That’s true, especially with Blender, which has a lot of little features hidden inside. And, you may get a lot of good comments in general regarding theory. I guess that I don’t have enough experience for that to have come to my mind.
Hm… those are interesting ideas. The only issue I see is that it would depend greatly upon the structure of a rig, making such a script difficult to implement. Does the rig use IK influence as an IK switch, without using different control chains for FK and IK? How does the rig position the IK pole target? These variables are difficult to account for without at least some scripting.
This is off topic, but there is a flexible roundabout way to do IK-FK snapping in Blender without long scripts. Blender already has an “Apply Visual Transform” function. If you add a “Copy Transformation” constraint to a bone, it will take the same position, scale, and rotation of another bone. When you “Apply Visual Transform” to the constrained bone, the bone will stay in place when the constraint is removed. The only thing that you need is a dummy IK pole target attached to the FK rig so that you can snap the real IK pole target to it. This would allow you to match IK and FK control chains. And, for simple setups where the IK influence turns the IK on-off, simply applying the visual transformation is enough, without messing with constraints. I thought this was off topic, but I guess it bring up the same question. Why are there no tutorials for something like this? It makes me think that I should make some tutorials on this topic.
As long as we stay somewhat on topic, we are probably fine. This topic is fairly vague anyway. But, we can if the original poster requests that we do.
I’m not really attempting to make a case for anything. I’ve never actually used a rig. I began with Humane Rigging and a few other tutorials. Then, I looked over the Mancandy rig. Since then, I have been making simple rigs for other people to use. And, until recently, my computer was too slow to run even a light rig. I have been developing an advanced prototype rig that is only a little lighter than Rigify. Then, I realized that Rigify includes everything that I was putting into my rig. I still don’t know if it will work for me; I’m still figuring that out.
Here is what I am thinking. Most artists seem to just want to get rigging out of the way; they do not want to learn rigging and scripting. And, during training, they animate using “basic” rigs that are actually quite advanced. Perhaps not all training programs are as spoiling as the ones that I have looked at. Squash and stretch, IK-FK switching and snapping, foot roll, and more seem to be considered standard. I have been told that even realistically animated characters benefit a lot from squash and stretch. For those artists, Rigify and BlenRig seem good.
For people who want lighter rigs, like you, Humane Rigging and other available tutorials seem to teach most things. And, where they don’t, they probably teach enough to reverse engineer those features from advanced rigs, like Rigify. If someone wants to completely reverse engineer an advanced rig and make all their own rigs from it for experience, they can. That is partly what I have been doing. But, I can say that the step from Humane Rigging to reverse engineering is steep. And, some decent tutorials would have saved me a lot of time and headaches. There is a pricey course that applies everything from Humane Rigging to fully rig a character. And, it also includes UI buttons for the armature layers. But, this rig is still a long ways from Mancandy or Rigify. CG Cookie also has a course on setting up UI buttons as well.
https://cgcookie.com/course/scripting-a-custom-rig-ui-add-on
I am trying to think of rigging topics that tutorials would have helped me with. The depsgraph limitation has been a thorn in my side since my first rig, so that would have been nice to have been taught about before hearing that the animator was having issues. But, that will change in Blender 2.8. There was a Blender 2.5 tutorial on foot controls that used action constraints. That was very interesting, and I am surprised that I never see action constraints used. I learned mechanism-based foot rolls eventually, but I don’t remember if it was from a tutorial, reverse engineering, or my own design. There seems to be plenty of tutorials on foot rolls available now, though. There are tutorials on squash and stretch like on Rigify.
I still have not found any IK-FK snapping tutorials. I have been intrigued by eyelids that move when the eyes move, but I have not found any tutorial on it. I have looked over such rigs for a few minutes without the implementation being obvious. I can imagine how it could be done with parents on the controllers, but that would be a nightmare to setup. I have not seen many good driver tutorials, but this is likely due to the depsgraph limitations making their usefulness sparse for rigging bones.
What are some rigging tutorials that you think are lacking?