src/landscape.cpp

   1 /* $Id$ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   6  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   7  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   8  */
   9
  10 /** @file landscape.cpp Functions related to the landscape (slopes etc.). */
  11
  12 /** @defgroup SnowLineGroup Snowline functions and data structures */
  13
  14 #include "stdafx.h"
  15 #include "map/ground.h"
  16 #include "map/slope.h"
  17 #include "heightmap.h"
  18 #include "spritecache.h"
  19 #include "viewport_func.h"
  20 #include "command_func.h"
  21 #include "landscape.h"
  22 #include "tgp.h"
  23 #include "genworld.h"
  24 #include "fios.h"
  25 #include "date_func.h"
  26 #include "water.h"
  27 #include "effectvehicle_func.h"
  28 #include "landscape_type.h"
  29 #include "animated_tile_func.h"
  30 #include "core/random_func.hpp"
  31 #include "object_base.h"
  32 #include "company_func.h"
  33 #include "pathfinder/yapf/astar.hpp"
  34 #include <list>
  35 #include <set>
  36
  37 #include "table/strings.h"
  38 #include "table/sprites.h"
  39
  40 extern const TileTypeProcs
  41         _tile_type_clear_procs,
  42         _tile_type_rail_procs,
  43         _tile_type_road_procs,
  44         _tile_type_town_procs,
  45         _tile_type_misc_procs,
  46         _tile_type_station_procs,
  47         _tile_type_water_procs,
  48         _tile_type_industry_procs,
  49         _tile_type_object_procs;
  50
  51 /**
  52  * Tile callback functions for each type of tile.
  53  * @ingroup TileCallbackGroup
  54  * @see TileType
  55  */
  56 extern const TileTypeProcs * const _tile_type_procs[16] = {
  57         &_tile_type_clear_procs,        ///< Callback functions for clear tiles
  58         &_tile_type_object_procs,       ///< Callback functions for object tiles
  59         &_tile_type_water_procs,        ///< Callback functions for water tiles
  60         NULL,
  61         &_tile_type_rail_procs,         ///< Callback functions for railway tiles
  62         &_tile_type_road_procs,         ///< Callback functions for road tiles
  63         &_tile_type_misc_procs,         ///< Callback functions for misc tiles
  64         &_tile_type_station_procs,      ///< Callback functions for station tiles
  65         &_tile_type_industry_procs,     ///< Callback functions for industry tiles
  66         &_tile_type_industry_procs,
  67         &_tile_type_industry_procs,
  68         &_tile_type_industry_procs,
  69         &_tile_type_town_procs,         ///< Callback functions for house tiles
  70         &_tile_type_town_procs,
  71         &_tile_type_town_procs,
  72         &_tile_type_town_procs,
  73 };
  74
  75 /** landscape slope => sprite */
  76 extern const byte _slope_to_sprite_offset[32] = {
  77         0, 1, 2, 3, 4, 5, 6,  7, 8, 9, 10, 11, 12, 13, 14, 0,
  78         0, 0, 0, 0, 0, 0, 0, 16, 0, 0,  0, 17,  0, 15, 18, 0,
  79 };
  80
  81 /**
  82  * Description of the snow line throughout the year.
  83  *
  84  * If it is \c NULL, a static snowline height is used, as set by \c _settings_game.game_creation.snow_line_height.
  85  * Otherwise it points to a table loaded from a newGRF file that describes the variable snowline.
  86  * @ingroup SnowLineGroup
  87  * @see GetSnowLine() GameCreationSettings
  88  */
  89 static SnowLine *_snow_line = NULL;
  90
  91 /**
  92  * Applies a foundation to a slope.
  93  *
  94  * @pre      Foundation and slope must be valid combined.
  95  * @param f  The #Foundation.
  96  * @param s  The #Slope to modify.
  97  * @return   Increment to the tile Z coordinate.
  98  */
  99 uint ApplyFoundationToSlope(Foundation f, Slope *s)
 100 {
 101         if (!IsFoundation(f)) return 0;
 102
 103         if (IsLeveledFoundation(f)) {
 104                 uint dz = 1 + (IsSteepSlope(*s) ? 1 : 0);
 105                 *s = SLOPE_FLAT;
 106                 return dz;
 107         }
 108
 109         if (f != FOUNDATION_STEEP_BOTH && IsNonContinuousFoundation(f)) {
 110                 *s = HalftileSlope(*s, GetHalftileFoundationCorner(f));
 111                 return 0;
 112         }
 113
 114         if (IsSpecialRailFoundation(f)) {
 115                 *s = SlopeWithThreeCornersRaised(OppositeCorner(GetRailFoundationCorner(f)));
 116                 return 0;
 117         }
 118
 119         uint dz = IsSteepSlope(*s) ? 1 : 0;
 120         Corner highest_corner = GetHighestSlopeCorner(*s);
 121
 122         switch (f) {
 123                 case FOUNDATION_INCLINED_X:
 124                         *s = (((highest_corner == CORNER_W) || (highest_corner == CORNER_S)) ? SLOPE_SW : SLOPE_NE);
 125                         break;
 126
 127                 case FOUNDATION_INCLINED_Y:
 128                         *s = (((highest_corner == CORNER_S) || (highest_corner == CORNER_E)) ? SLOPE_SE : SLOPE_NW);
 129                         break;
 130
 131                 case FOUNDATION_STEEP_LOWER:
 132                         *s = SlopeWithOneCornerRaised(highest_corner);
 133                         break;
 134
 135                 case FOUNDATION_STEEP_BOTH:
 136                         *s = HalftileSlope(SlopeWithOneCornerRaised(highest_corner), highest_corner);
 137                         break;
 138
 139                 default: NOT_REACHED();
 140         }
 141         return dz;
 142 }
 143
 144
 145 /**
 146  * Determines height at given coordinate of a slope
 147  * @param x x coordinate
 148  * @param y y coordinate
 149  * @param corners slope to examine
 150  * @return height of given point of given slope
 151  */
 152 uint GetPartialPixelZ(int x, int y, Slope corners)
 153 {
 154         if (IsHalftileSlope(corners)) {
 155                 switch (GetHalftileSlopeCorner(corners)) {
 156                         case CORNER_W:
 157                                 if (x - y >= 0) return GetSlopeMaxPixelZ(corners);
 158                                 break;
 159
 160                         case CORNER_S:
 161                                 if (x - (y ^ 0xF) >= 0) return GetSlopeMaxPixelZ(corners);
 162                                 break;
 163
 164                         case CORNER_E:
 165                                 if (y - x >= 0) return GetSlopeMaxPixelZ(corners);
 166                                 break;
 167
 168                         case CORNER_N:
 169                                 if ((y ^ 0xF) - x >= 0) return GetSlopeMaxPixelZ(corners);
 170                                 break;
 171
 172                         default: NOT_REACHED();
 173                 }
 174         }
 175
 176         int z = 0;
 177
 178         switch (RemoveHalftileSlope(corners)) {
 179                 case SLOPE_W:
 180                         if (x - y >= 0) {
 181                                 z = (x - y) >> 1;
 182                         }
 183                         break;
 184
 185                 case SLOPE_S:
 186                         y ^= 0xF;
 187                         if ((x - y) >= 0) {
 188                                 z = (x - y) >> 1;
 189                         }
 190                         break;
 191
 192                 case SLOPE_SW:
 193                         z = (x >> 1) + 1;
 194                         break;
 195
 196                 case SLOPE_E:
 197                         if (y - x >= 0) {
