DefenderAI that makes octs follow units (#4757)

core/src/mindustry/ai/types/DefenderAI.java

@@ -0,0 +1,34 @@
+package mindustry.ai.types;
+
+import arc.math.*;
+import mindustry.entities.*;
+import mindustry.entities.Units.*;
+import mindustry.entities.units.*;
+import mindustry.gen.*;
+import mindustry.world.meta.*;
+
+public class DefenderAI extends AIController{
+
+    @Override
+    public void updateMovement(){
+        if(target != null){
+            moveTo(target, unit.range(), 5f);
+            unit.lookAt(target);
+        }else{
+            Teamc block = targetFlag(unit.x, unit.y, BlockFlag.rally, false);
+            if(block == null) block = unit.closestCore();
+            moveTo(block, 60f);
+        }
+    }
+
+    @Override
+    protected void updateTargeting(){
+        if(retarget()) target = findTarget(unit.x, unit.y, 0f, true, true);
+    }
+    
+    @Override
+    protected Teamc findTarget(float x, float y, float range, boolean air, boolean ground){
+        //Sort by max health and closer target.
+        return Units.closest(unit.team, x, y, u -> !u.dead() && u.type != unit.type, (u, tx, ty) -> -u.maxHealth + Mathf.dst2(u.x, u.y, tx, ty) / 800f);
+    }
+}

core/src/mindustry/content/UnitTypes.java

@@ -1370,6 +1370,8 @@ public class UnitTypes implements ContentList{
         }};
 
         oct = new UnitType("oct"){{
+            defaultController = DefenderAI::new;
+
             armor = 16f;
             health = 24000;
             speed = 0.8f;

core/src/mindustry/entities/Units.java

@@ -248,7 +248,7 @@ public class Units{
         return result;
     }
 
-    /** Returns the closest ally of this team. Filter by predicate. */
+    /** Returns the closest ally of this team in a range. Filter by predicate. */
     public static Unit closest(Team team, float x, float y, float range, Boolf<Unit> predicate){
         result = null;
         cdist = 0f;
@@ -266,6 +266,24 @@ public class Units{
         return result;
     }
 
+    /** Returns the closest ally of this team using a custom comparison function. Filter by predicate. */
+    public static Unit closest(Team team, float x, float y, Boolf<Unit> predicate, Sortf sort){
+        result = null;
+        cdist = 0f;
+
+        for(Unit e : Groups.unit){
+            if(!predicate.get(e) || e.team() != team) continue;
+
+            float cost = sort.cost(e, x, y);
+            if(result == null || cost < cdist){
+                result = e;
+                cdist = cost;
+            }
+        }
+
+        return result;
+    }
+
     /** Returns the closest ally of this team. Filter by predicate.
      * Unlike the closest() function, this only guarantees that unit hitboxes overlap the range. */
     public static Unit closestOverlap(Team team, float x, float y, float range, Boolf<Unit> predicate){