src/subsidy.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * 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.
   4  * 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.
   5  * 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/>.
   6  */
   7
   8 /** @file subsidy.cpp Handling of subsidies. */
   9
  10 #include "stdafx.h"
  11 #include "company_func.h"
  12 #include "industry.h"
  13 #include "town.h"
  14 #include "news_func.h"
  15 #include "ai/ai.hpp"
  16 #include "station_base.h"
  17 #include "strings_func.h"
  18 #include "window_func.h"
  19 #include "subsidy_base.h"
  20 #include "subsidy_func.h"
  21 #include "core/pool_func.hpp"
  22 #include "core/random_func.hpp"
  23 #include "game/game.hpp"
  24 #include "command_func.h"
  25 #include "string_func.h"
  26 #include "tile_cmd.h"
  27
  28 #include "table/strings.h"
  29
  30 #include "safeguards.h"
  31
  32 SubsidyPool _subsidy_pool("Subsidy"); ///< Pool for the subsidies.
  33 INSTANTIATE_POOL_METHODS(Subsidy)
  34
  35 /**
  36  * Marks subsidy as awarded, creates news and AI event
  37  * @param company awarded company
  38  */
  39 void Subsidy::AwardTo(CompanyID company)
  40 {
  41         assert(!this->IsAwarded());
  42
  43         this->awarded = company;
  44         this->remaining = SUBSIDY_CONTRACT_MONTHS;
  45
  46         char company_name[MAX_LENGTH_COMPANY_NAME_CHARS * MAX_CHAR_LENGTH];
  47         SetDParam(0, company);
  48         GetString(company_name, STR_COMPANY_NAME, lastof(company_name));
  49
  50         char *cn = stredup(company_name);
  51
  52         /* Add a news item */
  53         Pair reftype = SetupSubsidyDecodeParam(this, false);
  54         InjectDParam(1);
  55
  56         SetDParamStr(0, cn);
  57         AddNewsItem(
  58                 STR_NEWS_SERVICE_SUBSIDY_AWARDED_HALF + _settings_game.difficulty.subsidy_multiplier,
  59                 NT_SUBSIDIES, NF_NORMAL,
  60                 (NewsReferenceType)reftype.a, this->src, (NewsReferenceType)reftype.b, this->dst,
  61                 cn
  62         );
  63         AI::BroadcastNewEvent(new ScriptEventSubsidyAwarded(this->index));
  64         Game::NewEvent(new ScriptEventSubsidyAwarded(this->index));
  65
  66         InvalidateWindowData(WC_SUBSIDIES_LIST, 0);
  67 }
  68
  69 /**
  70  * Setup the string parameters for printing the subsidy at the screen, and compute the news reference for the subsidy.
  71  * @param s %Subsidy being printed.
  72  * @param mode Unit of cargo used, \c true means general name, \c false means singular form.
  73  * @return Reference of the subsidy in the news system.
  74  */
  75 Pair SetupSubsidyDecodeParam(const Subsidy *s, bool mode)
  76 {
  77         NewsReferenceType reftype1 = NR_NONE;
  78         NewsReferenceType reftype2 = NR_NONE;
  79
  80         /* if mode is false, use the singular form */
  81         const CargoSpec *cs = CargoSpec::Get(s->cargo_type);
  82         SetDParam(0, mode ? cs->name : cs->name_single);
  83
  84         switch (s->src_type) {
  85                 case ST_INDUSTRY:
  86                         reftype1 = NR_INDUSTRY;
  87                         SetDParam(1, STR_INDUSTRY_NAME);
  88                         break;
  89                 case ST_TOWN:
  90                         reftype1 = NR_TOWN;
  91                         SetDParam(1, STR_TOWN_NAME);
  92                         break;
  93                 default: NOT_REACHED();
  94         }
  95         SetDParam(2, s->src);
  96
  97         switch (s->dst_type) {
  98                 case ST_INDUSTRY:
  99                         reftype2 = NR_INDUSTRY;
 100                         SetDParam(4, STR_INDUSTRY_NAME);
 101                         break;
 102                 case ST_TOWN:
 103                         reftype2 = NR_TOWN;
 104                         SetDParam(4, STR_TOWN_NAME);
 105                         break;
 106                 default: NOT_REACHED();
 107         }
 108         SetDParam(5, s->dst);
 109
 110         Pair p;
 111         p.a = reftype1;
 112         p.b = reftype2;
 113         return p;
 114 }
 115
 116 /**
 117  * Sets a flag indicating that given town/industry is part of subsidised route.
