IKChain

Solves an arbitrary bone chain so its tip reaches a target. It names bones directly instead of resolving canonical humanoid roles, so it works on any rig at all — a crane boom, a robot arm, a tentacle, a lamp, a humanoid limb.

crane.component.add("IKChain", {
    rootBone = "boom_base",
    tipBone = "boom_tip",
    target = hookRef,
    solver = "ccd",
})

Fields

• rootBone, tipBone — the chain's ends, named as the rig names them. The tip must be a descendant of the root; the bones between come from the rig's own parent links. Use ik.bones to see what the rig actually calls things.
• target — an EntityRef. Bones are strings, targets are refs.
• solver — "ccd", "fabrik", or "twoBone". CCD holds joint limits well on short runs; FABRIK converges faster on long floppy ones.
• weight — blends against the incoming animation. 0 is an exact pass-through and skips the solve entirely.
• iterations, tolerance — the iterative solvers' budget and stopping error.

Checking it

crane.component.get("IKChain"):chainState()
-- { ready, status, boneCount, reach, distanceToTarget, solver, weight, error }

status says in words what it is doing when ready is false — usually a body whose rig has not arrived yet, which clears on its own unless the engine is paused. distanceToTarget is the residual after solving, not the distance to compare against reach; for that, use ik.reach.