General information on shaders for materials.
If you are not very familiar with shader terminology (I’m still newbie myself). This document goes over the language, and for example explains such terms used in shaders as uniform or lowp. A little nicer presentation of similar information can be found here.
More info on shaders in Defold Material manual. What vertex shader attributes that are available are listed there.
This post by @sicher explains how to use render targets for post processing. I’m working on putting together various extra useful shaders and will include an example for how to apply shaders to your entire game screen or parts of it (giving your rendered screen a sepia tone but not applying it to your UI for example), such as for making a CRT like view of your game.
These docs are also useful to study