tree_cmd.cpp

Go to the documentation of this file.

/*
 * 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 <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#include "stdafx.h"
#include "clear_map.h"
#include "landscape.h"
#include "tree_map.h"
#include "viewport_func.h"
#include "command_func.h"
#include "town.h"
#include "genworld.h"
#include "clear_func.h"
#include "company_func.h"
#include "sound_func.h"
#include "water.h"
#include "company_base.h"
#include "core/geometry_type.hpp"
#include "core/random_func.hpp"
#include "newgrf_generic.h"
#include "timer/timer_game_tick.h"
#include "tree_cmd.h"
#include "landscape_cmd.h"
 
#include "table/strings.h"
#include "table/tree_land.h"
#include "table/clear_land.h"
 
#include "safeguards.h"

enum ExtraTreePlacement : uint8_t {
  ETP_NO_SPREAD,           
  ETP_SPREAD_RAINFOREST,   
  ETP_SPREAD_ALL,          
  ETP_NO_GROWTH_NO_SPREAD, 
};

uint8_t _trees_tick_ctr;
 
static const uint16_t DEFAULT_TREE_STEPS = 1000;             
static const uint16_t DEFAULT_RAINFOREST_TREE_STEPS = 15000; 
static const uint16_t EDITOR_TREE_DIV = 5;                   

static bool CanPlantTreesOnTile(TileIndex tile, bool allow_desert)
{
  switch (GetTileType(tile)) {
    case TileType::Water:
      return !IsBridgeAbove(tile) && IsCoast(tile) && !IsSlopeWithOneCornerRaised(GetTileSlope(tile));
 
    case TileType::Clear:
      return !IsBridgeAbove(tile) && !IsClearGround(tile, ClearGround::Fields) && !IsClearGround(tile, ClearGround::Rocks) &&
             (allow_desert || !IsClearGround(tile, ClearGround::Desert));
 
    default: return false;
  }
}

static TreeGround TreeGroundFromClearGround(ClearGround clearground)
{
  switch (clearground) {
    case ClearGround::Grass: return TreeGround::Grass;
    case ClearGround::Rough: return TreeGround::Rough;
    default: return TreeGround::SnowOrDesert;
  }
}

static void PlantTreesOnTile(TileIndex tile, TreeType treetype, uint count, TreeGrowthStage growth)
{
  assert(treetype != TREE_INVALID);
  assert(CanPlantTreesOnTile(tile, true));
 
  TreeGround ground;
  uint density = 3;
 
  switch (GetTileType(tile)) {
    case TileType::Water:
      ground = TreeGround::Shore;
      ClearNeighbourNonFloodingStates(tile);
      break;
 
    case TileType::Clear: {
      ClearGround clearground = GetClearGround(tile);
      if (IsSnowTile(tile)) {
        ground = clearground == ClearGround::Rough ? TreeGround::RoughSnow : TreeGround::SnowOrDesert;
      } else {
        ground = TreeGroundFromClearGround(clearground);
      }
      if (clearground != ClearGround::Rough) density = GetClearDensity(tile);
      break;
    }
 
    default: NOT_REACHED();
  }
 
  MakeTree(tile, treetype, count, growth, ground, density);
}

static TreeType GetRandomTreeType(TileIndex tile, uint seed)
{
  switch (_settings_game.game_creation.landscape) {
    case LandscapeType::Temperate:
      return static_cast<TreeType>(seed * TREE_COUNT_TEMPERATE / 256 + TREE_TEMPERATE);
 
    case LandscapeType::Arctic:
      return static_cast<TreeType>(seed * TREE_COUNT_SUB_ARCTIC / 256 + TREE_SUB_ARCTIC);
 
    case LandscapeType::Tropic:
      switch (GetTropicZone(tile)) {
        case TROPICZONE_NORMAL:  return static_cast<TreeType>(seed * TREE_COUNT_SUB_TROPICAL / 256 + TREE_SUB_TROPICAL);
        case TROPICZONE_DESERT:  return static_cast<TreeType>((seed > 12) ? TREE_INVALID : TREE_CACTUS);
        default:                 return static_cast<TreeType>(seed * TREE_COUNT_RAINFOREST / 256 + TREE_RAINFOREST);
      }
 
    default:
      return static_cast<TreeType>(seed * TREE_COUNT_TOYLAND / 256 + TREE_TOYLAND);
  }
}

void PlaceTree(TileIndex tile, uint32_t r, bool keep_density)
{
  TreeType tree = GetRandomTreeType(tile, GB(r, 24, 8));
 
  if (tree != TREE_INVALID) {
    PlantTreesOnTile(tile, tree, GB(r, 22, 2), static_cast<TreeGrowthStage>(std::min<uint8_t>(GB(r, 16, 3), 6)));
    MarkTileDirtyByTile(tile);
 
