path: root/src/landscape.cpp

/* $Id$ */

#include "stdafx.h"
#include "openttd.h"
#include "bridge_map.h"
#include "heightmap.h"
#include "clear_map.h"
#include "date.h"
#include "functions.h"
#include "map.h"
#include "player.h"
#include "spritecache.h"
#include "table/sprites.h"
#include "tile.h"
#include <stdarg.h>
#include "viewport.h"
#include "command.h"
#include "landscape.h"
#include "vehicle.h"
#include "variables.h"
#include "void_map.h"
#include "water_map.h"
#include "tgp.h"
#include "genworld.h"
#include "heightmap.h"

extern const TileTypeProcs
	_tile_type_clear_procs,
	_tile_type_rail_procs,
	_tile_type_road_procs,
	_tile_type_town_procs,
	_tile_type_trees_procs,
	_tile_type_station_procs,
	_tile_type_water_procs,
	_tile_type_dummy_procs,
	_tile_type_industry_procs,
	_tile_type_tunnelbridge_procs,
	_tile_type_unmovable_procs;

const TileTypeProcs * const _tile_type_procs[16] = {
	&_tile_type_clear_procs,
	&_tile_type_rail_procs,
	&_tile_type_road_procs,
	&_tile_type_town_procs,
	&_tile_type_trees_procs,
	&_tile_type_station_procs,
	&_tile_type_water_procs,
	&_tile_type_dummy_procs,
	&_tile_type_industry_procs,
	&_tile_type_tunnelbridge_procs,
	&_tile_type_unmovable_procs,
};

/* landscape slope => sprite */
const byte _tileh_to_sprite[32] = {
	0, 1, 2, 3, 4, 5, 6,  7, 8, 9, 10, 11, 12, 13, 14, 0,
	0, 0, 0, 0, 0, 0, 0, 16, 0, 0,  0, 17,  0, 15, 18, 0,
};

const Slope _inclined_tileh[] = {
	SLOPE_SW,  SLOPE_NW,  SLOPE_SW,  SLOPE_SE, SLOPE_NE, SLOPE_SE, SLOPE_NE, SLOPE_NW,
	SLOPE_E,   SLOPE_N,   SLOPE_W,   SLOPE_S,
	SLOPE_NWS, SLOPE_WSE, SLOPE_SEN, SLOPE_ENW
};

SnowLine *_snow_line = NULL;

uint GetPartialZ(int x, int y, Slope corners)
{
	int z = 0;

	switch (corners) {
	case SLOPE_W:
		if (x - y >= 0)
			z = (x - y) >> 1;
		break;

	case SLOPE_S:
		y ^= 0xF;
		if ( (x - y) >= 0)
			z = (x - y) >> 1;
		break;

	case SLOPE_SW:
		z = (x >> 1) + 1;
		break;

	case SLOPE_E:
		if (y - x >= 0)
			z = (y - x) >> 1;
		break;

	case SLOPE_EW:
	case SLOPE_NS:
	case SLOPE_ELEVATED:
		z = 4;
		break;

	case SLOPE_SE:
		z = (y >> 1) + 1;
		break;

	case SLOPE_WSE:
		z = 8;
		y ^= 0xF;
		if (x - y < 0)
			z += (x - y) >> 1;
		break;

	case SLOPE_N:
		y ^= 0xF;
		if (y - x >= 0)
			z = (y - x) >> 1;
		break;

	case SLOPE_NW:
		z = (y ^ 0xF) >> 1;
		break;

	case SLOPE_NWS:
		z = 8;
		if (x - y < 0)
			z += (x - y) >> 1;
		break;

	case SLOPE_NE:
		z = (x ^ 0xF) >> 1;
		break;

	case SLOPE_ENW:
		z = 8;
		y ^= 0xF;
		if (y - x < 0)
			z += (y - x) >> 1;
		break;

	case SLOPE_SEN:
		z = 8;
		if (y - x < 0)
			z += (y - x) >> 1;
		break;

	case SLOPE_STEEP_S:
		z = 1 + ((x + y) >> 1);
		break;

	case SLOPE_STEEP_W:
		z = 1 + ((x + (y ^ 0xF)) >> 1);
		break;

	case SLOPE_STEEP_N:
		z = 1 + (((x ^ 0xF) + (y ^ 0xF)) >> 1);
		break;

