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