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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 |
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IK |
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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. |
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Stretch Limits |
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X |
The ratio of the Max Limb Length, which is used to determine when to scale the bones. |
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Y |
The maximum allowable amount of scaling of the translation component. |
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Allow Stretching |
If true, allows the bones to be stretched. |
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End Effector |
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Effector Space Bone Name |
The name of the bone to use as the effector location when Effector Location Space is set to BCS_BoneSpace. |
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Take Rotation from Effector Space |
If enabled, the Rotation of the effector (component, parent, or bone) is applied to the IK Bone. |
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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 |
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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. |
The following pins are exposed by default on the�Two Bone IK node:�
Pin |
Description |
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Input Pins |
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Effector Location |
A Vector specifying the location effector in the Effector Location Space. |
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Joint Target Location |
A Vector specifying the location joint target in the Joint Target Location Space. |