	case SLOPE_STEEP_E:
		z = 1 + (((x ^ 0xF) + (y ^ 0xF)) >> 1);
		break;

		default: break;
	}

	return z;
}

uint GetSlopeZ(int x, int y)
{
	TileIndex tile = TileVirtXY(x, y);

	return _tile_type_procs[GetTileType(tile)]->get_slope_z_proc(tile, x, y);
}


static Slope GetFoundationSlope(TileIndex tile, uint* z)
{
	Slope tileh = GetTileSlope(tile, z);
	Slope slope = _tile_type_procs[GetTileType(tile)]->get_slope_tileh_proc(tile, tileh);

	/* Flatter slope -> higher base height */
	if (slope < tileh) *z += TILE_HEIGHT;
	return slope;
}


static bool HasFoundationNW(TileIndex tile, Slope slope_here, uint z_here)
{
	uint z;
	Slope slope = GetFoundationSlope(TILE_ADDXY(tile, 0, -1), &z);

	return
		(
			z_here + (slope_here & SLOPE_N ? TILE_HEIGHT : 0) + (slope_here == SLOPE_STEEP_N ? TILE_HEIGHT : 0) >
			z      + (slope      & SLOPE_E ? TILE_HEIGHT : 0) + (slope      == SLOPE_STEEP_E ? TILE_HEIGHT : 0)
		) || (
			z_here + (slope_here & SLOPE_W ? TILE_HEIGHT : 0) + (slope_here == SLOPE_STEEP_W ? TILE_HEIGHT : 0) >
			z      + (slope      & SLOPE_S ? TILE_HEIGHT : 0) + (slope      == SLOPE_STEEP_S ? TILE_HEIGHT : 0)
		);
}


static bool HasFoundationNE(TileIndex tile, Slope slope_here, uint z_here)
{
	uint z;
	Slope slope = GetFoundationSlope(TILE_ADDXY(tile, -1, 0), &z);

	return
		(
			z_here + (slope_here & SLOPE_N ? TILE_HEIGHT : 0) + (slope_here == SLOPE_STEEP_N ? TILE_HEIGHT : 0) >
			z      + (slope      & SLOPE_W ? TILE_HEIGHT : 0) + (slope      == SLOPE_STEEP_W ? TILE_HEIGHT : 0)
		) || (
			z_here + (slope_here & SLOPE_E ? TILE_HEIGHT : 0) + (slope_here == SLOPE_STEEP_E ? TILE_HEIGHT : 0) >
			z      + (slope      & SLOPE_S ? TILE_HEIGHT : 0) + (slope      == SLOPE_STEEP_S ? TILE_HEIGHT : 0)
		);
}


void DrawFoundation(TileInfo *ti, uint f)
{
	SpriteID sprite_base = SPR_SLOPES_BASE - 15;
	Slope slope;
	uint z;

	slope = GetFoundationSlope(ti->tile, &z);
	if (!HasFoundationNW(ti->tile, slope, z)) sprite_base += 22;
	if (!HasFoundationNE(ti->tile, slope, z)) sprite_base += 44;

	if (IsSteepSlope(ti->tileh)) {
		SpriteID lower_base;

		/* Lower part of foundation */
		lower_base = sprite_base;
		if (lower_base == SPR_SLOPES_BASE - 15) lower_base = SPR_FOUNDATION_BASE;
		AddSortableSpriteToDraw(
			lower_base + (ti->tileh & ~SLOPE_STEEP), PAL_NONE, ti->x, ti->y, 16, 16, 7, ti->z
		);
		ti->z += TILE_HEIGHT;
		ti->tileh = _inclined_tileh[f - 15];
		if (f < 15 + 8) {
			/* inclined */
			AddSortableSpriteToDraw(sprite_base + f, PAL_NONE, ti->x, ti->y, 16, 16, 1, ti->z);
			OffsetGroundSprite(31, 9);
		} else if (f >= 15 + 8 + 4) {
			/* three corners raised */
			SpriteID upper = sprite_base + 15 + (f - 15 - 8 - 4) * 2;

