The Two Bone IK control applies an Inverse Kinematic (IK) solver to a 3-joint chain, such as the limbs of a character.
Below, a series of Two Bone IK controllers are used, along with Hand IK Retargeting to control how the character holds a weapon.
Variables (HandIKWeight) are used to drive the�Joint Target Location�properties on the controller for the�hand_l�and�hand_r�bones of our character. By adjusting the�value�we can determine how the character holds the weapon without having to hand-animate different poses based on different characters.
The AnimGraph node network is shown below which you can copy and paste into your own Animation Blueprint.�
Based on your own setup, you may need to assign different joints and (or) animations.
The example used here can be further explored in the�Animation�map of�the�Content Examples�project�available from the Learn Tab of the Epic Games Launcher.
Two Bone IK Properties
The following properties are available within the�Details�panel for the Two Bone IK node:�
| Property | Description | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| IK | |||||||||
| IK Bone | Name of the bone to apply the IK solver to. This should be the bone at the end of the bone chain, i.e. the ankle or wrist bone. | ||||||||
| Stretch Limits | |||||||||
| X | The ratio of the Max Limb Length, which is used to determine when to scale the bones. | ||||||||
| Y | The maximum allowable amount of scaling of the translation component. | ||||||||
| Allow Stretching | If true, allows the bones to be stretched. | ||||||||
| End Effector | |||||||||
| Effector Space Bone Name | The name of the bone to use as the effector location when Effector Location Space is set to BCS_BoneSpace. | ||||||||
| Take Rotation from Effector Space | If enabled, the Rotation of the effector (component, parent, or bone) is applied to the IK Bone. | ||||||||
| Maintain Effector Rel Rot | This is overridden when Take Rotation from Effector Space is enabled. |
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| Effector Location Space | The reference frame for the Effector Location.
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| Joint Target | |||||||||
| Joint Target Location Space | The reference frame for the Joint Target Location.
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| Joint Target Space Bone Name | The name of the bone to use as the joint target location when Joint Target Location Space is set to BCS_BoneSpace. |
Two Bone IK Pins
The following pins are exposed by default on the�Two Bone IK node:�
| Pin | Description |
|---|---|
| Input Pins | |
| Effector Location | A Vector specifying the location effector in the Effector Location Space. |
| Joint Target Location | A Vector specifying the location joint target in the Joint Target Location Space. |