 198                                 z = (y - x) >> 1;
 199                         }
 200                         break;
 201
 202                 case SLOPE_EW:
 203                 case SLOPE_NS:
 204                 case SLOPE_ELEVATED:
 205                         z = 4;
 206                         break;
 207
 208                 case SLOPE_SE:
 209                         z = (y >> 1) + 1;
 210                         break;
 211
 212                 case SLOPE_WSE:
 213                         z = 8;
 214                         y ^= 0xF;
 215                         if (x - y < 0) {
 216                                 z += (x - y) >> 1;
 217                         }
 218                         break;
 219
 220                 case SLOPE_N:
 221                         y ^= 0xF;
 222                         if (y - x >= 0) {
 223                                 z = (y - x) >> 1;
 224                         }
 225                         break;
 226
 227                 case SLOPE_NW:
 228                         z = (y ^ 0xF) >> 1;
 229                         break;
 230
 231                 case SLOPE_NWS:
 232                         z = 8;
 233                         if (x - y < 0) {
 234                                 z += (x - y) >> 1;
 235                         }
 236                         break;
 237
 238                 case SLOPE_NE:
 239                         z = (x ^ 0xF) >> 1;
 240                         break;
 241
 242                 case SLOPE_ENW:
 243                         z = 8;
 244                         y ^= 0xF;
 245                         if (y - x < 0) {
 246                                 z += (y - x) >> 1;
 247                         }
 248                         break;
 249
 250                 case SLOPE_SEN:
 251                         z = 8;
 252                         if (y - x < 0) {
 253                                 z += (y - x) >> 1;
 254                         }
 255                         break;
 256
 257                 case SLOPE_STEEP_S:
 258                         z = 1 + ((x + y) >> 1);
 259                         break;
 260
 261                 case SLOPE_STEEP_W:
 262                         z = 1 + ((x + (y ^ 0xF)) >> 1);
 263                         break;
 264
 265                 case SLOPE_STEEP_N:
 266                         z = 1 + (((x ^ 0xF) + (y ^ 0xF)) >> 1);
 267                         break;
 268
 269                 case SLOPE_STEEP_E:
 270                         z = 1 + (((x ^ 0xF) + y) >> 1);
 271                         break;
 272
 273                 default: break;
 274         }
 275
 276         return z;
 277 }
 278
 279 int GetSlopePixelZ(int x, int y)
 280 {
 281         TileIndex tile = TileVirtXY(x, y);
 282
 283         return GetTileProcs(tile)->get_slope_z_proc(tile, x, y);
 284 }
 285
 286 /**
 287  * Determine the Z height of a corner relative to TileZ.
 288  *
 289  * @pre The slope must not be a halftile slope.
 290  *
 291  * @param tileh The slope.
 292  * @param corner The corner.
 293  * @return Z position of corner relative to TileZ.
 294  */
 295 int GetSlopeZInCorner(Slope tileh, Corner corner)
 296 {
 297         assert(!IsHalftileSlope(tileh));
 298         return ((tileh & SlopeWithOneCornerRaised(corner)) != 0 ? 1 : 0) + (tileh == SteepSlope(corner) ? 1 : 0);
 299 }
 300
 301 /**
 302  * Determine the Z height of the corners of a specific tile edge
 303  *
 304  * @note If a tile has a non-continuous halftile foundation, a corner can have different heights wrt. its edges.
 305  *
 306  * @pre z1 and z2 must be initialized (typ. with TileZ). The corner heights just get added.
 307  *
 308  * @param tileh The slope of the tile.
 309  * @param edge The edge of interest.
 310  * @param z1 Gets incremented by the height of the first corner of the edge. (near corner wrt. the camera)
 311  * @param z2 Gets incremented by the height of the second corner of the edge. (far corner wrt. the camera)
 312  */
 313 void GetSlopePixelZOnEdge(Slope tileh, DiagDirection edge, int *z1, int *z2)
 314 {
 315         static const Slope corners[4][4] = {
 316                 /*    corner     |          steep slope
 317                  *  z1      z2   |       z1             z2        */
 318                 {SLOPE_E, SLOPE_N, SLOPE_STEEP_E, SLOPE_STEEP_N}, // DIAGDIR_NE, z1 = E, z2 = N
 319                 {SLOPE_S, SLOPE_E, SLOPE_STEEP_S, SLOPE_STEEP_E}, // DIAGDIR_SE, z1 = S, z2 = E
 320                 {SLOPE_S, SLOPE_W, SLOPE_STEEP_S, SLOPE_STEEP_W}, // DIAGDIR_SW, z1 = S, z2 = W
 321                 {SLOPE_W, SLOPE_N, SLOPE_STEEP_W, SLOPE_STEEP_N}, // DIAGDIR_NW, z1 = W, z2 = N
 322         };
 323
 324         int halftile_test = (IsHalftileSlope(tileh) ? SlopeWithOneCornerRaised(GetHalftileSlopeCorner(tileh)) : 0);
 325         if (halftile_test == corners[edge][0]) *z2 += TILE_HEIGHT; // The slope is non-continuous in z2. z2 is on the upper side.
 326         if (halftile_test == corners[edge][1]) *z1 += TILE_HEIGHT; // The slope is non-continuous in z1. z1 is on the upper side.
 327
 328         if ((tileh & corners[edge][0]) != 0) *z1 += TILE_HEIGHT; // z1 is raised
 329         if ((tileh & corners[edge][1]) != 0) *z2 += TILE_HEIGHT; // z2 is raised
 330         if (RemoveHalftileSlope(tileh) == corners[edge][2]) *z1 += TILE_HEIGHT; // z1 is highest corner of a steep slope
 331         if (RemoveHalftileSlope(tileh) == corners[edge][3]) *z2 += TILE_HEIGHT; // z2 is highest corner of a steep slope
 332 }
 333
 334 /**
 335  * Get slope of a tile on top of a (possible) foundation
 336  * If a tile does not have a foundation, the function returns the same as GetTileSlope.
 337  *
 338  * @param tile The tile of interest.
 339  * @param z returns the z of the foundation slope. (Can be NULL, if not needed)
 340  * @return The slope on top of the foundation.
 341  */
 342 Slope GetFoundationSlope(TileIndex tile, int *z)
 343 {
 344         Slope tileh = GetTileSlope(tile, z);
 345         Foundation f = GetTileProcs(tile)->get_foundation_proc(tile, tileh);
 346         uint z_inc = ApplyFoundationToSlope(f, &tileh);
 347         if (z != NULL) *z += z_inc;
 348         return tileh;
 349 }
 350
 351
 352 bool HasFoundationNW(TileIndex tile, Slope slope_here, uint z_here)
 353 {
 354         int z;
 355
 356         int z_W_here = z_here;
 357         int z_N_here = z_here;
 358         GetSlopePixelZOnEdge(slope_here, DIAGDIR_NW, &z_W_here, &z_N_here);
 359
 360         Slope slope = GetFoundationPixelSlope(TILE_ADDXY(tile, 0, -1), &z);
 361         int z_W = z;
 362         int z_N = z;
 363         GetSlopePixelZOnEdge(slope, DIAGDIR_SE, &z_W, &z_N);
 364
 365         return (z_N_here > z_N) || (z_W_here > z_W);
 366 }
 367
 368
 369 bool HasFoundationNE(TileIndex tile, Slope slope_here, uint z_here)
 370 {
 371         int z;
 372
 373         int z_E_here = z_here;
 374         int z_N_here = z_here;
 375         GetSlopePixelZOnEdge(slope_here, DIAGDIR_NE, &z_E_here, &z_N_here);
 376
 377         Slope slope = GetFoundationPixelSlope(TILE_ADDXY(tile, -1, 0), &z);
 378         int z_E = z;
 379         int z_N = z;
 380         GetSlopePixelZOnEdge(slope, DIAGDIR_SW, &z_E, &z_N);
 381
 382         return (z_N_here > z_N) || (z_E_here > z_E);
 383 }
 384
 385 /**
 386  * Draw foundation \a f at tile \a ti. Updates \a ti.
