Skip to content

Commit

Permalink
Codechange: Rework FindShipTrack
Browse files Browse the repository at this point in the history
  • Loading branch information
@SamuXarick
SamuXarick committed Jan 13, 2019
1 parent 313faab commit 74e3985
Show file tree
Hide file tree
Showing 2 changed files with 34 additions and 28 deletions.
56 changes: 31 additions & 25 deletions src/pathfinder/opf/opf_ship.cpp
View file
Expand Up @@ -139,19 +139,24 @@ static const DiagDirection _ship_search_directions[6][4] = {
/** Track to "direction (& 3)" mapping. */
static const byte _pick_shiptrack_table[6] = {DIR_NE, DIR_SE, DIR_E, DIR_E, DIR_N, DIR_N};

static uint FindShipTrack(const Ship *v, TileIndex tile, DiagDirection dir, TrackBits bits, TileIndex skiptile, Track *track, uint max_path_length = OPF_MAX_LENGTH, TileIndex dest_coords = INVALID_TILE)
struct ShipTrackData {
Track best_track;
uint best_bird_dist;
uint best_length;
};

static void FindShipTrack(const Ship *v, TileIndex tile, DiagDirection dir, TrackBits bits, TileIndex skiptile, ShipTrackData *fstd, uint max_path_length = OPF_MAX_LENGTH, TileIndex dest_coords = INVALID_TILE)
{
TrackPathFinder pfs;
uint best_bird_dist = 0;
uint best_length = 0;
fstd->best_track = INVALID_TRACK;
fstd->best_bird_dist = 0;
fstd->best_length = 0;
byte ship_dir = v->direction & 3;

TrackPathFinder pfs;
pfs.dest_coords = dest_coords != INVALID_TILE ? dest_coords : v->dest_tile;
pfs.skiptile = skiptile;
pfs.max_path_length = max_path_length;

Track best_track = INVALID_TRACK;

assert(bits != TRACK_BIT_NONE);
do {
Track i = RemoveFirstTrack(&bits);
Expand All @@ -161,33 +166,30 @@ static uint FindShipTrack(const Ship *v, TileIndex tile, DiagDirection dir, Trac

OPFShipFollowTrack(tile, _ship_search_directions[i][dir], &pfs);

if (best_track != INVALID_TRACK) {
if (fstd->best_track != INVALID_TRACK) {
if (pfs.best_bird_dist != 0) {
/* neither reached the destination, pick the one with the smallest bird dist */
if (pfs.best_bird_dist > best_bird_dist) goto bad;
if (pfs.best_bird_dist < best_bird_dist) goto good;
if (pfs.best_bird_dist > fstd->best_bird_dist) goto bad;
if (pfs.best_bird_dist < fstd->best_bird_dist) goto good;
} else {
if (pfs.best_length > best_length) goto bad;
if (pfs.best_length < best_length) goto good;
if (pfs.best_length > fstd->best_length) goto bad;
if (pfs.best_length < fstd->best_length) goto good;
}

/* if we reach this position, there's two paths of equal value so far.
* pick one randomly. */
uint r = GB(Random(), 0, 8);
if (_pick_shiptrack_table[i] == ship_dir) r += 80;
if (_pick_shiptrack_table[best_track] == ship_dir) r -= 80;
if (_pick_shiptrack_table[fstd->best_track] == ship_dir) r -= 80;
if (r <= 127) goto bad;
}
good:;
best_track = i;
best_bird_dist = pfs.best_bird_dist;
best_length = pfs.best_length;
fstd->best_track = i;
fstd->best_bird_dist = pfs.best_bird_dist;
fstd->best_length = pfs.best_length;
bad:;

} while (bits != TRACK_BIT_NONE);

*track = best_track;
return best_length;
}

/**
Expand All @@ -205,7 +207,7 @@ Track OPFShipChooseTrack(const Ship *v, TileIndex tile, DiagDirection enterdir,
assert(IsValidDiagDirection(enterdir));

