From 4eeac3ea75232b5d5805c9b2d6b846eb5c50be15 Mon Sep 17 00:00:00 2001
From: matthijs <matthijs@openttd.org>
Date: Fri, 15 Apr 2005 13:48:08 +0000
Subject: [PATCH] (svn r2202) - Fix: [NPF] When a vehicle could not reach its
 target, it would choose a random direction. It will now try to get as close
 as possible.

---
 roadveh_cmd.c |  8 ++++++--
 ship_cmd.c    | 10 ++++++----
 train_cmd.c   |  9 +++++++--
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/roadveh_cmd.c b/roadveh_cmd.c
index 7106ce3d10..d5d42ba2b6 100644
--- a/roadveh_cmd.c
+++ b/roadveh_cmd.c
@@ -1090,12 +1090,16 @@ static int RoadFindPathToDest(Vehicle *v, uint tile, int enterdir)
 		//debug("Finding path. Enterdir: %d, Trackdir: %d", enterdir, trackdir);
 
 		ftd = NPFRouteToStationOrTile(tile - TileOffsByDir(enterdir), trackdir, &fstd, TRANSPORT_ROAD, v->owner);
-		if (ftd.best_bird_dist != 0 || ftd.best_trackdir == 0xff) {
-			/* Not found, just do something, or we are already there */
+		if (ftd.best_trackdir == 0xff) {
+			/* We are already at our target. Just do something */
 			//TODO: maybe display error?
 			//TODO: go straight ahead if possible?
 			return_track(FindFirstBit2x64(bitmask));
 		} else {
+			/* If ftd.best_bird_dist is 0, we found our target and ftd.best_trackdir contains
+			the direction we need to take to get there, if ftd.best_bird_dist is not 0,
+			we did not find our target, but ftd.best_trackdir contains the direction leading
+			to the tile closest to our target. */
 			return_track(ftd.best_trackdir);
 		}
 	} else {
diff --git a/ship_cmd.c b/ship_cmd.c
index 3ccf8c11c7..b988d50f19 100644
--- a/ship_cmd.c
+++ b/ship_cmd.c
@@ -576,12 +576,14 @@ static int ChooseShipTrack(Vehicle *v, uint tile, int enterdir, uint tracks)
 
 		ftd = NPFRouteToStationOrTile(src_tile, _track_direction_to_trackdir[track][v->direction], &fstd, TRANSPORT_WATER, v->owner);
 
-		if (ftd.best_bird_dist == 0 && ftd.best_trackdir != 0xff)
-			/* Found the target, and it is not our current tile */
+		if (ftd.best_trackdir != 0xff)
+			/* If ftd.best_bird_dist is 0, we found our target and ftd.best_trackdir contains
+			the direction we need to take to get there, if ftd.best_bird_dist is not 0,
+			we did not find our target, but ftd.best_trackdir contains the direction leading
+			to the tile closest to our target. */
 			return ftd.best_trackdir & 7; /* TODO: Wrapper function? */
 		else
-			return -1; /* Couldn't find target, reverse */
-			/* TODO: When the target is unreachable, the ship will keep reversing */
+			return -1; /* Already at target, reverse? */
 	} else {
 		uint b;
 		uint tot_dist, dist;
diff --git a/train_cmd.c b/train_cmd.c
index b10090732e..844d091530 100644
--- a/train_cmd.c
+++ b/train_cmd.c
@@ -1672,12 +1672,17 @@ static byte ChooseTrainTrack(Vehicle *v, uint tile, int enterdir, byte trackbits
 		assert(trackdir != 0xff);
 
 		ftd = NPFRouteToStationOrTile(tile - TileOffsByDir(enterdir), trackdir, &fstd, TRANSPORT_RAIL, v->owner);
-		if (ftd.best_bird_dist != 0 || ftd.best_trackdir == 0xff) {
-			/* Not found, or we are already there. Just do something */
+
+		if (ftd.best_trackdir == 0xff) {
+			/* We are already at our target. Just do something */
 			//TODO: maybe display error?
 			//TODO: go straight ahead if possible?
 			best_track = FIND_FIRST_BIT(bits);
 		} else {
+			/* If ftd.best_bird_dist is 0, we found our target and ftd.best_trackdir contains
+			the direction we need to take to get there, if ftd.best_bird_dist is not 0,
+			we did not find our target, but ftd.best_trackdir contains the direction leading
+			to the tile closest to our target. */
 			/* Discard enterdir information, making it a normal track */
 			best_track = ftd.best_trackdir & 7; /* TODO: Wrapper function? */
 		}