 118  * @param type is it a town or an industry?
 119  * @param index index of town/industry
 120  * @param flag flag to set
 121  */
 122 static inline void SetPartOfSubsidyFlag(SourceType type, SourceID index, PartOfSubsidy flag)
 123 {
 124         switch (type) {
 125                 case ST_INDUSTRY: Industry::Get(index)->part_of_subsidy |= flag; return;
 126                 case ST_TOWN:   Town::Get(index)->cache.part_of_subsidy |= flag; return;
 127                 default: NOT_REACHED();
 128         }
 129 }
 130
 131 /** Perform a full rebuild of the subsidies cache. */
 132 void RebuildSubsidisedSourceAndDestinationCache()
 133 {
 134         for (Town *t : Town::Iterate()) t->cache.part_of_subsidy = POS_NONE;
 135
 136         for (Industry *i : Industry::Iterate()) i->part_of_subsidy = POS_NONE;
 137
 138         for (const Subsidy *s : Subsidy::Iterate()) {
 139                 SetPartOfSubsidyFlag(s->src_type, s->src, POS_SRC);
 140                 SetPartOfSubsidyFlag(s->dst_type, s->dst, POS_DST);
 141         }
 142 }
 143
 144 /**
 145  * Delete the subsidies associated with a given cargo source type and id.
 146  * @param type  Cargo source type of the id.
 147  * @param index Id to remove.
 148  */
 149 void DeleteSubsidyWith(SourceType type, SourceID index)
 150 {
 151         bool dirty = false;
 152
 153         for (Subsidy *s : Subsidy::Iterate()) {
 154                 if ((s->src_type == type && s->src == index) || (s->dst_type == type && s->dst == index)) {
 155                         delete s;
 156                         dirty = true;
 157                 }
 158         }
 159
 160         if (dirty) {
 161                 InvalidateWindowData(WC_SUBSIDIES_LIST, 0);
 162                 RebuildSubsidisedSourceAndDestinationCache();
 163         }
 164 }
 165
 166 /**
 167  * Check whether a specific subsidy already exists.
 168  * @param cargo Cargo type.
 169  * @param src_type Type of source of the cargo, affects interpretation of \a src.
 170  * @param src Id of the source.
 171  * @param dst_type Type of the destination of the cargo, affects interpretation of \a dst.
 172  * @param dst Id of the destination.
 173  * @return \c true if the subsidy already exists, \c false if not.
 174  */
 175 static bool CheckSubsidyDuplicate(CargoID cargo, SourceType src_type, SourceID src, SourceType dst_type, SourceID dst)
 176 {
 177         for (const Subsidy *s : Subsidy::Iterate()) {
 178                 if (s->cargo_type == cargo &&
 179                                 s->src_type == src_type && s->src == src &&
 180                                 s->dst_type == dst_type && s->dst == dst) {
 181                         return true;
 182                 }
 183         }
 184         return false;
 185 }
 186
 187 /**
 188  * Checks if the source and destination of a subsidy are inside the distance limit.
 189  * @param src_type Type of \a src.
 190  * @param src      Index of source.
 191  * @param dst_type Type of \a dst.
 192  * @param dst      Index of destination.
 193  * @return True if they are inside the distance limit.
