I have a (somewhat) working IK script for Godot 3 that I'm making for the FPS tutorial.
You can see it in action here and here, though now it's farther along than either of those videos.
While I currently am not releasing the code, I will release it when either the FPS tutorial is finished, or when I have the IK plugin finished (either it will get its own tutorial, or maybe I'll just release it to the demo repository). Right now it needs some more polish and refining before I release it to the world :smiley:
However, this does not help you short term nor does it answer the question. I'll explain how my IK system works so you can make your own system (or you can wait until I release it :wink: ):
To make a look-at IK solver, you just need to get the bone want to rotate from the skeleton. It's important to use get_bone_global_pose(bone_name) (I think that is what it's called) to get the global transform. Transform has a look-at method and you then pass in the target's global_transform.origin to it. I think the function is called look_at(position) but I could be wrong. You can find the function in the documentation for Transform. Using the look-at IK solver you can make a system that handles IK chains (like a leg).
I'm using my own method to make an IK chain. I used this github repo as a reference for my IK chain, so maybe it will help you too?
Hopefully that gives you a leg up (pun intended?) on how to make your foot IK system.
