tanks教程：正交相机size控制

疑问：

private float FindRequiredSize()
    {
        Vector3 desiredLocalPos = transform.InverseTransformPoint(m_DesiredPosition);

        float size = 0f;

        for (int i = 0; i < m_Targets.Length; i++)
        {
            if (!m_Targets[i].gameObject.activeSelf)
                continue;

            Vector3 targetLocalPos = transform.InverseTransformPoint(m_Targets[i].position);

            Vector3 desiredPosToTarget = targetLocalPos - desiredLocalPos;
　　　　　　　　

　　　　　　　//这里为啥计算y，而不是z？y不是垂直于地面的吗？z和x才是平面的，很不理解，需要后续？

            size = Mathf.Max (size, Mathf.Abs (desiredPosToTarget.y));

            size = Mathf.Max (size, Mathf.Abs (desiredPosToTarget.x) / m_Camera.aspect);
        }
        
        size += m_ScreenEdgeBuffer;

        size = Mathf.Max(size, m_MinSize);

        return size;
    }