an introduction to shader art coding
Walks you rapidly through creating a 2d shader toy, introducing each step along the way.
Points a bunch at https://iquilezles.org, which looks like a really useful resource for this.
- palettes among many other useful functions
- graphtoy is a very cool way to visualize GLSL functions over time
Also points at this gradient tool from Karsten Schmidt, author of the very impressive but intimidating thingumbrella library of libraries