terraform_cmd.cpp

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/*
 * This file is part of OpenTTD.
 * 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.
 * 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.
 * 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/>.
 */
 
#include "stdafx.h"
#include "command_func.h"
#include "tunnel_map.h"
#include "bridge_map.h"
#include "viewport_func.h"
#include "genworld.h"
#include "object_base.h"
#include "company_base.h"
#include "company_func.h"
#include "core/backup_type.hpp"
#include "terraform_cmd.h"
#include "landscape_cmd.h"
 
#include "table/strings.h"
 
#include "safeguards.h"
 
typedef std::set<TileIndex> TileIndexSet;
typedef std::map<TileIndex, int> TileIndexToHeightMap;
 
struct TerraformerState {
  TileIndexSet dirty_tiles;                
  TileIndexToHeightMap tile_to_new_height; 
};
 
static int TerraformGetHeightOfTile(const TerraformerState *ts, TileIndex tile)
{
  TileIndexToHeightMap::const_iterator it = ts->tile_to_new_height.find(tile);
  return it != ts->tile_to_new_height.end() ? it->second : TileHeight(tile);
}
 
static void TerraformSetHeightOfTile(TerraformerState *ts, TileIndex tile, int height)
{
  ts->tile_to_new_height[tile] = height;
}
 
static void TerraformAddDirtyTile(TerraformerState *ts, TileIndex tile)
{
  ts->dirty_tiles.insert(tile);
}
 
static void TerraformAddDirtyTileAround(TerraformerState *ts, TileIndex tile)
{
  /* Make sure all tiles passed to TerraformAddDirtyTile are within [0, Map::Size()] */
  if (TileY(tile) >= 1) TerraformAddDirtyTile(ts, tile + TileDiffXY( 0, -1));
  if (TileY(tile) >= 1 && TileX(tile) >= 1) TerraformAddDirtyTile(ts, tile + TileDiffXY(-1, -1));
  if (TileX(tile) >= 1) TerraformAddDirtyTile(ts, tile + TileDiffXY(-1,  0));
  TerraformAddDirtyTile(ts, tile);
}
 
static std::tuple<CommandCost, TileIndex> TerraformTileHeight(TerraformerState *ts, TileIndex tile, int height)
{
  assert(tile < Map::Size());
 
  /* Check range of destination height */
  if (height < 0) return { CommandCost(STR_ERROR_ALREADY_AT_SEA_LEVEL), INVALID_TILE };
  if (height > _settings_game.construction.map_height_limit) return { CommandCost(STR_ERROR_TOO_HIGH), INVALID_TILE };
 
  /*
   * Check if the terraforming has any effect.
   * This can only be true, if multiple corners of the start-tile are terraformed (i.e. the terraforming is done by towns/industries etc.).
   * In this case the terraforming should fail. (Don't know why.)
   */
  if (height == TerraformGetHeightOfTile(ts, tile)) return { CMD_ERROR, INVALID_TILE };
 
  /* Check "too close to edge of map". Only possible when freeform-edges is off. */
  uint x = TileX(tile);
  uint y = TileY(tile);
  if (!_settings_game.construction.freeform_edges && ((x <= 1) || (y <= 1) || (x >= Map::MaxX() - 1) || (y >= Map::MaxY() - 1))) {
    /*
     * Determine a sensible error tile
     */
    if (x == 1) x = 0;
    if (y == 1) y = 0;
    return { CommandCost(STR_ERROR_TOO_CLOSE_TO_EDGE_OF_MAP), TileXY(x, y) };
  }
 
  /* Mark incident tiles that are involved in the terraforming. */
  TerraformAddDirtyTileAround(ts, tile);
 
  /* Store the height modification */
  TerraformSetHeightOfTile(ts, tile, height);
 
  CommandCost total_cost(EXPENSES_CONSTRUCTION);
 
  /* Increment cost */
  total_cost.AddCost(_price[PR_TERRAFORM]);
 
  /* Recurse to neighboured corners if height difference is larger than 1 */
  for (DiagDirection dir = DIAGDIR_BEGIN; dir < DIAGDIR_END; dir++) {
    TileIndex neighbour_tile = AddTileIndexDiffCWrap(tile, TileIndexDiffCByDiagDir(dir));
 
    /* Not using IsValidTile as we want to also change MP_VOID tiles, which IsValidTile excludes. */
    if (neighbour_tile == INVALID_TILE) continue;
 
    /* Get TileHeight of neighboured tile as of current terraform progress */
    int r = TerraformGetHeightOfTile(ts, neighbour_tile);
    int height_diff = height - r;
 
    /* Is the height difference to the neighboured corner greater than 1? */
    if (abs(height_diff) > 1) {
      /* Terraform the neighboured corner. The resulting height difference should be 1. */
      height_diff += (height_diff < 0 ? 1 : -1);
      auto [cost, err_tile] = TerraformTileHeight(ts, neighbour_tile, r + height_diff);
      if (cost.Failed()) return { cost, err_tile };
      total_cost.AddCost(cost);
    }
  }
 
  return { total_cost, INVALID_TILE };
}
 
std::tuple<CommandCost, Money, TileIndex> CmdTerraformLand(DoCommandFlag flags, TileIndex tile, Slope slope, bool dir_up)
{
  CommandCost total_cost(EXPENSES_CONSTRUCTION);
  int direction = (dir_up ? 1 : -1);
  TerraformerState ts;
 
