Switch FK/IK

Switch FK/IK changes an Arm or Leg limb’s mode while matching its current pose.

Run the switch

Select a controller from a weSkel Arm or Leg module with both FK and IK modes.

In the weSkel_Anim shelf, click the FK / IK Match icon.

From Python

from weSkel.src.tools.animation import switch_fk_ik

switch_fk_ik()  # Switch the selected limb at the current frame.

From the selection

Element	Behavior
Limb	One or more controllers from the same limb and side. Controller shapes are also accepted.
Direction	Determined automatically: FK → IK or IK → FK, according to the active mode.
Exact match	The evaluated pose meets the tolerances: the switch applies immediately.
Approximation	The viewport shows a proposal; a dialog lets you accept or cancel it.

The switch acts at the current frame, without rebuilding the rig. It does not convert an animation range.

Confirm an approximation

Some poses cannot be reproduced exactly in the other mode. weSkel | Approximate FK / IK Match shows the measured differences for the proposal displayed in Maya.

weSkel | Approximate FK / IK Match · Poseidon theme.

Reference	Purpose
1 · Direction	Switch direction, L / R side and Arm / Leg module type.
2 · Priorities	Arm: wrist, then elbow and arm orientations. Leg: foot and toes, then ankle, knee and leg orientations.
3 · Differences	Output identifies the evaluated output; Position (cm), Angle (deg) and Scale / shear give its differences from the initial pose.
4 · Decision	Accept approximation applies the proposal. Cancel, or closing the dialog, restores the original pose without keys or an Undo entry.

Animation and Undo

State or action	Effect
Auto Key OFF	Changes values at the current frame without creating or editing keys.
Auto Key ON · already animated channel	Changed, keyable channels receive a key at the current frame, or update the existing key.
Auto Key ON · channel without a curve	Changes the value without automatically creating its first animation curve.
Undo	Reverts the applied switch in one operation, including its key changes.
Redo	Reapplies the recorded result.

On an animated channel, a value changed without a key may be replaced by the curve value when time is reevaluated. Matching a pose and recording it in the animation are separate operations.

Integrate into a picker

Retain a limb target to invoke the tool independently of Maya selection:

from weSkel.src.tools.animation import resolve_fk_ik_target, switch_fk_ik

# Capture the target from the selected limb.
target = resolve_fk_ik_target().target

# Invoke later from the picker, independently of Maya selection.
result = switch_fk_ik(target)

Element	Purpose
Target	FkIkTarget(instance_id, side): module root UUID and side l or r, resolved on each call.
result.applied	Indicates whether the switch was applied.
result.report.exact	Indicates whether the match meets the tolerances.

Conditions and limits

Situation	Note
Ambiguous selection	An empty selection, components, different limbs or sides, or a shared center controller do not identify one limb.
Playback or disabled Undo	Stop playback and enable Maya Undo before switching.
Protected channels or incompatible connections	The tool rejects affected channels: locks, animation layers, character sets, proxy attributes or connections other than supported direct animation curves.
Animated trajectory	Matching concerns the current pose; it does not guarantee the trajectory, tangents or speed between frames.