 387  * @param ti Tile to draw foundation on
 388  * @param f  Foundation to draw
 389  * @param side Side to skip
 390  */
 391 void DrawFoundation(TileInfo *ti, Foundation f, DiagDirection side)
 392 {
 393         if (!IsFoundation(f)) return;
 394
 395         /* Two part foundations must be drawn separately */
 396         assert(f != FOUNDATION_STEEP_BOTH);
 397
 398         uint sprite_block = 0;
 399         int z;
 400         Slope slope = GetFoundationPixelSlope(ti->tile, &z);
 401
 402         /* Select the needed block of foundations sprites
 403          * Block 0: Walls at NW and NE edge
 404          * Block 1: Wall  at        NE edge
 405          * Block 2: Wall  at NW        edge
 406          * Block 3: No walls at NW or NE edge
 407          */
 408         if (side == DIAGDIR_NW || !HasFoundationNW(ti->tile, slope, z)) sprite_block += 1;
 409         if (side == DIAGDIR_NE || !HasFoundationNE(ti->tile, slope, z)) sprite_block += 2;
 410
 411         /* Use the original slope sprites if NW and NE borders should be visible */
 412         SpriteID leveled_base = (sprite_block == 0 ? (int)SPR_FOUNDATION_BASE : (SPR_SLOPES_VIRTUAL_BASE + sprite_block * SPR_TRKFOUND_BLOCK_SIZE));
 413         SpriteID inclined_base = SPR_SLOPES_VIRTUAL_BASE + SPR_SLOPES_INCLINED_OFFSET + sprite_block * SPR_TRKFOUND_BLOCK_SIZE;
 414         SpriteID halftile_base = SPR_HALFTILE_FOUNDATION_BASE + sprite_block * SPR_HALFTILE_BLOCK_SIZE;
 415
 416         if (IsSteepSlope(ti->tileh)) {
 417                 if (!IsNonContinuousFoundation(f)) {
 418                         /* Lower part of foundation */
 419                         AddSortableSpriteToDraw(
 420                                 leveled_base + (ti->tileh & ~SLOPE_STEEP), PAL_NONE, ti->x, ti->y, 16, 16, 7, ti->z
 421                         );
 422                 }
 423
 424                 Corner highest_corner = GetHighestSlopeCorner(ti->tileh);
 425                 ti->z += ApplyPixelFoundationToSlope(f, &ti->tileh);
 426
 427                 if (IsInclinedFoundation(f)) {
 428                         /* inclined foundation */
 429                         byte inclined = highest_corner * 2 + (f == FOUNDATION_INCLINED_Y ? 1 : 0);
 430
 431                         AddSortableSpriteToDraw(inclined_base + inclined, PAL_NONE, ti->x, ti->y,
 432                                 f == FOUNDATION_INCLINED_X ? 16 : 1,
 433                                 f == FOUNDATION_INCLINED_Y ? 16 : 1,
 434                                 TILE_HEIGHT, ti->z
 435                         );
 436                         OffsetGroundSprite(31, 9);
 437                 } else if (IsLeveledFoundation(f)) {
 438                         AddSortableSpriteToDraw(leveled_base + SlopeWithOneCornerRaised(highest_corner), PAL_NONE, ti->x, ti->y, 16, 16, 7, ti->z - TILE_HEIGHT);
 439                         OffsetGroundSprite(31, 1);
 440                 } else if (f == FOUNDATION_STEEP_LOWER) {
 441                         /* one corner raised */
 442                         OffsetGroundSprite(31, 1);
 443                 } else {
 444                         /* halftile foundation */
 445                         int x_bb = (((highest_corner == CORNER_W) || (highest_corner == CORNER_S)) ? 8 : 0);
 446                         int y_bb = (((highest_corner == CORNER_S) || (highest_corner == CORNER_E)) ? 8 : 0);
 447
 448                         AddSortableSpriteToDraw(halftile_base + highest_corner, PAL_NONE, ti->x + x_bb, ti->y + y_bb, 8, 8, 7, ti->z + TILE_HEIGHT);
 449                         OffsetGroundSprite(31, 9);
 450                 }
 451         } else {
 452                 if (IsLeveledFoundation(f)) {
 453                         /* leveled foundation */
 454                         AddSortableSpriteToDraw(leveled_base + ti->tileh, PAL_NONE, ti->x, ti->y, 16, 16, 7, ti->z);
 455                         OffsetGroundSprite(31, 1);
 456                 } else if (IsNonContinuousFoundation(f)) {
 457                         /* halftile foundation */
 458                         Corner halftile_corner = GetHalftileFoundationCorner(f);
 459                         int x_bb = (((halftile_corner == CORNER_W) || (halftile_corner == CORNER_S)) ? 8 : 0);
 460                         int y_bb = (((halftile_corner == CORNER_S) || (halftile_corner == CORNER_E)) ? 8 : 0);
 461
 462                         AddSortableSpriteToDraw(halftile_base + halftile_corner, PAL_NONE, ti->x + x_bb, ti->y + y_bb, 8, 8, 7, ti->z);
 463                         OffsetGroundSprite(31, 9);
 464                 } else if (IsSpecialRailFoundation(f)) {
 465                         /* anti-zig-zag foundation */
 466                         SpriteID spr;
 467                         if (ti->tileh == SLOPE_NS || ti->tileh == SLOPE_EW) {
 468                                 /* half of leveled foundation under track corner */
 469                                 spr = leveled_base + SlopeWithThreeCornersRaised(GetRailFoundationCorner(f));
 470                         } else {
 471                                 /* tile-slope = sloped along X/Y, foundation-slope = three corners raised */
 472                                 spr = inclined_base + 2 * GetRailFoundationCorner(f) + ((ti->tileh == SLOPE_SW || ti->tileh == SLOPE_NE) ? 1 : 0);
 473                         }
 474                         AddSortableSpriteToDraw(spr, PAL_NONE, ti->x, ti->y, 16, 16, 7, ti->z);
 475                         OffsetGroundSprite(31, 9);
 476                 } else {
 477                         /* inclined foundation */
 478                         byte inclined = GetHighestSlopeCorner(ti->tileh) * 2 + (f == FOUNDATION_INCLINED_Y ? 1 : 0);
 479
 480                         AddSortableSpriteToDraw(inclined_base + inclined, PAL_NONE, ti->x, ti->y,
 481                                 f == FOUNDATION_INCLINED_X ? 16 : 1,
 482                                 f == FOUNDATION_INCLINED_Y ? 16 : 1,
 483                                 TILE_HEIGHT, ti->z
 484                         );
 485                         OffsetGroundSprite(31, 9);
 486                 }
 487                 ti->z += ApplyPixelFoundationToSlope(f, &ti->tileh);
 488         }
 489 }
 490
 491 void DoClearSquare(TileIndex tile)
 492 {
 493         /* If the tile can have animation and we clear it, delete it from the animated tile list. */
 494         if (GetTileProcs(tile)->animate_tile_proc != NULL) DeleteAnimatedTile(tile);
 495
 496         MakeClear(tile, GROUND_GRASS, _generating_world ? 3 : 0);
 497         MarkTileDirtyByTile(tile);
 498 }
 499
 500 /**
 501  * Returns information about railway trackdirs and signal states.