			AddSortableSpriteToDraw(upper, PAL_NONE, ti->x, ti->y, 16, 16, 1, ti->z);
			AddChildSpriteScreen(upper + 1, PAL_NONE, 31, 9);
			OffsetGroundSprite(31, 9);
		} else {
			/* one corner raised */
			OffsetGroundSprite(31, 1);
		}
	} else {
		if (f < 15) {
			/* leveled foundation
			 * Use the original slope sprites if NW and NE borders should be visible */
			if (sprite_base  == SPR_SLOPES_BASE - 15) sprite_base = SPR_FOUNDATION_BASE;

			AddSortableSpriteToDraw(sprite_base + f, PAL_NONE, ti->x, ti->y, 16, 16, 7, ti->z);
			ti->z += TILE_HEIGHT;
			ti->tileh = SLOPE_FLAT;
			OffsetGroundSprite(31, 1);
		} else {
			/* inclined foundation */
			AddSortableSpriteToDraw(sprite_base + f, PAL_NONE, ti->x, ti->y, 16, 16, 1, ti->z);
			ti->tileh = _inclined_tileh[f - 15];
			OffsetGroundSprite(31, 9);
		}
	}
}

void DoClearSquare(TileIndex tile)
{
	MakeClear(tile, CLEAR_GRASS, _generating_world ? 3 : 0);
	MarkTileDirtyByTile(tile);
}

uint32 GetTileTrackStatus(TileIndex tile, TransportType mode, uint sub_mode)
{
	return _tile_type_procs[GetTileType(tile)]->get_tile_track_status_proc(tile, mode, sub_mode);
}

void ChangeTileOwner(TileIndex tile, PlayerID old_player, PlayerID new_player)
{
	_tile_type_procs[GetTileType(tile)]->change_tile_owner_proc(tile, old_player, new_player);
}

void GetAcceptedCargo(TileIndex tile, AcceptedCargo ac)
{
	memset(ac, 0, sizeof(AcceptedCargo));
	_tile_type_procs[GetTileType(tile)]->get_accepted_cargo_proc(tile, ac);
}

void AnimateTile(TileIndex tile)
{
	_tile_type_procs[GetTileType(tile)]->animate_tile_proc(tile);
}

void ClickTile(TileIndex tile)
{
	_tile_type_procs[GetTileType(tile)]->click_tile_proc(tile);
}

void GetTileDesc(TileIndex tile, TileDesc *td)
{
	_tile_type_procs[GetTileType(tile)]->get_tile_desc_proc(tile, td);
}

/**
 * Has a snow line table already been loaded.
 * @return true if the table has been loaded already.
 */
bool IsSnowLineSet(void)
{
	return _snow_line != NULL;
}

/**
 * Set a variable snow line, as loaded from a newgrf file.
 * @param table the 12 * 32 byte table containing the snowline for each day
 */
void SetSnowLine(byte table[SNOW_LINE_MONTHS][SNOW_LINE_DAYS])
{
	_snow_line = CallocT<SnowLine>(1);
	memcpy(_snow_line->table, table, sizeof(_snow_line->table));

	for (uint i = 0; i < SNOW_LINE_MONTHS; i++) {
		for (uint j = 0; j < SNOW_LINE_DAYS; j++) {
			_snow_line->highest_value = max(_snow_line->highest_value, table[i][j]);
		}
	}
}

/**
 * Get the current snow line, either variable or static.
 * @return the snow line height.
 */
byte GetSnowLine(void)
{
	if (_snow_line == NULL) return _opt.snow_line;

	YearMonthDay ymd;
	ConvertDateToYMD(_date, &ymd);
	return _snow_line->table[ymd.month][ymd.day];
}

/**
 * Get the highest possible snow line height, either variable or static.
 * @return the highest snow line height.
 */
byte HighestSnowLine(void)
{
	return _snow_line == NULL ? _opt.snow_line : _snow_line->highest_value;
}

/**
 * Clear the variable snow line table and free the memory.
 */
void ClearSnowLine(void)
{
	free(_snow_line);
	_snow_line = NULL;
}

/** Clear a piece of landscape
 * @param tile tile to clear
 * @param flags of operation to conduct
 * @param p1 unused
 * @param p2 unused
 */
CommandCost CmdLandscapeClear(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);

	return _tile_type_procs[GetTileType(tile)]->clear_tile_proc(tile, flags);
}

/** Clear a big piece of landscape
 * @param tile end tile of area dragging
 * @param p1 start tile of area dragging
 * @param flags of operation to conduct
 * @param p2 unused
 */
CommandCost CmdClearArea(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	CommandCost cost, ret, money;
	int ex;
	int ey;
	int sx, sy;
	int x, y;
	bool success = false;

	if (p1 >= MapSize()) return CMD_ERROR;

