Function TileAddWrap

src/map.cpp:120–132

* This function checks if we add addx/addy to tile, if we * do wrap around the edges. For example, tile = (10,2) and * addx = +3 and addy = -4. This function will now return * INVALID_TILE, because the y is wrapped. This is needed in * for example, farmland. When the tile is not wrapped, * the result will be tile + TileDiffXY(addx, addy) * * @param tile the 'starting' point of the adding *

 * @return translated tile, or INVALID_TILE when it would've wrapped.
 */
TileIndex TileAddWrap(TileIndex tile, int addx, int addy)
{
	uint x = TileX(tile) + addx;
	uint y = TileY(tile) + addy;

	/* Disallow void tiles at the north border. */
	if ((x == 0 || y == 0) && _settings_game.construction.freeform_edges) return INVALID_TILE;

	/* Are we about to wrap? */
	if (x >= Map::MaxX() || y >= Map::MaxY()) return INVALID_TILE;

	return TileXY(x, y);
}

/** 'Lookup table' for tile offsets given an Axis */
extern const TileIndexDiffC _tileoffs_by_axis[] = {