A custom node for Unity's ShaderGraph to capture lighting and use it into the shader. Works as of July 2018, but the APIs might change!

MainLightNode.cs

//This API to create new nodes has been deprecated in early 2019.
//This means that if you are on a more recent version of Shader Graph and Universal Render Pipeline, you should use instead a pre-made node, which acts like a container that allows you to inject custom HLSL code into Shader Graph without the need to create a node from scratch.
//Please use the new node, not the C# API described here.
//
//You can find more details about that node in the Docs: https://docs.unity3d.com/Packages/com.unity.shadergraph@6.7/manual/Custom-Function-Node.html
//I also blogged about it here: https://connect.unity.com/p/adding-your-own-hlsl-code-to-shader-graph-the-custom-function-node
//
//If you are still on a very old version of Lightweight Render Pipeline (you shouldn't!!), you can still see the C# code for this custom node by rolling back to a previous version.

EDIT:: NO

(maybe not)
importing both lwrp and hdrp made the errors go away BUT im not sure how the shader will handle it

I can't understand. I recreated the whole graph (and custom nodes), used the latest custom node from @baukeJansen, and nothing works. The problem came from the very start from the normal blend node.

No errors, no warnings, most of the previews are broken (except fresnel, of course). I've tested it with both 5.13 and 5.16 LWRP+SG, no difference.

@earthtojens First off, looking for an answer to your problem I accidently ran into this page which is honestly more hidden that it should be: Custom node documentation (may come in handy).
Secondly, I'm assuming you didn't put 'Light' in the name field of the custom function as this would give a similar error.

Just make this a little clearer, if you call your function "Main Light" you'll get this error, where as "MainLight" is perfectly fine. I guess space in the custom function name is not allowed.

Hey everyone, as I reported in the gist itself, the API described here is really obsolete now. Please refer to this blog post for the explanation: https://connect.unity.com/p/adding-your-own-hlsl-code-to-shader-graph-the-custom-function-node

As such, I hid the code. You shouldn't use it if you're in a recent version of Universal Render Pipeline. Please use the Custom Function Node instead: https://docs.unity3d.com/Packages/com.unity.shadergraph@6.7/manual/Custom-Function-Node.html