  /* Compute the costs and the terraforming result in a model of the landscape */
  if ((slope & SLOPE_W) != 0 && tile + TileDiffXY(1, 0) < Map::Size()) {
    TileIndex t = tile + TileDiffXY(1, 0);
    auto [cost, err_tile] = TerraformTileHeight(&ts, t, TileHeight(t) + direction);
    if (cost.Failed()) return { cost, 0, err_tile };
    total_cost.AddCost(cost);
  }
 
  if ((slope & SLOPE_S) != 0 && tile + TileDiffXY(1, 1) < Map::Size()) {
    TileIndex t = tile + TileDiffXY(1, 1);
    auto [cost, err_tile] = TerraformTileHeight(&ts, t, TileHeight(t) + direction);
    if (cost.Failed()) return { cost, 0, err_tile };
    total_cost.AddCost(cost);
  }
 
  if ((slope & SLOPE_E) != 0 && tile + TileDiffXY(0, 1) < Map::Size()) {
    TileIndex t = tile + TileDiffXY(0, 1);
    auto [cost, err_tile] = TerraformTileHeight(&ts, t, TileHeight(t) + direction);
    if (cost.Failed()) return { cost, 0, err_tile };
    total_cost.AddCost(cost);
  }
 
  if ((slope & SLOPE_N) != 0) {
    TileIndex t = tile + TileDiffXY(0, 0);
    auto [cost, err_tile] = TerraformTileHeight(&ts, t, TileHeight(t) + direction);
    if (cost.Failed()) return { cost, 0, err_tile };
    total_cost.AddCost(cost);
  }
 
  /* Check if the terraforming is valid wrt. tunnels, bridges and objects on the surface
   * Pass == 0: Collect tileareas which are caused to be auto-cleared.
   * Pass == 1: Collect the actual cost. */
  for (int pass = 0; pass < 2; pass++) {
    for (const auto &t : ts.dirty_tiles) {
      assert(t < Map::Size());
      /* MP_VOID tiles can be terraformed but as tunnels and bridges
       * cannot go under / over these tiles they don't need checking. */
      if (IsTileType(t, MP_VOID)) continue;
 
      /* Find new heights of tile corners */
      int z_N = TerraformGetHeightOfTile(&ts, t + TileDiffXY(0, 0));
      int z_W = TerraformGetHeightOfTile(&ts, t + TileDiffXY(1, 0));
      int z_S = TerraformGetHeightOfTile(&ts, t + TileDiffXY(1, 1));
      int z_E = TerraformGetHeightOfTile(&ts, t + TileDiffXY(0, 1));
 
      /* Find min and max height of tile */
      int z_min = std::min({z_N, z_W, z_S, z_E});
      int z_max = std::max({z_N, z_W, z_S, z_E});
 
      /* Compute tile slope */
      Slope tileh = (z_max > z_min + 1 ? SLOPE_STEEP : SLOPE_FLAT);
      if (z_W > z_min) tileh |= SLOPE_W;
      if (z_S > z_min) tileh |= SLOPE_S;
      if (z_E > z_min) tileh |= SLOPE_E;
      if (z_N > z_min) tileh |= SLOPE_N;
 
      if (pass == 0) {
        /* Check if bridge would take damage */
        if (IsBridgeAbove(t)) {
          int bridge_height = GetBridgeHeight(GetSouthernBridgeEnd(t));
 
          /* Check if bridge would take damage. */
          if (direction == 1 && bridge_height <= z_max) {
            return { CommandCost(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST), 0, t }; // highlight the tile under the bridge
          }
 
          /* Is the bridge above not too high afterwards? */
          if (direction == -1 && bridge_height > (z_min + _settings_game.construction.max_bridge_height)) {
            return { CommandCost(STR_ERROR_BRIDGE_TOO_HIGH_AFTER_LOWER_LAND), 0, t };
          }
        }
        /* Check if tunnel would take damage */
        if (direction == -1 && IsTunnelInWay(t, z_min)) {
          return { CommandCost(STR_ERROR_EXCAVATION_WOULD_DAMAGE), 0, t }; // highlight the tile above the tunnel
        }
      }
 
      /* Is the tile already cleared? */
      const ClearedObjectArea *coa = FindClearedObject(t);
      bool indirectly_cleared = coa != nullptr && coa->first_tile != t;
 
