From 71a5abd42b56fbbefbdddb253fbc746a54fdcb57 Mon Sep 17 00:00:00 2001
From: Jonathan G Rennison <j.g.rennison@gmail.com>
Date: Tue, 12 Oct 2021 20:19:53 +0100
Subject: [PATCH] Fix aircraft shadows being drawn facing the wrong direction

---
 src/aircraft.h       |  1 +
 src/aircraft_cmd.cpp | 24 +++++++++++++++++++-----
 src/vehicle_base.h   |  2 +-
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/src/aircraft.h b/src/aircraft.h
index c44d02f041..9e9d3106ed 100644
--- a/src/aircraft.h
+++ b/src/aircraft.h
@@ -96,6 +96,7 @@ struct Aircraft FINAL : public SpecializedVehicle<Aircraft, VEH_AIRCRAFT> {
 	ExpensesType GetExpenseType(bool income) const { return income ? EXPENSES_AIRCRAFT_INC : EXPENSES_AIRCRAFT_RUN; }
 	bool IsPrimaryVehicle() const                  { return this->IsNormalAircraft(); }
 	void GetImage(Direction direction, EngineImageType image_type, VehicleSpriteSeq *result) const;
+	Direction GetMapImageDirection() const { return this->First()->direction; }
 	int GetDisplaySpeed() const    { return this->cur_speed; }
 	int GetDisplayMaxSpeed() const { return this->vcache.cached_max_speed; }
 	int GetSpeedOldUnits() const   { return this->vcache.cached_max_speed * 10 / 128; }
diff --git a/src/aircraft_cmd.cpp b/src/aircraft_cmd.cpp
index f0167ae0d2..583ad7acc3 100644
--- a/src/aircraft_cmd.cpp
+++ b/src/aircraft_cmd.cpp
@@ -172,6 +172,22 @@ static StationID FindNearestHangar(const Aircraft *v)
 
 void Aircraft::GetImage(Direction direction, EngineImageType image_type, VehicleSpriteSeq *result) const
 {
+	if (this->subtype == AIR_SHADOW) {
+		Aircraft *first = this->First();
+		if (first->cur_image_valid_dir != direction || HasBit(first->vcache.cached_veh_flags, VCF_IMAGE_REFRESH)) {
+			VehicleSpriteSeq seq;
+			first->UpdateImageState(direction, seq);
+			if (first->sprite_seq != seq) {
+				first->sprite_seq = seq;
+				first->UpdateSpriteSeqBound();
+				first->Vehicle::UpdateViewport(true);
+			}
+		}
+
+		result->CopyWithoutPalette(first->sprite_seq); // the shadow is never coloured
+		return;
+	}
+
 	uint8 spritenum = this->spritenum;
 
 	if (is_custom_sprite(spritenum)) {
@@ -552,10 +568,8 @@ void SetAircraftPosition(Aircraft *v, int x, int y, int z)
 
 	safe_y = Clamp(u->y_pos, 0, MapMaxY() * TILE_SIZE);
 	u->z_pos = GetSlopePixelZ(safe_x, safe_y);
-	u->sprite_seq.CopyWithoutPalette(v->sprite_seq); // the shadow is never coloured
-	u->sprite_seq_bounds = v->sprite_seq_bounds;
-
-	u->UpdatePositionAndViewport();
+	u->UpdatePosition();
+	u->UpdateViewport(true, false);
 
 	u = u->Next();
 	if (u != nullptr) {
@@ -1364,7 +1378,7 @@ TileIndex Aircraft::GetOrderStationLocation(StationID station)
 void Aircraft::MarkDirty()
 {
 	this->colourmap = PAL_NONE;
-	this->InvalidateImageCache();
+	this->InvalidateImageCacheOfChain();
 	this->UpdateViewport(true, false);
 	if (this->subtype == AIR_HELICOPTER) {
 		Aircraft *rotor = this->Next()->Next();
diff --git a/src/vehicle_base.h b/src/vehicle_base.h
index 68012e51ac..c033ef56c9 100644
--- a/src/vehicle_base.h
+++ b/src/vehicle_base.h
@@ -1387,7 +1387,7 @@ public:
 
 	inline void UpdateImageStateUsingMapDirection(VehicleSpriteSeq &seq)
 	{
-		this->UpdateImageState(this->GetMapImageDirection(), seq);
+		this->UpdateImageState(((T *)this)->GetMapImageDirection(), seq);
 	}
 
 private: