Unit payload enter command snapping

core/src/mindustry/ai/UnitCommand.java

@@ -24,6 +24,8 @@ public class UnitCommand extends MappableContent{
     public boolean drawTarget = false;
     /** Whether to reset targets when switching to or from this command. */
     public boolean resetTarget = true;
+    /** Whether to snap the command destination to ally buildings. */
+    public boolean snapToBuilding = false;
     /** */
     public boolean exactArrival = false;
     /** If true, this command refreshes the list of stances when selected TODO: do not use, this will likely be removed later!*/
@@ -90,6 +92,7 @@ public class UnitCommand extends MappableContent{
             switchToMove = false;
             drawTarget = true;
             resetTarget = false;
+            snapToBuilding = true;
         }};
         loadUnitsCommand = new UnitCommand("loadUnits", "upload", Binding.unit_command_load_units, null){{
             switchToMove = false;

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

@@ -501,6 +501,12 @@ public class CommandAI extends AIController{
 
         //this is an allocation, but it's relatively rarely called anyway, and outside mutations must be prevented
         targetPos = lastTargetPos = pos.cpy();
+        if(command != null && command.snapToBuilding){
+            var build = world.buildWorld(targetPos.x, targetPos.y);
+            if(build != null && build.team == unit.team){
+                targetPos.set(build);
+            }
+        }
         attackTarget = null;
         this.stopWhenInRange = stopWhenInRange;
     }

core/src/mindustry/graphics/Drawf.java

@@ -394,6 +394,16 @@ public class Drawf{
         Draw.reset();
     }
 
+    public static void cross(float x, float y, float radius, Color color){
+        Lines.stroke(3f, Pal.gray.write(Tmp.c3).a(color.a));
+        Lines.lineAngleCenter(x, y, 45f, radius + 1f);
+        Lines.lineAngleCenter(x, y, 135f, radius + 1f);
+        Lines.stroke(1f, color);
+        Lines.lineAngleCenter(x, y, 45f, radius + 1f);
+        Lines.lineAngleCenter(x, y, 135f, radius + 1f);
+        Draw.reset();
+    }
+
     public static void poly(float x, float y, int sides, float radius, float rotation, Color color){
         Lines.stroke(3f, Pal.gray);
         Lines.poly(x, y, sides, radius + 1f, rotation);

core/src/mindustry/input/InputHandler.java

@@ -1123,26 +1123,29 @@ public abstract class InputHandler implements InputProcessor, GestureListener{
                 Position lastPos = null;
 
                 if(unit.controller() instanceof CommandAI ai){
+                    var cmd =  ai.currentCommand();
                     lastPos = ai.attackTarget != null ? ai.attackTarget : ai.targetPos;
 
-                    if(flying && ai.attackTarget != null && ai.currentCommand().drawTarget){
+                    if(flying && ai.attackTarget != null && cmd.drawTarget){
                         Drawf.target(ai.attackTarget.getX(), ai.attackTarget.getY(), 6f, Pal.remove);
                     }
 
                     if(unit.isFlying() != flying) continue;
 
                     //draw target line
-                    if(ai.targetPos != null && ai.currentCommand().drawTarget){
+                    if(ai.targetPos != null && cmd.drawTarget){
                         Position lineDest = ai.attackTarget != null ? ai.attackTarget : ai.targetPos;
                         Drawf.limitLine(unit, lineDest, unit.hitSize / unitSelectRadScl + 1f, lineLimit, color.write(Tmp.c1).a(alpha));
 
                         if(ai.attackTarget == null){
                             Drawf.square(lineDest.getX(), lineDest.getY(), 3.5f, color.write(Tmp.c1).a(alpha));
 
-                            if(ai.currentCommand() == UnitCommand.enterPayloadCommand){
+                            if(cmd == UnitCommand.enterPayloadCommand){
                                 var build = world.buildWorld(lineDest.getX(), lineDest.getY());
                                 if(build != null && build.block.acceptsUnitPayloads && build.team == unit.team){
                                     Drawf.selected(build, color);
+                                }else{
+                                    Drawf.cross(lineDest.getX(), lineDest.getY(), 7f, Pal.remove);
                                 }
                             }
                         }