 194  */
 195 static bool CheckSubsidyDistance(SourceType src_type, SourceID src, SourceType dst_type, SourceID dst)
 196 {
 197         TileIndex tile_src = (src_type == ST_TOWN) ? Town::Get(src)->xy : Industry::Get(src)->location.tile;
 198         TileIndex tile_dst = (dst_type == ST_TOWN) ? Town::Get(dst)->xy : Industry::Get(dst)->location.tile;
 199
 200         return (DistanceManhattan(tile_src, tile_dst) <= SUBSIDY_MAX_DISTANCE);
 201 }
 202
 203 /**
 204  * Creates a subsidy with the given parameters.
 205  * @param cid      Subsidised cargo.
 206  * @param src_type Type of \a src.
 207  * @param src      Index of source.
 208  * @param dst_type Type of \a dst.
 209  * @param dst      Index of destination.
 210  */
 211 void CreateSubsidy(CargoID cid, SourceType src_type, SourceID src, SourceType dst_type, SourceID dst)
 212 {
 213         Subsidy *s = new Subsidy();
 214         s->cargo_type = cid;
 215         s->src_type = src_type;
 216         s->src = src;
 217         s->dst_type = dst_type;
 218         s->dst = dst;
 219         s->remaining = SUBSIDY_OFFER_MONTHS;
 220         s->awarded = INVALID_COMPANY;
 221
 222         Pair reftype = SetupSubsidyDecodeParam(s, false);
 223         AddNewsItem(STR_NEWS_SERVICE_SUBSIDY_OFFERED, NT_SUBSIDIES, NF_NORMAL, (NewsReferenceType)reftype.a, s->src, (NewsReferenceType)reftype.b, s->dst);
 224         SetPartOfSubsidyFlag(s->src_type, s->src, POS_SRC);
 225         SetPartOfSubsidyFlag(s->dst_type, s->dst, POS_DST);
 226         AI::BroadcastNewEvent(new ScriptEventSubsidyOffer(s->index));
 227         Game::NewEvent(new ScriptEventSubsidyOffer(s->index));
 228
 229         InvalidateWindowData(WC_SUBSIDIES_LIST, 0);
 230 }
 231
 232 /**
 233  * Create a new subsidy.
 234  * @param tile unused.
 235  * @param flags type of operation
 236  * @param p1 various bitstuffed elements
 237  * - p1 = (bit  0 -  7) - SourceType of source.
 238  * - p1 = (bit  8 - 23) - SourceID of source.
 239  * - p1 = (bit 24 - 31) - CargoID of subsidy.
 240  * @param p2 various bitstuffed elements
 241  * - p2 = (bit  0 -  7) - SourceType of destination.
 242  * - p2 = (bit  8 - 23) - SourceID of destination.
 243  * @param text unused.
 244  * @return the cost of this operation or an error
 245  */
 246 CommandCost CmdCreateSubsidy(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
 247 {
 248         if (!Subsidy::CanAllocateItem()) return CMD_ERROR;
 249
 250         CargoID cid = GB(p1, 24, 8);
 251         SourceType src_type = (SourceType)GB(p1, 0, 8);
 252         SourceID src = GB(p1, 8, 16);
 253         SourceType dst_type = (SourceType)GB(p2, 0, 8);
 254         SourceID dst = GB(p2, 8, 16);
 255
 256         if (_current_company != OWNER_DEITY) return CMD_ERROR;
 257
 258         if (cid >= NUM_CARGO || !::CargoSpec::Get(cid)->IsValid()) return CMD_ERROR;
 259
 260         switch (src_type) {
 261                 case ST_TOWN:
 262                         if (!Town::IsValidID(src)) return CMD_ERROR;
 263                         break;
 264                 case ST_INDUSTRY:
 265                         if (!Industry::IsValidID(src)) return CMD_ERROR;
 266                         break;
 267                 default:
 268                         return CMD_ERROR;
 269         }
 270         switch (dst_type) {
 271                 case ST_TOWN:
 272                         if (!Town::IsValidID(dst)) return CMD_ERROR;
 273                         break;
 274                 case ST_INDUSTRY:
 275                         if (!Industry::IsValidID(dst)) return CMD_ERROR;
 276                         break;
 277                 default:
 278                         return CMD_ERROR;
 279         }
 280
 281         if (flags & DC_EXEC) {
 282                 CreateSubsidy(cid, src_type, src, dst_type, dst);
 283         }
 284
 285         return CommandCost();
 286 }
 287
 288 /**
 289  * Tries to create a passenger subsidy between two towns.
