unsigned int itemTopA = a.height + a.z; unsigned int itemTopB = b.height + b.z;  if (itemTopA == itemTopB) { if (a.height == 0 && a.walkable) { return true; }  if (b.height == 0 && b.walkable) { return true; } }
	bool operator()( stBlockItem a, stBlockItem b )	{		return ( ( a.height + a.z ) > ( b.height + b.z ) );	}