid by putting a ^ between them.

Example:

default_dirt.png^default_grass_side.png

default_grass_side.png is overlayed over default_dirt.png. The texture with the lower resolution will be automatically upscaled to the higher resolution texture.

Texture grouping

Textures can be grouped together by enclosing them in ( and ).

Example: cobble.png^(thing1.png^thing2.png)

A texture for thing1.png^thing2.png is created and the resulting texture is overlaid on top of cobble.png.

Escaping

Modifiers that accept texture names (e.g. [combine) accept escaping to allow passing complex texture names as arguments. Escaping is done with backslash and is required for ^ and :.

Example: cobble.png^[lowpart:50:color.png\^[mask\:trans.png

The lower 50 percent of color.png^[mask:trans.png are overlaid on top of cobble.png.

Advanced texture modifiers

[crack:<n>:<p>

Draw a step of the crack animation on the texture.

Example:

default_cobble.png^[crack:10:1

[combine:<w>x<h>:<x1>,<y1>=<file1>:<x2>,<y2>=<file2>:...

Creates a texture of size <w> times <h> and blits the listed files to their specified coordinates.

Example:

[combine:16x32:0,0=default_cobble.png:0,16=default_wood.png

[resize:<w>x<h>

Resizes the texture to the given dimensions.

Example:

default_sandstone.png^[resize:16x16

[opacity:<r>

Makes the base image transparent according to the given ratio.
r must be between 0 and 255.
0 means totally transparent.
255 means totally opaque.

Example:

default_sandstone.png^[opacity:127

[invert:<mode>

Inverts the given channels of the base image. Mode may contain the characters "r", "g", "b", "a". Only the channels that are mentioned in the mode string will be inverted.

Example:

default_apple.png^[invert:rgb

[brighten

Brightens the texture.

Example:

tnt_tnt_side.png^[brighten

[noalpha

Makes the texture completely opaque.

Example:

default_leaves.png^[noalpha

[makealpha:<r>,<g>,<b>

Convert one color to transparency.

Example:

default_cobble.png^[makealpha:128,128,128

[transform<t>

Rotates and/or flips the image.

<t> can be a number (between 0 and 7) or a transform name. Rotations are counter-clockwise.

0  I      identity
1  R90    rotate by 90 degrees
2  R180   rotate by 180 degrees
3  R270   rotate by 270 degrees
4  FX     flip X
5  FXR90  flip X then rotate by 90 degrees
6  FY     flip Y
7  FYR90  flip Y then rotate by 90 degrees

Example:

default_stone.png^[transformFXR90

[inventorycube{<top>{<left>{<right>

Escaping does not apply here and ^ is replaced by & in texture names instead.

Create an inventory cube texture using the side textures.

Example:

[inventorycube{grass.png{dirt.png&grass_side.png{dirt.png&grass_side.png

Creates an inventorycube with grass.png, dirt.png^grass_side.png and dirt.png^grass_side.png textures

[lowpart:<percent>:<file>

Blit the lower <percent>% part of <file> on the texture.

Example:

base.png^[lowpart:25:overlay.png

[verticalframe:<t>:<n>

Crops the texture to a frame of a vertical animation.

Example:

default_torch_animated.png^[verticalframe:16:8

[mask:<file>

Apply a mask to the base image.

The mask is applied using binary AND.

[sheet:<w>x<h>:<x>,<y>

Retrieves a tile at position x,y from the base image which it assumes to be a tilesheet with dimensions w,h.

[colorize:<color>:<ratio>

Colorize the textures with the given color. <color> is specified as a ColorString. <ratio> is an int ranging from 0 to 255 or the word "alpha". If it is an int, then it specifies how far to interpolate between the colors where 0 is only the texture color and 255 is only <color>. If omitted, the alpha of <color> will be used as the ratio. If it is the word "alpha", then each texture pixel will contain the RGB of <color> and the alpha of <color> multiplied by the alpha of the texture pixel.

[multiply:<color>

Multiplies texture colors with the given color. <color> is specified as a ColorString. Result is more like what you'd expect if you put a color on top of another color. Meaning white surfaces get a lot of your new color while black parts don't change very much.

Sounds

Only Ogg Vorbis files are supported.

For positional playing of sounds, only single-channel (mono) files are supported. Otherwise OpenAL will play them non-positionally.

Mods should generally prefix their sounds with modname_, e.g. given the mod name "foomod", a sound could be called:

foomod_foosound.ogg

Sounds are referred to by their name with a dot, a single digit and the file extension stripped out. When a sound is played, the actual sound file is chosen randomly from the matching sounds.

When playing the sound foomod_foosound, the sound is chosen randomly from the available ones of the following files:

Examples of sound parameter tables:

-- Play locationless on all clients
{
    gain = 1.0, -- default
}
-- Play locationless to one player
{
    to_player = name,
    gain = 1.0, -- default
}
-- Play locationless to one player, looped
{
    to_player = name,
    gain = 1.0, -- default
    loop = true,
}
-- Play in a location
{
    pos = {x = 1, y = 2, z = 3},
    gain = 1.0, -- default
    max_hear_distance = 32, -- default, uses an euclidean metric
}
-- Play connected to an object, looped
{
    object = <an ObjectRef>,
    gain = 1.0, -- default
    max_hear_distance = 32, -- default, uses an euclidean metric
    loop = true,
}

Looped sounds must either be connected to an object or played locationless to one player using to_player = name,

SimpleSoundSpec

Registered definitions of stuff

Anything added using certain minetest.register_* functions get added to the global minetest.registered_* tables.

Note that in some cases you will stumble upon things that are not contained in these tables (e.g. when a mod has been removed). Always check for existence before trying to access the fields.

Example: If you want to check the drawtype of a node, you could do:

local function get_nodedef_field(nodename, fieldname)
    if not minetest.registered_nodes[nodename] then
        return nil
    end
    return minetest.registered_nodes[nodename][fieldname]
end
local drawtype = get_nodedef_field(nodename, "drawtype")

Example: minetest.get_item_group(name, group) has been implemented as:

function minetest.get_item_group(name, group)
    if not minetest.registered_items[name] or not
            minetest.registered_items[name].groups[group] then
        return 0
    end
    return minetest.registered_items[name].groups[group]
end

Nodes

Nodes are the bulk data of the world: cubes and other things that take the space of a cube. Huge amounts of them are handled efficiently, but they are quite static.

The definition of a node is stored and can be accessed by name in

minetest.registered_nodes[node.name]

See "Registered definitions of stuff".

Nodes are passed by value between Lua and the engine. They are represented by a table:

{name="name", param1=num, param2=num}

param1 and param2 are 8-bit integers. The engine uses them for certain automated functions. If you don't use these functions, you can use them to store arbitrary values.

The functions of param1 and param2 are determined by certain fields in the node definition:

param1 is reserved for the engine when paramtype != "none":

paramtype = "light"
^ The value stores light with and without sun in its upper and lower 4 bits
  respectively. Allows light to propagate from or through the node with
  light value falling by 1 per node. This is essential for a light source
  node to spread its light.

param2 is reserved for the engine when any of these are used:

liquidtype == "flowing"
^ The level and some flags of the liquid is stored in param2
drawtype == "flowingliquid"
^ The drawn liquid level is read from param2
drawtype == "torchlike"
drawtype == "signlike"
paramtype2 == "wallmounted"
^ The rotation of the node is stored in param2. You can make this value
  by using minetest.dir_to_wallmounted().
paramtype2 == "facedir"
^ The rotation of the node is stored in param2. Furnaces and chests are
  rotated this way. Can be made by using minetest.dir_to_facedir().
  Values range 0 - 23
  facedir / 4 = axis direction:
  0 = y+    1 = z+    2 = z-    3 = x+    4 = x-    5 = y-
  facedir modulo 4 = rotation around that axis
paramtype2 == "leveled"
paramtype2 == "degrotate"
^ The rotation of this node is stored in param2. Plants are rotated this way.
  Values range 0 - 179. The value stored in param2 is multiplied by two to
  get the actual rotation of the node.
paramtype2 == "meshoptions"
^ Only valid for "plantlike". The value of param2 becomes a bitfield which can
  be used to change how the client draws plantlike nodes. Bits 0, 1 and 2 form
  a mesh selector. Currently the following meshes are choosable:
    0 = a "x" shaped plant (ordinary plant)
    1 = a "+" shaped plant (just rotated 45 degrees)
    2 = a "*" shaped plant with 3 faces instead of 2
    3 = a "#" shaped plant with 4 faces instead of 2
    4 = a "#" shaped plant with 4 faces that lean outwards
    5-7 are unused and reserved for future meshes.
  Bits 3 through 7 are optional flags that can be combined and give these
  effects:
    bit 3 (0x08) - Makes the plant slightly vary placement horizontally
    bit 4 (0x10) - Makes the plant mesh 1.4x larger
    bit 5 (0x20) - Moves each face randomly a small bit down (1/8 max)
    bits 6-7 are reserved for future use.
paramtype2 == "color"
^ `param2` tells which color is picked from the palette.
  The palette should have 256 pixels.
paramtype2 == "colorfacedir"
^ Same as `facedir`, but with colors.
  The first three bits of `param2` tells which color
  is picked from the palette.
  The palette should have 8 pixels.
paramtype2 == "colorwallmounted"
^ Same as `wallmounted`, but with colors.
  The first five bits of `param2` tells which color
  is picked from the palette.
  The palette should have 32 pixels.
paramtype2 == "glasslikeliquidlevel"
^ Only valid for "glasslike_framed" or "glasslike_framed_optional" drawtypes.
  param2 defines 64 levels of internal liquid.
  Liquid texture is defined using `special_tiles = {"modname_tilename.png"},`
collision_box = {
  type = "fixed",
  fixed = {
            {-0.5, -0.5, -0.5, 0.5, 0.5, 0.5},
  },
},
^ defines list of collision boxes for the node. If empty, collision boxes
  will be the same as nodeboxes, in case of any other nodes will be full cube
  as in the example above.

