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/* $Id$ */

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/** @file terraform_cmd.cpp Commands related to terraforming. */

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#include "stdafx.h"

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#include "openttd.h"

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#include "strings_type.h"

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#include "command_func.h"

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#include "tile_map.h"

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#include "tunnel_map.h"

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#include "bridge_map.h"

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#include "variables.h"

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#include "functions.h"

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#include "economy_func.h"

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#include "table/strings.h"

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/*

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 * In one terraforming command all four corners of a initial tile can be raised/lowered (though this is not available to the player).

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 * The maximal amount of height modifications is archieved when raising a complete flat land from sea level to MAX_TILE_HEIGHT or vice versa.

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 * This affects all corners with a manhatten distance smaller than MAX_TILE_HEIGHT to one of the initial 4 corners.

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 * Their maximal amount is computed to 4 * \sum_{i=1}^{h_max} i  =  2 * h_max * (h_max + 1).

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 */

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static const int TERRAFORMER_MODHEIGHT_SIZE = 2 * MAX_TILE_HEIGHT * (MAX_TILE_HEIGHT + 1);

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/*

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 * The maximal amount of affected tiles (i.e. the tiles that incident with one of the corners above, is computed similiar to

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 * 1 + 4 * \sum_{i=1}^{h_max} (i+1)  =  1 + 2 * h_max + (h_max + 3).

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 */

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static const int TERRAFORMER_TILE_TABLE_SIZE = 1 + 2 * MAX_TILE_HEIGHT * (MAX_TILE_HEIGHT + 3);

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struct TerraformerHeightMod {

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	TileIndex tile;   ///< Referenced tile.

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	byte height;      ///< New TileHeight (height of north corner) of the tile.

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};

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struct TerraformerState {

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	int modheight_count;                                         ///< amount of entries in "modheight".

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	int tile_table_count;                                        ///< amount of entries in "tile_table".

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	/**

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	 * Dirty tiles, i.e.\ at least one corner changed.

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	 *

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	 * This array contains the tiles which are or will be marked as dirty.

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	 *

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	 * @ingroup dirty

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	 */

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	TileIndex tile_table[TERRAFORMER_TILE_TABLE_SIZE];

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	TerraformerHeightMod modheight[TERRAFORMER_MODHEIGHT_SIZE];  ///< Height modifications.

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};

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TileIndex _terraform_err_tile;

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/**

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 * Gets the TileHeight (height of north corner) of a tile as of current terraforming progress.

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 *

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 * @param ts TerraformerState.

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 * @param tile Tile.

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 * @return TileHeight.

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 */

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static int TerraformGetHeightOfTile(TerraformerState *ts, TileIndex tile)

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{

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	TerraformerHeightMod *mod = ts->modheight;

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	int count;

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	for (count = ts->modheight_count; count != 0; count--, mod++) {

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		if (mod->tile == tile) return mod->height;

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	}

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	/* TileHeight unchanged so far, read value from map. */

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	return TileHeight(tile);

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}

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/**

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 * Stores the TileHeight (height of north corner) of a tile in a TerraformerState.

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 *

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 * @param ts TerraformerState.

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 * @param tile Tile.

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 * @param height New TileHeight.

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 */

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static void TerraformSetHeightOfTile(TerraformerState *ts, TileIndex tile, int height)

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{

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	/* Find tile in the "modheight" table.

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	 * Note: In a normal user-terraform command the tile will not be found in the "modheight" table.

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	 *       But during house- or industry-construction multiple corners can be terraformed at once. */

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	TerraformerHeightMod *mod = ts->modheight;

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	int count = ts->modheight_count;

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	while ((count > 0) && (mod->tile != tile)) {

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		mod++;

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		count--;

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	}

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	/* New entry? */

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	if (count == 0) {

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		assert(ts->modheight_count < TERRAFORMER_MODHEIGHT_SIZE);

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		ts->modheight_count++;

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	}

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	/* Finally store the new value */

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	mod->tile = tile;

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	mod->height = (byte)height;

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}

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/**

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 * Adds a tile to the "tile_table" in a TerraformerState.

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 *

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 * @param ts TerraformerState.

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 * @param tile Tile.

