@Scottss sadly there’s not a lot of documentation on how to write shaders using PlayCanvas’ shader chunks to take advantage of lighting, shadows, etc.
When I wrote the simple grass you’re trying to use, I was basically doing trial & error, but the starting point was https://developer.playcanvas.com/en/tutorials/custom-shaders/
This thread also helped a lot: Custom vertex attributes in chunk
And finally, @Leonidas put this together as well: http://pirron.one/playingincanvas/texture-masks-using-shader
Which basically walks you through how shaders work and gives you examples.
I still have pending writing a new grass system which is easy to implement & actually performant & with more features than what I had shared around here. Someday i’ll do it when I have some time.