Nodes can also contain extra data. See "Node Metadata".

Node drawtypes

There are a bunch of different looking node types.

Look for examples in games/minimal or games/minetest_game.

*_optional drawtypes need less rendering time if deactivated (always client side).

Node boxes

Node selection boxes are defined using "node boxes"

The nodebox node drawtype allows defining visual of nodes consisting of arbitrary number of boxes. It allows defining stuff like stairs. Only the fixed and leveled box type is supported for these.

Please note that this is still experimental, and may be incompatibly changed in the future.

A nodebox is defined as any of:

{
    -- A normal cube; the default in most things
    type = "regular"
}
{
    -- A fixed box (facedir param2 is used, if applicable)
    type = "fixed",
    fixed = box OR {box1, box2, ...}
}
{
    -- A box like the selection box for torches
    -- (wallmounted param2 is used, if applicable)
    type = "wallmounted",
    wall_top = box,
    wall_bottom = box,
    wall_side = box
}
{
    -- A node that has optional boxes depending on neighbouring nodes'
    -- presence and type. See also `connects_to`.
    type = "connected",
    fixed = box OR {box1, box2, ...}
    connect_top = box OR {box1, box2, ...}
    connect_bottom = box OR {box1, box2, ...}
    connect_front = box OR {box1, box2, ...}
    connect_left = box OR {box1, box2, ...}
    connect_back = box OR {box1, box2, ...}
    connect_right = box OR {box1, box2, ...}
}

A box is defined as:

{x1, y1, z1, x2, y2, z2}

A box of a regular node would look like:

{-0.5, -0.5, -0.5, 0.5, 0.5, 0.5},

type = "leveled" is same as type = "fixed", but y2 will be automatically set to level from param2.

Meshes

If drawtype mesh is used, tiles should hold model materials textures. Only static meshes are implemented. For supported model formats see Irrlicht engine documentation.

Noise Parameters

Noise Parameters, or commonly called "NoiseParams", define the properties of perlin noise.

offset

Offset that the noise is translated by (i.e. added) after calculation.

scale

Factor that the noise is scaled by (i.e. multiplied) after calculation.

spread

Vector containing values by which each coordinate is divided by before calculation. Higher spread values result in larger noise features.

A value of {x=250, y=250, z=250} is common.

seed

Random seed for the noise. Add the world seed to a seed offset for world-unique noise. In the case of minetest.get_perlin(), this value has the world seed automatically added.

octaves

Number of times the noise gradient is accumulated into the noise.

Increase this number to increase the amount of detail in the resulting noise.

A value of 6 is common.

persistence

Factor by which the effect of the noise gradient function changes with each successive octave.

Values less than 1 make the details of successive octaves' noise diminish, while values greater than 1 make successive octaves stronger.

A value of 0.6 is common.

lacunarity

Factor by which the noise feature sizes change with each successive octave.

A value of 2.0 is common.

flags

Leave this field unset for no special handling.

Currently supported are defaults, eased and absvalue.

defaults

Specify this if you would like to keep auto-selection of eased/not-eased while specifying some other flags.

eased

Maps noise gradient values onto a quintic S-curve before performing interpolation. This results in smooth, rolling noise. Disable this (noeased) for sharp-looking noise. If no flags are specified (or defaults is), 2D noise is eased and 3D noise is not eased.

absvalue

Accumulates the absolute value of each noise gradient result.

Noise parameters format example for 2D or 3D perlin noise or perlin noise maps: np_terrain = { offset = 0, scale = 1, spread = {x=500, y=500, z=500}, seed = 571347, octaves = 5, persist = 0.63, lacunarity = 2.0, flags = "defaults, absvalue" } ^ A single noise parameter table can be used to get 2D or 3D noise, when getting 2D noise spread.z is ignored.

Ore types

These tell in what manner the ore is generated.

All default ores are of the uniformly-distributed scatter type.

scatter

Randomly chooses a location and generates a cluster of ore.

If noise_params is specified, the ore will be placed if the 3D perlin noise at that point is greater than the noise_threshold, giving the ability to create a non-equal distribution of ore.

sheet

Creates a sheet of ore in a blob shape according to the 2D perlin noise described by noise_params and noise_threshold. This is essentially an improved version of the so-called "stratus" ore seen in some unofficial mods.

This sheet consists of vertical columns of uniform randomly distributed height, varying between the inclusive range column_height_min and column_height_max. If column_height_min is not specified, this parameter defaults to 1. If column_height_max is not specified, this parameter defaults to clust_size for reverse compatibility. New code should prefer column_height_max.

The column_midpoint_factor parameter controls the position of the column at which ore eminates from. If 1, columns grow upward. If 0, columns grow downward. If 0.5, columns grow equally starting from each direction. column_midpoint_factor is a decimal number ranging in value from 0 to 1. If this parameter is not specified, the default is 0.5.

The ore parameters clust_scarcity and clust_num_ores are ignored for this ore type.

puff

Creates a sheet of ore in a cloud-like puff shape.

As with the sheet ore type, the size and shape of puffs are described by noise_params and noise_threshold and are placed at random vertical positions within the currently generated chunk.

The vertical top and bottom displacement of each puff are determined by the noise parameters np_puff_top and np_puff_bottom, respectively.

blob

Creates a deformed sphere of ore according to 3d perlin noise described by noise_params. The maximum size of the blob is clust_size, and clust_scarcity has the same meaning as with the scatter type.

vein

Creates veins of ore varying in density by according to the intersection of two instances of 3d perlin noise with diffferent seeds, both described by noise_params. random_factor varies the influence random chance has on placement of an ore inside the vein, which is 1 by default. Note that modifying this parameter may require adjusting noise_threshold. The parameters clust_scarcity, clust_num_ores, and clust_size are ignored by this ore type. This ore type is difficult to control since it is sensitive to small changes. The following is a decent set of parameters to work from:

noise_params = {
    offset  = 0,
    scale   = 3,
    spread  = {x=200, y=200, z=200},
    seed    = 5390,
    octaves = 4,
    persist = 0.5,
    flags = "eased",
},
noise_threshold = 1.6

WARNING: Use this ore type very sparingly since it is ~200x more computationally expensive than any other ore.

Ore attributes

See section "Flag Specifier Format".

Currently supported flags: absheight

absheight

Also produce this same ore between the height range of -y_max and -y_min.

Useful for having ore in sky realms without having to duplicate ore entries.

puff_cliffs

If set, puff ore generation will not taper down large differences in displacement when approaching the edge of a puff. This flag has no effect for ore types other than puff.

puff_additive_composition

By default, when noise described by np_puff_top or np_puff_bottom results in a negative displacement, the sub-column at that point is not generated. With this attribute set, puff ore generation will instead generate the absolute difference in noise displacement values. This flag has no effect for ore types other than puff.

Decoration types

The varying types of decorations that can be placed.

simple

Creates a 1 times H times 1 column of a specified node (or a random node from a list, if a decoration list is specified). Can specify a certain node it must spawn next to, such as water or lava, for example. Can also generate a decoration of random height between a specified lower and upper bound. This type of decoration is intended for placement of grass, flowers, cacti, papyri, waterlilies and so on.

schematic

Copies a box of MapNodes from a specified schematic file (or raw description). Can specify a probability of a node randomly appearing when placed. This decoration type is intended to be used for multi-node sized discrete structures, such as trees, cave spikes, rocks, and so on.

Schematic specifier

A schematic specifier identifies a schematic by either a filename to a Minetest Schematic file (.mts) or through raw data supplied through Lua, in the form of a table. This table specifies the following fields:

About probability values: A probability value of 0 or 1 means that node will never appear (0% chance). A probability value of 254 or 255 means the node will always appear (100% chance). * If the probability value p is greater than 1, then there is a (p / 256 * 100) percent chance that node will appear when the schematic is placed on the map.

Schematic attributes

See section "Flag Specifier Format".

Currently supported flags: place_center_x, place_center_y, place_center_z, force_placement.

HUD element types

The position field is used for all element types.

To account for differing resolutions, the position coordinates are the percentage of the screen, ranging in value from 0 to 1.

The name field is not yet used, but should contain a description of what the HUD element represents. The direction field is the direction in which something is drawn.

0 draws from left to right, 1 draws from right to left, 2 draws from top to bottom, and 3 draws from bottom to top.

The alignment field specifies how the item will be aligned. It ranges from -1 to 1, with 0 being the center, -1 is moved to the left/up, and 1 is to the right/down. Fractional values can be used.

The offset field specifies a pixel offset from the position. Contrary to position, the offset is not scaled to screen size. This allows for some precisely-positioned items in the HUD.

Note: offset will adapt to screen DPI as well as user defined scaling factor!

Below are the specific uses for fields in each type; fields not listed for that type are ignored.

Note: Future revisions to the HUD API may be incompatible; the HUD API is still in the experimental stages.

image

Displays an image on the HUD.

text

Displays text on the HUD.

statbar

Displays a horizontal bar made up of half-images.

inventory

waypoint

Displays distance to selected world position.

Representations of simple things

Position/vector

{x=num, y=num, z=num}

For helper functions see "Vector helpers".

pointed_thing

Flag Specifier Format

Flags using the standardized flag specifier format can be specified in either of two ways, by string or table.

The string format is a comma-delimited set of flag names; whitespace and unrecognized flag fields are ignored. Specifying a flag in the string sets the flag, and specifying a flag prefixed by the string "no" explicitly clears the flag from whatever the default may be.