 290  * @return True iff the subsidy was created.
 291  */
 292 bool FindSubsidyPassengerRoute()
 293 {
 294         if (!Subsidy::CanAllocateItem()) return false;
 295
 296         const Town *src = Town::GetRandom();
 297         if (src->cache.population < SUBSIDY_PAX_MIN_POPULATION ||
 298                         src->GetPercentTransported(CT_PASSENGERS) > SUBSIDY_MAX_PCT_TRANSPORTED) {
 299                 return false;
 300         }
 301
 302         const Town *dst = Town::GetRandom();
 303         if (dst->cache.population < SUBSIDY_PAX_MIN_POPULATION || src == dst) {
 304                 return false;
 305         }
 306
 307         if (DistanceManhattan(src->xy, dst->xy) > SUBSIDY_MAX_DISTANCE) return false;
 308         if (CheckSubsidyDuplicate(CT_PASSENGERS, ST_TOWN, src->index, ST_TOWN, dst->index)) return false;
 309
 310         CreateSubsidy(CT_PASSENGERS, ST_TOWN, src->index, ST_TOWN, dst->index);
 311
 312         return true;
 313 }
 314
 315 bool FindSubsidyCargoDestination(CargoID cid, SourceType src_type, SourceID src);
 316
 317
 318 /**
 319  * Tries to create a cargo subsidy with a town as source.
 320  * @return True iff the subsidy was created.
 321  */
 322 bool FindSubsidyTownCargoRoute()
 323 {
 324         if (!Subsidy::CanAllocateItem()) return false;
 325
 326         SourceType src_type = ST_TOWN;
 327
 328         /* Select a random town. */
 329         const Town *src_town = Town::GetRandom();
 330         if (src_town->cache.population < SUBSIDY_CARGO_MIN_POPULATION) return false;
 331
 332         /* Calculate the produced cargo of houses around town center. */
 333         CargoArray town_cargo_produced;
 334         TileArea ta = TileArea(src_town->xy, 1, 1).Expand(SUBSIDY_TOWN_CARGO_RADIUS);
 335         TILE_AREA_LOOP(tile, ta) {
 336                 if (IsTileType(tile, MP_HOUSE)) {
 337                         AddProducedCargo(tile, town_cargo_produced);
 338                 }
 339         }
 340
 341         /* Passenger subsidies are not handled here. */
 342         town_cargo_produced[CT_PASSENGERS] = 0;
 343
 344         uint8 cargo_count = 0;
 345         for (CargoID i = 0; i < NUM_CARGO; i++) {
 346                 if (town_cargo_produced[i] > 0) cargo_count++;
 347         }
 348
 349         /* No cargo produced at all? */
 350         if (cargo_count == 0) return false;
 351
 352         /* Choose a random cargo that is produced in the town. */
 353         uint8 cargo_number = RandomRange(cargo_count);
 354         CargoID cid;
 355         for (cid = 0; cid < NUM_CARGO; cid++) {
 356                 if (town_cargo_produced[cid] > 0) {
 357                         if (cargo_number == 0) break;
 358                         cargo_number--;
 359                 }
 360         }
 361
 362         /* Avoid using invalid NewGRF cargoes. */
 363         if (!CargoSpec::Get(cid)->IsValid() ||
 364                         _settings_game.linkgraph.GetDistributionType(cid) != DT_MANUAL) {
 365                 return false;
 366         }
 367
 368         /* Quit if the percentage transported is large enough. */
 369         if (src_town->GetPercentTransported(cid) > SUBSIDY_MAX_PCT_TRANSPORTED) return false;
 370
 371         SourceID src = src_town->index;
 372
 373         return FindSubsidyCargoDestination(cid, src_type, src);
 374 }
 375
 376 /**
 377  * Tries to create a cargo subsidy with an industry as source.
