Scripting: Difference between revisions

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== NOTICE ==
<span style="font-family:natalya-alternate-one; font-size:300%; margin-right:-7px; margin-left:-10px;">This page refers to the legacy Javascript scripting which is no longer fully supported. The main scripting support available in modern Citizens is through [https://denizenscript.com/ Denizen].</span>
== Scripting Support in Citizens2 ==
== Scripting Support in Citizens2 ==
Citizens2 includes support for various scripting languages including Lua, Javascript and Python.
Citizens2 includes support for various scripting languages including Lua, Javascript and Python.


Javascript support is built into Java; additional languages can be added in through installing things such as JRuby (http://jruby.org/), Jython (http://www.jython.org/), Kahlua (http://www.ohloh.net/p/kahlua) and more. These use the Java Scripting API to give common scripting support to Citizens.
Javascript support is built into Java; additional languages can be added in through installing things such as JRuby (http://jruby.org/), Jython (http://www.jython.org/), Kahlua (https://github.com/krka/kahlua2) and more.


The scripting API contains a few built in objects in the global namespace which aid in some tasks. Currently, the 'events' object allows registering event listeners for Bukkit events and a reference to the Citizens plugin object is available under 'plugin'.  
The scripting API contains a few built in objects in the global namespace which aid in some tasks. Currently, the 'events' object allows registering event listeners for Bukkit events and a reference to the Citizens plugin object is available under 'plugin'.  


== Behaviours ==
== Behaviours ==
Let's see an example of how to use scripts. Citizens builds in by default the 'Behaviour' trait - this lets you specify AI tasks via scripts. Behaviours can be added to the NPC via the /npc behaviour [behaviours] command, where behaviours is a list of files to use.
Let's see an example of how to use scripts. Scripts can be added to an NPC via the /npc script --add [scripts] command, where scripts is a list of files inside the plugins/Citizens/scripts folder to use. Scripts are differentiated by their extension -- make sure it is correct!
 
When the script file is loaded by Citizens, it will call the method 'onLoad(NPC)' - anything can be performed at this time, although the NPC will not necessarily be spawned. If the method 'run(NPC)' exists it will also be called every tick by Citizens.


Scripts for behaviours should be placed in the plugins/Citizens/scripts/behaviours folder. Scripts are differentiated by their extension -- make sure it is correct!
    function leftClick(event) {
        event.getClicker().sendMessage("hello from Javascript scripting!");
    }


When the script file is loaded by Citizens, it will call the method 'addGoals(Goals, NPC)'. Goals can be added via calling goals.addGoal(priority, goal), where goal implements the interface specified here -http://jd.citizensnpcs.net/net/citizensnpcs/api/ai/Goal.html.
    function onLoad(npc) {
        events.on(Java.type('net.citizensnpcs.api.event.NPCLeftClickEvent').class, leftClick);
    }


An example of a behaviour file is given below - this implements a simple thief goal.
== Scripting Gotchas and Tips ==
=== Javascript (Nashorn) ===
* Nashorn is a much faster Javascript engine only included in Java 7 and above. It is recommended to run this over the older Rhino engine.
* Read https://docs.oracle.com/javase/8/docs/technotes/guides/scripting/nashorn/api.html for more information on Java-Javascript connection.


{{codebox|height=300px|Example done in Javascript|<syntaxhighlight line='true' lang="javascript">
=== Javascript (Rhino) ===
importPackage(Packages.net.citizensnpcs.api.ai);
* Some code will expect the methods equals and hashcode to be implemented - a simple equals function should be used often.
importPackage(Packages.org.bukkit.entity);
* for.. in loops do not work with Java collections.
importPackage(Packages.org.bukkit.inventory);
* Rhino cannot use abstract classes.
importPackage(java.util);
* You can implement Java interfaces by using new [interfacename](object), where object contains the methods implementing the interface.
function addGoals (goals, npc) {
* Use importPackage(Packages.name.space) or importClass(Packages.name.space.YourClass) to import other classes/packages. The Packages. prefix is not required if the class is in the java.util package.
var thiefGoal = {
        npc : npc,
reset : function() {
            this.player = null;
            this.selector = null;
        },
run : function() {
            if (!this.player || !this.player.isOnline()) {
                this.selector.finish();
                return;
            }
            if (this.npc.getLocation().distanceSquared(this.player.getLocation()) < 2) {
                this.player.damage(1);
                var inventory = this.player.getInventory();
                for (var i = 0; i < inventory.size(); i++) {
                    var item = inventory.getItem(i);
                    if (item == null || item.getType() == Material.AIR) {
                        continue;
                    }
                    if (item.getAmount() == 1) {
                        inventory.setItem(i, null);
                    } else {
                        item.setAmount(item.getAmount() - 1);
                        inventory.setItem(i, item);
                    }
                    break;
                }
                this.player.sendMessage(npc.getName() + " Ha! Stole an item!");
                this.npc.getNavigator().setTarget(this.home);
                this.selector.finish();
            }
        },
shouldExecute : function(selector) {
            if (!this.npc.isSpawned())
                return false;
            List nearby = this.npc.getBukkitEntity().getNearbyEntities(5,5,5);
            for (var entity in nearby) {
                if (entity instanceof Player) {
                    this.player = entity;
                    this.home = npc.getBukkitEntity().getLocation();
                    this.npc.getNavigator().setTarget(entity, false);
                    this.selector = selector;
                    return true;
                }
            }
    return false;
};
goals.addGoal(1, new Goal(thiefGoal));
}
</syntaxhighlight>
}}

Latest revision as of 19:16, 3 September 2021

NOTICE

This page refers to the legacy Javascript scripting which is no longer fully supported. The main scripting support available in modern Citizens is through Denizen.



Scripting Support in Citizens2

Citizens2 includes support for various scripting languages including Lua, Javascript and Python.

Javascript support is built into Java; additional languages can be added in through installing things such as JRuby (http://jruby.org/), Jython (http://www.jython.org/), Kahlua (https://github.com/krka/kahlua2) and more.

The scripting API contains a few built in objects in the global namespace which aid in some tasks. Currently, the 'events' object allows registering event listeners for Bukkit events and a reference to the Citizens plugin object is available under 'plugin'.

Behaviours

Let's see an example of how to use scripts. Scripts can be added to an NPC via the /npc script --add [scripts] command, where scripts is a list of files inside the plugins/Citizens/scripts folder to use. Scripts are differentiated by their extension -- make sure it is correct!

When the script file is loaded by Citizens, it will call the method 'onLoad(NPC)' - anything can be performed at this time, although the NPC will not necessarily be spawned. If the method 'run(NPC)' exists it will also be called every tick by Citizens. 

   function leftClick(event) {
       event.getClicker().sendMessage("hello from Javascript scripting!");
   }

   function onLoad(npc) {
       events.on(Java.type('net.citizensnpcs.api.event.NPCLeftClickEvent').class, leftClick);
   }

Scripting Gotchas and Tips

Javascript (Nashorn)

Javascript (Rhino)

  • Some code will expect the methods equals and hashcode to be implemented - a simple equals function should be used often.
  • for.. in loops do not work with Java collections.
  • Rhino cannot use abstract classes.
  • You can implement Java interfaces by using new [interfacename](object), where object contains the methods implementing the interface.
  • Use importPackage(Packages.name.space) or importClass(Packages.name.space.YourClass) to import other classes/packages. The Packages. prefix is not required if the class is in the java.util package.
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