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 * @ingroup dirty

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 */

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static void TerraformAddDirtyTile(TerraformerState *ts, TileIndex tile)

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{

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	int count;

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	TileIndex *t;

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	count = ts->tile_table_count;

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	for (t = ts->tile_table; count != 0; count--, t++) {

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		if (*t == tile) return;

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	}

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	assert(ts->tile_table_count < TERRAFORMER_TILE_TABLE_SIZE);

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	ts->tile_table[ts->tile_table_count++] = tile;

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}

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/**

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 * Adds all tiles that incident with the north corner of a specific tile to the "tile_table" in a TerraformerState.

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 *

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 * @param ts TerraformerState.

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 * @param tile Tile.

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 * @ingroup dirty

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 */

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static void TerraformAddDirtyTileAround(TerraformerState *ts, TileIndex tile)

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{

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	TerraformAddDirtyTile(ts, tile + TileDiffXY( 0, -1));

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	TerraformAddDirtyTile(ts, tile + TileDiffXY(-1, -1));

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	TerraformAddDirtyTile(ts, tile + TileDiffXY(-1,  0));

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	TerraformAddDirtyTile(ts, tile);

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}

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/**

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 * Terraform the north corner of a tile to a specific height.

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 *

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 * @param ts TerraformerState.

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 * @param tile Tile.

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 * @param height Aimed height.

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 * @param return Error code or cost.

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 */

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static CommandCost TerraformTileHeight(TerraformerState *ts, TileIndex tile, int height)

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{

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	CommandCost total_cost(EXPENSES_CONSTRUCTION);

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	assert(tile < MapSize());

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	/* Check range of destination height */

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	if (height < 0) return_cmd_error(STR_1003_ALREADY_AT_SEA_LEVEL);

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	if (height > MAX_TILE_HEIGHT) return_cmd_error(STR_1004_TOO_HIGH);

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	/*

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	 * Check if the terraforming has any effect.

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	 * This can only be true, if multiple corners of the start-tile are terraformed (i.e. the terraforming is done by towns/industries etc.).

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	 * In this case the terraforming should fail. (Don't know why.)

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	 */

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	if (height == TerraformGetHeightOfTile(ts, tile)) return CMD_ERROR;

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	/* Check "too close to edge of map" */

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	uint x = TileX(tile);

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	uint y = TileY(tile);

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	if ((x <= 1) || (y <= 1) || (x >= MapMaxX() - 1) || (y >= MapMaxY() - 1)) {

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		/*

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		 * Determine a sensible error tile

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		 * Note: If x and y are both zero this will disable the error tile. (Tile 0 cannot be highlighted :( )

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		 */

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		if ((x == 1) && (y != 0)) x = 0;

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		if ((y == 1) && (x != 0)) y = 0;

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		_terraform_err_tile = TileXY(x, y);

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		return_cmd_error(STR_0002_TOO_CLOSE_TO_EDGE_OF_MAP);

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	}

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	/* Mark incident tiles, that are involved in the terraforming */

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	TerraformAddDirtyTileAround(ts, tile);

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	/* Store the height modification */

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	TerraformSetHeightOfTile(ts, tile, height);

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	/* Increment cost */

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	total_cost.AddCost(_price.terraform);

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	/* Recurse to neighboured corners if height difference is larger than 1 */

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	{

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		const TileIndexDiffC *ttm;

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		static const TileIndexDiffC _terraform_tilepos[] = {

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			{ 1,  0}, // move to tile in SE

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			{-2,  0}, // undo last move, and move to tile in NW

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			{ 1,  1}, // undo last move, and move to tile in SW

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			{ 0, -2}  // undo last move, and move to tile in NE

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		};

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		for (ttm = _terraform_tilepos; ttm != endof(_terraform_tilepos); ttm++) {

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			tile += ToTileIndexDiff(*ttm);

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			/* Get TileHeight of neighboured tile as of current terraform progress */

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			int r = TerraformGetHeightOfTile(ts, tile);

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			int height_diff = height - r;

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			/* Is the height difference to the neighboured corner greater than 1? */

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			if (abs(height_diff) > 1) {

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				/* Terraform the neighboured corner. The resulting height difference should be 1. */

