# tile_map.cpp

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    00001 /* $Id$ */
    00002
    00003 /*
    00004  * This file is part of OpenTTD.
    00005  * 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.
    00006  * 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.
    00007  * 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/>.
    00008  */
    00009
    00012 #include "stdafx.h"
    00013 #include "tile_map.h"
    00014
    00021 Slope GetTileSlope(TileIndex tile, int *h)
    00022 {
    00023   assert(tile < MapSize());
    00024
    00025   uint x = TileX(tile);
    00026   uint y = TileY(tile);
    00027
    00028   if (x == MapMaxX() || y == MapMaxY() ||
    00029       ((x == 0 || y == 0) && _settings_game.construction.freeform_edges)) {
    00030     if (h != NULL) *h = TileHeight(tile);
    00031     return SLOPE_FLAT;
    00032   }
    00033
    00034   int a = TileHeight(tile); // Height of the N corner
    00035   int min = a; // Minimal height of all corners examined so far
    00036   int b = TileHeight(tile + TileDiffXY(1, 0)); // Height of the W corner
    00037   if (min > b) min = b;
    00038   int c = TileHeight(tile + TileDiffXY(0, 1)); // Height of the E corner
    00039   if (min > c) min = c;
    00040   int d = TileHeight(tile + TileDiffXY(1, 1)); // Height of the S corner
    00041   if (min > d) min = d;
    00042
    00043   /* Due to the fact that tiles must connect with each other without leaving gaps, the
    00044    * biggest difference in height between any corner and 'min' is between 0, 1, or 2.
    00045    *
    00046    * Also, there is at most 1 corner with height difference of 2.
    00047    */
    00048
    00049   uint r = SLOPE_FLAT; // Computed slope of the tile
    00050
    00051   /* For each corner if not equal to minimum height:
    00052    *  - set the SLOPE_STEEP flag if the difference is 2
    00053    *  - add the corresponding SLOPE_X constant to the computed slope
    00054    */
    00055   if ((a -= min) != 0) r += (--a << 4) + SLOPE_N;
    00056   if ((c -= min) != 0) r += (--c << 4) + SLOPE_E;
    00057   if ((d -= min) != 0) r += (--d << 4) + SLOPE_S;
    00058   if ((b -= min) != 0) r += (--b << 4) + SLOPE_W;
    00059
    00060   if (h != NULL) *h = min;
    00061
    00062   return (Slope)r;
    00063 }
    00064
    00070 int GetTileZ(TileIndex tile)
    00071 {
    00072   if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) return 0;
    00073
    00074   int h = TileHeight(tile); // N corner
    00075   h = min(h, TileHeight(tile + TileDiffXY(1, 0))); // W corner
    00076   h = min(h, TileHeight(tile + TileDiffXY(0, 1))); // E corner
    00077   h = min(h, TileHeight(tile + TileDiffXY(1, 1))); // S corner
    00078
    00079   return h;
    00080 }
    00081
    00087 int GetTileMaxZ(TileIndex t)
    00088 {
    00089   if (TileX(t) == MapMaxX() || TileY(t) == MapMaxY()) return 0;
    00090
    00091   int h = TileHeight(t); // N corner
    00092   h = max<int>(h, TileHeight(t + TileDiffXY(1, 0))); // W corner
    00093   h = max<int>(h, TileHeight(t + TileDiffXY(0, 1))); // E corner
    00094   h = max<int>(h, TileHeight(t + TileDiffXY(1, 1))); // S corner
    00095
    00096   return h;
    00097 }