 378  * @return True iff the subsidy was created.
 379  */
 380 bool FindSubsidyIndustryCargoRoute()
 381 {
 382         if (!Subsidy::CanAllocateItem()) return false;
 383
 384         SourceType src_type = ST_INDUSTRY;
 385
 386         /* Select a random industry. */
 387         const Industry *src_ind = Industry::GetRandom();
 388         if (src_ind == nullptr) return false;
 389
 390         uint trans, total;
 391
 392         CargoID cid;
 393
 394         /* Randomize cargo type */
 395         int num_cargos = 0;
 396         uint cargo_index;
 397         for (cargo_index = 0; cargo_index < lengthof(src_ind->produced_cargo); cargo_index++) {
 398                 if (src_ind->produced_cargo[cargo_index] != CT_INVALID) num_cargos++;
 399         }
 400         if (num_cargos == 0) return false; // industry produces nothing
 401         int cargo_num = RandomRange(num_cargos) + 1;
 402         for (cargo_index = 0; cargo_index < lengthof(src_ind->produced_cargo); cargo_index++) {
 403                 if (src_ind->produced_cargo[cargo_index] != CT_INVALID) cargo_num--;
 404                 if (cargo_num == 0) break;
 405         }
 406         assert(cargo_num == 0); // indicates loop didn't break as intended
 407         cid = src_ind->produced_cargo[cargo_index];
 408         trans = src_ind->last_month_pct_transported[cargo_index];
 409         total = src_ind->last_month_production[cargo_index];
 410
 411         /* Quit if no production in this industry
 412          * or if the pct transported is already large enough
 413          * or if the cargo is automatically distributed */
 414         if (total == 0 || trans > SUBSIDY_MAX_PCT_TRANSPORTED ||
 415                         cid == CT_INVALID ||
 416                         _settings_game.linkgraph.GetDistributionType(cid) != DT_MANUAL) {
 417                 return false;
 418         }
 419
 420         SourceID src = src_ind->index;
 421
 422         return FindSubsidyCargoDestination(cid, src_type, src);
 423 }
 424
 425 /**
 426  * Tries to find a suitable destination for the given source and cargo.
 427  * @param cid      Subsidized cargo.
 428  * @param src_type Type of \a src.
 429  * @param src      Index of source.
 430  * @return True iff the subsidy was created.
 431  */
 432 bool FindSubsidyCargoDestination(CargoID cid, SourceType src_type, SourceID src)
 433 {
 434         /* Choose a random destination. */
 435         SourceType dst_type = Chance16(1, 2) ? ST_TOWN : ST_INDUSTRY;
 436
 437         SourceID dst;
 438         switch (dst_type) {
 439                 case ST_TOWN: {
 440                         /* Select a random town. */
 441                         const Town *dst_town = Town::GetRandom();
 442
 443                         /* Calculate cargo acceptance of houses around town center. */
 444                         CargoArray town_cargo_accepted;
 445                         TileArea ta = TileArea(dst_town->xy, 1, 1).Expand(SUBSIDY_TOWN_CARGO_RADIUS);
 446                         TILE_AREA_LOOP(tile, ta) {
 447                                 if (IsTileType(tile, MP_HOUSE)) {
 448                                         AddAcceptedCargo(tile, town_cargo_accepted, nullptr);
 449                                 }
 450                         }
 451
 452                         /* Check if the town can accept this cargo. */
 453                         if (town_cargo_accepted[cid] < 8) return false;
 454
 455                         dst = dst_town->index;
 456                         break;
 457                 }
 458
 459                 case ST_INDUSTRY: {
 460                         /* Select a random industry. */
 461                         const Industry *dst_ind = Industry::GetRandom();
 462                         if (dst_ind == nullptr) return false;
 463
 464                         /* The industry must accept the cargo */
 465                         bool valid = std::find(dst_ind->accepts_cargo, endof(dst_ind->accepts_cargo), cid) != endof(dst_ind->accepts_cargo);
 466                         if (!valid) return false;
 467
 468                         dst = dst_ind->index;
 469                         break;
 470                 }
 471
 472                 default: NOT_REACHED();
 473         }
 474
 475         /* Check that the source and the destination are not the same. */
 476         if (src_type == dst_type && src == dst) return false;
 477
