arcsynthesis tutorial

Hi all, I’ve just started using a tutorial at a site called arcsynthesis to learn a bit about openGL. So far it’s been going good, there are a few parts I’m iffy on but the tutorial reassures that you should keep reading to get a better grasp of things and not sweat the small stuff just yet. However I’m a tad bit confused now as to how to go about doing one of his follow up problems.
He suggests that you:
Combine the FragPosition tutorial with the Vertex Color tutorial. Use interpolated color from the vertex shader and multiply that with the value computed based on the screen-space position of the fragment.

As I don’t really understand what the end result of doing this is supposed to be, I’m having trouble determining how to go about doing this.
I can’t link, but if you type arcsynthesis into google it’ll pop right up.

Any help is appreciated, this is one of those situations where I can’t tell if I should go back and re-read the chapter, or if I shouldn’t sweat it and move on. Currently it’s bugging me too much to move on from though :frowning: