/**
* Check whether growing on a half-tile coast tile ends up blocking a water connection
*
* @param tile The target tile
* @return true if building here blocks a water connection
*/
static bool NewGrowingBlocksWaterConnection(TileIndex tile)
{
if (!IsValidTile(tile) || !IsCoastTile(tile)) return false;
Slope slope = GetTileSlope(tile);
/* Is this a coast tile with one corner raised ? */
if (!IsSlopeWithOneCornerRaised(slope)) return false;
Corner corner = GetHighestSlopeCorner(slope);
/* Test opposite tile is valid */
static const Direction corner_to_direction[] = { DIR_W, DIR_S, DIR_E, DIR_N };
TileIndex opposite_tile = AddTileIndexDiffCWrap(tile, TileIndexDiffCByDir(corner_to_direction[OppositeCorner(corner)]));
if (!IsValidTile(opposite_tile)) return false;
/* Test adjacent tiles are traversible. */
Track track = TrackBitsToTrack(TrackStatusToTrackBits(GetTileTrackStatus(tile, TRANSPORT_WATER, 0)));
Trackdir main_trackdir = TrackToTrackdir(track);
DiagDirection main_dir_1 = TrackdirToExitdir(main_trackdir);
DiagDirection main_dir_2 = TrackdirToExitdir(ReverseTrackdir(main_trackdir));
TrackBits trackbits_1 = TrackStatusToTrackBits(GetTileTrackStatus(AddTileIndexDiffCWrap(tile, TileIndexDiffCByDiagDir(main_dir_1)), TRANSPORT_WATER, 0));
TrackBits trackbits_2 = TrackStatusToTrackBits(GetTileTrackStatus(AddTileIndexDiffCWrap(tile, TileIndexDiffCByDiagDir(main_dir_2)), TRANSPORT_WATER, 0));
TrackBits main_track_1 = trackbits_1 & DiagdirReachesTracks(main_dir_1);
TrackBits main_track_2 = trackbits_2 & DiagdirReachesTracks(main_dir_2);
/* Is main tile connected to adjacent tiles? */
if (!main_track_1 || !main_track_2) return false;
Track opposite_track = TrackToOppositeTrack(track);
Trackdir oppo_trackdir = TrackToTrackdir(opposite_track);
TrackBits oppo_track_1 = trackbits_1 & DiagdirReachesTracks(TrackdirToExitdir(oppo_trackdir));
TrackBits oppo_track_2 = trackbits_2 & DiagdirReachesTracks(TrackdirToExitdir(ReverseTrackdir(oppo_trackdir)));
TrackBits mirror = TRACK_BIT_CROSS | (corner & 1 ? TRACK_BIT_HORZ : TRACK_BIT_VERT);
/* Is there a connection between tile_1 and tile_2 via opposite_tile? */
if (HasTrack(TrackStatusToTrackBits(GetTileTrackStatus(opposite_tile, TRANSPORT_WATER, 0)), opposite_track) &&
oppo_track_1 & (main_track_1 ^ mirror) && oppo_track_2 & (main_track_2 ^ mirror)) return false;
/* There is either no track or an incomplete connection via opposite_tile. */
return true;
}