	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);

	/* make sure sx,sy are smaller than ex,ey */
	ex = TileX(tile);
	ey = TileY(tile);
	sx = TileX(p1);
	sy = TileY(p1);
	if (ex < sx) Swap(ex, sx);
	if (ey < sy) Swap(ey, sy);

	money.AddCost(GetAvailableMoneyForCommand());

	for (x = sx; x <= ex; ++x) {
		for (y = sy; y <= ey; ++y) {
			ret = DoCommand(TileXY(x, y), 0, 0, flags & ~DC_EXEC, CMD_LANDSCAPE_CLEAR);
			if (CmdFailed(ret)) continue;
			success = true;

			if (flags & DC_EXEC) {
				money.AddCost(-ret.GetCost());
				if (ret.GetCost() > 0 && money.GetCost() < 0) {
					_additional_cash_required = ret.GetCost();
					return cost;
				}
				DoCommand(TileXY(x, y), 0, 0, flags, CMD_LANDSCAPE_CLEAR);

				/* draw explosion animation... */
				if ((x == sx || x == ex) && (y == sy || y == ey)) {
					/* big explosion in each corner, or small explosion for single tiles */
					CreateEffectVehicleAbove(x * TILE_SIZE + TILE_SIZE / 2, y * TILE_SIZE + TILE_SIZE / 2, 2,
						sy == ey && sx == ex ? EV_EXPLOSION_SMALL : EV_EXPLOSION_LARGE
					);
				}
			}
			cost.AddCost(ret);
		}
	}

	return (success) ? cost : CMD_ERROR;
}


#define TILELOOP_BITS 4
#define TILELOOP_SIZE (1 << TILELOOP_BITS)
#define TILELOOP_ASSERTMASK ((TILELOOP_SIZE - 1) + ((TILELOOP_SIZE - 1) << MapLogX()))
#define TILELOOP_CHKMASK (((1 << (MapLogX() - TILELOOP_BITS))-1) << TILELOOP_BITS)

void RunTileLoop()
{
	TileIndex tile;
	uint count;

	tile = _cur_tileloop_tile;

	assert( (tile & ~TILELOOP_ASSERTMASK) == 0);
	count = (MapSizeX() / TILELOOP_SIZE) * (MapSizeY() / TILELOOP_SIZE);
	do {
		_tile_type_procs[GetTileType(tile)]->tile_loop_proc(tile);

		if (TileX(tile) < MapSizeX() - TILELOOP_SIZE) {
			tile += TILELOOP_SIZE; // no overflow
		} else {
			tile = TILE_MASK(tile - TILELOOP_SIZE * (MapSizeX() / TILELOOP_SIZE - 1) + TileDiffXY(0, TILELOOP_SIZE)); /* x would overflow, also increase y */
		}
	} while (--count);
	assert( (tile & ~TILELOOP_ASSERTMASK) == 0);

	tile += 9;
	if (tile & TILELOOP_CHKMASK)
		tile = (tile + MapSizeX()) & TILELOOP_ASSERTMASK;
	_cur_tileloop_tile = tile;
}

void InitializeLandscape()
{
	uint maxx = MapMaxX();
	uint maxy = MapMaxY();
	uint sizex = MapSizeX();
	uint x;
	uint y;

	for (y = 0; y < maxy; y++) {
		for (x = 0; x < maxx; x++) {
			MakeClear(sizex * y + x, CLEAR_GRASS, 3);
			SetTileHeight(sizex * y + x, 0);
			SetTropicZone(sizex * y + x, TROPICZONE_INVALID);
			ClearBridgeMiddle(sizex * y + x);
		}
		MakeVoid(sizex * y + x);
	}
	for (x = 0; x < sizex; x++) MakeVoid(sizex * y + x);
}

void ConvertGroundTilesIntoWaterTiles()
{
	TileIndex tile;
	uint z;
	Slope slope;

