API: Difference between revisions

From Citizens Wiki

No edit summary
No edit summary
Line 61: Line 61:
         // This does NOT get called when applying the trait for the first time, only loading onto an existing npc at server start.
         // This does NOT get called when applying the trait for the first time, only loading onto an existing npc at server start.
         // This is called AFTER onAttach so you can load defaults in onAttach and they will be overridden here.
         // This is called AFTER onAttach so you can load defaults in onAttach and they will be overridden here.
         // This is called AFTER onSpawn (2.0.4+), but npc.getBukkitEntity() may or may not be null.
         // This is called BEFORE onSpawn, npc.getBukkitEntity() will return null.
public void load(DataKey key) {
public void load(DataKey key) {
SomeSetting = key.getBoolean("SomeSetting", false);
SomeSetting = key.getBoolean("SomeSetting", false);
Line 85: Line 85:


//Run code when your trait is attached to a NPC.  
//Run code when your trait is attached to a NPC.  
         //This is called AFTER onSpawn, but npc.getBukkitEntity() may or may not be null
         //This is called BEFORE onSpawn, so npc.getBukkitEntity() will return null
         //This would be a good place to load configurable defaults for new NPCs.
         //This would be a good place to load configurable defaults for new NPCs.
@Override
@Override
Line 97: Line 97:
         }
         }


//Run code when the NPC is spawned. Note that npc.getBukkitEntity() may or may not be null until this method is called.
//Run code when the NPC is spawned. Note that npc.getBukkitEntity() will be null until this method is called.
         //This is called AFTER onAttach and AFTER Load when the server is started.
         //This is called AFTER onAttach and AFTER Load when the server is started.
@Override
@Override

Revision as of 14:53, 30 October 2012

Current Release Download: Jenkins

Developmental Builds: Jenkins

Documentation: JavaDocs

Source: Github

Citizens has an extensive API that can be used for making your plugins work with NPCs or even for adding a brand new character that can be attached to an NPC. Make sure you always are using an up-to-date build of the CitizensAPI to ensure that your plugin works with the latest release of Citizens.

Javadocs can be found at http://jd.citizensnpcs.com

Hooking Into Citizens

Hooking into Citizens is as simple as creating a basic plugin and adding the line depend: [Citizens] into your plugin.yml. From here, a common basic entry point is the CitizensAPI class. This gives you access to the NPCRegistry for NPC lookup, as well as the TraitFactory which allows trait registration.

Checking if an entity is a Citizens NPC

Citizens NPCs will have the "NPC" metadata set to true. Eg.

boolean isCitizensNPC = entity.hasMetadata("NPC");

Creating a Trait

Traits are persistent, attachable objects that are linked to an NPC and provide specific functionality. This can be anything from a full-blown dynamic villager AI to a simple talking trait.

If using Maven, Citizens' Maven repo is available at http://repo.citizensnpcs.com

To register a trait, we use the TraitFactory class. This controls registration for your custom traits.

Code: Example registration and simple trait

Dos and Don'ts

DO

  • Check npc.isSpawned() before using npc.getBukkitEntity()
  • Check npc.isSpawned() before using npc.getNavigator()
  • Create a separate singleton Listener class if you expect there to be many instances of this trait running. This may help performance with frequently called events.
  • Honor npc.data().get(NPC.DEFAULT_PROTECTED_METADATA) If this is true the NPC should be 'invulnerable' to normal damaging effects.
  • use CitizensAPI.getNPCRegistry().isNPC() to check if an entity is a NPC. Real players and player-type NPCs will both return true for instanceof Player.

DON'T

  • Attempt to access npc.getBukkitEntity() from within traits until onSpawn() has been called or npc.isSpawned() returns true.
  • Change anything in npc.getNavigator.getDefaultParams() unless you're sure you want a global change. Use the localParams() instead after setting a navigation target.
  • Assume a NPC is a player-type. Mob types have some important differences.