 478         /* Check distance between source and destination. */
 479         if (!CheckSubsidyDistance(src_type, src, dst_type, dst)) return false;
 480
 481         /* Avoid duplicate subsidies. */
 482         if (CheckSubsidyDuplicate(cid, src_type, src, dst_type, dst)) return false;
 483
 484         CreateSubsidy(cid, src_type, src, dst_type, dst);
 485
 486         return true;
 487 }
 488
 489 /** Perform the monthly update of open subsidies, and try to create a new one. */
 490 void SubsidyMonthlyLoop()
 491 {
 492         bool modified = false;
 493
 494         for (Subsidy *s : Subsidy::Iterate()) {
 495                 if (--s->remaining == 0) {
 496                         if (!s->IsAwarded()) {
 497                                 Pair reftype = SetupSubsidyDecodeParam(s, true);
 498                                 AddNewsItem(STR_NEWS_OFFER_OF_SUBSIDY_EXPIRED, NT_SUBSIDIES, NF_NORMAL, (NewsReferenceType)reftype.a, s->src, (NewsReferenceType)reftype.b, s->dst);
 499                                 AI::BroadcastNewEvent(new ScriptEventSubsidyOfferExpired(s->index));
 500                                 Game::NewEvent(new ScriptEventSubsidyOfferExpired(s->index));
 501                         } else {
 502                                 if (s->awarded == _local_company) {
 503                                         Pair reftype = SetupSubsidyDecodeParam(s, true);
 504                                         AddNewsItem(STR_NEWS_SUBSIDY_WITHDRAWN_SERVICE, NT_SUBSIDIES, NF_NORMAL, (NewsReferenceType)reftype.a, s->src, (NewsReferenceType)reftype.b, s->dst);
 505                                 }
 506                                 AI::BroadcastNewEvent(new ScriptEventSubsidyExpired(s->index));
 507                                 Game::NewEvent(new ScriptEventSubsidyExpired(s->index));
 508                         }
 509                         delete s;
 510                         modified = true;
 511                 }
 512         }
 513
 514         if (modified) {
 515                 RebuildSubsidisedSourceAndDestinationCache();
 516         } else if (_settings_game.linkgraph.distribution_pax != DT_MANUAL &&
 517                            _settings_game.linkgraph.distribution_mail != DT_MANUAL &&
 518                            _settings_game.linkgraph.distribution_armoured != DT_MANUAL &&
 519                            _settings_game.linkgraph.distribution_default != DT_MANUAL) {
 520                 /* Return early if there are no manually distributed cargoes and if we
 521                  * don't need to invalidate the subsidies window. */
 522                 return;
 523         }
 524
 525         bool passenger_subsidy = false;
 526         bool town_subsidy = false;
 527         bool industry_subsidy = false;
 528
 529         int random_chance = RandomRange(16);
 530
 531         if (random_chance < 2 && _settings_game.linkgraph.distribution_pax == DT_MANUAL) {
 532                 /* There is a 1/8 chance each month of generating a passenger subsidy. */
 533                 int n = 1000;
 534
 535                 do {
 536                         passenger_subsidy = FindSubsidyPassengerRoute();
 537                 } while (!passenger_subsidy && n--);
 538         } else if (random_chance == 2) {
 539                 /* Cargo subsidies with a town as a source have a 1/16 chance. */
 540                 int n = 1000;
 541
 542                 do {
 543                         town_subsidy = FindSubsidyTownCargoRoute();
 544                 } while (!town_subsidy && n--);
 545         } else if (random_chance == 3) {
 546                 /* Cargo subsidies with an industry as a source have a 1/16 chance. */
 547                 int n = 1000;
 548
 549                 do {
 550                         industry_subsidy = FindSubsidyIndustryCargoRoute();
 551                 } while (!industry_subsidy && n--);
 552         }
 553
 554         modified |= passenger_subsidy || town_subsidy || industry_subsidy;
 555
 556         if (modified) InvalidateWindowData(WC_SUBSIDIES_LIST, 0);
 557 }
 558
 559 /**
 560  * Tests whether given delivery is subsidised and possibly awards the subsidy to delivering company
 561  * @param cargo_type type of cargo
 562  * @param company company delivering the cargo
 563  * @param src_type type of \a src
 564  * @param src index of source
 565  * @param st station where the cargo is delivered to
 566  * @return is the delivery subsidised?