    /* Maybe keep the existing ground density.*/
    if (keep_density) return;
 
    /* Rerandomize ground, if neither snow nor shore */
    TreeGround ground = GetTreeGround(tile);
    if (ground != TreeGround::SnowOrDesert && ground != TreeGround::RoughSnow && ground != TreeGround::Shore) {
      SetTreeGroundDensity(tile, (TreeGround)GB(r, 28, 1), 3);
    }
  }
}
 
struct BlobHarmonic {
  int amplitude;
  float phase;
  int frequency;
};

static void CreateStarShapedPolygon(int radius, std::span<const BlobHarmonic> harmonics, std::span<Point> shape)
{
  float theta = 0;
  float step = (M_PI * 2) / std::size(shape);
 
  /* Divide a circle into a number of equally spaced divisions. */
  for (Point &vertex : shape) {
 
    /* Add up the values of each harmonic at this segment.*/
    float deviation = std::accumulate(std::begin(harmonics), std::end(harmonics), 0.f, [theta](float d, const BlobHarmonic &harmonic) -> float {
      return d + sinf((theta + harmonic.phase) * harmonic.frequency) * harmonic.amplitude;
    });
 
    /* Smooth out changes. */
    float adjusted_radius = (radius / 2.f) + (deviation / 2);
 
    /* Add to the final polygon. */
    vertex.x = cosf(theta) * adjusted_radius;
    vertex.y = sinf(theta) * adjusted_radius;
 
    /* Proceed to the next segment. */
    theta += step;
  }
}

static void CreateRandomStarShapedPolygon(int radius, std::span<Point> shape)
{
  /* Valid values for the phase of blob harmonics are between 0 and Tau. we can get a value in the correct range
   * from Random() by dividing the maximum possible value by the desired maximum, and then dividing the random
   * value by the result. */
  static constexpr float PHASE_DIVISOR = static_cast<float>(INT32_MAX / M_PI * 2);
 
  /* These values are ones found in testing that result in suitable-looking polygons that did not self-intersect
   * and fit within a square of radius * radius dimensions. */
  std::initializer_list<BlobHarmonic> harmonics = {
    {radius / 2, Random() / PHASE_DIVISOR, 1},
    {radius / 4, Random() / PHASE_DIVISOR, 2},
    {radius / 8, Random() / PHASE_DIVISOR, 3},
    {radius / 16, Random() / PHASE_DIVISOR, 4},
  };
 
  CreateStarShapedPolygon(radius, harmonics, shape);
}

static bool IsPointInTriangle(int x, int y, const Point &v1, const Point &v2, const Point &v3)
{
  const int s = ((v1.x - v3.x) * (y - v3.y)) - ((v1.y - v3.y) * (x - v3.x));
  const int t = ((v2.x - v1.x) * (y - v1.y)) - ((v2.y - v1.y) * (x - v1.x));
 
  if ((s < 0) != (t < 0) && s != 0 && t != 0) return false;
 
  const int d = (v3.x - v2.x) * (y - v2.y) - (v3.y - v2.y) * (x - v2.x);
  return (d < 0) == (s + t <= 0);
}

static bool IsPointInStarShapedPolygon(int x, int y, std::span<Point> shape)
{
  for (auto it = std::begin(shape); it != std::end(shape); /* nothing */) {
    const Point &v1 = *it;
    ++it;
    const Point &v2 = (it == std::end(shape)) ? shape.front() : *it;
 
    if (IsPointInTriangle(x, y, v1, v2, {0, 0})) return true;
  }
 
  return false;
}

static void PlaceTreeGroups(uint num_groups)
{
  static constexpr uint GROVE_SEGMENTS = 16; 
  static constexpr uint GROVE_RADIUS = 16; 
 
  /* Shape in which trees may be contained. Array is here to reduce allocations. */
  std::array<Point, GROVE_SEGMENTS> grove;
 
  do {
    TileIndex center_tile = RandomTile();
 
    CreateRandomStarShapedPolygon(GROVE_RADIUS, grove);
 
    for (uint i = 0; i < DEFAULT_TREE_STEPS; i++) {
      IncreaseGeneratingWorldProgress(GWP_TREE);
 
      uint32_t r = Random();
      int x = GB(r, 0, 5) - GROVE_RADIUS;
      int y = GB(r, 8, 5) - GROVE_RADIUS;
      TileIndex cur_tile = TileAddWrap(center_tile, x, y);
 
      if (cur_tile == INVALID_TILE) continue;
      if (!CanPlantTreesOnTile(cur_tile, true)) continue;
      if (!IsPointInStarShapedPolygon(x, y, grove)) continue;
 