Download an example

This is a link to a an example trait. It is similar to the code above, with some additional code for better handling commands, default configuration, and a plugin.yml

You will need to build against CitizensAPI.jar,Citizens.jar (although this is not always required), and Bukkit.jar.

NPC Events

Citizens implements its own Listeners and will call new NPC-specific versions of many common events. This saves Trait developers the trouble of finding their npcs from the normal event entities. The event object these events provide are just like their Bukkit counterparts with the addition of the getNPC() method. Citizens currently provides the following:

  • EntityTargetNPCEvent
  • NPCClickEvent
  • NPCCollisionEvent
  • NPCCombustByBlockEvent
  • NPCCombustByEntityEvent
  • NPCCombustEvent
  • NPCDamageByBlockEvent
  • NPCDamageByEntityEvent
  • NPCDamageEvent
  • NPCDespawnEvent
  • NPCEvent
  • NPCLeftClickEvent
  • NPCPushEvent
  • NPCRemoveEvent
  • NPCRightClickEvent
  • NPCSelectEvent
  • NPCSpawnEvent

See the [Javadocs] for details.

Using the AI API

The AI API of Citizens can be broken down into two parts - GoalController and Navigator.

A Goal is a repeatable, abstract unit of work that can be performed by an NPC. It can be registered with a GoalController with a priority (higher is more important). The highest priority goal which can be executed will be prioritised. NPC contains getDefaultGoalController() for this purpose.

The GoalSelector allows a great deal of flexibility within goal implementations. It allows firstly the dynamic selection of sub-goals and the concurrent execution of many sub-goals, and can stop execution at any time.


Code: Example
{{{2}}}

The second concept is the Navigator. This controls the pathfinding aspects of the NPC. The Navigator can have one target at a time, and will call events to notify of completion/cancellation.

The pathfinding range of the Navigator is the maximum range it will search when attempting to find a path to the target. This is usually set by the server admin. The speed of the Navigator is the movement speed of the NPC while moving to the target. The default speed is around 0.3.

Using the Persistence API

Sometimes, traits can store a lot of simple variables such as primitives, Strings, Locations, and others. Saving/loading them via the trait API can be a little bit of overkill.

Citizens 2.0.4+ provides a simple Persistence API to automatically save and load these variables using DataKeys. The key to this API is the @Persist annotation. Sample code is provided below. {{codebox|height=300px|width=100%|Example|<syntaxhighlight lang="java5">

public class MyTrait extends Trait {
    // logic omitted.
   @Persist boolean myVariable = false; // the default value of @Persist saves the value under the field name (in this case, 'myVariable').
   
   @Persist("newkey") int intVariable = 11; // this saves the value under 'newkey'. The default value of the variable has been set to 11 - this will be used when loading if the key doesn't exist.
   @Persist(value="newkey", required=true) String required; // if the value under 'newkey' doesn't exist, then the trait will fail to load.
}

</syntaxhighlight>

More advanced use of the API can be found in the @DelegatePersistence annotation. This allows complex types such as Locations to be saved and loaded with finer grained control. These types can be given default delegates by calling PersistenceLoader#registerPersistDelegate(Persister) - Location has a built in Persister for convenience.

{{codebox|height=300px|width=100%|Example|<syntaxhighlight lang="java5">

public class MyTrait extends Trait {
    // logic omitted.
   @Persist 
   @DelegatePersistence(ExplicitComplexTypePersister.class) // explicit delegation
   ComplexType myComplexType;
   @Persist ComplexType implicitComplexType; // implicit delegation
   static {
       PersistenceLoader.registerPersistDelegate(ImplicitComplexTypePersister.class);
   }
}

public class ExplicitComplexTypePersister implements Persister {
    public Object create(DataKey root) {
        return new ComplexType(root.getInteger("complexstructures"));
    }
    public void save(Object instance, DataKey root) {
        ComplexType real = (ComplexType) instance; // guaranteed cast - will always succeed.
        root.setInteger("complexstructures", real.getComplexStructure());
    }
}

</syntaxhighlight>

See Also

Characters