Well, I don’t know C++ myself, but there are plenty of people here who can help me with that. However, where would you get the parameter value from? You still have to grab the value and then apply it as a change. Correct me if I’m wrong, but I don’t really see much of a difference in there.
The way I currently approach it is to calculate the distance between the ground hitpoint and the current ik bone location where the Z height is equal to the root bone. Then I take this vector length and inverse transform it with the IK bone’s space. I then take this value as the effector location on the two bone ik node which is set to bone space.
So the height difference is added on top of the current animation.