Spherical Harmonics are kinda like Fourier, but on a sphere. That doesn’t mean terribly much to me, and could be wrong, but check out here for more details about how Spherical Harmonics work in this context!
However, the more prctical thing is, SH can be a function that describes a value over the surface of a sphere! This is particularly useful for lighting, since you can basically store the lighting information for a space in this value! This is often used for lightmap data, or a light probe grid, but StereoKit just uses a single SH for the entire scene. It’s a gross oversimplification, but looks quite good, and is really fast! That’s extremely great when you’re trying to hit 60fps, or even 144fps.
|Sample||Look up the color information in a particular direction!|
|FromLights||Creates a SphericalHarmonics approximation of the irradiance given from a set of directional lights!|