/**
* 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 GrowingBlocksWaterConnection(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)) {
Corner corner = GetHighestSlopeCorner(slope);
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)) {
Track main_track_mask = TrackBitsToTrack(TrackStatusToTrackBits(GetTileTrackStatus(tile, TRANSPORT_WATER, 0)));
Trackdir main_trackdir = TrackToTrackdir(main_track_mask);
DiagDirection main_dir_1 = TrackdirToExitdir(main_trackdir);
DiagDirection main_dir_2 = TrackdirToExitdir(ReverseTrackdir(main_trackdir));
TileIndex tile_1 = AddTileIndexDiffCWrap(tile, TileIndexDiffCByDiagDir(main_dir_1));
TileIndex tile_2 = AddTileIndexDiffCWrap(tile, TileIndexDiffCByDiagDir(main_dir_2));
TrackBits track_1 = TrackStatusToTrackBits(GetTileTrackStatus(tile_1, TRANSPORT_WATER, 0));
TrackBits track_2 = TrackStatusToTrackBits(GetTileTrackStatus(tile_2, TRANSPORT_WATER, 0));
TrackBits main_trackbits_mask_1 = DiagdirReachesTracks(main_dir_1);
TrackBits main_trackbits_mask_2 = DiagdirReachesTracks(main_dir_2);
TrackBits main_track_1 = main_trackbits_mask_1 & track_1;
TrackBits main_track_2 = main_trackbits_mask_2 & track_2;
/* Is there a connection between tile_1 and tile_2 via tile? */
if (main_track_1 && main_track_2) {
TrackBits oppo_trackbits = TrackStatusToTrackBits(GetTileTrackStatus(opposite_tile, TRANSPORT_WATER, 0));
Track oppo_track_mask = TrackToOppositeTrack(main_track_mask);
/* Is there a track in the opposite_tile that can be used to try an alternative connection? */
if (HasTrack(oppo_trackbits, oppo_track_mask)) {
TrackBits mirror = TRACK_BIT_CROSS | (corner & 1 ? TRACK_BIT_HORZ : TRACK_BIT_VERT);
Trackdir oppo_trackdir = TrackToTrackdir(oppo_track_mask);
DiagDirection oppo_dir_1 = TrackdirToExitdir(oppo_trackdir);
DiagDirection oppo_dir_2 = TrackdirToExitdir(ReverseTrackdir(oppo_trackdir));
TrackBits oppo_trackbits_mask_1 = DiagdirReachesTracks(oppo_dir_1);
TrackBits oppo_trackbits_mask_2 = DiagdirReachesTracks(oppo_dir_2);
TrackBits oppo_track_1 = oppo_trackbits_mask_1 & track_1;
TrackBits oppo_track_2 = oppo_trackbits_mask_2 & track_2;
/* Is there a connection between tile_1 and tile_2 via opposite_tile? */
if (oppo_track_1 & (main_track_1 ^ mirror) && oppo_track_2 & (main_track_2 ^ mirror)) {
/* There is an alternative connection. Town can grow on tile. */
return false;
}
}
/* There is either no track or an incomplete connection via opposite_tile. */
return true;
}
}
}
/* There was no connection via tile, or it was incomplete, or the opposite_tile is outside the map. */
return false;
}