 502  * If there is any trackbit at 'side', return all trackdirbits.
 503  * @param tile tile to get info about
 504  * @param side side we are entering from, INVALID_DIAGDIR to return all trackbits
 505  * @return trackdirbits and other info
 506  */
 507 TrackStatus GetTileRailwayStatus(TileIndex tile, DiagDirection side)
 508 {
 509         GetTileTrackStatusProc *proc = GetTileProcs(tile)->get_tile_railway_status_proc;
 510         return proc != NULL ? proc(tile, side) : 0;
 511 }
 512
 513 /**
 514  * Returns information about road trackdirs and signal states.
 515  * If there is any trackbit at 'side', return all trackdirbits.
 516  * Return no trackbits if there is no roadbit (of given subtype) at given side.
 517  * @param tile tile to get info about
 518  * @param sub_mode roadtypes to check
 519  * @param side side we are entering from, INVALID_DIAGDIR to return all trackbits
 520  * @return trackdirbits and other info
 521  */
 522 TrackStatus GetTileRoadStatus(TileIndex tile, uint sub_mode, DiagDirection side)
 523 {
 524         GetTileRoadStatusProc *proc = GetTileProcs(tile)->get_tile_road_status_proc;
 525         return proc != NULL ? proc(tile, sub_mode, side) : 0;
 526 }
 527
 528 /**
 529  * Returns information about waterway trackdirs.
 530  * If there is any trackbit at 'side', return all trackdirbits.
 531  * @param tile tile to get info about
 532  * @param side side we are entering from, INVALID_DIAGDIR to return all trackbits
 533  * @return trackdirbits
 534  */
 535 TrackdirBits GetTileWaterwayStatus(TileIndex tile, DiagDirection side)
 536 {
 537         GetTileWaterStatusProc *proc = GetTileProcs(tile)->get_tile_waterway_status_proc;
 538         return proc != NULL ? proc(tile, side) : TRACKDIR_BIT_NONE;
 539 }
 540
 541 /**
 542  * Change the owner of a tile
 543  * @param tile      Tile to change
 544  * @param old_owner Current owner of the tile
 545  * @param new_owner New owner of the tile
 546  */
 547 void ChangeTileOwner(TileIndex tile, Owner old_owner, Owner new_owner)
 548 {
 549         GetTileProcs(tile)->change_tile_owner_proc(tile, old_owner, new_owner);
 550 }
 551
 552 void GetTileDesc(TileIndex tile, TileDesc *td)
 553 {
 554         GetTileProcs(tile)->get_tile_desc_proc(tile, td);
 555 }
 556
 557 /**
 558  * Has a snow line table already been loaded.
 559  * @return true if the table has been loaded already.
 560  * @ingroup SnowLineGroup
 561  */
 562 bool IsSnowLineSet()
 563 {
 564         return _snow_line != NULL;
 565 }
 566
 567 /**
 568  * Set a variable snow line, as loaded from a newgrf file.
 569  * @param table the 12 * 32 byte table containing the snowline for each day
 570  * @ingroup SnowLineGroup
 571  */
 572 void SetSnowLine(byte table[SNOW_LINE_MONTHS][SNOW_LINE_DAYS])
 573 {
 574         _snow_line = CallocT<SnowLine>(1);
 575         _snow_line->lowest_value = 0xFF;
 576         memcpy(_snow_line->table, table, sizeof(_snow_line->table));
 577
 578         for (uint i = 0; i < SNOW_LINE_MONTHS; i++) {
 579                 for (uint j = 0; j < SNOW_LINE_DAYS; j++) {
 580                         _snow_line->highest_value = max(_snow_line->highest_value, table[i][j]);
 581                         _snow_line->lowest_value = min(_snow_line->lowest_value, table[i][j]);
 582                 }
 583         }
 584 }
 585
 586 /**
 587  * Get the current snow line, either variable or static.
 588  * @return the snow line height.
 589  * @ingroup SnowLineGroup
 590  */
 591 byte GetSnowLine()
 592 {
 593         if (_snow_line == NULL) return _settings_game.game_creation.snow_line_height;
 594
 595         YearMonthDay ymd;
 596         ConvertDateToYMD(_date, &ymd);
 597         return _snow_line->table[ymd.month][ymd.day];
 598 }
 599
 600 /**
 601  * Get the highest possible snow line height, either variable or static.
 602  * @return the highest snow line height.
 603  * @ingroup SnowLineGroup
 604  */
 605 byte HighestSnowLine()
 606 {
 607         return _snow_line == NULL ? _settings_game.game_creation.snow_line_height : _snow_line->highest_value;
 608 }
 609
 610 /**
 611  * Get the lowest possible snow line height, either variable or static.
 612  * @return the lowest snow line height.
 613  * @ingroup SnowLineGroup
 614  */
 615 byte LowestSnowLine()
 616 {
 617         return _snow_line == NULL ? _settings_game.game_creation.snow_line_height : _snow_line->lowest_value;
 618 }
 619
 620 /**
 621  * Clear the variable snow line table and free the memory.
 622  * @ingroup SnowLineGroup
 623  */
 624 void ClearSnowLine()
 625 {
 626         free(_snow_line);
 627         _snow_line = NULL;
 628 }
 629
 630 /**
 631  * Clear a piece of landscape
 632  * @param tile tile to clear
 633  * @param flags of operation to conduct
 634  * @param p1 unused
 635  * @param p2 unused
 636  * @param text unused
 637  * @return the cost of this operation or an error
 638  */
 639 CommandCost CmdLandscapeClear(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
 640 {
 641         CommandCost cost(EXPENSES_CONSTRUCTION);
 642         bool do_clear = false;
 643         /* Test for stuff which results in water when cleared. Then add the cost to also clear the water. */
 644         if ((flags & DC_FORCE_CLEAR_TILE) && HasTileWaterClass(tile) && IsTileOnWater(tile) && !IsPlainWaterTile(tile) && !IsCoastTile(tile)) {
 645                 if ((flags & DC_AUTO) && GetWaterClass(tile) == WATER_CLASS_CANAL) return_cmd_error(STR_ERROR_MUST_DEMOLISH_CANAL_FIRST);
 646                 do_clear = true;
 647                 cost.AddCost(GetWaterClass(tile) == WATER_CLASS_CANAL ? _price[PR_CLEAR_CANAL] : _price[PR_CLEAR_WATER]);
 648         }
 649
 650         Company *c = (flags & (DC_AUTO | DC_BANKRUPT)) ? NULL : Company::GetIfValid(_current_company);
 651         if (c != NULL && (int)GB(c->clear_limit, 16, 16) < 1) {
 652                 return_cmd_error(STR_ERROR_CLEARING_LIMIT_REACHED);
 653         }
 654
 655         const ClearedObjectArea *coa = FindClearedObject(tile);
 656
 657         /* If this tile was the first tile which caused object destruction, always
 658          * pass it on to the tile_type_proc. That way multiple test runs and the exec run stay consistent. */
 659         if (coa != NULL && coa->first_tile != tile) {
 660                 /* If this tile belongs to an object which was already cleared via another tile, pretend it has been
 661                  * already removed.