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				height_diff += (height_diff < 0 ? 1 : -1);

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				CommandCost cost = TerraformTileHeight(ts, tile, r + height_diff);

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				if (CmdFailed(cost)) return cost;

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				total_cost.AddCost(cost);

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			}

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		}

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	}

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	return total_cost;

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}

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/** Terraform land

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 * @param tile tile to terraform

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 * @param flags for this command type

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 * @param p1 corners to terraform (SLOPE_xxx)

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 * @param p2 direction; eg up (non-zero) or down (zero)

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 * @return error or cost of terraforming

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 */

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CommandCost CmdTerraformLand(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)

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{

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	TerraformerState ts;

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	CommandCost total_cost(EXPENSES_CONSTRUCTION);

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	int direction = (p2 != 0 ? 1 : -1);

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	_terraform_err_tile = 0;

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	ts.modheight_count = ts.tile_table_count = 0;

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	/* Make an extra check for map-bounds cause we add tiles to the originating tile */

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	if (tile + TileDiffXY(1, 1) >= MapSize()) return CMD_ERROR;

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	/* Compute the costs and the terraforming result in a model of the landscape */

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	if ((p1 & SLOPE_W) != 0) {

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		TileIndex t = tile + TileDiffXY(1, 0);

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		CommandCost cost = TerraformTileHeight(&ts, t, TileHeight(t) + direction);

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		if (CmdFailed(cost)) return cost;

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		total_cost.AddCost(cost);

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	}

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	if ((p1 & SLOPE_S) != 0) {

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		TileIndex t = tile + TileDiffXY(1, 1);

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		CommandCost cost = TerraformTileHeight(&ts, t, TileHeight(t) + direction);

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		if (CmdFailed(cost)) return cost;

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		total_cost.AddCost(cost);

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	}

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	if ((p1 & SLOPE_E) != 0) {

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		TileIndex t = tile + TileDiffXY(0, 1);

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		CommandCost cost = TerraformTileHeight(&ts, t, TileHeight(t) + direction);

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		if (CmdFailed(cost)) return cost;

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		total_cost.AddCost(cost);

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	}

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	if ((p1 & SLOPE_N) != 0) {

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		TileIndex t = tile + TileDiffXY(0, 0);

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		CommandCost cost = TerraformTileHeight(&ts, t, TileHeight(t) + direction);

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		if (CmdFailed(cost)) return cost;

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		total_cost.AddCost(cost);

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	}

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	/* Check if the terraforming is valid wrt. tunnels, bridges and objects on the surface */

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	{

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		int count;

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		TileIndex *ti = ts.tile_table;

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		for (count = ts.tile_table_count; count != 0; count--, ti++) {

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			TileIndex tile = *ti;

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			/* Find new heights of tile corners */

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			uint z_N = TerraformGetHeightOfTile(&ts, tile + TileDiffXY(0, 0));

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			uint z_W = TerraformGetHeightOfTile(&ts, tile + TileDiffXY(1, 0));

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			uint z_S = TerraformGetHeightOfTile(&ts, tile + TileDiffXY(1, 1));

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			uint z_E = TerraformGetHeightOfTile(&ts, tile + TileDiffXY(0, 1));

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			/* Find min and max height of tile */

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			uint z_min = min(min(z_N, z_W), min(z_S, z_E));

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			uint z_max = max(max(z_N, z_W), max(z_S, z_E));

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			/* Compute tile slope */

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			uint tileh = (z_max > z_min + 1 ? SLOPE_STEEP : SLOPE_FLAT);

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			if (z_W > z_min) tileh += SLOPE_W;

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			if (z_S > z_min) tileh += SLOPE_S;

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			if (z_E > z_min) tileh += SLOPE_E;

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			if (z_N > z_min) tileh += SLOPE_N;

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			/* Check if bridge would take damage */

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			if (direction == 1 && MayHaveBridgeAbove(tile) && IsBridgeAbove(tile) &&

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					GetBridgeHeight(GetSouthernBridgeEnd(tile)) <= z_max * TILE_HEIGHT) {

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				_terraform_err_tile = tile; // highlight the tile under the bridge

