Function solveFABRIK

solveFABRIK(
    chain: IKChain,
    target: Vector3,
    options?: IKSolveOptions,
    out?: Vector3[],
): IKSolveResult
Writes chain's world positions into out and solves FABRIK (Forward And Backward Reaching Inverse Kinematics) so the tip reaches target.

Each iteration pulls the tip onto the target and walks back to the root at the recorded bone lengths, then pins the root and walks forward again. Limits are applied on the forward pass, after each child is placed. An unreachable target leaves converged: false and the last iterate — the chain points at the target, stretched as far as the lengths allow.

Allocation-free when out is provided (see solveCCD). The solver does not retain nodes. No RNG.
Parameters
- chain: IKChain
  World positions or nodes; length >= 2. Not modified.
- target: Vector3
  World position the tip should reach. Not modified.
- Optionaloptions: IKSolveOptions
  Tolerance, iteration budget, optional per-joint limits.
- Optionalout: Vector3[]
  Positions to write; allocated when omitted.
Returns IKSolveResult

Throws
RangeError when the chain is shorter than two, out is too short, a length/option is not finite, or a limit has min > max.
- Defined in packages/motion/dist/ik.d.ts:267