 662                  * However, we need to check stuff, which is not the same for all object tiles. (e.g. being on water or not) */
 663
 664                 /* If a object is removed, it leaves either bare land or water. */
 665                 if ((flags & DC_NO_WATER) && HasTileWaterClass(tile) && IsTileOnWater(tile)) {
 666                         return_cmd_error(STR_ERROR_CAN_T_BUILD_ON_WATER);
 667                 }
 668         } else {
 669                 cost.AddCost(GetTileProcs(tile)->clear_tile_proc(tile, flags));
 670         }
 671
 672         if (flags & DC_EXEC) {
 673                 if (c != NULL) c->clear_limit -= 1 << 16;
 674                 if (do_clear) DoClearSquare(tile);
 675         }
 676         return cost;
 677 }
 678
 679 /**
 680  * Clear a big piece of landscape
 681  * @param tile end tile of area dragging
 682  * @param flags of operation to conduct
 683  * @param p1 start tile of area dragging
 684  * @param p2 various bitstuffed data.
 685  *  bit      0: Whether to use the Orthogonal (0) or Diagonal (1) iterator.
 686  * @param text unused
 687  * @return the cost of this operation or an error
 688  */
 689 CommandCost CmdClearArea(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
 690 {
 691         if (p1 >= MapSize()) return CMD_ERROR;
 692
 693         Money money = GetAvailableMoneyForCommand();
 694         CommandCost cost(EXPENSES_CONSTRUCTION);
 695         CommandCost last_error = CMD_ERROR;
 696         bool had_success = false;
 697
 698         const Company *c = (flags & (DC_AUTO | DC_BANKRUPT)) ? NULL : Company::GetIfValid(_current_company);
 699         int limit = (c == NULL ? INT32_MAX : GB(c->clear_limit, 16, 16));
 700
 701         TileArea ta(tile, p1);
 702         TileIterator *iter = HasBit(p2, 0) ? (TileIterator *)new DiagonalTileIterator(tile, p1) : new OrthogonalTileIterator(ta);
 703         for (; *iter != INVALID_TILE; ++(*iter)) {
 704                 TileIndex t = *iter;
 705                 CommandCost ret = DoCommand(t, 0, 0, flags & ~DC_EXEC, CMD_LANDSCAPE_CLEAR);
 706                 if (ret.Failed()) {
 707                         last_error = ret;
 708
 709                         /* We may not clear more tiles. */
 710                         if (c != NULL && GB(c->clear_limit, 16, 16) < 1) break;
 711                         continue;
 712                 }
 713
 714                 had_success = true;
 715                 if (flags & DC_EXEC) {
 716                         money -= ret.GetCost();
 717                         if (ret.GetCost() > 0 && money < 0) {
 718                                 _additional_cash_required = ret.GetCost();
 719                                 delete iter;
 720                                 return cost;
 721                         }
 722                         DoCommand(t, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
 723
 724                         /* draw explosion animation...
 725                          * Disable explosions when game is paused. Looks silly and blocks the view. */
 726                         TileIndex off = t - ta.tile;
 727                         if ((TileX(off) == 0 || TileX(off) == ta.w - 1U) && (TileY(off) == 0 || TileY(off) == ta.h - 1U) && _pause_mode == PM_UNPAUSED) {
 728                                 /* big explosion in each corner, or small explosion for single tiles */
 729                                 CreateEffectVehicleAbove(TileX(t) * TILE_SIZE + TILE_SIZE / 2, TileY(t) * TILE_SIZE + TILE_SIZE / 2, 2,
 730                                         ta.w == 1 && ta.h == 1 ? EV_EXPLOSION_SMALL : EV_EXPLOSION_LARGE
 731                                 );
 732                         }
 733                 } else {
 734                         /* When we're at the clearing limit we better bail (unneed) testing as well. */
 735                         if (ret.GetCost() != 0 && --limit <= 0) break;
 736                 }
 737                 cost.AddCost(ret);
 738         }
 739
 740         delete iter;
 741         return had_success ? cost : last_error;
 742 }
 743
 744
 745 TileIndex _cur_tileloop_tile;
 746
 747 /**
 748  * Gradually iterate over all tiles on the map, calling their TileLoopProcs once every 256 ticks.
 749  */
 750 void RunTileLoop()
 751 {
 752         /* The pseudorandom sequence of tiles is generated using a Galois linear feedback
 753          * shift register (LFSR). This allows a deterministic pseudorandom ordering, but
 754          * still with minimal state and fast iteration. */
 755
 756         /* Maximal length LFSR feedback terms, from 12-bit (for 64x64 maps) to 24-bit (for 4096x4096 maps).
 757          * Extracted from http://www.ece.cmu.edu/~koopman/lfsr/ */
 758         static const uint32 feedbacks[] = {
 759                 0xD8F, 0x1296, 0x2496, 0x4357, 0x8679, 0x1030E, 0x206CD, 0x403FE, 0x807B8, 0x1004B2, 0x2006A8, 0x4004B2, 0x800B87
 760         };
 761         assert_compile(lengthof(feedbacks) == 2 * MAX_MAP_SIZE_BITS - 2 * MIN_MAP_SIZE_BITS + 1);
 762         const uint32 feedback = feedbacks[MapLogX() + MapLogY() - 2 * MIN_MAP_SIZE_BITS];
 763
 764         /* We update every tile every 256 ticks, so divide the map size by 2^8 = 256 */
 765         uint count = 1 << (MapLogX() + MapLogY() - 8);
 766
 767         TileIndex tile = _cur_tileloop_tile;
 768         /* The LFSR cannot have a zeroed state. */
 769         assert(tile != 0);
 770
 771         /* Manually update tile 0 every 256 ticks - the LFSR never iterates over it itself.  */
 772         if (_tick_counter % 256 == 0) {
 773                 GetTileProcs(0)->tile_loop_proc(0);
 774                 count--;
 775         }
 776
 777         while (count--) {
 778                 GetTileProcs(tile)->tile_loop_proc(tile);
 779
 780                 /* Get the next tile in sequence using a Galois LFSR. */
 781                 tile = (tile >> 1) ^ (-(int32)(tile & 1) & feedback);
 782         }
 783
 784         _cur_tileloop_tile = tile;
 785 }
 786
 787 void InitializeLandscape()
 788 {
 789         uint maxx = MapMaxX();
 790         uint maxy = MapMaxY();
 791         uint sizex = MapSizeX();
 792
 793         uint y;
 794         for (y = _settings_game.construction.freeform_edges ? 1 : 0; y < maxy; y++) {
 795                 uint x;
 796                 for (x = _settings_game.construction.freeform_edges ? 1 : 0; x < maxx; x++) {
 797                         MakeClear(sizex * y + x, GROUND_GRASS, 3);
 798                         SetTileHeight(sizex * y + x, 0);
 799                         SetTropicZone(sizex * y + x, TROPICZONE_NORMAL);
 800                         ClearBridgeMiddle(sizex * y + x);
 801                 }
 802                 MakeVoid(sizex * y + x);
 803         }
 804         for (uint x = 0; x < sizex; x++) MakeVoid(sizex * y + x);
 805 }
 806
 807 static const byte _genterrain_tbl_1[5] = { 10, 22, 33, 37, 4  };
 808 static const byte _genterrain_tbl_2[5] = {  0,  0,  0,  0, 33 };
 809
 810 static void GenerateTerrain(int type, uint flag)
 811 {
 812         uint32 r = Random();
 813
 814         const Sprite *templ = GetSprite((((r >> 24) * _genterrain_tbl_1[type]) >> 8) + _genterrain_tbl_2[type] + 4845, ST_MAPGEN);
 815         if (templ == NULL) usererror("Map generator sprites could not be loaded");
 816
 817         uint x = r & MapMaxX();
 818         uint y = (r >> MapLogX()) & MapMaxY();
 819
 820         if (x < 2 || y < 2) return;
 821
 822         DiagDirection direction = (DiagDirection)GB(r, 22, 2);
 823         uint w = templ->width;
 824         uint h = templ->height;
 825
