/* $Id$ */ /* * 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/>. */ /** @file tile_map.cpp Global tile accessors. */ #include "stdafx.h" #include "tile_map.h" #include "core/math_func.hpp" /** * Return the slope of a given tile * @param tile Tile to compute slope of * @param h If not \c NULL, pointer to storage of z height * @return Slope of the tile, except for the HALFTILE part */ Slope GetTileSlope(TileIndex tile, uint *h) { assert(tile < MapSize()); if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY() || (_settings_game.construction.freeform_edges && (TileX(tile) == 0 || TileY(tile) == 0))) { if (h != NULL) *h = TileHeight(tile) * TILE_HEIGHT; return SLOPE_FLAT; } uint a = TileHeight(tile); // Height of the N corner uint min = a; // Minimal height of all corners examined so far uint b = TileHeight(tile + TileDiffXY(1, 0)); // Height of the W corner if (min > b) min = b; uint c = TileHeight(tile + TileDiffXY(0, 1)); // Height of the E corner if (min > c) min = c; uint d = TileHeight(tile + TileDiffXY(1, 1)); // Height of the S corner if (min > d) min = d; /* Due to the fact that tiles must connect with each other without leaving gaps, the * biggest difference in height between any corner and 'min' is between 0, 1, or 2. * * Also, there is at most 1 corner with height difference of 2. */ uint r = SLOPE_FLAT; // Computed slope of the tile /* For each corner if not equal to minimum height: * - set the SLOPE_STEEP flag if the difference is 2 * - add the corresponding SLOPE_X constant to the computed slope */ if ((a -= min) != 0) r += (--a << 4) + SLOPE_N; if ((c -= min) != 0) r += (--c << 4) + SLOPE_E; if ((d -= min) != 0) r += (--d << 4) + SLOPE_S; if ((b -= min) != 0) r += (--b << 4) + SLOPE_W; if (h != NULL) *h = min * TILE_HEIGHT; return (Slope)r; } /** * Get bottom height of the tile * @param tile Tile to compute height of * @return Minimum height of the tile */ uint GetTileZ(TileIndex tile) { if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) return 0; uint h = TileHeight(tile); // N corner h = min(h, TileHeight(tile + TileDiffXY(1, 0))); // W corner h = min(h, TileHeight(tile + TileDiffXY(0, 1))); // E corner h = min(h, TileHeight(tile + TileDiffXY(1, 1))); // S corner return h * TILE_HEIGHT; } /** * Get top height of the tile * @param t Tile to compute height of * @return Maximum height of the tile */ uint GetTileMaxZ(TileIndex t) { if (TileX(t) == MapMaxX() || TileY(t) == MapMaxY()) return 0; uint h = TileHeight(t); // N corner h = max(h, TileHeight(t + TileDiffXY(1, 0))); // W corner h = max(h, TileHeight(t + TileDiffXY(0, 1))); // E corner h = max(h, TileHeight(t + TileDiffXY(1, 1))); // S corner return h * TILE_HEIGHT; }