Fix viewport kdtree not being updated for waypoints when sign moved

src/waypoint.cpp

@@ -51,6 +51,21 @@ void Waypoint::GetTileArea(TileArea *ta, StationType type) const
 	}
 }
 
+/**
+ * Move the waypoint main coordinate somewhere else.
+ * @param new_xy new tile location of the sign
+ */
+void Waypoint::MoveSign(TileIndex new_xy)
+{
+	if (this->xy == new_xy) return;
+
+	if (_viewport_sign_kdtree_valid) _viewport_sign_kdtree.Remove(ViewportSignKdtreeItem::MakeWaypoint(this->index, this->viewport_sign_kdtree_pt));
+
+	this->BaseStation::MoveSign(new_xy);
+
+	if (_viewport_sign_kdtree_valid) _viewport_sign_kdtree.Insert(ViewportSignKdtreeItem::MakeWaypoint(this->index));
+}
+
 Waypoint::~Waypoint()
 {
 	if (CleaningPool()) return;

src/waypoint_base.h

@@ -27,6 +27,8 @@ struct Waypoint FINAL : SpecializedStation<Waypoint, true> {
 
 	void UpdateVirtCoord() override;
 
+	void MoveSign(TileIndex new_xy) override;
+
 	inline bool TileBelongsToRailStation(TileIndex tile) const override
 	{
 		return IsRailWaypointTile(tile) && GetStationIndex(tile) == this->index;