refactor(ravengard): mobs ride the real entity ai

The mob is an EntityCreature with melee attack and closest player targeting through the
engine's pathfinding rather than straight line steering, with the captured rig, animations
and health bar glued onto wherever navigation takes it. Vanilla damage drives the bar and
knockback, and the attack goal plays the captured swing.

Author: Swofty-Developments

type.ravengardgeneric/src/main/java/net/swofty/type/ravengardgeneric/commands/SpawnCommand.java

@@ -35,7 +35,7 @@ public void registerUsage(MinestomCommand command) {
             }
             RavengardAnimationClip clip = RavengardAnimationClip.loadMob(name);
             RavengardMob mob = new RavengardMob(clip, player.getPosition());
-            mob.spawn(player.getInstance());
+            mob.spawnMob(player.getInstance());
             player.sendMessage("§aSpawned §f" + name + "§a.");
         }, mobArg);
     }

type.ravengardgeneric/src/main/java/net/swofty/type/ravengardgeneric/entity/mob/RavengardMob.java

@@ -29,7 +29,7 @@
  * it chases the nearest player and swings when in reach, and the captured ten square health bar
  * floats above it, draining as it takes hits.
  */
-public class RavengardMob {
+public class RavengardMob extends net.minestom.server.entity.EntityCreature {
     private static final List<RavengardMob> MOBS = new CopyOnWriteArrayList<>();
     private static final TextColor BAR_FULL = TextColor.color(0x5FEC7B);
     private static final TextColor BAR_EMPTY = TextColor.color(0x3D3D3D);
@@ -44,30 +44,68 @@ public class RavengardMob {
     private final List<Entity> parts = new ArrayList<>();
     private final List<Vec> partOffsets = new ArrayList<>();
     private LivingEntity healthBar;
-    private InteractionEntity hitbox;
     private Instance instance;
 
     private Pos position;
     private double health;
     private final double maxHealth;
     private int frame;
     private int attackTicksLeft;
-    private int attackCooldown;
-    private Vec knockback = Vec.ZERO;
 
     public RavengardMob(RavengardAnimationClip clip, Pos position) {
+        super(EntityType.ZOMBIE);
         this.clip = clip;
         this.position = position;
         this.maxHealth = clip.health() <= 0 ? 100 : clip.health();
         this.health = maxHealth;
+        setInvisible(true);
+        setSilent(true);
+        getAttribute(net.minestom.server.entity.attribute.Attribute.MOVEMENT_SPEED)
+                .setBaseValue(Math.max(0.15, clip.walkSpeed() * 2));
+        getAttribute(net.minestom.server.entity.attribute.Attribute.MAX_HEALTH)
+                .setBaseValue((float) maxHealth);
+        setHealth((float) maxHealth);
+        addAIGroup(
+                List.of(new net.minestom.server.entity.ai.goal.MeleeAttackGoal(this, 1.8,
+                        java.time.Duration.ofMillis(1500))),
+                List.of(new net.minestom.server.entity.ai.target.LastEntityDamagerTarget(this, 16),
+                        new net.minestom.server.entity.ai.target.ClosestEntityTarget(this, 14,
+                                entity -> entity instanceof Player)));
+    }
+
+    /** MeleeAttackGoal path: play the captured swing and hurt the target. */
+    @Override
+    public void attack(Entity target, boolean swingHand) {
+        if (attackTicksLeft <= 0) {
+            attackTicksLeft = attackFrames();
+            frame = 0;
+        }
+        if (target instanceof net.minestom.server.entity.LivingEntity living) {
+            living.damage(net.minestom.server.entity.damage.DamageType.MOB_ATTACK, PLAYER_DAMAGE_PER_HIT);
+        }
+    }
+
+    /** Damage from any source drains the captured bar; vanilla handles the knockback. */
+    @Override
+    public boolean damage(net.minestom.server.registry.RegistryKey<net.minestom.server.entity.damage.DamageType> type, float amount) {
+        boolean applied = super.damage(type, amount);
+        health = getHealth();
+        if (healthBar != null) {
+            healthBar.editEntityMeta(TextDisplayMeta.class, meta -> meta.setText(barText()));
+        }
+        if (health <= 0) {
+            removeRig();
+        }
+        return applied;
     }
 
     public static List<RavengardMob> mobs() {
         return MOBS;
     }
 
-    public void spawn(Instance instance) {
+    public void spawnMob(Instance instance) {
         this.instance = instance;
+        setInstance(instance, position);
         for (RavengardAnimationClip.Part part : clip.parts()) {
             RavengardAnimationClip.Base base = part.base();
             Entity display = new Entity(EntityType.ITEM_DISPLAY);
@@ -105,9 +143,6 @@ public void spawn(Instance instance) {
         });
         healthBar.setInstance(instance, position.add(0, 2.25, 0));
 