 826         if (DiagDirToAxis(direction) == AXIS_Y) Swap(w, h);
 827
 828         const byte *p = templ->data;
 829
 830         if ((flag & 4) != 0) {
 831                 uint xw = x * MapSizeY();
 832                 uint yw = y * MapSizeX();
 833                 uint bias = (MapSizeX() + MapSizeY()) * 16;
 834
 835                 switch (flag & 3) {
 836                         default: NOT_REACHED();
 837                         case 0:
 838                                 if (xw + yw > MapSize() - bias) return;
 839                                 break;
 840
 841                         case 1:
 842                                 if (yw < xw + bias) return;
 843                                 break;
 844
 845                         case 2:
 846                                 if (xw + yw < MapSize() + bias) return;
 847                                 break;
 848
 849                         case 3:
 850                                 if (xw < yw + bias) return;
 851                                 break;
 852                 }
 853         }
 854
 855         if (x + w >= MapMaxX() - 1) return;
 856         if (y + h >= MapMaxY() - 1) return;
 857
 858         TileIndex tile = TileXY(x, y);
 859
 860         switch (direction) {
 861                 default: NOT_REACHED();
 862                 case DIAGDIR_NE:
 863                         do {
 864                                 TileIndex tile_cur = tile;
 865
 866                                 for (uint w_cur = w; w_cur != 0; --w_cur) {
 867                                         if (GB(*p, 0, 4) >= TileHeight(tile_cur)) SetTileHeight(tile_cur, GB(*p, 0, 4));
 868                                         p++;
 869                                         tile_cur++;
 870                                 }
 871                                 tile += TileDiffXY(0, 1);
 872                         } while (--h != 0);
 873                         break;
 874
 875                 case DIAGDIR_SE:
 876                         do {
 877                                 TileIndex tile_cur = tile;
 878
 879                                 for (uint h_cur = h; h_cur != 0; --h_cur) {
 880                                         if (GB(*p, 0, 4) >= TileHeight(tile_cur)) SetTileHeight(tile_cur, GB(*p, 0, 4));
 881                                         p++;
 882                                         tile_cur += TileDiffXY(0, 1);
 883                                 }
 884                                 tile += TileDiffXY(1, 0);
 885                         } while (--w != 0);
 886                         break;
 887
 888                 case DIAGDIR_SW:
 889                         tile += TileDiffXY(w - 1, 0);
 890                         do {
 891                                 TileIndex tile_cur = tile;
 892
 893                                 for (uint w_cur = w; w_cur != 0; --w_cur) {
 894                                         if (GB(*p, 0, 4) >= TileHeight(tile_cur)) SetTileHeight(tile_cur, GB(*p, 0, 4));
 895                                         p++;
 896                                         tile_cur--;
 897                                 }
 898                                 tile += TileDiffXY(0, 1);
 899                         } while (--h != 0);
 900                         break;
 901
 902                 case DIAGDIR_NW:
 903                         tile += TileDiffXY(0, h - 1);
 904                         do {
 905                                 TileIndex tile_cur = tile;
 906
 907                                 for (uint h_cur = h; h_cur != 0; --h_cur) {
 908                                         if (GB(*p, 0, 4) >= TileHeight(tile_cur)) SetTileHeight(tile_cur, GB(*p, 0, 4));
 909                                         p++;
 910                                         tile_cur -= TileDiffXY(0, 1);
 911                                 }
 912                                 tile += TileDiffXY(1, 0);
 913                         } while (--w != 0);
 914                         break;
 915         }
 916 }
 917
 918
 919 #include "table/genland.h"
 920
 921 static void CreateDesertOrRainForest()
 922 {
 923         TileIndex update_freq = MapSize() / 4;
 924         const CoordDiff *data;
 925
 926         for (TileIndex tile = 0; tile != MapSize(); ++tile) {
 927                 if ((tile % update_freq) == 0) IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
 928
 929                 if (!IsValidTile(tile)) continue;
 930
 931                 for (data = _make_desert_or_rainforest_data;
 932                                 data != endof(_make_desert_or_rainforest_data); ++data) {
 933                         TileIndex t = AddCoordDiffWrap(tile, *data);
 934                         if (t != INVALID_TILE && (TileHeight(t) >= 4 || IsWaterTile(t))) break;
 935                 }
 936                 if (data == endof(_make_desert_or_rainforest_data)) {
 937                         SetTropicZone(tile, TROPICZONE_DESERT);
 938                 }
 939         }
 940
 941         for (uint i = 0; i != 256; i++) {
 942                 if ((i % 64) == 0) IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
 943
 944                 RunTileLoop();
 945         }
 946
 947         for (TileIndex tile = 0; tile != MapSize(); ++tile) {
 948                 if ((tile % update_freq) == 0) IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
 949
 950                 if (!IsValidTile(tile)) continue;
 951
 952                 for (data = _make_desert_or_rainforest_data;
 953                                 data != endof(_make_desert_or_rainforest_data); ++data) {
 954                         TileIndex t = AddCoordDiffWrap(tile, *data);
 955                         if (t != INVALID_TILE && IsClearTile(t) && IsClearGround(t, GROUND_DESERT)) break;
 956                 }
 957                 if (data == endof(_make_desert_or_rainforest_data)) {
 958                         SetTropicZone(tile, TROPICZONE_RAINFOREST);
 959                 }
 960         }
 961 }
 962
 963 /**
 964  * Find the spring of a river.
 965  * @param tile The tile to consider for being the spring.
 966  * @param user_data Ignored data.
 967  * @return True iff it is suitable as a spring.
 968  */
 969 static bool FindSpring(TileIndex tile, void *user_data)
 970 {
 971         int referenceHeight;
 972         if (!IsTileFlat(tile, &referenceHeight) || IsPlainWaterTile(tile)) return false;
 973
 974         /* In the tropics rivers start in the rainforest. */
 975         if (_settings_game.game_creation.landscape == LT_TROPIC && GetTropicZone(tile) != TROPICZONE_RAINFOREST) return false;
 976
 977         /* Are there enough higher tiles to warrant a 'spring'? */
 978         uint num = 0;
 979         for (int dx = -1; dx <= 1; dx++) {
 980                 for (int dy = -1; dy <= 1; dy++) {
 981                         TileIndex t = TileAddWrap(tile, dx, dy);
 982                         if (t != INVALID_TILE && GetTileMaxZ(t) > referenceHeight) num++;
 983                 }
 984         }
 985
 986         if (num < 4) return false;
 987
 988         /* Are we near the top of a hill? */
 989         for (int dx = -16; dx <= 16; dx++) {
 990                 for (int dy = -16; dy <= 16; dy++) {
 991                         TileIndex t = TileAddWrap(tile, dx, dy);
 992                         if (t != INVALID_TILE && GetTileMaxZ(t) > referenceHeight + 2) return false;
 993                 }
 994         }
 995
 996         return true;
 997 }
 998
 999 /**
1000  * Make a connected lake; fill all tiles in the circular tile search that are connected.
