GLSL Programming/Unity/Diffuse Reflection of Skylight
https://en.wikibooks.org/wiki/GLSL_Programming/Unity/Diffuse_Reflection_of_Skylight

GLSL Programming/Unity/Diffuse Reflection
https://en.wikibooks.org/wiki/GLSL_Programming/Unity/Diffuse_Reflection

PBR Theory
https://learnopengl.com/PBR/Theory

Lighitng
https://learnopengl.com/PBR/Lighting

IBL Diffuse irradiance
https://learnopengl.com/PBR/IBL/Diffuse-irradiance

Specular IBL
https://learnopengl.com/PBR/IBL/Specular-IBL

貴重な資料に感謝。