Rigify pinning knee elbow

When I’m setting the legs of my rigify rig to IK, I can move the torso bone and the feet will stay in place. But what if I want to pose the character in a kneeing pose. If I now move the torso bone the feet stay in place but the knees are lifting from the ground. If I place an empty to the knee tweak bone and copy the location of the empty to the knee bone, the knees will stay in place. But this way the thighs will stretch.
Is there a better way of pinning the knees or elbows into place?

I just found out that there is a rigify feature set which brings exactly this feature.

https://github.com/angavrilov/angavrilov-rigs

Is there a way to exchange my old rig with the one from the new feature set?
Sadly, I don’t have the meta rig anymore.

Rigify’s meta rig can be re-created from the generated rig. The bones are on the last bone layer and all prefixed with ORG-. You can copy these bones and batch rename them. Then add a new meta rig to the scene and use a script to copy the bone layout from the extracted bone template to the fresh meta rig. Have a look here: How do I convert a rig back into a metarig?

Sorry, but I can’t get it to work. Hope that someone can help me a little further.

I have a character with a rigify rig that I have been working on for a long time now. All I’m trying to achieve is to make it possible to apply an option to have the IK not only on the foot and on the hand, but also on the knee and on the elbows. My first try was to copy the location of the knee tweak to an empty. This works, but results in stretching the thighs. Next try was to “update” my old rigify rig with the new experimental one. But I can’t get it to work. Even with restoring my meta rig, I can’t apply the new features from the experimental one. Maybe there is an easier way to achieve this?

I’m not really a rigger, but I have some experience in “forcing” rigs to do what I want/setting up custom behaviour.

In this case (based on the information given). I would probably have done one of three things.

1 - Either created my own controller/empty (in the scene, not in the rig) that is on the ground where the knee is, and then constrained the hip/cog/torso bone to that. As the distance between the hip and the knee shouldn’t anatomically get longer or shorter, the hips translate should basically pivot/rotate from the knee/new controller.

This can then be built upon, so that you, for example, also constrain the foot to another controller/empty that’s also at the knee so that these also pivot from the knee. In other words, you change the rig to “start” at the knee and move outward.

2 - Another way that could work is to, again, create an empty or something at the knee, then use a “limit distance” constraint on the hip with the empty as the target, and set the clamp region to ‘On surface’. It basically does the same thing as the first example, but this way you still animate the torso bone’s translate instead of rotating the new controller.

How complex any of the setups needs to be depends on the animation (if the character is walking around on their knees or something), the camera angle and so on, but hopefully it provided two basic examples of how to solve it.

3 - Just brute force it without any fancy setup. Yes it probably requires frame-by-frame animation, but it gets the job done :slight_smile:

Also, if you plan on doing lots of animations with the character on their knees/elbows, I’d probably try and solve it the rig way instead to avoid having to set this up each time.

Hope this helps!