Add: Road vehicle path cache. (#7261)

src/roadveh.h

@@ -18,6 +18,7 @@
 #include "track_func.h"
 #include "road_type.h"
 #include "newgrf_engine.h"
+#include <deque>
 
 struct RoadVehicle;
 
@@ -82,10 +83,30 @@ static const byte RV_OVERTAKE_TIMEOUT = 35;
 void RoadVehUpdateCache(RoadVehicle *v, bool same_length = false);
 void GetRoadVehSpriteSize(EngineID engine, uint &width, uint &height, int &xoffs, int &yoffs, EngineImageType image_type);
 
+struct RoadVehPathCache {
+	std::deque<TrackdirByte> td;
+	std::deque<TileIndex> tile;
+
+	inline bool empty() const { return this->td.empty(); }
+
+	inline size_t size() const
+	{
+		assert(this->td.size() == this->tile.size());
+		return this->td.size();
+	}
+
+	inline void clear()
+	{
+		this->td.clear();
+		this->tile.clear();
+	}
+};
+
 /**
  * Buses, trucks and trams belong to this class.
  */
 struct RoadVehicle FINAL : public GroundVehicle<RoadVehicle, VEH_ROAD> {
+	RoadVehPathCache path;  ///< Cached path.
 	byte state;             ///< @see RoadVehicleStates
 	byte frame;
 	uint16 blocked_ctr;
@@ -125,6 +146,7 @@ struct RoadVehicle FINAL : public GroundVehicle<RoadVehicle, VEH_ROAD> {
 
 	int GetCurrentMaxSpeed() const;
 	int UpdateSpeed();
+	void SetDestTile(TileIndex tile);
 
 protected: // These functions should not be called outside acceleration code.