1001  * @param tile The tile to consider for lake making.
1002  * @param user_data The height of the lake.
1003  * @return Always false, so it continues searching.
1004  */
1005 static bool MakeLake(TileIndex tile, void *user_data)
1006 {
1007         uint height = *(uint*)user_data;
1008         if (!IsValidTile(tile) || TileHeight(tile) != height || !IsTileFlat(tile)) return false;
1009         if (_settings_game.game_creation.landscape == LT_TROPIC && GetTropicZone(tile) == TROPICZONE_DESERT) return false;
1010
1011         for (DiagDirection d = DIAGDIR_BEGIN; d < DIAGDIR_END; d++) {
1012                 TileIndex t2 = tile + TileOffsByDiagDir(d);
1013                 if (IsPlainWaterTile(t2)) {
1014                         MakeRiver(tile, Random());
1015                         return false;
1016                 }
1017         }
1018
1019         return false;
1020 }
1021
1022 /**
1023  * Check whether a river at begin could (logically) flow down to end.
1024  * @param begin The origin of the flow.
1025  * @param end The destination of the flow.
1026  * @return True iff the water can be flowing down.
1027  */
1028 static bool FlowsDown(TileIndex begin, TileIndex end)
1029 {
1030         assert(DistanceManhattan(begin, end) == 1);
1031
1032         int heightBegin;
1033         int heightEnd;
1034         Slope slopeBegin = GetTileSlope(begin, &heightBegin);
1035         Slope slopeEnd   = GetTileSlope(end, &heightEnd);
1036
1037         /* Slope is either inclined or flat; rivers don't support other slopes. */
1038         if (slopeEnd == SLOPE_FLAT) {
1039                 return heightEnd <= heightBegin;
1040         } else if (slopeBegin == SLOPE_FLAT) {
1041                 return heightEnd <= heightBegin && IsInclinedSlope(slopeEnd);
1042         } else {
1043                 /* Slope continues, then it must be lower. */
1044                 assert (IsInclinedSlope(slopeBegin));
1045                 return heightEnd < heightBegin && slopeEnd == slopeBegin;
1046         }
1047 }
1048
1049 /** River node struct for Astar. */
1050 struct RiverNode : AstarNodeBase<RiverNode> {
1051         typedef AstarNodeBase<RiverNode> Base;
1052         typedef RiverNode Key; // we are our own key
1053
1054         TileIndex tile;
1055
1056         void Set (RiverNode *parent, TileIndex t)
1057         {
1058                 Base::Set (parent);
1059                 tile = t;
1060         }
1061
1062         bool operator == (const RiverNode &other) const
1063         {
1064                 return tile == other.tile;
1065         }
1066
1067         const Key& GetKey() const
1068         {
1069                 return *this;
1070         }
1071
1072         int CalcHash() const
1073         {
1074                 return TileHash (TileX(tile), TileY(tile));
1075         }
1076 };
1077
1078 /** River pathfinder. */
1079 struct RiverAstar : Astar <RiverNode, 8, 8>
1080 {
1081         const TileIndex target;
1082
1083         RiverAstar (TileIndex target) : target(target) { }
1084 };
1085
1086 /**
1087  * River neighbour finder for the A-star algorithm
1088  */
1089 static void RiverFollow (RiverAstar *a, RiverNode *n)
1090 {
1091         for (DiagDirection d = DIAGDIR_BEGIN; d < DIAGDIR_END; d++) {
1092                 TileIndex tile = TileAddByDiagDir (n->tile, d);
1093                 if (IsValidTile(tile) && FlowsDown(n->tile, tile)) {
1094                         RiverNode *m = a->CreateNewNode (n, tile);
1095                         m->m_cost = n->m_cost + 1 + RandomRange(_settings_game.game_creation.river_route_random);
1096                         if (tile == a->target) {
1097                                 m->m_estimate = m->m_cost;
1098                                 a->FoundTarget(m);
1099                         } else {
1100                                 m->m_estimate = m->m_cost + DistanceManhattan(tile, a->target);
1101                                 a->InsertNode(m);
1102                         }
1103                 }
1104         }
1105 }
1106
1107 /**
1108  * Actually build the river between the begin and end tiles using AyStar.
1109  * @param begin The begin of the river.
1110  * @param end The end of the river.
1111  */
1112 static void BuildRiver(TileIndex begin, TileIndex end)
1113 {
1114         RiverAstar finder (end);
1115         finder.InsertInitialNode (finder.CreateNewNode (NULL, begin));
1116
1117         if (finder.FindPath(&RiverFollow)) {
1118                 for (RiverNode *n = finder.best; n != NULL; n = n->m_parent) {
1119                         TileIndex tile = n->tile;
1120                         if (!IsPlainWaterTile(tile)) {
1121                                 MakeRiver(tile, Random());
1122                                 /* Remove desert directly around the river tile. */
1123                                 CircularTileSearch(&tile, 5, RiverModifyDesertZone, NULL);
1124                         }
1125                 }
1126         }
1127 }
1128
1129 /**
1130  * Try to flow the river down from a given begin.
1131  * @param spring The springing point of the river.
1132  * @param begin  The begin point we are looking from; somewhere down hill from the spring.
1133  * @return True iff a river could/has been built, otherwise false.
1134  */
1135 static bool FlowRiver(TileIndex spring, TileIndex begin)
1136 {
1137         #define SET_MARK(x) marks.insert(x)
1138         #define IS_MARKED(x) (marks.find(x) != marks.end())
1139
1140         uint height = TileHeight(begin);
1141         if (IsPlainWaterTile(begin)) return DistanceManhattan(spring, begin) > _settings_game.game_creation.min_river_length;
1142
1143         std::set<TileIndex> marks;
1144         SET_MARK(begin);
1145
1146         /* Breadth first search for the closest tile we can flow down to. */
1147         std::list<TileIndex> queue;
1148         queue.push_back(begin);
1149
1150         bool found = false;
1151         uint count = 0; // Number of tiles considered; to be used for lake location guessing.