 567  */
 568 bool CheckSubsidised(CargoID cargo_type, CompanyID company, SourceType src_type, SourceID src, const Station *st)
 569 {
 570         /* If the source isn't subsidised, don't continue */
 571         if (src == INVALID_SOURCE) return false;
 572         switch (src_type) {
 573                 case ST_INDUSTRY:
 574                         if (!(Industry::Get(src)->part_of_subsidy & POS_SRC)) return false;
 575                         break;
 576                 case ST_TOWN:
 577                         if (!(Town::Get(src)->cache.part_of_subsidy & POS_SRC)) return false;
 578                         break;
 579                 default: return false;
 580         }
 581
 582         /* Remember all towns near this station (at least one house in its catchment radius)
 583          * which are destination of subsidised path. Do that only if needed */
 584         std::vector<const Town *> towns_near;
 585         if (!st->rect.IsEmpty()) {
 586                 for (const Subsidy *s : Subsidy::Iterate()) {
 587                         /* Don't create the cache if there is no applicable subsidy with town as destination */
 588                         if (s->dst_type != ST_TOWN) continue;
 589                         if (s->cargo_type != cargo_type || s->src_type != src_type || s->src != src) continue;
 590                         if (s->IsAwarded() && s->awarded != company) continue;
 591
 592                         BitmapTileIterator it(st->catchment_tiles);
 593                         for (TileIndex tile = it; tile != INVALID_TILE; tile = ++it) {
 594                                 if (!IsTileType(tile, MP_HOUSE)) continue;
 595                                 const Town *t = Town::GetByTile(tile);
 596                                 if (t->cache.part_of_subsidy & POS_DST) include(towns_near, t);
 597                         }
 598                         break;
 599                 }
 600         }
 601
 602         bool subsidised = false;
 603
 604         /* Check if there's a (new) subsidy that applies. There can be more subsidies triggered by this delivery!
 605          * Think about the case that subsidies are A->B and A->C and station has both B and C in its catchment area */
 606         for (Subsidy *s : Subsidy::Iterate()) {
 607                 if (s->cargo_type == cargo_type && s->src_type == src_type && s->src == src && (!s->IsAwarded() || s->awarded == company)) {
 608                         switch (s->dst_type) {
 609                                 case ST_INDUSTRY:
 610                                         for (Industry *ind : st->industries_near) {
 611                                                 if (s->dst == ind->index) {
 612                                                         assert(ind->part_of_subsidy & POS_DST);
 613                                                         subsidised = true;
 614                                                         if (!s->IsAwarded()) s->AwardTo(company);
 615                                                 }
 616                                         }
 617                                         break;
 618                                 case ST_TOWN:
 619                                         for (const Town *tp : towns_near) {
 620                                                 if (s->dst == tp->index) {
 621                                                         assert(tp->cache.part_of_subsidy & POS_DST);
 622                                                         subsidised = true;
 623                                                         if (!s->IsAwarded()) s->AwardTo(company);
 624                                                 }
 625                                         }
 626                                         break;
 627                                 default:
 628                                         NOT_REACHED();
 629                         }
 630                 }
 631         }
 632
 633         return subsidised;
 634 }