CCD Solver(IK Solver) constraint, directly calls the CCDSolver to bend theto reach the specified target, it can also utilize IK-constraints such as AngleConstraint & ConeConstraint to improve quality;
To find out how to setup IK-constraints to improve the IK solver calculation quality, check the CCDIK part of skeleton animation manual.
Check the preview image below:
Here we explain each options in the CCDSolver editor;
CCDSolver can setup the IK-link in auto-mode by "BoneCount" if all the joints are in a hierarchy formed by transform.parent.
Or user can setup manually the IK-link in manual-mode, this could enable to make up a link without constraint of hierarchy.
In most cases, auto-mode should be able to satisfy the needs.
(Be noted to click "Apply" button after modifying the link)