In addition to the standard string flag format, the schematic flags field can also be a table of flag names to boolean values representing whether or not the flag is set. Additionally, if a field with the flag name prefixed with "no" is present, mapped to a boolean of any value, the specified flag is unset.

E.g. A flag field of value

{place_center_x = true, place_center_y=false, place_center_z=true}

is equivalent to

{place_center_x = true, noplace_center_y=true, place_center_z=true}

which is equivalent to

"place_center_x, noplace_center_y, place_center_z"

or even

"place_center_x, place_center_z"

since, by default, no schematic attributes are set.

Items

Item types

There are three kinds of items: nodes, tools and craftitems.

Item formats

Items and item stacks can exist in three formats: Serializes, table format and ItemStack.

Serialized

This is called "stackstring" or "itemstring":

Table format

Examples:

5 dirt nodes:

{name="default:dirt", count=5, wear=0, metadata=""}

A wooden pick about 1/3 worn out:

{name="default:pick_wood", count=1, wear=21323, metadata=""}

An apple:

{name="default:apple", count=1, wear=0, metadata=""}

ItemStack

A native C++ format with many helper methods. Useful for converting between formats. See the Class reference section for details.

When an item must be passed to a function, it can usually be in any of these formats.

Groups

In a number of places, there is a group table. Groups define the properties of a thing (item, node, armor of entity, capabilities of tool) in such a way that the engine and other mods can can interact with the thing without actually knowing what the thing is.

Usage

Groups are stored in a table, having the group names with keys and the group ratings as values. For example:

groups = {crumbly=3, soil=1}
-- ^ Default dirt

groups = {crumbly=2, soil=1, level=2, outerspace=1}
-- ^ A more special dirt-kind of thing

Groups always have a rating associated with them. If there is no useful meaning for a rating for an enabled group, it shall be 1.

When not defined, the rating of a group defaults to 0. Thus when you read groups, you must interpret nil and 0 as the same value, 0.

You can read the rating of a group for an item or a node by using

minetest.get_item_group(itemname, groupname)

Groups of items

Groups of items can define what kind of an item it is (e.g. wool).

Groups of nodes

In addition to the general item things, groups are used to define whether a node is destroyable and how long it takes to destroy by a tool.

Groups of entities

For entities, groups are, as of now, used only for calculating damage. The rating is the percentage of damage caused by tools with this damage group. See "Entity damage mechanism".

object.get_armor_groups() --> a group-rating table (e.g. {fleshy=100})
object.set_armor_groups({fleshy=30, cracky=80})

Groups of tools

Groups in tools define which groups of nodes and entities they are effective towards.

Groups in crafting recipes

An example: Make meat soup from any meat, any water and any bowl:

{
    output = 'food:meat_soup_raw',
    recipe = {
        {'group:meat'},
        {'group:water'},
        {'group:bowl'},
    },
    -- preserve = {'group:bowl'}, -- Not implemented yet (TODO)
}

Another example: Make red wool from white wool and red dye:

{
    type = 'shapeless',
    output = 'wool:red',
    recipe = {'wool:white', 'group:dye,basecolor_red'},
}

Special groups

Known damage and digging time defining groups

Examples of custom groups

Item groups are often used for defining, well, groups of items. meat: any meat-kind of a thing (rating might define the size or healing ability or be irrelevant -- it is not defined as of yet) eatable: anything that can be eaten. Rating might define HP gain in half hearts. flammable: can be set on fire. Rating might define the intensity of the fire, affecting e.g. the speed of the spreading of an open fire. wool: any wool (any origin, any color) metal: any metal weapon: any weapon * heavy: anything considerably heavy

Digging time calculation specifics

Groups such as crumbly, cracky and snappy are used for this purpose. Rating is 1, 2 or 3. A higher rating for such a group implies faster digging time.

The level group is used to limit the toughness of nodes a tool can dig and to scale the digging times / damage to a greater extent.

Please do understand this, otherwise you cannot use the system to it's full potential.

Tools define their properties by a list of parameters for groups. They cannot dig other groups; thus it is important to use a standard bunch of groups to enable interaction with tools.

Tools definition

Tools define:

Full punch interval

When used as a weapon, the tool will do full damage if this time is spent between punches. If e.g. half the time is spent, the tool will do half damage.

Maximum drop level

Suggests the maximum level of node, when dug with the tool, that will drop it's useful item. (e.g. iron ore to drop a lump of iron).

This is not automated; it is the responsibility of the node definition to implement this.

Uses

Determines how many uses the tool has when it is used for digging a node, of this group, of the maximum level. For lower leveled nodes, the use count is multiplied by 3^leveldiff.

Maximum level

Tells what is the maximum level of a node of this group that the tool will be able to dig.

Digging times

List of digging times for different ratings of the group, for nodes of the maximum level.

For example, as a Lua table, times={2=2.00, 3=0.70}. This would result in the tool to be able to dig nodes that have a rating of 2 or 3 for this group, and unable to dig the rating 1, which is the toughest. Unless there is a matching group that enables digging otherwise.

Damage groups

List of damage for groups of entities. See "Entity damage mechanism".

Example definition of the capabilities of a tool

tool_capabilities = {
    full_punch_interval=1.5,
    max_drop_level=1,
    groupcaps={
        crumbly={maxlevel=2, uses=20, times={[1]=1.60, [2]=1.20, [3]=0.80}}
    }
    damage_groups = {fleshy=2},
}

This makes the tool be able to dig nodes that fulfil both of these:

Table of resulting digging times:

crumbly        0     1     2     3     4  <- level
     ->  0     -     -     -     -     -
         1  0.80  1.60  1.60     -     -
         2  0.60  1.20  1.20     -     -
         3  0.40  0.80  0.80     -     -

level diff:    2     1     0    -1    -2

Table of resulting tool uses:

->  0     -     -     -     -     -
    1   180    60    20     -     -
    2   180    60    20     -     -
    3   180    60    20     -     -

Notes:

Entity damage mechanism

Damage calculation:

damage = 0
foreach group in cap.damage_groups:
    damage += cap.damage_groups[group] * limit(actual_interval /
           cap.full_punch_interval, 0.0, 1.0)
        * (object.armor_groups[group] / 100.0)
        -- Where object.armor_groups[group] is 0 for inexistent values
return damage

Client predicts damage based on damage groups. Because of this, it is able to give an immediate response when an entity is damaged or dies; the response is pre-defined somehow (e.g. by defining a sprite animation) (not implemented; TODO). Currently a smoke puff will appear when an entity dies.

The group immortal completely disables normal damage.

Entities can define a special armor group, which is punch_operable. This group disables the regular damage mechanism for players punching it by hand or a non-tool item, so that it can do something else than take damage.

On the Lua side, every punch calls:

entity:on_punch(puncher, time_from_last_punch, tool_capabilities, direction, damage)

This should never be called directly, because damage is usually not handled by the entity itself.

To punch an entity/object in Lua, call:

object:punch(puncher, time_from_last_punch, tool_capabilities, direction)

Node Metadata

The instance of a node in the world normally only contains the three values mentioned in "Nodes". However, it is possible to insert extra data into a node. It is called "node metadata"; See NodeMetaRef.

Node metadata contains two things:

Some of the values in the key-value store are handled specially:

Example stuff:

local meta = minetest.get_meta(pos)
meta:set_string("formspec",
        "size[8,9]"..
        "list[context;main;0,0;8,4;]"..
        "list[current_player;main;0,5;8,4;]")
meta:set_string("infotext", "Chest");
local inv = meta:get_inventory()
inv:set_size("main", 8*4)
print(dump(meta:to_table()))
meta:from_table({
    inventory = {
        main = {[1] = "default:dirt", [2] = "", [3] = "", [4] = "",
                [5] = "", [6] = "", [7] = "", [8] = "", [9] = "",
                [10] = "", [11] = "", [12] = "", [13] = "",
                [14] = "default:cobble", [15] = "", [16] = "", [17] = "",
                [18] = "", [19] = "", [20] = "default:cobble", [21] = "",
                [22] = "", [23] = "", [24] = "", [25] = "", [26] = "",
                [27] = "", [28] = "", [29] = "", [30] = "", [31] = "",
                [32] = ""}
    },
    fields = {
        formspec = "size[8,9]list[context;main;0,0;8,4;]list[current_player;main;0,5;8,4;]",
        infotext = "Chest"
    }
})

Item Metadata

Item stacks can store metadata too. See ItemStackMetaRef.

Item metadata only contains a key-value store.

Some of the values in the key-value store are handled specially:

Example stuff:

local meta = stack:get_meta()
meta:set_string("key", "value")
print(dump(meta:to_table()))

Formspec

Formspec defines a menu. Currently not much else than inventories are supported. It is a string, with a somewhat strange format.

Spaces and newlines can be inserted between the blocks, as is used in the examples.

