Difference between revisions of "Scripting Oolite with JavaScript"

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[[Oolite]] 1.68 and later supports scripts written in [http://en.wikipedia.org/wiki/ECMAScript ECMAScript] (more commonly known as [http://en.wikipedia.org/wiki/JavaScript JavaScript]) in addition to its traditional model based on [[property lists]]. This page provides an overview of the JavaScript environment. The page [[Oolite JavaScript object model]] provides reference for Oolite-specific objects and methods. The language standards and some tutorials can be found through the Wikipedia links provided above.
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[[Oolite]] 1.68 and later supports scripts written in [http://en.wikipedia.org/wiki/ECMAScript ECMAScript] (more commonly known as [http://en.wikipedia.org/wiki/JavaScript JavaScript]) in addition to its traditional model based on [[property lists]]. This page provides an overview of how JavaScript is used in Oolite. The page [[Oolite JavaScript object model]] provides reference for Oolite-specific objects and methods. The page [[Oolite JavaScript event handler reference]] provides reference for the event handlers Oolite supports. The language standards and some tutorials can be found through the Wikipedia links provided above.
  
 
== Using JavaScript ==
 
== Using JavaScript ==
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If your OXP only uses one script, place a JavaScript file named ''script.js'' (or ''script.es'') in the OXP’s ''Config'' directory. If you wish to use multiple scripts, you may instead create file named ''world-scripts.plist'' in the ''Config'' directory. This [[property list]] file should consist of an array of script names; the named scripts should exist in a directory named ''Scripts'' inside your OXP. As with most “atomic” files (files which cannot be merged), such script files must have a unique name to avoid conflicts with other OXPs. Using the ''world-scripts.plist'' method, you can combine JavaScript, plist and OOS scripts however you wish.
 
If your OXP only uses one script, place a JavaScript file named ''script.js'' (or ''script.es'') in the OXP’s ''Config'' directory. If you wish to use multiple scripts, you may instead create file named ''world-scripts.plist'' in the ''Config'' directory. This [[property list]] file should consist of an array of script names; the named scripts should exist in a directory named ''Scripts'' inside your OXP. As with most “atomic” files (files which cannot be merged), such script files must have a unique name to avoid conflicts with other OXPs. Using the ''world-scripts.plist'' method, you can combine JavaScript, plist and OOS scripts however you wish.
  
Whereas plist scripts are based on polling – all scripts are run at semi-regular intervals, whether they need to be or not – scripts written in JavaScript are “event driven” – different functions of the script are called in response to state changes in the game, or when other events of interest happen. For instance, <code>STATUS_EXITING_WITCHSPACE</code> is called once when the player exits witchspace, and <code>alertConditionChanged</code> is called whenever the alert condition changes.
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Whereas plist scripts are based on polling – all scripts are run at semi-regular intervals, whether they need to be or not – scripts written in JavaScript are “event driven” – different functions, or ''event handlers'', in the script are called in response to state changes in the game, or when other events of interest happen. For instance, <code>willExitWitchSpace</code> is called just before player exits witchspace, and <code>alertConditionChanged</code> is called whenever the alert condition changes. See the [[Oolite JavaScript event handler reference|event handler reference]] for a full list of handlers and when Oolite will call them.
  
Certain special “tickle” handlers, such as <code>STATUS_DOCKED</code> and <code>STATUS_IN_FLIGHT</code>, will be called periodically. These functions will be called about every 10 seconds as long as the game is in the relevant state. For efficiency, however, it is best to avoid these events if possible.
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The <code>tickle</code> handler is similar to event handlers, but is called periodically at the same times as plist scripts are run – about every 10 seconds, and when certain state changes occur. For efficiency, however, it is best to avoid using <code>tickle</code> if possible.
  
  
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     Log("Initialising OXP " + name);
 
     Log("Initialising OXP " + name);
 
}</pre>
 
}</pre>
 
=== Scripting Events ===
 
 
The following events are available to OXP scripts written in JavaScript.
 
 
==== <code>startUp</code> ====
 
 
The <code>startUp</code> handler is called after all OXPs have been loaded. It can be used to do once-off initialisation such as registering to listen for certain keystrokes etc.
 
 
this.startUp = function()
 
{
 
      // Your code here
 
}
 
 
==== <code>reset</code> ====
 
 
The <code>reset</code> handler is called whenever the player is respawned, such as after dying or when loading a saved game. It should be used to reset any local state in the script.
 
 
this.reset = function()
 
{
 
      // Your code here
 
}
 
 
 
<!--
 
==== keyPressed ====
 
 
''' Broken due to merge from trunk '''
 
 
The <tt>keyPressed</tt> event is called when a key the OXP is listening for has been pressed. It will be called once for each time the key is pressed, and will not be called again until the key is released and then pressed again.
 
