GT-VBAO: Ground Truth Visibility Bitmask Ambient Occlusion:
shadertoy.com/view/XXGSDd
1. image: GT-VBAO (left) vs. Reference (right).
2. image: the same as the 1., but converged.
GT-VBAO matches the results of a brute force ray-marcher. This work was partially funded by
@1000orks.