[1.16.3]I want to change the AI of an existing mob

[KGJP]

Assumptions and what we want to achieve

If you can change or delete the goals added to the goalSelector and targetSelector, you can solve this problem.
(See below for targetSelector only)

What I tried below is an example: "Erase the movement of existing zombies from trying to target the player

 

What I've tried

1. reassign the new instance to targetSelector

   public final GoalSelector goalSelector;
   public final GoalSelector targetSelector;

→ Can't do it for final.

 

 

2. writing code to eliminate a specific goal

  @SubscribeEvent
  public static void mobEvent(LivingSpawnEvent event) {

    if (!(event.getEntity() instanceof ZombieEntity)) {
      return;
    }
    ZombieEntity zombie = (ZombieEntity) event.getEntity();
    Stream<PrioritizedGoal> pgStream = zombie.targetSelector.getRunningGoals()
        .filter(prioritizedGoal -> prioritizedGoal.getPriority() == 2);
    Optional<PrioritizedGoal> prioritizedGoal = pgStream.findAny();
    if (prioritizedGoal.isPresent()) {
      zombie.targetSelector.removeGoal(prioritizedGoal.get().getGoal());
    }

targetSelector.removeGoal is provided, but it has to be an instance of the target.
The goal the zombie targets the player with is set in PrioritizedGoal's Priority 2.
The only way to get the existing goal is with targetSelector.getRunningGoals(), so the moment RunningGoal becomes Priority 2 (the moment it tries to target the player), it's forced to remove the Priority 2 goal. code

 

supplementary information

minecraft version 1.16.3
minecraft forge version 1.16.3

 

I have looked into various things and tried, but I can't seem to solve the problem and I am having trouble.
Please help me out.

What is the best practice coding for overwriting or changing the AI of an existing MOB?

Edited October 25, 2020 by KGJP

[ChampionAsh5357]

31 minutes ago, KGJP said:

but it has to be an instance of the target

Yes, if you want to edit an entity's AI, you should add or remove goals within EntityJoinWorldEvent. This will need to be done for every instance a zombie spawns, so this is necessary. However, you do need to grab all goals.

31 minutes ago, KGJP said:

Can't do it for final.

31 minutes ago, KGJP said:

The only way to get the existing goal is with targetSelector.getRunningGoals()

Both of these are incorrect statements. You should take a look into Reflection or Access Transformers and apply what you know to what you need.

[KGJP]

1 hour ago, ChampionAsh5357 said:

Yes, if you want to edit an entity's AI, you should add or remove goals within EntityJoinWorldEvent. This will need to be done for every instance a zombie spawns, so this is necessary. However, you do need to grab all goals.

Both of these are incorrect statements. You should take a look into Reflection or Access Transformers and apply what you know to what you need.

jar {
    manifest {
        attributes([
                "Specification-Title"     : "examplemod",
                "Specification-Vendor"    : "examplemodsareus",
                "Specification-Version"   : "1", // We are version 1 of ourselves
                "Implementation-Title"    : project.name,
                "Implementation-Version"  : "${version}",
                "Implementation-Vendor"   : "examplemodsareus",
                "Implementation-Timestamp": new Date().format("yyyy-MM-dd'T'HH:mm:ssZ")
        ])
        accessTransformer = file('src/main/resources/META-INF/accesstransformer.cfg')
    }
}

public-f net.minecraft.entity.ai.goal.GoalSelector goals

I decided to use Access Transformer.

But it doesn't take a gradle build.

 

org.gradle.api.GradleScriptException: A problem occurred evaluating root project 'MyMod'.
Caused by: groovy.lang.MissingPropertyException: Could not set unknown property 'accessTransformer' for object of type org.gradle.api.java.archives.internal.DefaultManifest.
    at org.gradle.internal.metaobject.AbstractDynamicObject.setMissingProperty(AbstractDynamicObject.java:118)
    at org.gradle.internal.metaobject.ConfigureDelegate.setProperty(ConfigureDelegate.java:105)
 

[ChampionAsh5357]

That's not how access transformers work. Read the default mdk of where it's placed and how to use it. You can also look at the docs.

[KGJP]

I went to that page and implemented it.
I believe it is as written, but what is wrong with it?

[KGJP]

http://tutorials.jenkov.com/java-reflection/private-fields-and-methods.html

You can do this kind of hack-like coding with Java features.
I'd like to try it with this.

 

  private static Field privateFieldGoals;

  static {
    try {
      privateFieldGoals = GoalSelector.class.getDeclaredField("goals");
      privateFieldGoals.setAccessible(true);
    } catch (NoSuchFieldException e) {
      System.err.println("Error");
    }
  }

 

[ChampionAsh5357]

22 minutes ago, KGJP said:

I believe it is as written, but what is wrong with it?

Nope, you moved the line where that was originally written.

12 minutes ago, KGJP said:

I'd like to try it with this.

Using reflection requires you to make use of ObfuscationReflectionHelper as you need to supply the srg name.

[KGJP]

7 minutes ago, ChampionAsh5357 said:

Nope, you moved the line where that was originally written.

You mean you have to describe it at the top?

7 minutes ago, ChampionAsh5357 said:

Using reflection requires you to make use of ObfuscationReflectionHelper as you need to supply the srg name.

      Set<PrioritizedGoal> goals = (Set) privateFieldGoals.get(zombie.targetSelector);

      goals.removeAll(goals.stream()
          .filter(prioritizedGoal -> prioritizedGoal.getPriority() == 2)
          .collect(Collectors.toList()));

It worked with the code I wrote.
What is the benefit of using the ObfuscationReflectionHelper that Forge provides?

Edited October 25, 2020 by KGJP

[ChampionAsh5357]

1 minute ago, KGJP said:

What is the benefit of using the ObfuscationReflectionHelper that Forge provides?

It will not work outside the dev workspace since the field name is obfuscated. This means that if you try and call "goal", it will not exist at runtime. Therefore, you need to grab the associated srg name. Since the name is mapped in the dev workspace however, this will also throw an error. Enter ObfuscationReflectionHelper. This takes in a srg name and maps it to the current environment you are running on. This way it will work in and out of dev.

[KGJP]

3 minutes ago, ChampionAsh5357 said:

It will not work outside the dev workspace since the field name is obfuscated. This means that if you try and call "goal", it will not exist at runtime. Therefore, you need to grab the associated srg name. Since the name is mapped in the dev workspace however, this will also throw an error. Enter ObfuscationReflectionHelper. This takes in a srg name and maps it to the current environment you are running on. This way it will work in and out of dev.

I see, so you're saying that what you're running now is the runClient development environment?
So when you write it out to a jar file, the current code won't work?

[ChampionAsh5357]

9 minutes ago, KGJP said:

So when you write it out to a jar file, the current code won't work?

Exactly.

[KGJP]

On 10/26/2020 at 3:41 AM, ChampionAsh5357 said:

Exactly.

Thank you.
I love you.

Edited October 27, 2020 by KGJP