From d112a7f0897be76ef6879f36d88ddb3ccfb6feff Mon Sep 17 00:00:00 2001
From: Peter Nelson <peter1138@openttd.org>
Date: Sun, 11 Feb 2024 18:35:05 +0000
Subject: [PATCH] Change: Small UFOs no longer target a vehicle which is
 already a target.

---
 src/disaster_vehicle.cpp    |  5 +++++
 src/saveload/vehicle_sl.cpp | 10 +++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/disaster_vehicle.cpp b/src/disaster_vehicle.cpp
index a2a97a279f..60b93eaf11 100644
--- a/src/disaster_vehicle.cpp
+++ b/src/disaster_vehicle.cpp
@@ -348,6 +348,11 @@ static bool DisasterTick_Ufo(DisasterVehicle *v)
 		for (RoadVehicle *u : RoadVehicle::Iterate()) {
 			/* Find (n+1)-th road vehicle. */
 			if (u->IsFrontEngine() && (n-- == 0)) {
+				if (u->crashed_ctr != 0 || u->disaster_vehicle != INVALID_VEHICLE) {
+					/* Targetted vehicle is crashed or already a target, destroy the UFO. */
+					delete v;
+					return false;
+				}
 				/* Target it. */
 				v->dest_tile = u->index;
 				v->age = 0;
diff --git a/src/saveload/vehicle_sl.cpp b/src/saveload/vehicle_sl.cpp
index 04ad699284..449c8c44f1 100644
--- a/src/saveload/vehicle_sl.cpp
+++ b/src/saveload/vehicle_sl.cpp
@@ -501,7 +501,15 @@ void AfterLoadVehicles(bool part_of_load)
 				auto *dv = DisasterVehicle::From(v);
 				if (dv->subtype == ST_SMALL_UFO && dv->state != 0) {
 					RoadVehicle *u = RoadVehicle::GetIfValid(v->dest_tile.base());
-					if (u != nullptr && u->IsFrontEngine()) u->disaster_vehicle = dv->index;
+					if (u != nullptr && u->IsFrontEngine()) {
+						/* Delete UFO targetting a vehicle which is already a target. */
+						if (u->disaster_vehicle != INVALID_VEHICLE) {
+							delete v;
+							continue;
+						} else {
+							u->disaster_vehicle = dv->index;
+						}
+					}
 				}
 				break;
 			}