This page is meant to be a resource for modders. If you want to use mods in Avorion, check out this page: Using Mods
Avorion can be modded by changing existing or adding new scripts to the game. As of now, there are multiple kinds of script that are used by the game. These scripts are loaded by the game and provide functions that will be executed by the game, all during runtime. This interface varies from script type to script type. There are already a lot of scripts running in the game, for missions, objects, sectors, items, generating sectors and many more.
You can review the script code for the core game, Workshop mods and manually installed mods.
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Disclaimer: In order to mod the game, you should have a basic understanding of programming and the programming language Lua.
General Interface Overview[edit | edit source]
Scripting API[edit | edit source]
Note: These are only a few excerpts of the API for an initial overview. For a full overview of the API provided by Avorion, please check out the Scripting API or the included documentation in your Avorion install folder (open Avorion\documentation\index.html in a web browser).
Script Functions[edit | edit source]
Scripts need to have a certain methods defined, depending on the type of the script, that will be called by the game at specific points during the update loop. When a script is loaded into memory, the entire script will be executed once. After this, the game will invoke certain functions defined in the script. Which functions are called, as well as their names and arguments, depend on the kind of script you're working with.
Here's an example of what the predefined functions of a script can look like:
function initialize() -- called only once in the lifetime of a script, when the script is first attached to an entity, player or sector -- or when the object it's attached to is loaded from disk end function update(timeStep) -- will be called periodically, every frame if not configured otherwise end
Note: Script functions that are not used by the script (especially functions like update above that would be called every update frame) should not be defined in the script in order to improve performance. It is faster not to call a function at all, than to execute an empty lua function.
API Functions[edit | edit source]
The game exposes a large API of various functions that can be called from scripts. These functions are either bound to an object, or can be called without a specific object.
An example for such a function would be:
Entity(id):moveBy(vec3(1, 0, 3))
This function is called "moveBy" and is associated with the object type "Entity".
Depending on which application the script runs on (server or client), different API calls will be available. For example, there won't be any rendering functionality on the server scripting API.
Callbacks[edit | edit source]
Sometimes, when scripting, it is easier to be notified when something special happens in the game, than checking every update step whether or not that special event happened. So scripts can register callback handlers for different callbacks. These handlers will then be executed whenever a certain event happens.
To register a callback handler, use the callback registration functions. Registering a callback would look something like this:
function onStartUp() Server():registerCallback("onPlayerLogOff", "handlePlayerLogoff") end function handlePlayerLogoff(context, player) print("A player has logged out.") end
In this example, a function called "handlePlayerLogOff" is registered at the server as the callback handler for the event "onPlayerLogOff". So, whenever a player logs out of the server this function will be executed.
Avorion Modding Quirks[edit | edit source]
Avorion has a few quirks considering modding and its handling of lua. You may have come across these quirks while reading its lua code.
include() instead of require()[edit | edit source]
Avorion defines its own version of
include() behaves the exact same way as
require(), with one important difference: It can load mod file extensions.
require() can only load a single file, and that can be problematic. It can be necessary for mods to modify files such as data/scripts/lib/utility.lua, which are being
required by other lua files. But
require() doesn't know about Avorion's mod structure, and so it cannot load additional files provided by mods, that are supposed to change how data/scripts/lib/utility.lua works.
include() looks for those files in addition to the vanilla file, and includes them into the loaded file.
require() is still around and wasn't altered at all.
Restricted Access to local File System[edit | edit source]
In Avorion, client mods only have restricted access to the file system, for security reasons. So with
io functions, you cannot modify files outside of %AppData%/Avorion (~/.avorion/ on Unix).
print()[edit | edit source]
Avorion extends the basic
print() function of lua a little, to implicitly format strings. You can use
print() like this:
print("Hello World") > Hello World
print("%s was here", "Someone") > Someone was here
print("%s was here %i days ago", "Someone", 5) > Someone was here 5 days ago