diff options
| -rw-r--r-- | src/town_cmd.cpp | 135 |
1 files changed, 125 insertions, 10 deletions
diff --git a/src/town_cmd.cpp b/src/town_cmd.cpp index a9420b459..9b46343db 100644 --- a/src/town_cmd.cpp +++ b/src/town_cmd.cpp @@ -1604,21 +1604,132 @@ CommandCost CmdBuildTown(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 return CommandCost(); } +/** + * Towns must all be placed on the same grid or when they eventually + * interpenetrate their road networks will not mesh nicely; this + * function adjusts a tile so that it aligns properly. + * + * @param tile the tile to start at + * @param layout which town layout algo is in effect + * @return the adjusted tile + */ +static TileIndex AlignTileToGrid(TileIndex tile, TownLayout layout) +{ + switch (layout) { + case TL_2X2_GRID: return TileXY(TileX(tile) - TileX(tile) % 3, TileY(tile) - TileY(tile) % 3); + case TL_3X3_GRID: return TileXY(TileX(tile) & ~3, TileY(tile) & ~3); + default: return tile; + } +} + +/** + * Towns must all be placed on the same grid or when they eventually + * interpenetrate their road networks will not mesh nicely; this + * function tells you if a tile is properly aligned. + * + * @param tile the tile to start at + * @param layout which town layout algo is in effect + * @return true if the tile is in the correct location + */ +static bool IsTileAlignedToGrid(TileIndex tile, TownLayout layout) +{ + switch (layout) { + case TL_2X2_GRID: return TileX(tile) % 3 == 0 && TileY(tile) % 3 == 0; + case TL_3X3_GRID: return TileX(tile) % 4 == 0 && TileY(tile) % 4 == 0; + default: return true; + } +} + +/** + * Used as the user_data for FindFurthestFromWater + */ +struct SpotData { + TileIndex tile; ///< holds the tile that was found + uint max_dist; ///< holds the distance that tile is from the water + TownLayout layout; ///< tells us what kind of town we're building +}; + +/** + * CircularTileSearch callback; finds the tile furthest from any + * water. slightly bit tricky, since it has to do a search of it's own + * in order to find the distance to the water from each square in the + * radius. + * + * Also, this never returns true, because it needs to take into + * account all locations being searched before it knows which is the + * furthest. + * + * @param tile Start looking from this tile + * @param user_data Storage area for data that must last across calls; + * must be a pointer to struct SpotData + * + * @return always false + */ +static bool FindFurthestFromWater(TileIndex tile, void *user_data) +{ + SpotData *sp = (SpotData*)user_data; + uint dist = GetClosestWaterDistance(tile, true); + + if (IsTileType(tile, MP_CLEAR) && + GetTileSlope(tile, NULL) == SLOPE_FLAT && + IsTileAlignedToGrid(tile, sp->layout) && + dist > sp->max_dist) { + sp->tile = tile; + sp->max_dist = dist; + } + + return false; +} + +/** + * CircularTileSearch callback; finds the nearest land tile + * + * @param tile Start looking from this tile + * @param user_data not used + */ +static bool FindNearestEmptyLand(TileIndex tile, void *user_data) +{ + return IsTileType(tile, MP_CLEAR); +} + +/** + * Given a spot on the map (presumed to be a water tile), find a good + * coastal spot to build a city. We don't want to build too close to + * the edge if we can help it (since that retards city growth) hence + * the search within a search within a search. O(n*m^2), where n is + * how far to search for land, and m is how far inland to look for a + * flat spot. + * + * @param tile Start looking from this spot. + * @return tile that was found + */ +static TileIndex FindNearestGoodCoastalTownSpot(TileIndex tile, TownLayout layout) +{ + SpotData sp = { INVALID_TILE, 0, layout }; + + TileIndex coast = tile; + if (CircularTileSearch(&coast, 40, FindNearestEmptyLand, NULL)) { + CircularTileSearch(&coast, 10, FindFurthestFromWater, &sp); + return sp.tile; + } + + /* if we get here just give up */ + return INVALID_TILE; +} + Town *CreateRandomTown(uint attempts, TownSize size, bool city, TownLayout layout) { if (!Town::CanAllocateItem()) return NULL; do { /* Generate a tile index not too close from the edge */ - TileIndex tile = RandomTile(); - switch (layout) { - case TL_2X2_GRID: - tile = TileXY(TileX(tile) - TileX(tile) % 3, TileY(tile) - TileY(tile) % 3); - break; - case TL_3X3_GRID: - tile = TileXY(TileX(tile) & ~3, TileY(tile) & ~3); - break; - default: break; + TileIndex tile = AlignTileToGrid(RandomTile(), layout); + + /* if we tried to place the town on water, slide it over onto + * the nearest likely-looking spot */ + if (IsTileType(tile, MP_WATER)) { + tile = FindNearestGoodCoastalTownSpot(tile, layout); + if (tile == INVALID_TILE) continue; } /* Make sure town can be placed here */ @@ -1632,7 +1743,11 @@ Town *CreateRandomTown(uint attempts, TownSize size, bool city, TownLayout layou Town *t = new Town(tile); DoCreateTown(t, tile, townnameparts, size, city, layout); - return t; + + /* if the population is still 0 at the point, then the + * placement is so bad it couldn't grow at all */ + if (t->population > 0) return t; + delete t; } while (--attempts != 0); return NULL; |