-        hitbox = new InteractionEntity(0.9f, 2.0f, (player, event) -> hit(player));
-        hitbox.setInstance(instance, position);
-
         MOBS.add(this);
     }
 
@@ -117,67 +152,24 @@ private Component barText() {
                 .append(Component.text("\u25A0".repeat(BAR_SEGMENTS - full)).color(BAR_EMPTY));
     }
 
-    public void hit(Player player) {
-        if (health <= 0) {
-            return;
-        }
-        health -= HIT_DAMAGE;
-        Vec away = position.sub(player.getPosition()).asVec().withY(0);
-        if (away.lengthSquared() > 0.001) {
-            knockback = away.normalize().mul(0.45).withY(0.1);
-        }
-        healthBar.editEntityMeta(TextDisplayMeta.class, meta -> meta.setText(barText()));
-        if (health <= 0) {
-            remove();
-        }
-    }
-
-    public void remove() {
+    public void removeRig() {
         parts.forEach(Entity::remove);
         if (healthBar != null) healthBar.remove();
-        if (hitbox != null) hitbox.remove();
         MOBS.remove(this);
+        remove();
     }
 
-    public void tick() {
-        if (instance == null || health <= 0) {
+    /** Glues the rig, bar and animations onto wherever the creature's pathfinding took it. */
+    public void tickRig() {
+        if (instance == null || isDead()) {
             return;
         }
-
-        Player target = nearestPlayer();
+        Pos previous = position;
+        position = getPosition();
         boolean attacking = attackTicksLeft > 0;
-        boolean moved = false;
+        boolean moved = !previous.samePoint(position);
         float yaw = position.yaw();
 
-        if (!attacking && target != null) {
-            double distance = position.distance(target.getPosition());
-            Vec toTarget = target.getPosition().sub(position).asVec().withY(0);
-            if (toTarget.lengthSquared() > 0.01) {
-                yaw = (float) Math.toDegrees(Math.atan2(-toTarget.x(), toTarget.z()));
-            }
-            if (distance <= ATTACK_RANGE && attackCooldown <= 0) {
-                attackTicksLeft = attackFrames();
-                attackCooldown = ATTACK_COOLDOWN_TICKS;
-                frame = 0;
-                target.damage(net.minestom.server.entity.damage.DamageType.MOB_ATTACK, PLAYER_DAMAGE_PER_HIT);
-            } else if (distance > ATTACK_RANGE && distance <= CHASE_RANGE && clip.walkSpeed() > 0) {
-                Vec step = toTarget.normalize().mul(clip.walkSpeed());
-                position = position.add(step.x(), 0, step.z()).withYaw(yaw);
-                moved = true;
-            } else {
-                position = position.withYaw(yaw);
-            }
-        }
-
-        if (knockback.lengthSquared() > 0.001) {
-            position = position.add(knockback.x(), 0, knockback.z());
-            knockback = knockback.mul(0.6);
-            moved = true;
-        }
-
-        if (attackCooldown > 0) attackCooldown--;
-
-        String phase = attacking ? "talk" : "idle";
         List<RavengardAnimationClip.Part> clipParts = clip.parts();
         for (int i = 0; i < parts.size() && i < clipParts.size(); i++) {
             Entity part = parts.get(i);
@@ -201,7 +193,6 @@ public void tick() {
         }
         if (moved || attacking) {
             healthBar.teleport(position.add(0, 2.25, 0));
-            hitbox.teleport(position);
         }
 
         frame++;
@@ -221,20 +212,6 @@ private int attackFrames() {
         return Math.max(1, max);
     }
 
-    private Player nearestPlayer() {
-        Player nearest = null;
-        double best = CHASE_RANGE * CHASE_RANGE;
-        for (var player : HypixelGenericLoader.getLoadedPlayers()) {
-            if (player.getInstance() != instance) continue;
-            double distance = player.getPosition().distanceSquared(position);
-            if (distance < best) {
-                best = distance;
-                nearest = player;
-            }
-        }
-        return nearest;
-    }
-
     private static Vec vec(float[] values) {
         return new Vec(values[0], values[1], values[2]);
     }
@@ -261,7 +238,7 @@ public static void startTicking() {
         MinecraftServer.getSchedulerManager()
                 .buildTask(() -> MOBS.forEach(mob -> {
                     try {
-                        mob.tick();
+                        mob.tickRig();
                     } catch (Exception ignored) {
                     }
                 }))