As far as rig requirements, IK2.0 should generally work on a wide variety of rigs. It doesn’t require you to be a pro rigger, however there were some ways of operating that people got used to from mods that aren’t the same because IK2.0 is not the same as those mods.
If you’d like things to just work simply I’d recommend following these steps without skipping any.
- Set your User Real Height to your actual height.
- Set the Avatar Measurement toggle to measure by height.
- Use the lock-hip mode. This mode is the main one that prioritizes appealing pose results. If view position matching is more important for you, use lock-head mode. Avoid lock-all mode (more details at bottom)
- Try toggling off locomotion animations (in the Tracking and IK quickmenu settings). This will prevent the default crouch and prone animations from affecting your IK.
- If you feel that you need to adjust the knee bend direction, use a custom IKPose in your avatar setup.
If you have a specific issue that’s not solved by following all of the above steps, please leave some feedback on the IK2.0 Canny board here. It’s still being updated and feedback provided there will be taken into consideration.
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Lengthy explanation about lock-all follows:
Currently lock-all is the only part of IK2.0 that’s reserved for rigging enthusiasts and is provided “as-is” mostly in response to user request for an option to simultaneously match both ends of the spine. Because of this, it strictly follows multiple constraints at the cost of permitting odd pose results. Real human spines have more vertebrae with more leeway to stretch and compress than the bones in an avatar rig. Also, you have the freedom to set how far forward your view position is in your avatar descriptor (changing how you drag around the avatar head bone pivot as you move your real head). With these factors combined, when you look down, the distance between your avatar’s hip and head will likely contract. However, the hip and head tracking are both locked in with this IK option. The IK will solve the spine while honoring this length shortening by finding a way to bend the spine so that both ends still match their tracking points. Odd poses may result. Conceptually this is like trying to squeeze both ends of a twig an arbitrary amount but also not wanting it to bend too much. Lock-all allows it to bend too much, lock-hip or lock-head allows the unlocked end to slide out a bit to prevent severe bending.
An interim technique to introduce a bit of leeway into lock-all behavior is to look down slightly (while not using legacy calibration) when you bind in. This will sink the avatar relative to your lower body tracking binding points, binding them slightly higher up. When you look straight after binding, your lower body trackers will be pulling the spine tight and when you shorten your spine by looking down again it will be using the calibration you bound when looking down previously, possibly avoiding odd spine angles. This is just a workaround though and future development on lock-all (possibly introducing dynamic bone length compression) is still planned.