	for (tile = 0; tile < MapSize(); ++tile) {
		slope = GetTileSlope(tile, &z);
		if (IsTileType(tile, MP_CLEAR) && z == 0) {
			/* Make both water for tiles at level 0
			 * and make shore, as that looks much better
			 * during the generation. */
			switch (slope) {
				case SLOPE_FLAT:
					MakeWater(tile);
					break;

				case SLOPE_N:
				case SLOPE_E:
				case SLOPE_S:
				case SLOPE_W:
				case SLOPE_NW:
				case SLOPE_SW:
				case SLOPE_SE:
				case SLOPE_NE:
					MakeShore(tile);
					break;

				default:
					break;
			}
		}
	}
}

static const byte _genterrain_tbl_1[5] = { 10, 22, 33, 37, 4  };
static const byte _genterrain_tbl_2[5] = {  0,  0,  0,  0, 33 };

static void GenerateTerrain(int type, int flag)
{
	uint32 r;
	uint x;
	uint y;
	uint w;
	uint h;
	const Sprite* templ;
	const byte *p;
	Tile* tile;
	byte direction;

	r = Random();
	templ = GetSprite((((r >> 24) * _genterrain_tbl_1[type]) >> 8) + _genterrain_tbl_2[type] + 4845);

	x = r & MapMaxX();
	y = (r >> MapLogX()) & MapMaxY();


	if (x < 2 || y < 2) return;

	direction = GB(r, 22, 2);
	if (direction & 1) {
		w = templ->height;
		h = templ->width;
	} else {
		w = templ->width;
		h = templ->height;
	}
	p = templ->data;

	if (flag & 4) {
		uint xw = x * MapSizeY();
		uint yw = y * MapSizeX();
		uint bias = (MapSizeX() + MapSizeY()) * 16;

		switch (flag & 3) {
			case 0:
				if (xw + yw > MapSize() - bias) return;
				break;

			case 1:
				if (yw < xw + bias) return;
				break;

			case 2:
				if (xw + yw < MapSize() + bias) return;
				break;

			case 3:
				if (xw < yw + bias) return;
				break;
		}
	}

	if (x + w >= MapMaxX() - 1) return;
	if (y + h >= MapMaxY() - 1) return;

	tile = &_m[TileXY(x, y)];

	switch (direction) {
		case 0:
			do {
				Tile* tile_cur = tile;
				uint w_cur;

				for (w_cur = w; w_cur != 0; --w_cur) {
					if (*p >= tile_cur->type_height) tile_cur->type_height = *p;
					p++;
					tile_cur++;
				}
				tile += TileDiffXY(0, 1);
			} while (--h != 0);
			break;

		case 1:
			do {
				Tile* tile_cur = tile;
				uint h_cur;

				for (h_cur = h; h_cur != 0; --h_cur) {
					if (*p >= tile_cur->type_height) tile_cur->type_height = *p;
					p++;
					tile_cur += TileDiffXY(0, 1);
				}
				tile++;
			} while (--w != 0);
			break;

		case 2:
			tile += TileDiffXY(w - 1, 0);
			do {
				Tile* tile_cur = tile;
				uint w_cur;

				for (w_cur = w; w_cur != 0; --w_cur) {
					if (*p >= tile_cur->type_height) tile_cur->type_height = *p;
					p++;
					tile_cur--;
				}
				tile += TileDiffXY(0, 1);
			} while (--h != 0);
			break;

		case 3:
			tile += TileDiffXY(0, h - 1);
			do {
				Tile* tile_cur = tile;
				uint h_cur;

				for (h_cur = h; h_cur != 0; --h_cur) {
					if (*p >= tile_cur->type_height) tile_cur->type_height = *p;
					p++;
					tile_cur -= TileDiffXY(0, 1);
				}
				tile++;
			} while (--w != 0);
			break;
	}
}


#include "table/genland.h"

static void CreateDesertOrRainForest()
{
	TileIndex tile;
	TileIndex update_freq = MapSize() / 4;
	const TileIndexDiffC *data;
	uint i;

	for (tile = 0; tile != MapSize(); ++tile) {
		if ((tile % update_freq) == 0) IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);

		for (data = _make_desert_or_rainforest_data;
				data != endof(_make_desert_or_rainforest_data); ++data) {
			TileIndex t = TILE_MASK(tile + ToTileIndexDiff(*data));
			if (TileHeight(t) >= 4 || IsTileType(t, MP_WATER)) break;
		}
		if (data == endof(_make_desert_or_rainforest_data))
			SetTropicZone(tile, TROPICZONE_DESERT);
	}

	for (i = 0; i != 256; i++) {
		if ((i % 64) == 0) IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);

