https://gpuopen.com/gdc-presentations/2019/gdc-2019-agtd4-high-zombie-throughput-in-modern-graphics.pdf
HZB
http://www.cs.cmu.edu/afs/cs/academic/class/15869-f11/www/readings/greene93_hierarchicalz.pdf
http://www.cs.tau.ac.il/~dcor/Graphics/adv-slides/short-image-based-culling.pdf
https://www.nickdarnell.com/hierarchical-z-buffer-occlusion-culling/