      /* Check tiletype-specific things, and add extra-cost */
      Backup<bool> old_generating_world(_generating_world);
      if (_game_mode == GM_EDITOR) old_generating_world.Change(true); // used to create green terraformed land
      DoCommandFlag tile_flags = flags | DC_AUTO | DC_FORCE_CLEAR_TILE;
      if (pass == 0) {
        tile_flags &= ~DC_EXEC;
        tile_flags |= DC_NO_MODIFY_TOWN_RATING;
      }
      CommandCost cost;
      if (indirectly_cleared) {
        cost = Command<CMD_LANDSCAPE_CLEAR>::Do(tile_flags, t);
      } else {
        cost = _tile_type_procs[GetTileType(t)]->terraform_tile_proc(t, tile_flags, z_min, tileh);
      }
      old_generating_world.Restore();
      if (cost.Failed()) {
        return { cost, 0, t };
      }
      if (pass == 1) total_cost.AddCost(cost);
    }
  }
 
  Company *c = Company::GetIfValid(_current_company);
  if (c != nullptr && GB(c->terraform_limit, 16, 16) < ts.tile_to_new_height.size()) {
    return { CommandCost(STR_ERROR_TERRAFORM_LIMIT_REACHED), 0, INVALID_TILE };
  }
 
  if (flags & DC_EXEC) {
    /* Mark affected areas dirty. */
    for (const auto &t : ts.dirty_tiles) {
      MarkTileDirtyByTile(t);
      TileIndexToHeightMap::const_iterator new_height = ts.tile_to_new_height.find(t);
      if (new_height == ts.tile_to_new_height.end()) continue;
      MarkTileDirtyByTile(t, 0, new_height->second);
    }
 
    /* change the height */
    for (const auto &it : ts.tile_to_new_height) {
      TileIndex t = it.first;
      int height = it.second;
 
      SetTileHeight(t, (uint)height);
    }
 
    if (c != nullptr) c->terraform_limit -= (uint32_t)ts.tile_to_new_height.size() << 16;
  }
  return { total_cost, 0, total_cost.Succeeded() ? tile : INVALID_TILE };
}
 
 
std::tuple<CommandCost, Money, TileIndex> CmdLevelLand(DoCommandFlag flags, TileIndex tile, TileIndex start_tile, bool diagonal, LevelMode lm)
{
  if (start_tile >= Map::Size()) return { CMD_ERROR, 0, INVALID_TILE };
 
  /* remember level height */
  uint oldh = TileHeight(start_tile);
 
  /* compute new height */
  uint h = oldh;
  switch (lm) {
    case LM_LEVEL: break;
    case LM_RAISE: h++; break;
    case LM_LOWER: h--; break;
    default: return { CMD_ERROR, 0, INVALID_TILE };
  }
 
  /* Check range of destination height */
  if (h > _settings_game.construction.map_height_limit) return { CommandCost(oldh == 0 ? STR_ERROR_ALREADY_AT_SEA_LEVEL : STR_ERROR_TOO_HIGH), 0, INVALID_TILE };
 
  Money money = GetAvailableMoneyForCommand();
  CommandCost cost(EXPENSES_CONSTRUCTION);
  CommandCost last_error(lm == LM_LEVEL ? STR_ERROR_ALREADY_LEVELLED : INVALID_STRING_ID);
  bool had_success = false;
 
  const Company *c = Company::GetIfValid(_current_company);
  int limit = (c == nullptr ? INT32_MAX : GB(c->terraform_limit, 16, 16));
  if (limit == 0) return { CommandCost(STR_ERROR_TERRAFORM_LIMIT_REACHED), 0, INVALID_TILE };
 
  TileIndex error_tile = INVALID_TILE;
  std::unique_ptr<TileIterator> iter = TileIterator::Create(tile, start_tile, diagonal);
  for (; *iter != INVALID_TILE; ++(*iter)) {
    TileIndex t = *iter;
    uint curh = TileHeight(t);
    while (curh != h) {
      CommandCost ret;
      std::tie(ret, std::ignore, error_tile) = Command<CMD_TERRAFORM_LAND>::Do(flags & ~DC_EXEC, t, SLOPE_N, curh <= h);
      if (ret.Failed()) {
        last_error = ret;
 
        /* Did we reach the limit? */
        if (ret.GetErrorMessage() == STR_ERROR_TERRAFORM_LIMIT_REACHED) limit = 0;
        break;
      }
 
      if (flags & DC_EXEC) {
        money -= ret.GetCost();
        if (money < 0) {
          return { cost, ret.GetCost(), error_tile };
        }
        Command<CMD_TERRAFORM_LAND>::Do(flags, t, SLOPE_N, curh <= h);
      } else {
        /* When we're at the terraform limit we better bail (unneeded) testing as well.
         * This will probably cause the terraforming cost to be underestimated, but only
         * when it's near the terraforming limit. Even then, the estimation is
         * completely off due to it basically counting terraforming double, so it being
         * cut off earlier might even give a better estimate in some cases. */
        if (--limit <= 0) {
          had_success = true;
          break;
        }
      }
 
      cost.AddCost(ret);
      curh += (curh > h) ? -1 : 1;
      had_success = true;
    }
 
    if (limit <= 0) break;
  }
 
  CommandCost cc_ret = had_success ? cost : last_error;
  return { cc_ret, 0, cc_ret.Succeeded() ? tile : error_tile };
}