My question is about spherical harmonic lightning, in the context of computing the coefficients with an expensive GI algorithm and passing them to the vertex shader
Another way is to just use an expensive GI algorithm to compute vertex colors and just use them instead.
What is the advantage of using the former method? I'm thinking that you can't do reflections with the latter method, and also there's rotational symmetry in SH (i don't know much about) that allows you to do some very simple dynamics with your lights and meshes. Is there any more points i'm missing?