public bool Collides(GameObject obj)
 {
     return obj != null && obj.X == X && obj.Y == Y;
 }
 bool InViewport(GameObject x)
 {
     return (x.X * blockSize).Between(currentX - blockSize, currentX + width + blockSize)
         && (x.Y * blockSize).Between(currentY, currentY + height + blockSize);
 }