Examples

Chest

size[8,9]
list[context;main;0,0;8,4;]
list[current_player;main;0,5;8,4;]

Furnace

size[8,9]
list[context;fuel;2,3;1,1;]
list[context;src;2,1;1,1;]
list[context;dst;5,1;2,2;]
list[current_player;main;0,5;8,4;]

Minecraft-like player inventory

size[8,7.5]
image[1,0.6;1,2;player.png]
list[current_player;main;0,3.5;8,4;]
list[current_player;craft;3,0;3,3;]
list[current_player;craftpreview;7,1;1,1;]

Elements

size[<W>,<H>,<fixed_size>]

position[<X>,<Y>]

anchor[<X>,<Y>]

container[<X>,<Y>]

container_end[]

list[<inventory location>;<list name>;<X>,<Y>;<W>,<H>;]

list[<inventory location>;<list name>;<X>,<Y>;<W>,<H>;<starting item index>]

listring[<inventory location>;<list name>]

listring[]

listcolors[<slot_bg_normal>;<slot_bg_hover>]

listcolors[<slot_bg_normal>;<slot_bg_hover>;<slot_border>]

listcolors[<slot_bg_normal>;<slot_bg_hover>;<slot_border>;<tooltip_bgcolor>;<tooltip_fontcolor>]

tooltip[<gui_element_name>;<tooltip_text>;<bgcolor>,<fontcolor>]

image[<X>,<Y>;<W>,<H>;<texture name>]

item_image[<X>,<Y>;<W>,<H>;<item name>]

bgcolor[<color>;<fullscreen>]

background[<X>,<Y>;<W>,<H>;<texture name>]

background[<X>,<Y>;<W>,<H>;<texture name>;<auto_clip>]

pwdfield[<X>,<Y>;<W>,<H>;<name>;<label>]

field[<X>,<Y>;<W>,<H>;<name>;<label>;<default>]

field[<name>;<label>;<default>]

field_close_on_enter[<name>;<close_on_enter>]

textarea[<X>,<Y>;<W>,<H>;<name>;<label>;<default>]

label[<X>,<Y>;<label>]

vertlabel[<X>,<Y>;<label>]

button[<X>,<Y>;<W>,<H>;<name>;<label>]

image_button[<X>,<Y>;<W>,<H>;<texture name>;<name>;<label>]

image_button[<X>,<Y>;<W>,<H>;<texture name>;<name>;<label>;<noclip>;<drawborder>;<pressed texture name>]

item_image_button[<X>,<Y>;<W>,<H>;<item name>;<name>;<label>]

button_exit[<X>,<Y>;<W>,<H>;<name>;<label>]

image_button_exit[<X>,<Y>;<W>,<H>;<texture name>;<name>;<label>]

textlist[<X>,<Y>;<W>,<H>;<name>;<listelem 1>,<listelem 2>,...,<listelem n>]

textlist[<X>,<Y>;<W>,<H>;<name>;<listelem 1>,<listelem 2>,...,<listelem n>;<selected idx>;<transparent>]

tabheader[<X>,<Y>;<name>;<caption 1>,<caption 2>,...,<caption n>;<current_tab>;<transparent>;<draw_border>]

box[<X>,<Y>;<W>,<H>;<color>]

checkbox[<X>,<Y>;<name>;<label>;<selected>]

scrollbar[<X>,<Y>;<W>,<H>;<orientation>;<name>;<value>]

table[<X>,<Y>;<W>,<H>;<name>;<cell 1>,<cell 2>,...,<cell n>;<selected idx>]

tableoptions[<opt 1>;<opt 2>;...]

tablecolumns[<type 1>,<opt 1a>,<opt 1b>,...;<type 2>,<opt 2a>,<opt 2b>;...]

Note: do not use a element name starting with key_; those names are reserved to pass key press events to formspec!

Inventory locations

Player Inventory lists

ColorString

#RGB defines a color in hexadecimal format.

#RGBA defines a color in hexadecimal format and alpha channel.

#RRGGBB defines a color in hexadecimal format.

#RRGGBBAA defines a color in hexadecimal format and alpha channel.

Named colors are also supported and are equivalent to CSS Color Module Level 4. To specify the value of the alpha channel, append #AA to the end of the color name (e.g. colorname#08). For named colors the hexadecimal string representing the alpha value must (always) be two hexadecimal digits.

ColorSpec

A ColorSpec specifies a 32-bit color. It can be written in either: table form, each element ranging from 0..255 (a, if absent, defaults to 255): colorspec = {a=255, r=0, g=255, b=0} numerical form, the raw integer value of an ARGB8 quad: colorspec = 0xFF00FF00 or string form, a ColorString (defined above): colorspec = "green"

Escape sequences

Most text can contain escape sequences, that can for example color the text. There are a few exceptions: tab headers, dropdowns and vertical labels can't. The following functions provide escape sequences: core.get_color_escape_sequence(color): * color is a ColorString * The escape sequence sets the text color to color core.colorize(color, message): * Equivalent to: core.get_color_escape_sequence(color) .. message .. core.get_color_escape_sequence("#ffffff") color.get_background_escape_sequence(color) * color is a ColorString * The escape sequence sets the background of the whole text element to color. Only defined for item descriptions and tooltips. color.strip_foreground_colors(str) * Removes foreground colors added by get_color_escape_sequence. color.strip_background_colors(str) * Removes background colors added by get_background_escape_sequence. color.strip_colors(str) * Removes all color escape sequences.

Spatial Vectors

For the following functions x can be either a vector or a number:

Helper functions

minetest namespace reference

Utilities

Logging

Registration functions

Call these functions only at load time!

Global callback registration functions

Call these functions only at load time!

Other registration functions

Authentication

minetest.set_player_password, minetest_set_player_privs, minetest_get_player_privs and minetest.auth_reload call the authetification handler.

Chat

Environment access

Inventory

minetest.get_inventory(location): returns an InvRef

Formspec

Item handling

Rollback

Defaults for the on_* item definition functions

These functions return the leftover itemstack.

Defaults for the on_punch and on_dig node definition callbacks

Sounds

Timing

Server

Bans

Particles

Schematics

HTTP Requests:

Storage API:

Misc.

Global objects

Global tables

Class reference

MetaDataRef

See StorageRef, NodeMetaRef and ItemStackMetaRef.

Methods

NodeMetaRef

Node metadata: reference extra data and functionality stored in a node. Can be obtained via minetest.get_meta(pos).

Methods

ItemStackMetaRef

ItemStack metadata: reference extra data and functionality stored in a stack. Can be obtained via item:get_meta().

Methods

StorageRef

Mod metadata: per mod metadata, saved automatically. Can be obtained via minetest.get_mod_storage() during load time.

Methods

NodeTimerRef

Node Timers: a high resolution persistent per-node timer. Can be gotten via minetest.get_node_timer(pos).

Methods

ObjectRef

Moving things in the game are generally these.

This is basically a reference to a C++ ServerActiveObject

Methods

LuaEntitySAO-only (no-op for other objects)
Player-only (no-op for other objects)

InvRef

An InvRef is a reference to an inventory.

Methods

AreaStore

A fast access data structure to store areas, and find areas near a given position or area. Every area has a data string attribute to store additional information. You can create an empty AreaStore by calling AreaStore(), or AreaStore(type_name). If you chose the parameter-less constructor, a fast implementation will be automatically chosen for you.

Methods

ItemStack

An ItemStack is a stack of items.

It can be created via ItemStack(x), where x is an ItemStack, an itemstring, a table or nil.

Methods

PseudoRandom

A 16-bit pseudorandom number generator. Uses a well-known LCG algorithm introduced by K&R.

It can be created via PseudoRandom(seed).

Methods

PcgRandom

A 32-bit pseudorandom number generator. Uses PCG32, an algorithm of the permuted congruential generator family, offering very strong randomness.

It can be created via PcgRandom(seed) or PcgRandom(seed, sequence).

Methods

SecureRandom

Interface for the operating system's crypto-secure PRNG.

It can be created via SecureRandom(). The constructor returns nil if a secure random device cannot be be found on the system.

Methods

PerlinNoise

A perlin noise generator. It can be created via PerlinNoise(seed, octaves, persistence, scale) or PerlinNoise(noiseparams). Alternatively with minetest.get_perlin(seeddiff, octaves, persistence, scale) or minetest.get_perlin(noiseparams).

Methods

PerlinNoiseMap

A fast, bulk perlin noise generator.

It can be created via PerlinNoiseMap(noiseparams, size) or minetest.get_perlin_map(noiseparams, size).

Format of size is {x=dimx, y=dimy, z=dimz}. The z conponent is ommitted for 2D noise, and it must be must be larger than 1 for 3D noise (otherwise nil is returned).

For each of the functions with an optional buffer parameter: If buffer is not nil, this table will be used to store the result instead of creating a new table.

Methods

VoxelManip

About VoxelManip

VoxelManip is a scripting interface to the internal 'Map Voxel Manipulator' facility. The purpose of this object is for fast, low-level, bulk access to reading and writing Map content. As such, setting map nodes through VoxelManip will lack many of the higher level features and concepts you may be used to with other methods of setting nodes. For example, nodes will not have their construction and destruction callbacks run, and no rollback information is logged.

It is important to note that VoxelManip is designed for speed, and not ease of use or flexibility. If your mod requires a map manipulation facility that will handle 100% of all edge cases, or the use of high level node placement features, perhaps minetest.set_node() is better suited for the job.

In addition, VoxelManip might not be faster, or could even be slower, for your specific use case. VoxelManip is most effective when setting very large areas of map at once - for example, if only setting a 5x5x5 node area, a minetest.set_node() loop may be more optimal. Always profile code using both methods of map manipulation to determine which is most appropriate for your usage.

Using VoxelManip

A VoxelManip object can be created any time using either: VoxelManip([p1, p2]), or minetest.get_voxel_manip([p1, p2]).

If the optional position parameters are present for either of these routines, the specified region will be pre-loaded into the VoxelManip object on creation. Otherwise, the area of map you wish to manipulate must first be loaded into the VoxelManip object using VoxelManip:read_from_map().

Note that VoxelManip:read_from_map() returns two position vectors. The region formed by these positions indicate the minimum and maximum (respectively) positions of the area actually loaded in the VoxelManip, which may be larger than the area requested. For convenience, the loaded area coordinates can also be queried any time after loading map data with VoxelManip:get_emerged_area().