TileIndex tile2 = TILE_ADD(tile, -TileOffsByDiagDir(enterdir));
Track track;
ShipTrackData fstd;

/* Let's find out how far it would be if we would reverse first */
uint rev_dist = UINT_MAX; // distance if we reverse
Expand All @@ -215,16 +217,18 @@ Track OPFShipChooseTrack(const Ship *v, TileIndex tile, DiagDirection enterdir,
DiagdirReachesTracks(rev_enterdir);

if (HasTrack(rev_tracks, cur_track)) {
rev_dist = FindShipTrack(v, tile2, rev_enterdir, TrackToTrackBits(cur_track), tile, &track);
FindShipTrack(v, tile2, rev_enterdir, TrackToTrackBits(cur_track), tile, &fstd);
rev_dist = fstd.best_bird_dist;
if (rev_dist != UINT_MAX) rev_dist++; // penalty for reversing
}

/* And if we would not reverse? */
uint dist = FindShipTrack(v, tile, enterdir, tracks, 0, &track);
FindShipTrack(v, tile, enterdir, tracks, 0, &fstd);
uint dist = fstd.best_bird_dist;

/* Due to the way this pathfinder works we cannot determine whether we're lost or not. */
path_found = true;
if (dist <= rev_dist) return track;
if (dist <= rev_dist) return fstd.best_track;
return INVALID_TRACK; // We could better reverse
}

Expand All @@ -244,7 +248,7 @@ FindDepotData OPFShipFindNearestDepot(const Ship *v, int max_distance)
TileIndex tile_rev = v->tile;
TrackBits tracks_rev = TrackStatusToTrackBits(GetTileTrackStatus(tile_rev, TRANSPORT_WATER, 0)) & DiagdirReachesTracks(enterdir_rev) & TrackdirBitsToTrackBits(TrackdirToTrackdirBits(trackdir));

Track track; // initialized, but unused
ShipTrackData fstd;
if (max_distance == 0) max_distance = OPF_MAX_LENGTH;
uint best_dist = UINT_MAX;

Expand All @@ -258,12 +262,14 @@ FindDepotData OPFShipFindNearestDepot(const Ship *v, int max_distance)
/* Let's find the length it would be if we would reverse first */
uint length_rev = UINT_MAX;
if (tracks_rev != 0) {
length_rev = FindShipTrack(v, tile_rev, enterdir_rev, tracks_rev, tile, &track, max_distance, depottile);
FindShipTrack(v, tile_rev, enterdir_rev, tracks_rev, tile, &fstd, max_distance, depottile);
length_rev = fstd.best_length;
if (length_rev != UINT_MAX) length_rev++; // penalty for reversing
}

/* And if we would not reverse? */
uint length = FindShipTrack(v, tile, enterdir, tracks, 0, &track, max_distance, depottile);
FindShipTrack(v, tile, enterdir, tracks, 0, &fstd, max_distance, depottile);
uint length = fstd.best_length;

/* Get the shortest length */
uint min_length = minu(length_rev, length);
Expand Down
6 changes: 3 additions & 3 deletions src/ship_cmd.cpp
View file
Expand Up @@ -176,11 +176,11 @@ static FindDepotData FindClosestReachableShipDepot(const Ship *v, int max_distan
if ((IsShipDepotTile(v->tile) && GetShipDepotPart(v->tile) == DEPOT_PART_NORTH) && IsTileOwner(v->tile, v->owner)) return FindDepotData(v->tile, 0);

switch (_settings_game.pf.pathfinder_for_ships) {
case VPF_OPF: return OPFShipFindNearestDepot(v, max_distance);
case VPF_NPF: return NPFShipFindNearestDepot(v, max_distance);
case VPF_OPF : return OPFShipFindNearestDepot(v, max_distance);
case VPF_NPF : return NPFShipFindNearestDepot(v, max_distance);
case VPF_YAPF: return YapfShipFindNearestDepot(v, max_distance);

default: NOT_REACHED();
default: NOT_REACHED();
}
}

Expand Down

0 comments on commit 74e3985

Please sign in to comment.