public void SetSubTileBasicCollision(int index, int x, int y, bool val) { byte b = tilesetHeaderGroup.GetCollisionsData(index); byte i = (byte)(1 << (3 - (x + y * 2))); b = (byte)(b & ~i); if (val) { b |= i; } tilesetHeaderGroup.SetCollisionsData(index, b); }