Now that the VoxelManip object is populated with map data, your mod can fetch a copy of this data using either of two methods. VoxelManip:get_node_at(), which retrieves an individual node in a MapNode formatted table at the position requested is the simplest method to use, but also the slowest.

Nodes in a VoxelManip object may also be read in bulk to a flat array table using: VoxelManip:get_data() for node content (in Content ID form, see section 'Content IDs'), VoxelManip:get_light_data() for node light levels, and VoxelManip:get_param2_data() for the node type-dependent "param2" values.

See section 'Flat array format' for more details.

It is very important to understand that the tables returned by any of the above three functions represent a snapshot of the VoxelManip's internal state at the time of the call. This copy of the data will not magically update itself if another function modifies the internal VoxelManip state. Any functions that modify a VoxelManip's contents work on the VoxelManip's internal state unless otherwise explicitly stated.

Once the bulk data has been edited to your liking, the internal VoxelManip state can be set using: VoxelManip:set_data() for node content (in Content ID form, see section 'Content IDs'), VoxelManip:set_light_data() for node light levels, and VoxelManip:set_param2_data() for the node type-dependent "param2" values.

The parameter to each of the above three functions can use any table at all in the same flat array format as produced by get_data() et al. and is not required to be a table retrieved from get_data().

Once the internal VoxelManip state has been modified to your liking, the changes can be committed back to the map by calling VoxelManip:write_to_map().

Flat array format

Let Nx = p2.X - p1.X + 1, Ny = p2.Y - p1.Y + 1, and Nz = p2.Z - p1.Z + 1.

Then, for a loaded region of p1..p2, this array ranges from 1 up to and including the value of the expression Nx * Ny * Nz.

Positions offset from p1 are present in the array with the format of: [ (0, 0, 0), (1, 0, 0), (2, 0, 0), ... (Nx, 0, 0), (0, 1, 0), (1, 1, 0), (2, 1, 0), ... (Nx, 1, 0), ... (0, Ny, 0), (1, Ny, 0), (2, Ny, 0), ... (Nx, Ny, 0), (0, 0, 1), (1, 0, 1), (2, 0, 1), ... (Nx, 0, 1), ... (0, Ny, 2), (1, Ny, 2), (2, Ny, 2), ... (Nx, Ny, 2), ... (0, Ny, Nz), (1, Ny, Nz), (2, Ny, Nz), ... (Nx, Ny, Nz) ]

and the array index for a position p contained completely in p1..p2 is:

(p.Z - p1.Z) * Ny * Nx + (p.Y - p1.Y) * Nx + (p.X - p1.X) + 1

Note that this is the same "flat 3D array" format as PerlinNoiseMap:get3dMap_flat(). VoxelArea objects (see section 'VoxelArea') can be used to simplify calculation of the index for a single point in a flat VoxelManip array.

Content IDs

A Content ID is a unique integer identifier for a specific node type. These IDs are used by VoxelManip in place of the node name string for VoxelManip:get_data() and VoxelManip:set_data(). You can use minetest.get_content_id() to look up the Content ID for the specified node name, and minetest.get_name_from_content_id() to look up the node name string for a given Content ID. After registration of a node, its Content ID will remain the same throughout execution of the mod. Note that the node being queried needs to have already been been registered.

The following builtin node types have their Content IDs defined as constants: core.CONTENT_UNKNOWN (ID for "unknown" nodes) core.CONTENT_AIR (ID for "air" nodes) core.CONTENT_IGNORE (ID for "ignore" nodes)

Mapgen VoxelManip objects

Inside of on_generated() callbacks, it is possible to retrieve the same VoxelManip object used by the core's Map Generator (commonly abbreviated Mapgen). Most of the rules previously described still apply but with a few differences:

Other API functions operating on a VoxelManip

If any VoxelManip contents were set to a liquid node, VoxelManip:update_liquids() must be called for these liquid nodes to begin flowing. It is recommended to call this function only after having written all buffered data back to the VoxelManip object, save for special situations where the modder desires to only have certain liquid nodes begin flowing.

The functions minetest.generate_ores() and minetest.generate_decorations() will generate all registered decorations and ores throughout the full area inside of the specified VoxelManip object.

minetest.place_schematic_on_vmanip() is otherwise identical to minetest.place_schematic(), except instead of placing the specified schematic directly on the map at the specified position, it will place the schematic inside of the VoxelManip.

Notes

Methods

VoxelArea

A helper class for voxel areas. It can be created via VoxelArea:new{MinEdge=pmin, MaxEdge=pmax}. The coordinates are inclusive, like most other things in Minetest.

Methods

Settings

An interface to read config files in the format of minetest.conf.

It can be created via Settings(filename).

Methods

Mapgen objects

A mapgen object is a construct used in map generation. Mapgen objects can be used by an on_generate callback to speed up operations by avoiding unnecessary recalculations; these can be retrieved using the minetest.get_mapgen_object() function. If the requested Mapgen object is unavailable, or get_mapgen_object() was called outside of an on_generate() callback, nil is returned.

The following Mapgen objects are currently available:

voxelmanip

This returns three values; the VoxelManip object to be used, minimum and maximum emerged position, in that order. All mapgens support this object.

heightmap

Returns an array containing the y coordinates of the ground levels of nodes in the most recently generated chunk by the current mapgen.

biomemap

Returns an array containing the biome IDs of nodes in the most recently generated chunk by the current mapgen.

heatmap

Returns an array containing the temperature values of nodes in the most recently generated chunk by the current mapgen.

humiditymap

Returns an array containing the humidity values of nodes in the most recently generated chunk by the current mapgen.

gennotify

Returns a table mapping requested generation notification types to arrays of positions at which the corresponding generated structures are located at within the current chunk. To set the capture of positions of interest to be recorded on generate, use minetest.set_gen_notify().

Possible fields of the table returned are:

Decorations have a key in the format of "decoration#id", where id is the numeric unique decoration ID.

Registered entities

L-system trees

Warning L-system generation currently creates lighting bugs in the form of mapblock-sized shadows. Often these bugs appear as subtle shadows in water.

Tree definition

treedef={
    axiom,         --string  initial tree axiom
    rules_a,       --string  rules set A
    rules_b,       --string  rules set B
    rules_c,       --string  rules set C
    rules_d,       --string  rules set D
    trunk,         --string  trunk node name
    leaves,        --string  leaves node name
    leaves2,       --string  secondary leaves node name
    leaves2_chance,--num     chance (0-100) to replace leaves with leaves2
    angle,         --num     angle in deg
    iterations,    --num     max # of iterations, usually 2 -5
    random_level,  --num     factor to lower nr of iterations, usually 0 - 3
    trunk_type,    --string  single/double/crossed) type of trunk: 1 node,
                   --        2x2 nodes or 3x3 in cross shape
    thin_branches, --boolean true -> use thin (1 node) branches
    fruit,         --string  fruit node name
    fruit_chance,  --num     chance (0-100) to replace leaves with fruit node
    seed,          --num     random seed; if no seed is provided, the engine will create one
}

Key for Special L-System Symbols used in Axioms

Example

Spawn a small apple tree:

pos = {x=230,y=20,z=4}
apple_tree={
    axiom="FFFFFAFFBF",
    rules_a="[&&&FFFFF&&FFFF][&&&++++FFFFF&&FFFF][&&&----FFFFF&&FFFF]",
    rules_b="[&&&++FFFFF&&FFFF][&&&--FFFFF&&FFFF][&&&------FFFFF&&FFFF]",
    trunk="default:tree",
    leaves="default:leaves",
    angle=30,
    iterations=2,
    random_level=0,
    trunk_type="single",
    thin_branches=true,
    fruit_chance=10,
    fruit="default:apple"
}
minetest.spawn_tree(pos,apple_tree)

Definition tables

Object Properties

{
    hp_max = 1,
    physical = true,
    collide_with_objects = true, -- collide with other objects if physical=true
    weight = 5,
    collisionbox = {-0.5,-0.5,-0.5, 0.5,0.5,0.5},
    visual = "cube"/"sprite"/"upright_sprite"/"mesh"/"wielditem",
    visual_size = {x=1, y=1},
    mesh = "model",
    textures = {}, -- number of required textures depends on visual
    colors = {}, -- number of required colors depends on visual
    spritediv = {x=1, y=1},
    initial_sprite_basepos = {x=0, y=0},
    is_visible = true,
    makes_footstep_sound = false,
    automatic_rotate = false,
    stepheight = 0,
    automatic_face_movement_dir = 0.0,
--  ^ automatically set yaw to movement direction; offset in degrees; false to disable
    automatic_face_movement_max_rotation_per_sec = -1,
--  ^ limit automatic rotation to this value in degrees per second. values < 0 no limit
    backface_culling = true, -- false to disable backface_culling for model
    nametag = "", -- by default empty, for players their name is shown if empty
    nametag_color = <color>, -- sets color of nametag as ColorSpec
    infotext = "", -- by default empty, text to be shown when pointed at object
}

Entity definition (register_entity)

{
--  Deprecated: Everything in object properties is read directly from here

    initial_properties = --[[<initial object properties>]],

    on_activate = function(self, staticdata, dtime_s),
    on_step = function(self, dtime),
    on_punch = function(self, puncher, time_from_last_punch, tool_capabilities, dir),
    on_rightclick = function(self, clicker),
    get_staticdata = function(self),
--  ^ Called sometimes; the string returned is passed to on_activate when
--    the entity is re-activated from static state

    -- Also you can define arbitrary member variables here (see item definition for
    -- more info)
    _custom_field = whatever,
}

ABM (ActiveBlockModifier) definition (register_abm)

