OpenTTD-patches/tile.c
celestar b5b348bdce (svn r3992) -Fix: Rewrote the code to determine whether a rail-tile can be terraformed.
Fixes a bug where you could terraform a tunnel (fixed by r3228, but reverted that one)
Fixes a bug introduced by r3228 which allowed steep rail tiles resulting in ... unwanted effects such as display artifacts.
That means the terraform feature should not work as intended; it also uses _valid_tileh_slopes to determine valid configurations instead of hand-brewn stuff.
TODO: _terraform_err_tile and similar TileIndices should have INVALID_TILE as "unused", not 0. (0 is a valid tile).
2006-03-20 16:43:48 +00:00

71 lines
1.3 KiB
C

/* $Id$ */
#include "stdafx.h"
#include "tile.h"
void SetMapExtraBits(TileIndex tile, byte bits)
{
assert(tile < MapSize());
SB(_m[tile].extra, 0, 2, bits & 3);
}
uint GetMapExtraBits(TileIndex tile)
{
assert(tile < MapSize());
return GB(_m[tile].extra, 0, 2);
}
/** Converts the heights of 4 corners into a tileh, and returns the minimum height of the tile
* @param n,w,e,s the four corners
* @param h uint pointer to write the height to
* @return the tileh
*/
uint GetTileh(uint n, uint w, uint e, uint s, uint *h)
{
uint min = n;
uint r;
if (min >= w) min = w;
if (min >= e) min = e;
if (min >= s) min = s;
r = 0;
if ((n -= min) != 0) r += (--n << 4) + 8;
if ((e -= min) != 0) r += (--e << 4) + 4;
if ((s -= min) != 0) r += (--s << 4) + 2;
if ((w -= min) != 0) r += (--w << 4) + 1;
if (h != NULL) *h = min * 8;
return r;
}
uint GetTileSlope(TileIndex tile, uint *h)
{
uint a;
uint b;
uint c;
uint d;
assert(tile < MapSize());
if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) {
if (h != NULL) *h = 0;
return 0;
}
a = TileHeight(tile);
b = TileHeight(tile + TileDiffXY(1, 0));
c = TileHeight(tile + TileDiffXY(0, 1));
d = TileHeight(tile + TileDiffXY(1, 1));
return GetTileh(a, b, c, d, h);
}
uint GetTileZ(TileIndex tile)
{
uint h;
GetTileSlope(tile, &h);
return h;
}