[Youtube video][1]
[1]: UE Basic IK pole target ignored for straightened chains - YouTube
Hi. Am I missing something? I noticed it working on my own rig, so I checked the rig Epic provides and I an see the same behavior (video linked). As soon as the IK chain stretches fully, bones rotations reset, no longer pointing at pole target. This means I can’t rotate for example straightened arm around it’s axis, also it causes sudden jumps in rotation when pole target is far from default pointing direction.
Edit: Ok, I’m not clear what’s my question, so: Is there some workaround for it, or an easy solution that I’m missing?
Someone on reddit suggested it happens when the target gets past the reach on IK chain, but no, it happens right when it reaches 100% stretch, there’s a way to test it (when effector item and effector transform is the same objects instead of hand and hand_ctrl like here). If Epic wants Control Rig to be a serious alternative to animating in Blender or Maya, it can’t work like this (unless it works fine and I just don’t know how to use it, in which case please enlighten me).
[EDITED] Ok, so I found a workaround that seems to mostly fix it. There needs to be an AIM constraint executed right before before BASIC IK. In case of arm IK this AIM constraint would affect upper arm bone and it would use two targets in opposite order to IK constraint. In my case it’s aiming at pole target at -1 Z axis and then at hand as secondary target with -1 Y axis. This AIM constraint does what IK pole target does, but without IK, so it ignores the issue of straightened arm. It still acts weirdly with some weird pole target positions.