{
    label = "Lava cooling",
--  ^ Descriptive label for profiling purposes (optional).
--    Definitions with identical labels will be listed as one.
--  In the following two fields, also group:groupname will work.
    nodenames = {"default:lava_source"},
    neighbors = {"default:water_source", "default:water_flowing"}, -- Any of these --[[
    ^ If left out or empty, any neighbor will do ]]
    interval = 1.0, -- Operation interval in seconds
    chance = 1, -- Chance of trigger per-node per-interval is 1.0 / this
    catch_up = true, -- If true, catch-up behaviour is enabled --[[
    ^ The chance value is temporarily reduced when returning to
      an area to simulate time lost by the area being unattended.
    ^ Note chance value can often be reduced to 1 ]]
    action = func(pos, node, active_object_count, active_object_count_wider),
}

LBM (LoadingBlockModifier) definition (register_lbm)

{
    label = "Upgrade legacy doors",
--  ^ Descriptive label for profiling purposes (optional).
--    Definitions with identical labels will be listed as one.
    name = "modname:replace_legacy_door",
    nodenames = {"default:lava_source"},
--  ^ List of node names to trigger the LBM on.
--    Also non-registered nodes will work.
--    Groups (as of group:groupname) will work as well.
    run_at_every_load = false,
--  ^ Whether to run the LBM's action every time a block gets loaded,
--    and not just for blocks that were saved last time before LBMs were
--    introduced to the world.
    action = func(pos, node),
}

Item definition (register_node, register_craftitem, register_tool)

{
    description = "Steel Axe",
    groups = {}, -- key = name, value = rating; rating = 1..3.
                    if rating not applicable, use 1.
                    e.g. {wool = 1, fluffy = 3}
                        {soil = 2, outerspace = 1, crumbly = 1}
                        {bendy = 2, snappy = 1},
                        {hard = 1, metal = 1, spikes = 1}
    inventory_image = "default_tool_steelaxe.png",
    wield_image = "",
    palette = "",
    --[[
    ^ An image file containing the palette of a node.
    ^ You can set the currently used color as the
    ^ "palette_index" field of the item stack metadata.
    ^ The palette is always stretched to fit indices
    ^ between 0 and 255, to ensure compatibility with
    ^ "colorfacedir" and "colorwallmounted" nodes.
    ]]
    color = "0xFFFFFFFF",
    --[[
    ^ The color of the item. The palette overrides this.
    ]]
    wield_scale = {x = 1, y = 1, z = 1},
    stack_max = 99,
    range = 4.0,
    liquids_pointable = false,
    tool_capabilities = {
        full_punch_interval = 1.0,
        max_drop_level = 0,
        groupcaps = {
            -- For example:
            choppy = {times = {[1] = 2.50, [2] = 1.40, [3] = 1.00}, uses = 20, maxlevel = 2},
        },
        damage_groups = {groupname = damage},
    },
    node_placement_prediction = nil,
    --[[
    ^ If nil and item is node, prediction is made automatically
    ^ If nil and item is not a node, no prediction is made
    ^ If "" and item is anything, no prediction is made
    ^ Otherwise should be name of node which the client immediately places
      on ground when the player places the item. Server will always update
      actual result to client in a short moment.
    ]]
    sound = {
        breaks = "default_tool_break", -- tools only
        place = --[[<SimpleSoundSpec>]],
    },

    on_place = func(itemstack, placer, pointed_thing),
    --[[
    ^ Shall place item and return the leftover itemstack
    ^ The placer may be any ObjectRef or nil.
    ^ default: minetest.item_place ]]
    on_secondary_use = func(itemstack, user, pointed_thing),
    --[[
    ^ Same as on_place but called when pointing at nothing.
    ^ The user may be any ObjectRef or nil.
    ^ pointed_thing : always { type = "nothing" }
    ]]
    on_drop = func(itemstack, dropper, pos),
    --[[
    ^ Shall drop item and return the leftover itemstack
    ^ The dropper may be any ObjectRef or nil.
    ^ default: minetest.item_drop ]]
    on_use = func(itemstack, user, pointed_thing),
    --[[
    ^  default: nil
    ^ Function must return either nil if no item shall be removed from
      inventory, or an itemstack to replace the original itemstack.
        e.g. itemstack:take_item(); return itemstack
    ^ Otherwise, the function is free to do what it wants.
    ^ The user may be any ObjectRef or nil.
    ^ The default functions handle regular use cases.
    ]]
    after_use = func(itemstack, user, node, digparams),
    --[[
    ^  default: nil
    ^ If defined, should return an itemstack and will be called instead of
      wearing out the tool. If returns nil, does nothing.
      If after_use doesn't exist, it is the same as:
        function(itemstack, user, node, digparams)
          itemstack:add_wear(digparams.wear)
          return itemstack
        end
    ^ The user may be any ObjectRef or nil.
    ]]
    _custom_field = whatever,
    --[[
    ^ Add your own custom fields. By convention, all custom field names
      should start with `_` to avoid naming collisions with future engine
      usage.
    ]]
}

Tile definition

Tile animation definition

{
    type = "vertical_frames",
    aspect_w = 16,
    -- ^ specify width of a frame in pixels
    aspect_h = 16,
    -- ^ specify height of a frame in pixels
    length = 3.0,
    -- ^ specify full loop length
}

{
    type = "sheet_2d",
    frames_w = 5,
    -- ^ specify width in number of frames
    frames_h = 3,
    -- ^ specify height in number of frames
    frame_length = 0.5,
    -- ^ specify length of a single frame
}

Node definition (register_node)

{
    -- <all fields allowed in item definitions>,

    drawtype = "normal", -- See "Node drawtypes"
    visual_scale = 1.0, --[[
    ^ Supported for drawtypes "plantlike", "signlike", "torchlike",
    ^ "firelike", "mesh".
    ^ For plantlike and firelike, the image will start at the bottom of the
    ^ node, for the other drawtypes the image will be centered on the node.
    ^ Note that positioning for "torchlike" may still change. ]]
    tiles = {tile definition 1, def2, def3, def4, def5, def6}, --[[
    ^ Textures of node; +Y, -Y, +X, -X, +Z, -Z (old field name: tile_images)
    ^ List can be shortened to needed length ]]
    overlay_tiles = {tile definition 1, def2, def3, def4, def5, def6}, --[[
    ^ Same as `tiles`, but these textures are drawn on top of the
    ^ base tiles. You can use this to colorize only specific parts of
    ^ your texture. If the texture name is an empty string, that
    ^ overlay is not drawn. Since such tiles are drawn twice, it
    ^ is not recommended to use overlays on very common nodes.
    special_tiles = {tile definition 1, Tile definition 2}, --[[
    ^ Special textures of node; used rarely (old field name: special_materials)
    ^ List can be shortened to needed length ]]
    color = ColorSpec, --[[
    ^ The node's original color will be multiplied with this color.
    ^ If the node has a palette, then this setting only has an effect
    ^ in the inventory and on the wield item. ]]
    use_texture_alpha = false, -- Use texture's alpha channel
    palette = "palette.png", --[[
    ^ The node's `param2` is used to select a pixel from the image
    ^ (pixels are arranged from left to right and from top to bottom).
    ^ The node's color will be multiplied with the selected pixel's
    ^ color. Tiles can override this behavior.
    ^ Only when `paramtype2` supports palettes. ]]
    post_effect_color = "green#0F", -- If player is inside node, see "ColorSpec"
    paramtype = "none", -- See "Nodes" --[[
    ^ paramtype = "light" allows light to propagate from or through the node with light value
    ^ falling by 1 per node. This line is essential for a light source node to spread its light. ]]
    paramtype2 = "none", -- See "Nodes"
    place_param2 = nil, -- Force value for param2 when player places node
    is_ground_content = true, -- If false, the cave generator will not carve through this
    sunlight_propagates = false, -- If true, sunlight will go infinitely through this
    walkable = true, -- If true, objects collide with node
    pointable = true, -- If true, can be pointed at
    diggable = true, -- If false, can never be dug
    climbable = false, -- If true, can be climbed on (ladder)
    buildable_to = false, -- If true, placed nodes can replace this node
    floodable = false, -- If true, liquids flow into and replace this node
    liquidtype = "none", -- "none"/"source"/"flowing"
    liquid_alternative_flowing = "", -- Flowing version of source liquid
    liquid_alternative_source = "", -- Source version of flowing liquid
    liquid_viscosity = 0, -- Higher viscosity = slower flow (max. 7)
    liquid_renewable = true, --[[
    ^ If true, a new liquid source can be created by placing two or more sources nearby ]]
    leveled = 0, --[[
    ^ Block contains level in param2. Value is default level, used for snow.
    ^ Don't forget to use "leveled" type nodebox. ]]
    liquid_range = 8, -- number of flowing nodes around source (max. 8)
    drowning = 0, -- Player will take this amount of damage if no bubbles are left
    light_source = 0, --[[
    ^ Amount of light emitted by node.
    ^ To set the maximum (currently 14), use the value 'minetest.LIGHT_MAX'.
    ^ A value outside the range 0 to minetest.LIGHT_MAX causes undefined behavior.]]
    damage_per_second = 0, -- If player is inside node, this damage is caused
    node_box = {type="regular"}, -- See "Node boxes"
    connects_to = nodenames, --[[
    * Used for nodebox nodes with the type == "connected"
    * Specifies to what neighboring nodes connections will be drawn
    * e.g. `{"group:fence", "default:wood"}` or `"default:stone"` ]]
    connect_sides = { "top", "bottom", "front", "left", "back", "right" }, --[[
    ^ Tells connected nodebox nodes to connect only to these sides of this node. ]]
    mesh = "model",
    selection_box = {type="regular"}, -- See "Node boxes" --[[
    ^ If drawtype "nodebox" is used and selection_box is nil, then node_box is used. ]]
    legacy_facedir_simple = false, -- Support maps made in and before January 2012
    legacy_wallmounted = false, -- Support maps made in and before January 2012
    sounds = {
        footstep = <SimpleSoundSpec>,
        dig = <SimpleSoundSpec>, -- "__group" = group-based sound (default)
        dug = <SimpleSoundSpec>,
        place = <SimpleSoundSpec>,
        place_failed = <SimpleSoundSpec>,
    },
    drop = "",  -- Name of dropped node when dug. Default is the node itself.
    -- Alternatively:
    drop = {
        max_items = 1,  -- Maximum number of items to drop.
        items = { -- Choose max_items randomly from this list.
            {
                items = {"foo:bar", "baz:frob"},  -- Items to drop.
                rarity = 1,  -- Probability of dropping is 1 / rarity.
            },
        },
    },