      PlaceTree(cur_tile, r);
    }
 
  } while (--num_groups);
}

static void PlaceTreeAtSameHeight(TileIndex tile, int height)
{
  for (uint i = 0; i < DEFAULT_TREE_STEPS; i++) {
    uint32_t r = Random();
    int x = GB(r, 0, 5) - 16;
    int y = GB(r, 8, 5) - 16;
    TileIndex cur_tile = TileAddWrap(tile, x, y);
    if (cur_tile == INVALID_TILE) continue;
 
    /* Keep in range of the existing tree */
    if (abs(x) + abs(y) > 16) continue;
 
    /* Clear tile, no farm-tiles or rocks */
    if (!CanPlantTreesOnTile(cur_tile, true)) continue;
 
    /* Not too much height difference */
    if (Delta(GetTileZ(cur_tile), height) > 2) continue;
 
    /* Place one tree and quit */
    PlaceTree(cur_tile, r);
    break;
  }
}

void PlaceTreesRandomly()
{
  int i, j, ht;
  uint8_t max_height = _settings_game.construction.map_height_limit;
 
  i = Map::ScaleBySize(DEFAULT_TREE_STEPS);
  if (_game_mode == GM_EDITOR) i /= EDITOR_TREE_DIV;
  do {
    uint32_t r = Random();
    TileIndex tile = RandomTileSeed(r);
 
    IncreaseGeneratingWorldProgress(GWP_TREE);
 
    if (CanPlantTreesOnTile(tile, true)) {
      PlaceTree(tile, r);
      if (_settings_game.game_creation.tree_placer != TreePlacer::Improved) continue;
 
      /* Place a number of trees based on the tile height.
       *  This gives a cool effect of multiple trees close together.
       *  It is almost real life ;) */
      ht = GetTileZ(tile);
      /* The higher we get, the more trees we plant */
      j = GetTileZ(tile) * 2;
      /* Above snowline more trees! */
      if (_settings_game.game_creation.landscape == LandscapeType::Arctic && ht > GetSnowLine()) j *= 3;
      /* Scale generation by maximum map height. */
      if (max_height > MAP_HEIGHT_LIMIT_ORIGINAL) j = j * MAP_HEIGHT_LIMIT_ORIGINAL / max_height;
      while (j--) {
        PlaceTreeAtSameHeight(tile, ht);
      }
    }
  } while (--i);
 
  /* place extra trees at rainforest area */
  if (_settings_game.game_creation.landscape == LandscapeType::Tropic) {
    i = Map::ScaleBySize(DEFAULT_RAINFOREST_TREE_STEPS);
    if (_game_mode == GM_EDITOR) i /= EDITOR_TREE_DIV;
 
    do {
      uint32_t r = Random();
      TileIndex tile = RandomTileSeed(r);
 
      IncreaseGeneratingWorldProgress(GWP_TREE);
 
      if (GetTropicZone(tile) == TROPICZONE_RAINFOREST && CanPlantTreesOnTile(tile, false)) {
        PlaceTree(tile, r);
      }
    } while (--i);
  }
}

uint PlaceTreeGroupAroundTile(TileIndex tile, TreeType treetype, uint radius, uint count, bool set_zone)
{
  assert(_game_mode == GM_EDITOR); // Due to InteractiveRandom being used in this function
  assert(treetype < TREE_TOYLAND + TREE_COUNT_TOYLAND);
  const bool allow_desert = treetype == TREE_CACTUS;
  uint planted = 0;
 
  for (; count > 0; count--) {
    /* Simple quasi-normal distribution with range [-radius; radius) */
    auto mkcoord = [&]() -> int32_t {
      const uint32_t rand = InteractiveRandom();
      const int32_t dist = GB<int32_t>(rand, 0, 8) + GB<int32_t>(rand, 8, 8) + GB<int32_t>(rand, 16, 8) + GB<int32_t>(rand, 24, 8);
      const int32_t scu = dist * radius / 512;
      return scu - radius;
    };
    const int32_t xofs = mkcoord();
    const int32_t yofs = mkcoord();
    const TileIndex tile_to_plant = TileAddWrap(tile, xofs, yofs);
    if (tile_to_plant != INVALID_TILE) {
      if (IsTileType(tile_to_plant, TileType::Trees) && GetTreeCount(tile_to_plant) < 4) {
        AddTreeCount(tile_to_plant, 1);
        SetTreeGrowth(tile_to_plant, TreeGrowthStage::Growing1);
        MarkTileDirtyByTile(tile_to_plant, 0);
        planted++;
      } else if (CanPlantTreesOnTile(tile_to_plant, allow_desert)) {
        PlantTreesOnTile(tile_to_plant, treetype, 0, TreeGrowthStage::Grown);
        MarkTileDirtyByTile(tile_to_plant, 0);
        planted++;
      }
    }
  }
 
