Hey all. I’m using the Cookie Flex Rig for an 11 Second Club animation, using Blender 2.81, and I have two character variations made for the scene. However, when I link them in from their respective libraries and make the proxy rig, I run into a problem. See, in the original files, the IK legs work just fine at a -90 degree pole angle, but when the rig becomes a proxy after being linked, the IK leg folds backward instead of forward. I cannot for the life of me figure out why this is happening, where in the pipeline this is going wrong, and how I can fix it. As far as I know, I’ve not seen anything about this topic anywhere online, so I thought I’d suck it up and finally put out my cry for help here. Thanks in advance.
Hey Blenderguy15,
I know the flex rig isn't really optimized for Blender 2.8x and I'm not sure if it will be. But I can give you my theory on what is going on and how I fixed it.
The IK solver in the leg needs a clue in what direction it wants to bend. Usually when in edit mode of the armature you would want to put a slight bend in the knee in order to provide that clue.
Nathan Vegdahl was one of the creators of this rig. He also has a rigging course on Blender Cloud and YouTube called "Humane Rigging". There he teaches a technique where you could keep that IK chain straight, then put a slight bend in the mechanism bone in pose mode and that would provide the clue to the IK solver in what direction to bend the knee. It worked in 2.5 up to 2.7x. For whatever reason I don't think that technique is working in 2.8. I could be wrong, I haven't ruled out everything but its what seems to stand out the most to me.
To solve it, tab into edit mode on the armature and turn on all the bone layers to unhide all the bones. Then take the heads/tails of all the bones at the knee and move them forward to introduce a slight bend. There are 2 bones that lay on top of the thigh bone and 2 bones that lay on top of the shin bone that will be misaligned slightly. You can move them forward as well to stay in line with the thigh and shin bone. Now when you link the rig to another scene the knees will bend the correct direction toward the pole targets. I hope this helps you, feel free to ask questions if you get lost.
Happy animating (rigging)!
Oh my god, you're a lifesaver! Thank you so much! This worked like a charm for me! It is sad to see this fantastic rig not be optimized, as it is such a useful tool for animation in Blender. I was about to go download an older version just to get this working correctly.