    on_construct = func(pos), --[[
    ^ Node constructor; called after adding node
    ^ Can set up metadata and stuff like that
    ^ Not called for bulk node placement (i.e. schematics and VoxelManip)
    ^ default: nil ]]
    on_destruct = func(pos), --[[
    ^ Node destructor; called before removing node
    ^ Not called for bulk node placement (i.e. schematics and VoxelManip)
    ^ default: nil ]]
    after_destruct = func(pos, oldnode), --[[
    ^ Node destructor; called after removing node
    ^ Not called for bulk node placement (i.e. schematics and VoxelManip)
    ^ default: nil ]]
    on_flood = func(pos, oldnode, newnode), --[[
    ^ Called when a liquid (newnode) is about to flood oldnode, if
    ^ it has `floodable = true` in the nodedef. Not called for bulk
    ^ node placement (i.e. schematics and VoxelManip) or air nodes. If
    ^ return true the node is not flooded, but on_flood callback will
    ^ most likely be called over and over again every liquid update
    ^ interval. Default: nil ]]

    after_place_node = func(pos, placer, itemstack, pointed_thing) --[[
    ^ Called after constructing node when node was placed using
      minetest.item_place_node / minetest.place_node
    ^ If return true no item is taken from itemstack
    ^ default: nil ]]
    after_dig_node = func(pos, oldnode, oldmetadata, digger), --[[
    ^ oldmetadata is in table format
    ^ Called after destructing node when node was dug using
      minetest.node_dig / minetest.dig_node
    ^ default: nil ]]
    can_dig = function(pos, [player]) --[[
    ^ returns true if node can be dug, or false if not
    ^ default: nil ]]

    on_punch = func(pos, node, puncher, pointed_thing), --[[
    ^ default: minetest.node_punch
    ^ By default: Calls minetest.register_on_punchnode callbacks ]]
    on_rightclick = func(pos, node, clicker, itemstack, pointed_thing), --[[
    ^ default: nil
    ^ if defined, itemstack will hold clicker's wielded item
    ^ Shall return the leftover itemstack
    ^ Note: pointed_thing can be nil, if a mod calls this function ]]

    on_dig = func(pos, node, digger), --[[
    ^ default: minetest.node_dig
    ^ By default: checks privileges, wears out tool and removes node ]]

    on_timer = function(pos,elapsed), --[[
    ^ default: nil
    ^ called by NodeTimers, see minetest.get_node_timer and NodeTimerRef
    ^ elapsed is the total time passed since the timer was started
    ^ return true to run the timer for another cycle with the same timeout value ]]

    on_receive_fields = func(pos, formname, fields, sender), --[[
    ^ fields = {name1 = value1, name2 = value2, ...}
    ^ Called when an UI form (e.g. sign text input) returns data
    ^ default: nil ]]

    allow_metadata_inventory_move = func(pos, from_list, from_index,
            to_list, to_index, count, player), --[[
    ^ Called when a player wants to move items inside the inventory
    ^ Return value: number of items allowed to move ]]

    allow_metadata_inventory_put = func(pos, listname, index, stack, player), --[[
    ^ Called when a player wants to put something into the inventory
    ^ Return value: number of items allowed to put
    ^ Return value: -1: Allow and don't modify item count in inventory ]]

    allow_metadata_inventory_take = func(pos, listname, index, stack, player), --[[
    ^ Called when a player wants to take something out of the inventory
    ^ Return value: number of items allowed to take
    ^ Return value: -1: Allow and don't modify item count in inventory ]]

    on_metadata_inventory_move = func(pos, from_list, from_index,
            to_list, to_index, count, player),
    on_metadata_inventory_put = func(pos, listname, index, stack, player),
    on_metadata_inventory_take = func(pos, listname, index, stack, player), --[[
    ^ Called after the actual action has happened, according to what was allowed.
    ^ No return value ]]

    on_blast = func(pos, intensity), --[[
    ^ intensity: 1.0 = mid range of regular TNT
    ^ If defined, called when an explosion touches the node, instead of
      removing the node ]]
}

Recipe for register_craft (shaped)

{
    output = 'default:pick_stone',
    recipe = {
        {'default:cobble', 'default:cobble', 'default:cobble'},
        {'', 'default:stick', ''},
        {'', 'default:stick', ''}, -- Also groups; e.g. 'group:crumbly'
    },
    replacements = --[[<optional list of item pairs,
                    replace one input item with another item on crafting>]]
}

Recipe for register_craft (shapeless)

{
   type = "shapeless",
   output = 'mushrooms:mushroom_stew',
   recipe = {
       "mushrooms:bowl",
       "mushrooms:mushroom_brown",
       "mushrooms:mushroom_red",
   },
   replacements = --[[<optional list of item pairs,
                   replace one input item with another item on crafting>]]

}

Recipe for register_craft (tool repair)

{
    type = "toolrepair",
    additional_wear = -0.02,
}

Recipe for register_craft (cooking)

{
    type = "cooking",
    output = "default:glass",
    recipe = "default:sand",
    cooktime = 3,
}

Recipe for register_craft (furnace fuel)

{
    type = "fuel",
    recipe = "default:leaves",
    burntime = 1,
}

Ore definition (register_ore)

{
    ore_type = "scatter", -- See "Ore types"
    ore = "default:stone_with_coal",
    wherein = "default:stone",
--  ^ a list of nodenames is supported too
    clust_scarcity = 8*8*8,
--  ^ Ore has a 1 out of clust_scarcity chance of spawning in a node
--  ^ This value should be *MUCH* higher than your intuition might tell you!
    clust_num_ores = 8,
--  ^ Number of ores in a cluster
    clust_size = 3,
--  ^ Size of the bounding box of the cluster
--  ^ In this example, there is a 3x3x3 cluster where 8 out of the 27 nodes are coal ore
    y_min = -31000,
    y_max = 64,
    flags = "",
--  ^ Attributes for this ore generation
    noise_threshold = 0.5,
--  ^ If noise is above this threshold, ore is placed.  Not needed for a uniform distribution
    noise_params = {offset=0, scale=1, spread={x=100, y=100, z=100}, seed=23, octaves=3, persist=0.70}
--  ^ NoiseParams structure describing the perlin noise used for ore distribution.
--  ^ Needed for sheet ore_type.  Omit from scatter ore_type for a uniform ore distribution
    random_factor = 1.0,
--  ^ Multiplier of the randomness contribution to the noise value at any
--   given point to decide if ore should be placed.  Set to 0 for solid veins.
--  ^ This parameter is only valid for ore_type == "vein".
    biomes = {"desert", "rainforest"}
--  ^ List of biomes in which this decoration occurs.  Occurs in all biomes if this is omitted,
--  ^ and ignored if the Mapgen being used does not support biomes.
--  ^ Can be a list of (or a single) biome names, IDs, or definitions.
}

Biome definition (register_biome)

Note The Biome API is still in an experimental phase and subject to change.

{
    name = "tundra",
    node_dust = "default:snow",
--  ^ Node dropped onto upper surface after all else is generated.
    node_top = "default:dirt_with_snow",
    depth_top = 1,
--  ^ Node forming surface layer of biome and thickness of this layer.
    node_filler = "default:permafrost",
    depth_filler = 3,
--  ^ Node forming lower layer of biome and thickness of this layer.
    node_stone = "default:bluestone",
--  ^ Node that replaces all stone nodes between roughly y_min and y_max.
    node_water_top = "default:ice",
    depth_water_top = 10,
--  ^ Node forming a surface layer in seawater with the defined thickness.
    node_water = "",
--  ^ Node that replaces all seawater nodes not in the defined surface layer.
    node_river_water = "default:ice",
--  ^ Node that replaces river water in mapgens that use default:river_water.
    node_riverbed = "default:gravel",
    depth_riverbed = 2,
--  ^ Node placed under river water and thickness of this layer.
    y_min = 1,
    y_max = 31000,
--  ^ Lower and upper limits for biome.
--  ^ Because biome is not recalculated for every node in a node column
--  ^ some biome materials can exceed their limits, especially stone.
--  ^ For each node column in a mapchunk, biome is only recalculated at column
--  ^ top and at each of these surfaces:
--  ^ Ground below air, water below air, ground below water.
--  ^ The selected biome then stays in effect for all nodes below until
--  ^ column base or the next biome recalculation.
    heat_point = 0,
    humidity_point = 50,
--  ^ Characteristic average temperature and humidity for the biome.
--  ^ These values create 'biome points' on a voronoi diagram that has heat
--  ^ and humidity as axes. The resulting voronoi cells determine which
--  ^ heat/humidity points belong to which biome, and therefore determine
--  ^ the area and location of each biome in the world.
--  ^ The biome points need to be carefully and evenly spaced on the voronoi
--  ^ diagram to result in roughly equal size biomes.
--  ^ Heat and humidity have average values of 50, vary mostly between
--  ^ 0 and 100 but also often exceed these values.
--  ^ Heat is not in degrees celcius, both values are abstract.
}