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				return_cmd_error(STR_5007_MUST_DEMOLISH_BRIDGE_FIRST);

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			}

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			/* Check if tunnel would take damage */

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			if (direction == -1 && IsTunnelInWay(tile, z_min * TILE_HEIGHT)) {

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				_terraform_err_tile = tile; // highlight the tile above the tunnel

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				return_cmd_error(STR_1002_EXCAVATION_WOULD_DAMAGE);

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			}

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			/* Check tiletype-specific things, and add extra-cost */

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			CommandCost cost = _tile_type_procs[GetTileType(tile)]->terraform_tile_proc(tile, flags | DC_AUTO, z_min * TILE_HEIGHT, (Slope) tileh);

   309

			if (CmdFailed(cost)) {

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				_terraform_err_tile = tile;

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				return cost;

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			}

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			total_cost.AddCost(cost);

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		}

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	}

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	if (flags & DC_EXEC) {

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		/* change the height */

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		{

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			int count;

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			TerraformerHeightMod *mod;

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			mod = ts.modheight;

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			for (count = ts.modheight_count; count != 0; count--, mod++) {

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				TileIndex til = mod->tile;

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				SetTileHeight(til, mod->height);

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			}

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		}

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		/* finally mark the dirty tiles dirty */

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		{

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			int count;

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			TileIndex *ti = ts.tile_table;

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			for (count = ts.tile_table_count; count != 0; count--, ti++) {

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				MarkTileDirtyByTile(*ti);

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			}

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		}

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	}

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	return total_cost;

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}

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/** Levels a selected (rectangle) area of land

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 * @param tile end tile of area-drag

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 * @param flags for this command type

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 * @param p1 start tile of area drag

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 * @param p2 height difference; eg raise (+1), lower (-1) or level (0)

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 * @return  error or cost of terraforming

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 */

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CommandCost CmdLevelLand(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)

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{

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	int size_x, size_y;

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	int ex;

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	int ey;

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	int sx, sy;

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	uint h, oldh, curh;

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	CommandCost money;

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	CommandCost ret;

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	CommandCost cost(EXPENSES_CONSTRUCTION);

   361

   362

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

   363

   364

	/* remember level height */

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	oldh = TileHeight(p1);

   366

   367

	/* compute new height */

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	h = oldh + p2;

   369

   370

	/* Check range of destination height */

   371

	if (h > MAX_TILE_HEIGHT) return_cmd_error((oldh == 0) ? STR_1003_ALREADY_AT_SEA_LEVEL : STR_1004_TOO_HIGH);

   372

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	/* make sure sx,sy are smaller than ex,ey */

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	ex = TileX(tile);

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	ey = TileY(tile);

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	sx = TileX(p1);

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	sy = TileY(p1);

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	if (ex < sx) Swap(ex, sx);

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	if (ey < sy) Swap(ey, sy);

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	tile = TileXY(sx, sy);

   381

   382

	size_x = ex - sx + 1;

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	size_y = ey - sy + 1;

   384

   385

	money.AddCost(GetAvailableMoneyForCommand());

   386

   387

	BEGIN_TILE_LOOP(tile2, size_x, size_y, tile) {

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		curh = TileHeight(tile2);

   389

		while (curh != h) {

   390

			ret = DoCommand(tile2, SLOPE_N, (curh > h) ? 0 : 1, flags & ~DC_EXEC, CMD_TERRAFORM_LAND);

   391

			if (CmdFailed(ret)) break;

   392

   393

			if (flags & DC_EXEC) {

   394

				money.AddCost(-ret.GetCost());

   395

				if (money.GetCost() < 0) {

   396

					_additional_cash_required = ret.GetCost();

   397

					return cost;

   398

				}

   399

				DoCommand(tile2, SLOPE_N, (curh > h) ? 0 : 1, flags, CMD_TERRAFORM_LAND);

   400

			}

   401

   402

			cost.AddCost(ret);

   403

			curh += (curh > h) ? -1 : 1;

   404

		}

   405

	} END_TILE_LOOP(tile2, size_x, size_y, tile)

   406

   407

	return (cost.GetCost() == 0) ? CMD_ERROR : cost;

   408

}