IK-FK Switch & Snap

When animating a character, you need to choose to either use IK or FK. But sometimes you might find yourself needing to use both. In this guide, you'll learn how to switch from IK to FK and vice versa (for more, check the IK-FK Switch & Snap Demo file on the Samples & Demo Files page).

IK-FK Switch & Snap Demo file on the Samples & Demo Files page

In this example, let's imagine that you want to switch your Arm control from IK to FK on frame 30 and switch again from FK to IK on frame 60.

Copy Global Transform Add-on

Before we start, you need to enable the Copy Global Transform add-on in the Preferences -> Add-on settings.

Enable the Copy Global Transform add-on

Once you've done that, you can access the Global Transform panel, in the Sidebar -> Animation.

Global Transform panel on the side panel

The Copy Global Transform add-on makes it possible to copy the world-space transform of the active object/bone and paste it onto any object/bone.

IK to FK Switch

• First, enable both Limb FK and Limb Extras layers. You can enable it either by using the Rig UI or manually in the armature layers (marked with a red square).

Enable Limb FK and Limb Extras layer on the Rig UI or Armature layers

• Go to frame 29 and keyframe the IK bones (IK Control, IK Pole if you use them, and Wrist IK if you use them) and the IK-FK settings on the Rig UI or PROP bones.

Keyframe the IK bones and the IK-FK settings on the Rig UI or PROP bones

• Before the switch, make sure to keyframe the FK bones (Upper FK, Lower FK, and Wrist FK if you use the wrist control on the IK) on frame 29.

Keyframe the FK bones before the switch

• Go forward one frame to frame 30, select the Upper IK, click copy on the Global Transform panel, select the Upper FK, and then click paste on the Global Transform panel. Do the same thing on the Lower IK and Lower FK. And if you use the wrist control, do the same on Wrist IK and Wrist FK.

Copy the IK bones Global Transform and paste it to the FK bones

• After that, keyframe the Upper FK, Lower FK, and Wrist FK (If you use the wrist control on IK) on frame 30. And to finish it off, change the IK-FK settings to FK and keyframe it on frame 30. If you play the animation, the controls should change from IK to FK.

Keyframe the FK bones, switch IK-FK setting to FK and then keyframe it

FK to IK Switch

• First, enable both Limb IK and Limb Extras layers. You can enable it either by using the Rig UI or manually in the armature layers (marked with a red square).

Enable Limb IK and Limb Extras layer on the Rig UI or Armature layers

• Go to frame 59 and keyframe the FK bones (Upper FK, Lower FK, and Wrist FK if you use them) and the IK-FK settings on the Rig UI or PROP bones.

Keyframe the FK bones and the IK-FK settings on the Rig UI or PROP bones

• Before the switch, make sure to keyframe the IK bones (IK Control, IK Pole if you use them, and Wrist IK if you use the wrist control on FK) on frame 59.

Keyframe the IK bones before the switch

• Go forward one frame to frame 60, select the IK Control Target, click copy on the Global Transform panel, select the IK Control, and then click paste on the Global Transform panel. Do the same thing on the IK Pole Target and IK Pole. And if you use the wrist control, do the same on Wrist FK and Wrist IK.

Copy the FK bones Global Transform and paste it to the IK bones

• After that, keyframe the IK Control, IK Pole, and Wrist IK (If you use the wrist control on the FK) on frame 60. And to finish it off, change the IK-FK settings to FK and keyframe it on frame 60. If you play the animation, the controls should change from IK to FK.

Keyframe the IK bones, switch IK-FK setting to FK and then keyframe it