# tile_map.cpp

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    00001 /* $Id: tile_map.cpp 15299 2009-01-31 20:16:06Z smatz $ */
    00002
    00005 #include "stdafx.h"
    00006 #include "tile_map.h"
    00007 #include "core/math_func.hpp"
    00008 #include "settings_type.h"
    00009
    00015 Slope GetTileSlope(TileIndex tile, uint *h)
    00016 {
    00017   assert(tile < MapSize());
    00018
    00019   if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY() ||
    00020       (_settings_game.construction.freeform_edges && (TileX(tile) == 0 || TileY(tile) == 0))) {
    00021     if (h != NULL) *h = TileHeight(tile) * TILE_HEIGHT;
    00022     return SLOPE_FLAT;
    00023   }
    00024
    00025   uint a = TileHeight(tile); // Height of the N corner
    00026   uint min = a; // Minimal height of all corners examined so far
    00027   uint b = TileHeight(tile + TileDiffXY(1, 0)); // Height of the W corner
    00028   if (min > b) min = b;
    00029   uint c = TileHeight(tile + TileDiffXY(0, 1)); // Height of the E corner
    00030   if (min > c) min = c;
    00031   uint d = TileHeight(tile + TileDiffXY(1, 1)); // Height of the S corner
    00032   if (min > d) min = d;
    00033
    00034   /* Due to the fact that tiles must connect with each other without leaving gaps, the
    00035    * biggest difference in height between any corner and 'min' is between 0, 1, or 2.
    00036    *
    00037    * Also, there is at most 1 corner with height difference of 2.
    00038    */
    00039
    00040   uint r = SLOPE_FLAT; // Computed slope of the tile
    00041
    00042   /* For each corner if not equal to minimum height:
    00043    *  - set the SLOPE_STEEP flag if the difference is 2
    00044    *  - add the corresponding SLOPE_X constant to the computed slope
    00045    */
    00046   if ((a -= min) != 0) r += (--a << 4) + SLOPE_N;
    00047   if ((c -= min) != 0) r += (--c << 4) + SLOPE_E;
    00048   if ((d -= min) != 0) r += (--d << 4) + SLOPE_S;
    00049   if ((b -= min) != 0) r += (--b << 4) + SLOPE_W;
    00050
    00051   if (h != NULL) *h = min * TILE_HEIGHT;
    00052
    00053   return (Slope)r;
    00054 }
    00055
    00060 uint GetTileZ(TileIndex tile)
    00061 {
    00062   if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) return 0;
    00063
    00064   uint h = TileHeight(tile); // N corner
    00065   h = min(h, TileHeight(tile + TileDiffXY(1, 0))); // W corner
    00066   h = min(h, TileHeight(tile + TileDiffXY(0, 1))); // E corner
    00067   h = min(h, TileHeight(tile + TileDiffXY(1, 1))); // S corner
    00068
    00069   return h * TILE_HEIGHT;
    00070 }
    00071
    00076 uint GetTileMaxZ(TileIndex t)
    00077 {
    00078   if (TileX(t) == MapMaxX() || TileY(t) == MapMaxY()) return 0;
    00079
    00080   uint h = TileHeight(t); // N corner
    00081   h = max(h, TileHeight(t + TileDiffXY(1, 0))); // W corner
    00082   h = max(h, TileHeight(t + TileDiffXY(0, 1))); // E corner
    00083   h = max(h, TileHeight(t + TileDiffXY(1, 1))); // S corner
    00084
    00085   return h * TILE_HEIGHT;
    00086 }