  if (set_zone && IsInsideMM(treetype, TREE_RAINFOREST, TREE_CACTUS)) {
    for (TileIndex t : TileArea(tile).Expand(radius)) {
      if (GetTileType(t) != TileType::Void && DistanceSquare(tile, t) < radius * radius) SetTropicZone(t, TROPICZONE_RAINFOREST);
    }
  }
 
  return planted;
}

void GenerateTrees()
{
  uint i, total;
 
  if (_settings_game.game_creation.tree_placer == TreePlacer::None) return;
 
  switch (_settings_game.game_creation.tree_placer) {
    case TreePlacer::Original: i = _settings_game.game_creation.landscape == LandscapeType::Arctic ? 15 : 6; break;
    case TreePlacer::Improved: i = _settings_game.game_creation.landscape == LandscapeType::Arctic ?  4 : 2; break;
    default: NOT_REACHED();
  }
 
  total = Map::ScaleBySize(DEFAULT_TREE_STEPS);
  if (_settings_game.game_creation.landscape == LandscapeType::Tropic) total += Map::ScaleBySize(DEFAULT_RAINFOREST_TREE_STEPS);
  total *= i;
  uint num_groups = (_settings_game.game_creation.landscape != LandscapeType::Toyland) ? Map::ScaleBySize(GB(Random(), 0, 5) + 25) : 0;
  total += num_groups * DEFAULT_TREE_STEPS;
  SetGeneratingWorldProgress(GWP_TREE, total);
 
  if (num_groups != 0) PlaceTreeGroups(num_groups);
 
  for (; i != 0; i--) {
    PlaceTreesRandomly();
  }
}

CommandCost CmdPlantTree(DoCommandFlags flags, TileIndex tile, TileIndex start_tile, uint8_t tree_to_plant, bool diagonal)
{
  StringID msg = INVALID_STRING_ID;
  CommandCost cost(EXPENSES_OTHER);
 
  if (start_tile >= Map::Size()) return CMD_ERROR;
  /* Check the tree type within the current climate */
  if (tree_to_plant != TREE_INVALID && !IsInsideBS(tree_to_plant, _tree_base_by_landscape[to_underlying(_settings_game.game_creation.landscape)], _tree_count_by_landscape[to_underlying(_settings_game.game_creation.landscape)])) return CMD_ERROR;
 
  Company *c = (_game_mode != GM_EDITOR) ? Company::GetIfValid(_current_company) : nullptr;
  int limit = (c == nullptr ? INT32_MAX : GB(c->tree_limit, 16, 16));
 
  std::unique_ptr<TileIterator> iter = TileIterator::Create(tile, start_tile, diagonal);
  for (; *iter != INVALID_TILE; ++(*iter)) {
    TileIndex current_tile = *iter;
    switch (GetTileType(current_tile)) {
      case TileType::Trees:
        /* no more space for trees? */
        if (GetTreeCount(current_tile) == 4) {
          msg = STR_ERROR_TREE_ALREADY_HERE;
          continue;
        }
 
        /* Test tree limit. */
        if (--limit < 1) {
          msg = STR_ERROR_TREE_PLANT_LIMIT_REACHED;
          break;
        }
 
        if (flags.Test(DoCommandFlag::Execute)) {
          AddTreeCount(current_tile, 1);
          MarkTileDirtyByTile(current_tile);
          if (c != nullptr) c->tree_limit -= 1 << 16;
        }
        /* 2x as expensive to add more trees to an existing tile */
        cost.AddCost(_price[Price::BuildTrees] * 2);
        break;
 
      case TileType::Water:
        if (!IsCoast(current_tile) || IsSlopeWithOneCornerRaised(GetTileSlope(current_tile))) {
          msg = STR_ERROR_CAN_T_BUILD_ON_WATER;
          continue;
        }
        [[fallthrough]];
 
      case TileType::Clear: {
        if (IsBridgeAbove(current_tile)) {
          msg = STR_ERROR_SITE_UNSUITABLE;
          continue;
        }
 
