Writing a vert/frag physically based shader?

Hi everyone! I'm trying to write my own physically based shader and that's because I want to implement some additional effects which won't be possible to achieve using shaderLab language, but the only problem I have is that I just cannot find information on how physically based shaders are constructed and the correct equations and stuff.

You can find how blinn-phong model is constructed pretty much everywhere, but that doesn't look like the case for PBS.

So to all you smart people, I'm gonna need your help on this one!

 

search for Sebastian Laguarde's blog, selfshadow's blog and Filmicworld's blog, you should also find reference from there toward other one

 

Thanks Bro!

 

Why write it yourself from scratch? You can make copies of UnityStandardCore.cginc and UnityStandardInput.cginc from Unity 5\Editor\Data\CGIncludes folder, then download the source for the standard shader, make copy of that and just make it so that it uses your duplicated cgincs instead of original one. Then inside of cgincs you can add whatever functionality you can imagine