 
The <tt>keycode</tt> argument gives the keycode of the key that was pressed. This can be used to determine which key was pressed if the OXP is listening for more than one key.
 
 
this.keyPressed = function (keycode) {
 
}-->
 
 
==== alertConditionChanged ====
 
 
The <code>alertConditionChanged</code> handler is called when the alert condition changes. The current alert condition can be read from <code>olayer.alertCondition</code> and the current alert flags can be read from <code>player.alertFlags</code>.
 
 
this.alertConditionChanged = function ()
 
{
 
      // Your code here
 
}
 
 
 
==== STATUS_DOCKED ====
 
 
The <tt>STATUS_DOCKED</tt> event is called periodically while the player is docked at a station or other entity with a docking port.
 
 
this.STATUS_DOCKED = function () {
 
}
 
 
 
==== STATUS_IN_FLIGHT ====
 
 
The <tt>STATUS_IN_FLIGHT</tt> event is called periodically while the player is flying in normal space or interstellar space (due to a misjump).
 
 
this.STATUS_IN_FLIGHT = function () {
 
}
 
 
 
==== STATUS_LAUNCHING ====
 
 
The <tt>STATUS_LAUNCHING</tt> event is called once when the player has launched from a dock.
 
 
this.STATUS_LAUNCHING = function () {
 
}
 
 
 
==== STATUS_EXITING_WITCHSPACE ====
 
 
The <tt>STATUS_EXITING_WITCHSPACE</tt> event is called once when the player arrives in a new system.
 
 
this.STATUS_EXITING_WITCHSPACE = function () {
 
}
 
  
 
[[Category:Oolite]] [[Category:Oolite scripting]]
 
[[Category:Oolite]] [[Category:Oolite scripting]]

Revision as of 16:21, 1 April 2007

Oolite 1.68 and later supports scripts written in ECMAScript (more commonly known as JavaScript) in addition to its traditional model based on property lists. This page provides an overview of how JavaScript is used in Oolite. The page Oolite JavaScript object model provides reference for Oolite-specific objects and methods. The page Oolite JavaScript event handler reference provides reference for the event handlers Oolite supports. The language standards and some tutorials can be found through the Wikipedia links provided above.

Using JavaScript

Currently, JavaScript is only supported for “world scripts”, that is, as a replacement for scripts in script.plist. While a script.plist file may contain any number of separate scripts, a single JavaScript file may contain only one script.

If your OXP only uses one script, place a JavaScript file named script.js (or script.es) in the OXP’s Config directory. If you wish to use multiple scripts, you may instead create file named world-scripts.plist in the Config directory. This property list file should consist of an array of script names; the named scripts should exist in a directory named Scripts inside your OXP. As with most “atomic” files (files which cannot be merged), such script files must have a unique name to avoid conflicts with other OXPs. Using the world-scripts.plist method, you can combine JavaScript, plist and OOS scripts however you wish.

Whereas plist scripts are based on polling – all scripts are run at semi-regular intervals, whether they need to be or not – scripts written in JavaScript are “event driven” – different functions, or event handlers, in the script are called in response to state changes in the game, or when other events of interest happen. For instance, willExitWitchSpace is called just before player exits witchspace, and alertConditionChanged is called whenever the alert condition changes. See the event handler reference for a full list of handlers and when Oolite will call them.

The tickle handler is similar to event handlers, but is called periodically at the same times as plist scripts are run – about every 10 seconds, and when certain state changes occur. For efficiency, however, it is best to avoid using tickle if possible.


script.js File Template

Copy and paste this template into a file called script.js in the OXP Config directory. Ensure you change at least the Name value. Every script must have a unique name. If multiple scripts with the same name are encountered, Oolite will arbitrary select one and discard the others.

this.name           = "My OXP Script";
this.author         = "Your Name Here";
this.copyright      = "(C) 2007 Me.";
this.description    = "This OXP doesn't do very much yet.";
this.version        = "1.0 alpha 1";


/*  You can copy and paste this function and just change the "startUp"
    to another event name to handle other OXP events (eg "STATUS_DOCKED",
    "alertConditionChanged", etc).
*/
this.startUp = function()
{
    Log("Initialising OXP " + name);
}