		RunTileLoop();
	}

	for (tile = 0; tile != MapSize(); ++tile) {
		if ((tile % update_freq) == 0) IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);

		for (data = _make_desert_or_rainforest_data;
				data != endof(_make_desert_or_rainforest_data); ++data) {
			TileIndex t = TILE_MASK(tile + ToTileIndexDiff(*data));
			if (IsTileType(t, MP_CLEAR) && IsClearGround(t, CLEAR_DESERT)) break;
		}
		if (data == endof(_make_desert_or_rainforest_data))
			SetTropicZone(tile, TROPICZONE_RAINFOREST);
	}
}

void GenerateLandscape(byte mode)
{
	const int gwp_desert_amount = 4 + 8;
	uint i;
	uint flag;
	uint32 r;

	if (mode == GW_HEIGHTMAP) {
		SetGeneratingWorldProgress(GWP_LANDSCAPE, (_opt.landscape == LT_TROPIC) ? 1 + gwp_desert_amount : 1);
		LoadHeightmap(_file_to_saveload.name);
		IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
	} else if (_patches.land_generator == LG_TERRAGENESIS) {
		SetGeneratingWorldProgress(GWP_LANDSCAPE, (_opt.landscape == LT_TROPIC) ? 3 + gwp_desert_amount : 3);
		GenerateTerrainPerlin();
	} else {
		switch (_opt.landscape) {
			case LT_ARCTIC:
				SetGeneratingWorldProgress(GWP_LANDSCAPE, 2);

				for (i = ScaleByMapSize((Random() & 0x7F) + 950); i != 0; --i) {
					GenerateTerrain(2, 0);
				}
				IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);

				r = Random();
				flag = GB(r, 0, 2) | 4;
				for (i = ScaleByMapSize(GB(r, 16, 7) + 450); i != 0; --i) {
					GenerateTerrain(4, flag);
				}
				IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
				break;

			case LT_TROPIC:
				SetGeneratingWorldProgress(GWP_LANDSCAPE, 3 + gwp_desert_amount);

				for (i = ScaleByMapSize((Random() & 0x7F) + 170); i != 0; --i) {
					GenerateTerrain(0, 0);
				}
				IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);

				r = Random();
				flag = GB(r, 0, 2) | 4;
				for (i = ScaleByMapSize(GB(r, 16, 8) + 1700); i != 0; --i) {
					GenerateTerrain(0, flag);
				}
				IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);

				flag ^= 2;

				for (i = ScaleByMapSize((Random() & 0x7F) + 410); i != 0; --i) {
					GenerateTerrain(3, flag);
				}
				IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
				break;

			default:
				SetGeneratingWorldProgress(GWP_LANDSCAPE, 1);

				i = ScaleByMapSize((Random() & 0x7F) + (3 - _opt.diff.quantity_sea_lakes) * 256 + 100);
				for (; i != 0; --i) {
					GenerateTerrain(_opt.diff.terrain_type, 0);
				}
				IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
				break;
		}
	}

	ConvertGroundTilesIntoWaterTiles();

	if (_opt.landscape == LT_TROPIC) CreateDesertOrRainForest();
}

void OnTick_Town();
void OnTick_Trees();
void OnTick_Station();
void OnTick_Industry();

void OnTick_Players();
void OnTick_Train();

void CallLandscapeTick()
{
	OnTick_Town();
	OnTick_Trees();
	OnTick_Station();
	OnTick_Industry();

	OnTick_Players();
	OnTick_Train();
}

TileIndex AdjustTileCoordRandomly(TileIndex a, byte rng)
{
	int rn = rng;
	uint32 r = Random();

	return TILE_MASK(TileXY(
		TileX(a) + (GB(r, 0, 8) * rn * 2 >> 8) - rn,
		TileY(a) + (GB(r, 8, 8) * rn * 2 >> 8) - rn
	));
}

bool IsValidTile(TileIndex tile)
{
	return (tile < MapSizeX() * MapMaxY() && TileX(tile) != MapMaxX());
}