        TreeType treetype = (TreeType)tree_to_plant;
        /* Be a bit picky about which trees go where. */
        if (_settings_game.game_creation.landscape == LandscapeType::Tropic && treetype != TREE_INVALID && (
            /* No cacti outside the desert */
            (treetype == TREE_CACTUS && GetTropicZone(current_tile) != TROPICZONE_DESERT) ||
            /* No rainforest trees outside the rainforest, except in the editor mode where it makes those tiles rainforest tile */
            (IsInsideMM(treetype, TREE_RAINFOREST, TREE_CACTUS) && GetTropicZone(current_tile) != TROPICZONE_RAINFOREST && _game_mode != GM_EDITOR) ||
            /* And no subtropical trees in the desert/rainforest */
            (IsInsideMM(treetype, TREE_SUB_TROPICAL, TREE_TOYLAND) && GetTropicZone(current_tile) != TROPICZONE_NORMAL))) {
          msg = STR_ERROR_TREE_WRONG_TERRAIN_FOR_TREE_TYPE;
          continue;
        }
 
        /* Test tree limit. */
        if (--limit < 1) {
          msg = STR_ERROR_TREE_PLANT_LIMIT_REACHED;
          break;
        }
 
        if (IsTileType(current_tile, TileType::Clear)) {
          /* Remove fields or rocks. Note that the ground will get barrened */
          switch (GetClearGround(current_tile)) {
            case ClearGround::Fields:
            case ClearGround::Rocks: {
              CommandCost ret = Command<Commands::LandscapeClear>::Do(flags, current_tile);
              if (ret.Failed()) return ret;
              cost.AddCost(ret.GetCost());
              break;
            }
 
            default: break;
          }
        }
 
        if (_game_mode != GM_EDITOR && Company::IsValidID(_current_company)) {
          Town *t = ClosestTownFromTile(current_tile, _settings_game.economy.dist_local_authority);
          if (t != nullptr) ChangeTownRating(t, RATING_TREE_UP_STEP, RATING_TREE_MAXIMUM, flags);
        }
 
        if (flags.Test(DoCommandFlag::Execute)) {
          if (treetype == TREE_INVALID) {
            treetype = GetRandomTreeType(current_tile, GB(Random(), 24, 8));
            if (treetype == TREE_INVALID) treetype = TREE_CACTUS;
          }
 
          /* Plant full grown trees in scenario editor */
          PlantTreesOnTile(current_tile, treetype, 0, _game_mode == GM_EDITOR ? TreeGrowthStage::Grown : TreeGrowthStage::Growing1);
          MarkTileDirtyByTile(current_tile);
          if (c != nullptr) c->tree_limit -= 1 << 16;
 
          /* When planting rainforest-trees, set tropiczone to rainforest in editor. */
          if (_game_mode == GM_EDITOR && IsInsideMM(treetype, TREE_RAINFOREST, TREE_CACTUS)) {
            SetTropicZone(current_tile, TROPICZONE_RAINFOREST);
          }
        }
        cost.AddCost(_price[Price::BuildTrees]);
        break;
      }
 
      default:
        msg = STR_ERROR_SITE_UNSUITABLE;
        break;
    }
 
    /* Tree limit used up? No need to check more. */
    if (limit < 0) break;
  }
 
  if (cost.GetCost() == 0) {
    return CommandCost(msg);
  } else {
    return cost;
  }
}
 
struct TreeListEnt : PalSpriteID {
  int8_t x, y;
};

static void DrawTile_Trees(TileInfo *ti)
{
  switch (GetTreeGround(ti->tile)) {
    case TreeGround::Shore: DrawShoreTile(ti->tileh); break;
    case TreeGround::Grass: DrawClearLandTile(ti, GetTreeDensity(ti->tile)); break;
    case TreeGround::Rough: DrawHillyLandTile(ti); break;
    default: DrawGroundSprite(_clear_land_sprites_snow_desert[GetTreeDensity(ti->tile)] + SlopeToSpriteOffset(ti->tileh), PAL_NONE); break;
  }
 
  /* Do not draw trees when the invisible trees setting is set */
  if (IsInvisibilitySet(TO_TREES)) return;
 
  uint tmp = CountBits(ti->tile.base() + ti->x + ti->y);
  uint index = GB(tmp, 0, 2) + (GetTreeType(ti->tile) << 2);
 
  /* different tree styles above one of the grounds */
  if ((GetTreeGround(ti->tile) == TreeGround::SnowOrDesert || GetTreeGround(ti->tile) == TreeGround::RoughSnow) &&
      GetTreeDensity(ti->tile) >= 2 &&
      IsInsideMM(index, TREE_SUB_ARCTIC << 2, TREE_RAINFOREST << 2)) {
    index += 164 - (TREE_SUB_ARCTIC << 2);
  }
 
  assert(index < lengthof(_tree_layout_sprite));
 
  const PalSpriteID *s = _tree_layout_sprite[index];
  const TreePos *d = _tree_layout_xy[GB(tmp, 2, 2)];
 
