Partial impl of #2923

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

@@ -6,10 +6,14 @@ import mindustry.entities.units.*;
 import mindustry.gen.*;
 import mindustry.world.meta.*;
 
+import static mindustry.Vars.*;
+
 public class DefenderAI extends AIController{
 
     @Override
     public void updateMovement(){
+        unloadPayloads();
+
         if(target != null){
             moveTo(target, (target instanceof Sized s ? s.hitSize()/2f * 1.1f : 0f) + unit.hitSize/2f + 15f, 50f);
             unit.lookAt(target);
@@ -23,6 +27,7 @@ public class DefenderAI extends AIController{
     
     @Override
     protected Teamc findTarget(float x, float y, float range, boolean air, boolean ground){
+
         //find unit to follow if not in rally mode
         if(command() != UnitCommand.rally){
             //Sort by max health and closer target.
@@ -34,6 +39,14 @@ public class DefenderAI extends AIController{
         var block = targetFlag(unit.x, unit.y, BlockFlag.rally, false);
         if(block != null) return block;
         //return core if found
-        return unit.closestCore();
+        var core = unit.closestCore();
+        if(core != null) return core;
+
+        //for enemies, target the enemy core.
+        if(state.rules.waves && unit.team == state.rules.waveTeam){
+            return unit.closestEnemyCore();
+        }
+
+        return null;
     }
 }

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

@@ -11,6 +11,8 @@ public class FlyingAI extends AIController{
 
     @Override
     public void updateMovement(){
+        unloadPayloads();
+
         if(target != null && unit.hasWeapons() && command() == UnitCommand.attack){
             if(!unit.type.circleTarget){
                 moveTo(target, unit.type.range * 0.8f);

core/src/mindustry/entities/units/AIController.java

@@ -9,6 +9,7 @@ import mindustry.entities.*;
 import mindustry.gen.*;
 import mindustry.type.*;
 import mindustry.world.*;
+import mindustry.world.blocks.payloads.*;
 import mindustry.world.meta.*;
 
 import static mindustry.Vars.*;
@@ -178,6 +179,14 @@ public class AIController implements UnitController{
         return Geometry.findClosest(unit.x, unit.y, Vars.spawner.getSpawns());
     }
 
+    protected void unloadPayloads(){
+        if(unit instanceof Payloadc pay && pay.hasPayload() && target instanceof Building && pay.payloads().peek() instanceof UnitPayload){
+            if(target.within(unit, Math.max(unit.type().range + 1f, 75f))){
+                pay.dropLastPayload();
+            }
+        }
+    }
+
     protected void circle(Position target, float circleLength){
         circle(target, circleLength, unit.speed());
     }

core/src/mindustry/game/SpawnGroup.java

@@ -1,5 +1,6 @@
 package mindustry.game;
 
+import arc.struct.*;
 import arc.util.*;
 import arc.util.serialization.*;
 import arc.util.serialization.Json.*;
@@ -39,12 +40,12 @@ public class SpawnGroup implements JsonSerializable{
     public float shieldScaling = 0f;
     /** Amount of enemies spawned initially, with no scaling */
     public int unitAmount = 1;
+    /** Seq of payloads that this unit will spawn with. */
+    public @Nullable Seq<UnitType> payloads;
     /** Status effect applied to the spawned unit. Null to disable. */
-    @Nullable
-    public StatusEffect effect;
+    public @Nullable StatusEffect effect;
     /** Items this unit spawns with. Null to disable. */
-    @Nullable
-    public ItemStack items;
+    public @Nullable ItemStack items;
 
     public SpawnGroup(UnitType type){
         this.type = type;
@@ -85,6 +86,15 @@ public class SpawnGroup implements JsonSerializable{
 
         unit.shield = getShield(wave);
 
+        //load up spawn payloads
+        if(payloads != null && unit instanceof Payloadc pay){
+            for(var type : payloads){
+                if(type == null) continue;
+                Unit payload = type.create(unit.team);
+                pay.pickup(payload);
+            }
+        }
+
         return unit;
     }
 
@@ -101,6 +111,9 @@ public class SpawnGroup implements JsonSerializable{
         if(shieldScaling != 0) json.writeValue("shieldScaling", shieldScaling);
         if(unitAmount != 1) json.writeValue("amount", unitAmount);
         if(effect != null) json.writeValue("effect", effect.name);
+        if(payloads != null && payloads.size > 0){
+            json.writeValue("payloads", payloads.map(u -> u.name).toArray(String.class));
+        }
     }
 
     @Override
@@ -117,6 +130,9 @@ public class SpawnGroup implements JsonSerializable{
         shields = data.getFloat("shields", 0);
         shieldScaling = data.getFloat("shieldScaling", 0);
         unitAmount = data.getInt("amount", 1);
+        if(data.has("payloads")){
+            payloads = Seq.with(json.readValue(String[].class, data.get("payloads"))).map(s -> content.getByName(ContentType.unit, s));
+        }
 
         //old boss effect ID
         if(data.has("effect") && data.get("effect").isNumber() && data.getInt("effect", -1) == 8){