As has been said before, Blue Nodes are almost entirely standard mathematical operators or things that are familiar to anyone who understands how math turns into graphics, which is a subject largely separate from how Terragen works (though there are some Terragen-specific details which we *should* cover properly, that part I agree with). The basic point is that we literally cannot teach people how to use Function (Blue) Nodes without potentially giving them a thorough grounding in intermediate-to-advanced math and computer graphics shading principles, which seems like a pretty big ask for us to do alongside documenting the things that *are* actually unique and specific to Terragen (e.g. Terragen shaders/nodes like Power Fractal, Fractal Warp, Strata and Outcrops, etc, etc.). In fact there are whole books on this stuff.
So if you are serious about wanting to understand and take advantage of Function Nodes in Terragen (and much more, the info is applicable to a wide range of graphics programs), I would recommend one or all of these books:
https://smile.amazon.com/Math-Primer-Graphics-Game-Development/dp/1568817231/https://smile.amazon.com/Mathematics-Programming-Computer-Graphics-Edition/dp/1435458869/https://smile.amazon.com/Graphics-Shaders-Theory-Practice-Second/dp/1568814348/This is the advice I almost always give when this subject comes up and it remains the same, yet very few people seem to ever go for it. I think they hope there is a shortcut or easy answer, a way that we could somehow just tell them the minimum they need to know in order to build exactly what they want. But that's just not the case. Effective use of Function Nodes - anything beyond simply dissecting an existing node network - fundamentally relies on a reasonable understanding of non-trivial (for many of us) math, and how that works in a computer graphics shading system. So you either learn that through a lot of trial and error, as Ulco has (look up his early posts on the forums, he was no math expert to start with, and as far as I know hasn't read the books I recommended either), or you read the books and get a more thorough grounding in how all this stuff works. If you do that I guarantee you'll be a Function Node Wizard by the end.
I think in the end as Ulco said, part of the problem is the belief - and at times observation - that important and useful things that people want to do actually require Function Nodes to do. Often times there are other ways that don't involve them. Where that is not the case *and* it is something that would be commonly used, that would ideally be a feature we could implement, since it would benefit a lot of less advanced users and we want Terragen to be easier to use. So I think the best approach to these issues would be to ask how to do something *without Function Nodes*, and if there isn't a solution, then to suggest a feature be added. We'll consider it but will have to weigh its value to the overall user base. Obviously getting more people to chime in supporting the idea is helpful.
- Oshyan