Some code that I have seen from example HLSL and GLSL code samples is the LightDirection or** light vector variables**. From my understanding, the engine does not support light vectors.
How do I experiment these codes when I don’t have access to light information ?
You can fake the presence of a light by using your own light vector and outputting the result directly to emissive. That is essentially what you’re restricted to with the material editor, but you can always go deeper…
Edit: Actually, deferred decal materials can use the light vector. I should look that up.