  /* combine trees into one sprite object */
  StartSpriteCombine();
 
  TreeListEnt te[4];
 
  /* put the trees to draw in a list */
  uint trees = GetTreeCount(ti->tile);
 
  for (uint i = 0; i < trees; i++) {
    SpriteID sprite = s[0].sprite + (i == trees - 1 ? to_underlying(GetTreeGrowth(ti->tile)) : 3);
    PaletteID pal = s[0].pal;
 
    te[i].sprite = sprite;
    te[i].pal    = pal;
    te[i].x = d->x;
    te[i].y = d->y;
    s++;
    d++;
  }
 
  /* draw them in a sorted way */
  int z = ti->z + GetSlopeMaxPixelZ(ti->tileh) / 2;
 
  for (; trees > 0; trees--) {
    uint min = te[0].x + te[0].y;
    uint mi = 0;
 
    for (uint i = 1; i < trees; i++) {
      if ((uint)(te[i].x + te[i].y) < min) {
        min = te[i].x + te[i].y;
        mi = i;
      }
    }
 
    SpriteBounds bounds{{}, {TILE_SIZE, TILE_SIZE, 48}, {te[mi].x, te[mi].y, 0}};
    AddSortableSpriteToDraw(te[mi].sprite, te[mi].pal, ti->x, ti->y, z, bounds, IsTransparencySet(TO_TREES));
 
    /* replace the removed one with the last one */
    te[mi] = te[trees - 1];
  }
 
  EndSpriteCombine();
}
 

static int GetSlopePixelZ_Trees(TileIndex tile, uint x, uint y, [[maybe_unused]] bool ground_vehicle)
{
  auto [tileh, z] = GetTilePixelSlope(tile);
 
  return z + GetPartialPixelZ(x & 0xF, y & 0xF, tileh);
}

static CommandCost ClearTile_Trees(TileIndex tile, DoCommandFlags flags)
{
  if (Company::IsValidID(_current_company)) {
    Town *t = ClosestTownFromTile(tile, _settings_game.economy.dist_local_authority);
    if (t != nullptr) ChangeTownRating(t, RATING_TREE_DOWN_STEP, RATING_TREE_MINIMUM, flags);
  }
 
  uint num = GetTreeCount(tile);
  if (IsInsideMM(GetTreeType(tile), TREE_RAINFOREST, TREE_CACTUS)) num *= 4;
 
  if (flags.Test(DoCommandFlag::Execute)) DoClearSquare(tile);
 
  return CommandCost(EXPENSES_CONSTRUCTION, num * _price[Price::ClearTrees]);
}

static void GetTileDesc_Trees(TileIndex tile, TileDesc &td)
{
  TreeType tt = GetTreeType(tile);
 
  if (IsInsideMM(tt, TREE_RAINFOREST, TREE_CACTUS)) {
    td.str = STR_LAI_TREE_NAME_RAINFOREST;
  } else {
    td.str = tt == TREE_CACTUS ? STR_LAI_TREE_NAME_CACTUS_PLANTS : STR_LAI_TREE_NAME_TREES;
  }
 
  td.owner[0] = GetTileOwner(tile);
}
 
static void TileLoopTreesDesert(TileIndex tile)
{
  switch (GetTropicZone(tile)) {
    case TROPICZONE_DESERT:
      if (GetTreeGround(tile) != TreeGround::SnowOrDesert) {
        SetTreeGroundDensity(tile, TreeGround::SnowOrDesert, 3);
        MarkTileDirtyByTile(tile);
      }
      break;
 
    case TROPICZONE_RAINFOREST: {
      static const SoundFx forest_sounds[] = {
        SND_42_RAINFOREST_1,
        SND_43_RAINFOREST_2,
        SND_44_RAINFOREST_3,
        SND_48_RAINFOREST_4
      };
      uint32_t r = Random();
 
      if (Chance16I(1, 200, r) && _settings_client.sound.ambient) SndPlayTileFx(forest_sounds[GB(r, 16, 2)], tile);
      break;
    }
 
    default: break;
  }
}
 
static void TileLoopTreesAlps(TileIndex tile)
{
  int k = GetTileZ(tile) - GetSnowLine() + 1;
 
  if (k < 0) {
    switch (GetTreeGround(tile)) {
      case TreeGround::SnowOrDesert: SetTreeGroundDensity(tile, TreeGround::Grass, 3); break;
      case TreeGround::RoughSnow:  SetTreeGroundDensity(tile, TreeGround::Rough, 3); break;
      default: return;
    }
  } else {
    uint density = std::min<uint>(k, 3);
 
