Unit enter payload command

core/src/mindustry/ai/UnitCommand.java

@@ -17,7 +17,7 @@ public class UnitCommand extends MappableContent{
     @Deprecated
     public static final Seq<UnitCommand> all = new Seq<>();
 
-    public static UnitCommand moveCommand, repairCommand, rebuildCommand, assistCommand, mineCommand, boostCommand, loadUnitsCommand, loadBlocksCommand, unloadPayloadCommand;
+    public static UnitCommand moveCommand, repairCommand, rebuildCommand, assistCommand, mineCommand, boostCommand, enterPayloadCommand, loadUnitsCommand, loadBlocksCommand, unloadPayloadCommand;
 
     /** Name of UI icon (from Icon class). */
     public final String icon;
@@ -87,6 +87,11 @@ public class UnitCommand extends MappableContent{
             drawTarget = true;
             resetTarget = false;
         }};
+        enterPayloadCommand = new UnitCommand("enterPayload", "downOpen", Binding.unit_command_enter_payload, null){{
+            switchToMove = false;
+            drawTarget = true;
+            resetTarget = false;
+        }};
         loadUnitsCommand = new UnitCommand("loadUnits", "upload", Binding.unit_command_load_units, null){{
             switchToMove = false;
             drawTarget = true;

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

@@ -20,6 +20,7 @@ public class CommandAI extends AIController{
     protected static final int maxCommandQueueSize = 50, avoidInterval = 10;
     protected static final Vec2 vecOut = new Vec2(), vecMovePos = new Vec2();
     protected static final boolean[] noFound = {false};
+    protected static final UnitPayload tmpPayload = new UnitPayload(null);
 
     public Seq<Position> commandQueue = new Seq<>(5);
     public @Nullable Vec2 targetPos;
@@ -145,6 +146,15 @@ public class CommandAI extends AIController{
             }
         }
 
+        if(!net.client() && command == UnitCommand.enterPayloadCommand && unit.buildOn() != null && (targetPos == null || (world.buildWorld(targetPos.x, targetPos.y) != null && world.buildWorld(targetPos.x, targetPos.y) == unit.buildOn()))){
+            var build = unit.buildOn();
+            tmpPayload.unit = unit;
+            if(build.team == unit.team && build.acceptPayload(build, tmpPayload)){
+                Call.unitEnteredPayload(unit, build);
+                return; //no use updating after this, the unit is gone!
+            }
+        }
+
         //acquiring naval targets isn't supported yet, so use the fallback dumb AI
         if(unit.team.isAI() && unit.team.rules().rtsAi && unit.type.naval){
             if(fallback == null) fallback = new GroundAI();
@@ -198,7 +208,8 @@ public class CommandAI extends AIController{
             vecOut.set(targetPos);
             vecMovePos.set(targetPos);
 
-            if(group != null && group.valid && groupIndex < group.units.size){
+            //the enter payload command requires an exact position
+            if(group != null && group.valid && groupIndex < group.units.size && command != UnitCommand.enterPayloadCommand){
                 vecMovePos.add(group.positions[groupIndex * 2], group.positions[groupIndex * 2 + 1]);
             }
 
@@ -295,6 +306,11 @@ public class CommandAI extends AIController{
     }
 
     void finishPath(){
+        //the enter payload command never finishes until they are actually accepted
+        if(command == UnitCommand.enterPayloadCommand && commandQueue.size == 0 && targetPos != null && world.buildWorld(targetPos.x, targetPos.y) != null && world.buildWorld(targetPos.x, targetPos.y).block.acceptsPayloads){
+            return;
+        }
+
         Vec2 prev = targetPos;
         targetPos = null;