Approximates single-bounce ambient occlusion to multi-bounce ambient occlusion https://blog.selfshadow.com/publications/s2016-shading-course/activision/s2016_pbs_activision_occlusion.pdf#page=78
Approximates single-bounce ambient occlusion to multi-bounce ambient occlusion https://blog.selfshadow.com/publications/s2016-shading-course/activision/s2016_pbs_activision_occlusion.pdf#page=78