Decoration definition (register_decoration)

{
    deco_type = "simple", -- See "Decoration types"
    place_on = "default:dirt_with_grass",
--  ^ Node (or list of nodes) that the decoration can be placed on
    sidelen = 8,
--  ^ Size of divisions made in the chunk being generated.
--  ^ If the chunk size is not evenly divisible by sidelen, sidelen is made equal to the chunk size.
    fill_ratio = 0.02,
--  ^ Ratio of the area to be uniformly filled by the decoration.
--  ^ Used only if noise_params is not specified.
    noise_params = {offset=0, scale=.45, spread={x=100, y=100, z=100}, seed=354, octaves=3, persist=0.7},
--  ^ NoiseParams structure describing the perlin noise used for decoration distribution.
--  ^ The result of this is multiplied by the 2d area of the division being decorated.
    biomes = {"Oceanside", "Hills", "Plains"},
--  ^ List of biomes in which this decoration occurs.  Occurs in all biomes if this is omitted,
--  ^ and ignored if the Mapgen being used does not support biomes.
--  ^ Can be a list of (or a single) biome names, IDs, or definitions.
    y_min = -31000
    y_max = 31000
-- ^ Minimum and maximum `y` positions these decorations can be generated at.
-- ^ This parameter refers to the `y` position of the decoration base, so
--   the actual maximum height would be `height_max + size.Y`.
    spawn_by = "default:water",
--  ^ Node (or list of nodes) that the decoration only spawns next to.
--  ^ Checks two horizontal planes of neighbouring nodes (including diagonal neighbours),
--  ^ one plane at Y = surface and one plane at Y = surface = + 1.
    num_spawn_by = 1,
--  ^ Number of spawn_by nodes that must be surrounding the decoration position to occur.
--  ^ If absent or -1, decorations occur next to any nodes.
    flags = "liquid_surface, force_placement",
--  ^ Flags for all decoration types.
--  ^ "liquid_surface": Instead of placement on the highest solid surface
--  ^ in a mapchunk column, placement is on the highest liquid surface.
--  ^ Placement is disabled if solid nodes are found above the liquid surface.
--  ^ "force_placement": Nodes other than "air" and "ignore" are replaced by the decoration.

    ----- Simple-type parameters
    decoration = "default:grass",
--  ^ The node name used as the decoration.
--  ^ If instead a list of strings, a randomly selected node from the list is placed as the decoration.
    height = 1,
--  ^ Number of nodes high the decoration is made.
--  ^ If height_max is not 0, this is the lower bound of the randomly selected height.
    height_max = 0,
--  ^ Number of nodes the decoration can be at maximum.
--  ^ If absent, the parameter 'height' is used as a constant.
    param2 = 0,
--  ^ Param2 value of placed decoration node.

    ----- Schematic-type parameters
    schematic = "foobar.mts",
--  ^ If schematic is a string, it is the filepath relative to the current working directory of the
--  ^ specified Minetest schematic file.
--  ^  - OR -, could be the ID of a previously registered schematic
--  ^  - OR -, could instead be a table containing two mandatory fields, size and data,
--  ^ and an optional table yslice_prob:
    schematic = {
        size = {x=4, y=6, z=4},
        data = {
            {name="default:cobble", param1=255, param2=0},
            {name="default:dirt_with_grass", param1=255, param2=0},
            {name="ignore", param1=255, param2=0},
            {name="air", param1=255, param2=0},
             ...
        },
        yslice_prob = {
            {ypos=2, prob=128},
            {ypos=5, prob=64},
             ...
        },
    },
--  ^ See 'Schematic specifier' for details.
    replacements = {["oldname"] = "convert_to", ...},
    flags = "place_center_x, place_center_y, place_center_z",
--  ^ Flags for schematic decorations.  See 'Schematic attributes'.
    rotation = "90" -- rotate schematic 90 degrees on placement
--  ^ Rotation can be "0", "90", "180", "270", or "random".
}

Chat command definition (register_chatcommand)

{
    params = "<name> <privilege>", -- Short parameter description
    description = "Remove privilege from player", -- Full description
    privs = {privs=true}, -- Require the "privs" privilege to run
    func = function(name, param), -- Called when command is run.
                                  -- Returns boolean success and text output.
}

Detached inventory callbacks

{
    allow_move = func(inv, from_list, from_index, to_list, to_index, count, player),
--  ^ Called when a player wants to move items inside the inventory
--  ^ Return value: number of items allowed to move

    allow_put = func(inv, listname, index, stack, player),
--  ^ Called when a player wants to put something into the inventory
--  ^ Return value: number of items allowed to put
--  ^ Return value: -1: Allow and don't modify item count in inventory

    allow_take = func(inv, listname, index, stack, player),
--  ^ Called when a player wants to take something out of the inventory
--  ^ Return value: number of items allowed to take
--  ^ Return value: -1: Allow and don't modify item count in inventory

    on_move = func(inv, from_list, from_index, to_list, to_index, count, player),
    on_put = func(inv, listname, index, stack, player),
    on_take = func(inv, listname, index, stack, player),
--  ^ Called after the actual action has happened, according to what was allowed.
--  ^ No return value
}

HUD Definition (hud_add, hud_get)

{
    hud_elem_type = "image", -- see HUD element types
--  ^ type of HUD element, can be either of "image", "text", "statbar", or "inventory"
    position = {x=0.5, y=0.5},
--  ^ Left corner position of element
    name = "<name>",
    scale = {x=2, y=2},
    text = "<text>",
    number = 2,
    item = 3,
--  ^ Selected item in inventory.  0 for no item selected.
    direction = 0,
--  ^ Direction: 0: left-right, 1: right-left, 2: top-bottom, 3: bottom-top
    alignment = {x=0, y=0},
--  ^ See "HUD Element Types"
    offset = {x=0, y=0},
--  ^ See "HUD Element Types"
    size = { x=100, y=100 },
--  ^ Size of element in pixels
}

Particle definition (add_particle)

{
    pos = {x=0, y=0, z=0},
    velocity = {x=0, y=0, z=0},
    acceleration = {x=0, y=0, z=0},
--  ^ Spawn particle at pos with velocity and acceleration
    expirationtime = 1,
--  ^ Disappears after expirationtime seconds
    size = 1,
    collisiondetection = false,
--  ^ collisiondetection: if true collides with physical objects
    collision_removal = false,
--  ^ collision_removal: if true then particle is removed when it collides,
--  ^ requires collisiondetection = true to have any effect
    vertical = false,
--  ^ vertical: if true faces player using y axis only
    texture = "image.png",
--  ^ Uses texture (string)
    playername = "singleplayer",
--  ^ optional, if specified spawns particle only on the player's client
    animation = {Tile Animation definition},
--  ^ optional, specifies how to animate the particle texture
    glow = 0
--  ^ optional, specify particle self-luminescence in darkness
}

ParticleSpawner definition (add_particlespawner)

{
    amount = 1,
    time = 1,
--  ^ If time is 0 has infinite lifespan and spawns the amount on a per-second base
    minpos = {x=0, y=0, z=0},
    maxpos = {x=0, y=0, z=0},
    minvel = {x=0, y=0, z=0},
    maxvel = {x=0, y=0, z=0},
    minacc = {x=0, y=0, z=0},
    maxacc = {x=0, y=0, z=0},
    minexptime = 1,
    maxexptime = 1,
    minsize = 1,
    maxsize = 1,
--  ^ The particle's properties are random values in between the bounds:
--  ^ minpos/maxpos, minvel/maxvel (velocity), minacc/maxacc (acceleration),
--  ^ minsize/maxsize, minexptime/maxexptime (expirationtime)
    collisiondetection = false,
--  ^ collisiondetection: if true uses collision detection
    collision_removal = false,
--  ^ collision_removal: if true then particle is removed when it collides,
--  ^ requires collisiondetection = true to have any effect
    attached = ObjectRef,
--  ^ attached: if defined, particle positions, velocities and accelerations
--  ^ are relative to this object's position and yaw.
    vertical = false,
--  ^ vertical: if true faces player using y axis only
    texture = "image.png",
--  ^ Uses texture (string)
    playername = "singleplayer"
--  ^ Playername is optional, if specified spawns particle only on the player's client
}

HTTPRequest definition (HTTPApiTable.fetch_async, HTTPApiTable.fetch_async)

{
    url = "http://example.org",
    timeout = 10,
 -- ^ Timeout for connection in seconds. Default is 3 seconds.
    post_data = "Raw POST request data string" OR { field1 = "data1", field2 = "data2" },
 -- ^ Optional, if specified a POST request with post_data is performed.
 -- ^ Accepts both a string and a table. If a table is specified, encodes table
 -- ^ as x-www-form-urlencoded key-value pairs.
 -- ^ If post_data ist not specified, a GET request is performed instead.
    user_agent = "ExampleUserAgent",
 -- ^ Optional, if specified replaces the default minetest user agent with given string
    extra_headers = { "Accept-Language: en-us", "Accept-Charset: utf-8" },
 -- ^ Optional, if specified adds additional headers to the HTTP request. You must make sure
 -- ^ that the header strings follow HTTP specification ("Key: Value").
    multipart = boolean
 -- ^ Optional, if true performs a multipart HTTP request. Default is false.
}

HTTPRequestResult definition (HTTPApiTable.fetch callback, HTTPApiTable.fetch_async_get)

{
    completed = true,
 -- ^ If true, the request has finished (either succeeded, failed or timed out)
    succeeded = true,
 -- ^ If true, the request was succesful
    timeout = false,
 -- ^ If true, the request timed out
    code = 200,
 -- ^ HTTP status code
    data = "response"
}