Tutorials / Documentation:

"Makin' Stuff Look Good" youtube channel : https://www.youtube.com/channel

ALan Zucconi website : http://www.alanzucconi.com/

CatLikeCoding website : http://catlikecoding.com/

ALastair AiTchison Website : https://alastaira.wordpress.com/

Book of shaders website : https://thebookofshaders.com/

Learning modern 3d graphics programming :  https://paroj.github.io/gltut/

Cg programming : https://en.wikibooks.org/wiki/Cg_Programming/Unity

Unity shaders reference : https://docs.unity3d.com/Manual/SL-Reference.html

Inigo Quilez articles : http://www.iquilezles.org/www/index.htm

UnityGem : https://unitygem.wordpress.com/shader-part-1/

 

Ressources :

Keijiro Takahashi GitHub : https://github.com/keijiro

 

Tools :

To learn GLSL shaders basics : https://github.com/stackgl/shader-school

ShaderToy website : https://www.shadertoy.com/

GLSL Sandbox Gallery : http://glslsandbox.com/

ShaderFrog : http://shaderfrog.com/app

PixelShaders : http://pixelshaders.com

 

Forum / Threads :

SHADERS.XYZ website : http://www.shaders.xyz/

Subreddit "shaders" : https://www.reddit.com/r/shaders/