SH irradiance (2)

https://mynameismjp.wordpress.com/2011/01/31/radiosity-dx11-style/

http://jankautz.com/courses/GameCourse/05_EnvMaps.pdf

http://gdcvault.com/play/1015312/Light-Probe-Interpolation-Using-Tetrahedral

https://mynameismjp.wordpress.com/2016/10/09/new-blog-series-lightmap-baking-and-spherical-gaussians/

https://www.gamedev.net/forums/topic/673634-questions-on-baked-gi-spherical-harmonics/

https://github.com/superwills/gtp