扫描线Zbuffer算法 1。算出模型的包围盒。 2．每条扫描线打点时并不是包围盒内整条线打点，而是先搜索需要刷新的范围， 只是该范围内打点。 -One scan line Zbuffer algorithm. Calculate the model bounding box. 2. Each scan line runs inside the box when not surrounded by the entire line runs, but first need to ref