    if (GetTreeGround(tile) != TreeGround::SnowOrDesert && GetTreeGround(tile) != TreeGround::RoughSnow) {
      TreeGround tg = GetTreeGround(tile) == TreeGround::Rough ? TreeGround::RoughSnow : TreeGround::SnowOrDesert;
      SetTreeGroundDensity(tile, tg, density);
    } else if (GetTreeDensity(tile) != density) {
      SetTreeGroundDensity(tile, GetTreeGround(tile), density);
    } else {
      if (GetTreeDensity(tile) == 3) {
        uint32_t r = Random();
        if (Chance16I(1, 200, r) && _settings_client.sound.ambient) {
          SndPlayTileFx((r & 0x80000000) ? SND_39_ARCTIC_SNOW_2 : SND_34_ARCTIC_SNOW_1, tile);
        }
      }
      return;
    }
  }
  MarkTileDirtyByTile(tile);
}

static bool TreesOnTileCanSpread(TileIndex tile)
{
  /* Desert and rainforest trees need special handling. */
  if (_settings_game.game_creation.landscape == LandscapeType::Tropic) {
    switch (GetTropicZone(tile)) {
      case TROPICZONE_DESERT:
        /* Cacti never spread. */
        return false;
      case TROPICZONE_RAINFOREST:
        return (_settings_game.construction.extra_tree_placement == ETP_SPREAD_ALL || _settings_game.construction.extra_tree_placement == ETP_SPREAD_RAINFOREST);
      default:
        return _settings_game.construction.extra_tree_placement == ETP_SPREAD_ALL;
    }
  }
 
  return (_settings_game.construction.extra_tree_placement == ETP_SPREAD_ALL);
}

static void TileLoop_Trees(TileIndex tile)
{
  if (GetTreeGround(tile) == TreeGround::Shore) {
    TileLoop_Water(tile);
  } else {
    switch (_settings_game.game_creation.landscape) {
      case LandscapeType::Tropic: TileLoopTreesDesert(tile); break;
      case LandscapeType::Arctic: TileLoopTreesAlps(tile);   break;
      default: break;
    }
  }
 
  AmbientSoundEffect(tile);
 
  /* TimerGameTick::counter is incremented by 256 between each call, so ignore lower 8 bits.
   * Also, we use a simple hash to spread the updates evenly over the map.
   * 11 and 9 are just some co-prime numbers for better spread.
   */
  uint32_t cycle = 11 * TileX(tile) + 9 * TileY(tile) + (TimerGameTick::counter >> 8);
 
  /* Handle growth of grass (under trees/on TileType::Trees tiles) at every 8th processings, like it's done for grass on TileType::Clear tiles. */
  if ((cycle & 7) == 7 && GetTreeGround(tile) == TreeGround::Grass) {
    uint density = GetTreeDensity(tile);
    if (density < 3) {
      SetTreeGroundDensity(tile, TreeGround::Grass, density + 1);
      MarkTileDirtyByTile(tile);
    }
  }
 
  if (_settings_game.construction.extra_tree_placement == ETP_NO_GROWTH_NO_SPREAD) return;
 
  static const uint32_t TREE_UPDATE_FREQUENCY = 16;  // How many tile updates happen for one tree update
  if (cycle % TREE_UPDATE_FREQUENCY != TREE_UPDATE_FREQUENCY - 1) return;
 
  switch (GetTreeGrowth(tile)) {
    case TreeGrowthStage::Grown: // regular sized tree
      if (_settings_game.game_creation.landscape == LandscapeType::Tropic &&
          GetTreeType(tile) != TREE_CACTUS &&
          GetTropicZone(tile) == TROPICZONE_DESERT) {
        AddTreeGrowth(tile, 1);
      } else {
        switch (GB(Random(), 0, 3)) {
          case 0: // start destructing
            AddTreeGrowth(tile, 1);
            break;
 
          case 1: // add a tree
            if (GetTreeCount(tile) < 4 && TreesOnTileCanSpread(tile)) {
              AddTreeCount(tile, 1);
              SetTreeGrowth(tile, TreeGrowthStage::Growing1);
              break;
            }
            [[fallthrough]];
 
          case 2: { // add a neighbouring tree
            if (!TreesOnTileCanSpread(tile)) break;
 
            TreeType treetype = GetTreeType(tile);
 
            tile += TileOffsByDir(static_cast<Direction>(Random() % DIR_END));
 
            if (!CanPlantTreesOnTile(tile, false)) return;
 
            /* Don't plant trees, if ground was freshly cleared */
            if (IsTileType(tile, TileType::Clear) && GetClearGround(tile) == ClearGround::Grass && !IsSnowTile(tile) && GetClearDensity(tile) != 3) return;
 
