I’m trying to understand how the IK is set up. The [IK documentation] points to the content example, which I checked out. However, the documentation doesn’t mention where the values for the vectors Joint Target Left and Joint Target Right in the AnimGraph come from. I couldn’t see where they were being set in the actual content example either.
Are they hard coded by setting the defaults? If yes, isn’t this a bad practice and where do the values come from?
They are static values set in the defaults. If you open the Owen_IKAnimBlueprint in the Animation Content Example, you can see that section in the AnimGraph. If you take a look at the IK SkelControls in there, you can see the Joint Target for each is set to bone space and the bone chosen is the Thigh of each leg; so, the variables ‘Joint Target Left’ and ‘Joint Target Right’ that you point out are just offsets from the Thigh bone. As the character animates, the Joint Targets (pole vectors in Maya terminology) maintain that offset distance from the Thigh bone which keeps them in front of the character which, in turn, keeps the knees pointing forward.
Hope that makes sense. If not, or if you have other questions, just yell.
How you set them up will really depend on what you are trying to achieve. If you are just looking for a basic IK setup and you would like for the knees to stay oriented basically the way they are in your animation assets, you would probably opt for a setup similar to the one used in the Animation Content Example (ie, Joint Target set to Bone Space with an offset from the knee or thigh bone).
However, if you are looking for greater control over the knee or elbow angle, you could drive the Joint Target location procedurally with a variable. I’ve never had the need for that level of control, but if you do, it should be straightforward.
Yeah I’m in the same boat here. It would seem like it’s so obvious that it can only be understated, but I’m really at a loss where to go from here? Where do you get the idea to put the static values as you have them currently? By looking at the skeleton and hazarding a guess?