void shift(int offX, int offY) {
		System.out.println("Shift to new offset " + offX + ", " + offY + ".");
		Tile[][][] newTiles = new Tile[tiles.length][tiles[0].length][LAYERS];

		int xStart = Math.max(0, -offX);
		int yStart = Math.max(0, -offY);
		int xEnd = Math.min(tiles.length, tiles.length - offX);
		int yEnd = Math.min(tiles[0].length, tiles[0].length - offY);

		for (int x = xStart; x < xEnd; x++) {
			for (int y = yStart; y < yEnd; y++) {
				for (int l = 0; l < LAYERS; l++) {
					newTiles[x + offX][y + offY][l] = tiles[x][y][l];
				}
			}
		}
		tiles = newTiles;
	}