1152         TileIndex end;
1153         do {
1154                 end = queue.front();
1155                 queue.pop_front();
1156
1157                 uint height2 = TileHeight(end);
1158                 if (IsTileFlat(end) && (height2 < height || (height2 == height && IsPlainWaterTile(end)))) {
1159                         found = true;
1160                         break;
1161                 }
1162
1163                 for (DiagDirection d = DIAGDIR_BEGIN; d < DIAGDIR_END; d++) {
1164                         TileIndex t2 = end + TileOffsByDiagDir(d);
1165                         if (IsValidTile(t2) && !IS_MARKED(t2) && FlowsDown(end, t2)) {
1166                                 SET_MARK(t2);
1167                                 count++;
1168                                 queue.push_back(t2);
1169                         }
1170                 }
1171         } while (!queue.empty());
1172
1173         if (found) {
1174                 /* Flow further down hill. */
1175                 found = FlowRiver(spring, end);
1176         } else if (count > 32) {
1177                 /* Maybe we can make a lake. Find the Nth of the considered tiles. */
1178                 TileIndex lakeCenter = 0;
1179                 int i = RandomRange(count - 1) + 1;
1180                 std::set<TileIndex>::const_iterator cit = marks.begin();
1181                 while (--i) cit++;
1182                 lakeCenter = *cit;
1183
1184                 if (IsValidTile(lakeCenter) &&
1185                                 /* A river, or lake, can only be built on flat slopes. */
1186                                 IsTileFlat(lakeCenter) &&
1187                                 /* We want the lake to be built at the height of the river. */
1188                                 TileHeight(begin) == TileHeight(lakeCenter) &&
1189                                 /* We don't want the lake at the entry of the valley. */
1190                                 lakeCenter != begin &&
1191                                 /* We don't want lakes in the desert. */
1192                                 (_settings_game.game_creation.landscape != LT_TROPIC || GetTropicZone(lakeCenter) != TROPICZONE_DESERT) &&
1193                                 /* We only want a lake if the river is long enough. */
1194                                 DistanceManhattan(spring, lakeCenter) > _settings_game.game_creation.min_river_length) {
1195                         end = lakeCenter;
1196                         MakeRiver(lakeCenter, Random());
1197                         uint range = RandomRange(8) + 3;
1198                         CircularTileSearch(&lakeCenter, range, MakeLake, &height);
1199                         /* Call the search a second time so artefacts from going circular in one direction get (mostly) hidden. */
1200                         lakeCenter = end;
1201                         CircularTileSearch(&lakeCenter, range, MakeLake, &height);
1202                         found = true;
1203                 }
1204         }
1205
1206         marks.clear();
1207         if (found) BuildRiver(begin, end);
1208         return found;
1209 }
1210
1211 /**
1212  * Actually (try to) create some rivers.
1213  */
1214 static void CreateRivers()
1215 {
1216         int amount = _settings_game.game_creation.amount_of_rivers;
1217         if (amount == 0) return;
1218
1219         uint wells = ScaleByMapSize(4 << _settings_game.game_creation.amount_of_rivers);
1220         SetGeneratingWorldProgress(GWP_RIVER, wells + 256 / 64); // Include the tile loop calls below.
1221
1222         for (; wells != 0; wells--) {
1223                 IncreaseGeneratingWorldProgress(GWP_RIVER);
1224                 for (int tries = 0; tries < 128; tries++) {
1225                         TileIndex t = RandomTile();
1226                         if (!CircularTileSearch(&t, 8, FindSpring, NULL)) continue;
1227                         if (FlowRiver(t, t)) break;
1228                 }
1229         }
1230
1231         /* Run tile loop to update the ground density. */
1232         for (uint i = 0; i != 256; i++) {
1233                 if (i % 64 == 0) IncreaseGeneratingWorldProgress(GWP_RIVER);
1234                 RunTileLoop();
1235         }
1236 }
1237
1238 void GenerateLandscape(byte mode)
1239 {
1240         /** Number of steps of landscape generation */
1241         enum GenLandscapeSteps {
1242                 GLS_HEIGHTMAP    =  3, ///< Loading a heightmap
1243                 GLS_TERRAGENESIS =  5, ///< Terragenesis generator
1244                 GLS_ORIGINAL     =  2, ///< Original generator
1245                 GLS_TROPIC       = 12, ///< Extra steps needed for tropic landscape
1246                 GLS_OTHER        =  0, ///< Extra steps for other landscapes
1247         };
1248         uint steps = (_settings_game.game_creation.landscape == LT_TROPIC) ? GLS_TROPIC : GLS_OTHER;
1249
1250         if (mode == GWM_HEIGHTMAP) {
1251                 SetGeneratingWorldProgress(GWP_LANDSCAPE, steps + GLS_HEIGHTMAP);
1252                 LoadHeightmap(_file_to_saveload.name);
1253                 IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
1254         } else if (_settings_game.game_creation.land_generator == LG_TERRAGENESIS) {
1255                 SetGeneratingWorldProgress(GWP_LANDSCAPE, steps + GLS_TERRAGENESIS);
1256                 GenerateTerrainPerlin();
1257         } else {
1258                 SetGeneratingWorldProgress(GWP_LANDSCAPE, steps + GLS_ORIGINAL);
1259                 if (_settings_game.construction.freeform_edges) {
1260                         for (uint x = 0; x < MapSizeX(); x++) MakeVoid(TileXY(x, 0));
1261                         for (uint y = 0; y < MapSizeY(); y++) MakeVoid(TileXY(0, y));
1262                 }
1263                 switch (_settings_game.game_creation.landscape) {
1264                         case LT_ARCTIC: {
1265                                 uint32 r = Random();
1266
1267                                 for (uint i = ScaleByMapSize(GB(r, 0, 7) + 950); i != 0; --i) {
1268                                         GenerateTerrain(2, 0);
1269                                 }
1270
1271                                 uint flag = GB(r, 7, 2) | 4;
1272                                 for (uint i = ScaleByMapSize(GB(r, 9, 7) + 450); i != 0; --i) {
1273                                         GenerateTerrain(4, flag);
1274                                 }
1275                                 break;
1276                         }
1277
1278                         case LT_TROPIC: {
1279                                 uint32 r = Random();
1280
1281                                 for (uint i = ScaleByMapSize(GB(r, 0, 7) + 170); i != 0; --i) {
1282                                         GenerateTerrain(0, 0);
1283                                 }
1284
1285                                 uint flag = GB(r, 7, 2) | 4;
1286                                 for (uint i = ScaleByMapSize(GB(r, 9, 8) + 1700); i != 0; --i) {
1287                                         GenerateTerrain(0, flag);
1288                                 }
1289
1290                                 flag ^= 2;
1291
1292                                 for (uint i = ScaleByMapSize(GB(r, 17, 7) + 410); i != 0; --i) {
1293                                         GenerateTerrain(3, flag);
1294                                 }
1295                                 break;
1296                         }
1297
1298                         default: {
1299                                 uint32 r = Random();
1300
1301                                 assert(_settings_game.difficulty.quantity_sea_lakes != CUSTOM_SEA_LEVEL_NUMBER_DIFFICULTY);
1302                                 uint i = ScaleByMapSize(GB(r, 0, 7) + (3 - _settings_game.difficulty.quantity_sea_lakes) * 256 + 100);
1303                                 for (; i != 0; --i) {
1304                                         GenerateTerrain(_settings_game.difficulty.terrain_type, 0);
1305                                 }
1306                                 break;
1307                         }
1308                 }
1309         }
1310
1311         /* Do not call IncreaseGeneratingWorldProgress() before FixSlopes(),
1312          * it allows screen redraw. Drawing of broken slopes crashes the game */
1313         FixSlopes();
1314         IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
1315         ConvertGroundTilesIntoWaterTiles();
1316         IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
1317
1318         if (_settings_game.game_creation.landscape == LT_TROPIC) CreateDesertOrRainForest();
1319
1320         CreateRivers();
1321 }
1322
1323 void OnTick_Town();
1324 void OnTick_Trees();
1325 void OnTick_Station();
1326 void OnTick_Industry();
1327
1328 void OnTick_Companies();
1329 void OnTick_LinkGraph();
1330
1331 void CallLandscapeTick()
1332 {
1333         OnTick_Town();
1334         OnTick_Trees();
1335         OnTick_Station();
1336         OnTick_Industry();
1337
1338         OnTick_Companies();
1339         OnTick_LinkGraph();
1340 }