Patricio Gonzalez Vivo's The Book of Shaders is one of the best resources out there to learn how to code GLSL shaders. I use it extensively to create ISF shaders in VDMX.

With the intention of eventually porting my Saturday Shaders project over to Houdini Vex I've started to go through the The Book of Shaders examples in order to learn how.

While Houdini does support GLSL code to render shaders into the viewport, I have not implemented this yet. For now these examples are only visible in the render view using the Ray Tracing render engine.

###Chapters completed so far Chapter 3 - Uniforms

While uniforms like gl_FragCoord aren't really applicable to Vex Shaders, this chapter was handy in figuring out how to get the u_time paramater to work in Vex as well as getting UVs to work (which I'm guessing is pretty much what gl_FragCoord.xy is).