A method of occlusion culling of graphic objects, comprising the steps of storing a first mask and one or more depth values associated with areas inside and outside the mask for a pre-defined region, and evaluating the visibility of the primitive covering the same region, wherein visibility evaluation begins after the computation of the coverage mask of the primitive in the region, and the computation of one or more depth values representing the pixels of the primitive. The method of the present invention is a real-time method of generating per-region coverage mask and associated Z values after the second primitive is rendered in the same region, which can maximize the bandwidth savings for Z read for both overlapping and non-overlapping primitives, with different relations between their depth values.