            PlantTreesOnTile(tile, treetype, 0, TreeGrowthStage::Growing1);
 
            break;
          }
 
          default:
            return;
        }
      }
      break;
 
    case TreeGrowthStage::Dead: // final stage of tree destruction
      if (!TreesOnTileCanSpread(tile)) {
        /* if trees can't spread just plant a new one to prevent deforestation */
        SetTreeGrowth(tile, TreeGrowthStage::Growing1);
      } else if (GetTreeCount(tile) > 1) {
        /* more than one tree, delete it */
        AddTreeCount(tile, -1);
        SetTreeGrowth(tile, TreeGrowthStage::Grown);
      } else {
        /* just one tree, change type into TileType::Clear */
        switch (GetTreeGround(tile)) {
          case TreeGround::Shore: MakeShore(tile); break;
          case TreeGround::Grass: MakeClear(tile, ClearGround::Grass, GetTreeDensity(tile)); break;
          case TreeGround::Rough: MakeClear(tile, ClearGround::Rough, 3); break;
          case TreeGround::RoughSnow: {
            uint density = GetTreeDensity(tile);
            MakeClear(tile, ClearGround::Rough, 3);
            MakeSnow(tile, density);
            break;
          }
          default: // snow or desert
            if (_settings_game.game_creation.landscape == LandscapeType::Tropic) {
              MakeClear(tile, ClearGround::Desert, GetTreeDensity(tile));
            } else {
              uint density = GetTreeDensity(tile);
              MakeClear(tile, ClearGround::Grass, 3);
              MakeSnow(tile, density);
            }
            break;
        }
      }
      break;
 
    default:
      AddTreeGrowth(tile, 1);
      break;
  }
 
  MarkTileDirtyByTile(tile);
}

bool DecrementTreeCounter()
{
  /* Ensure _trees_tick_ctr can be decremented past zero only once for the largest map size. */
  static_assert(2 * (MAX_MAP_SIZE_BITS - MIN_MAP_SIZE_BITS) - 4 <= std::numeric_limits<uint8_t>::digits);
 
  /* byte underflow */
  uint8_t old_trees_tick_ctr = _trees_tick_ctr;
  _trees_tick_ctr -= Map::ScaleBySize(1);
  return old_trees_tick_ctr <= _trees_tick_ctr;
}

static void PlantRandomTree(bool rainforest)
{
  uint32_t r = Random();
  TileIndex tile = RandomTileSeed(r);
 
  if (rainforest && GetTropicZone(tile) != TROPICZONE_RAINFOREST) return;
  if (!CanPlantTreesOnTile(tile, false)) return;
 
  TreeType tree = GetRandomTreeType(tile, GB(r, 24, 8));
  if (tree == TREE_INVALID) return;
 
  PlantTreesOnTile(tile, tree, 0, TreeGrowthStage::Growing1);
}
 
void OnTick_Trees()
{
  /* Don't spread trees if that's not allowed */
  if (_settings_game.construction.extra_tree_placement == ETP_NO_SPREAD || _settings_game.construction.extra_tree_placement == ETP_NO_GROWTH_NO_SPREAD) return;
 
  /* Skip some tree ticks for map sizes below 256 * 256. 64 * 64 is 16 times smaller, so
   * this is the maximum number of ticks that are skipped. Number of ticks to skip is
   * inversely proportional to map size, so that is handled to create a mask. */
  int skip = Map::ScaleBySize(16);
  if (skip < 16 && (TimerGameTick::counter & (16 / skip - 1)) != 0) return;
 
  /* place a tree at a random rainforest spot */
  if (_settings_game.game_creation.landscape == LandscapeType::Tropic) {
    for (uint c = Map::ScaleBySize(1); c > 0; c--) {
      PlantRandomTree(true);
    }
  }
 
  if (!DecrementTreeCounter() || _settings_game.construction.extra_tree_placement == ETP_SPREAD_RAINFOREST) return;
 
  /* place a tree at a random spot */
  PlantRandomTree(false);
}
 
void InitializeTrees()
{
  _trees_tick_ctr = 0;
}
 

extern const TileTypeProcs _tile_type_trees_procs = {
  .draw_tile_proc = DrawTile_Trees,
  .get_slope_pixel_z_proc = GetSlopePixelZ_Trees,
  .clear_tile_proc = ClearTile_Trees,
  .get_tile_desc_proc = GetTileDesc_Trees,
  .tile_loop_proc = TileLoop_Trees,
  .terraform_tile_proc = [](TileIndex tile, DoCommandFlags flags, int, Slope) { return Command<Commands::LandscapeClear>::Do(flags, tile); }
};