So I’m still experimenting with adding PBR to my engine. I came across split sum approximation recently which I think is great and I’d like to consider implementing something similar.
What I’m confused about is the second part of the split sum approximation, IBL specular and the pre-computed BRDF texture which is a 2 channel approximation texture for the specular highlight. In all implementations I’ve seen, two sample the BRDF texture, they use roughness (0-1) and n dot v (normal dot view vector). How does this approximate specular with a view to the position of the …